Fix awslambda progressbar.update() error

Fixes #759

.coveragerc

@@ -1,25 +0,0 @@
-[paths]
-source =
-	src
-	*/site-packages
-
-[run]
-branch = true
-parallel = true
-concurrency =
-	thread
-	multiprocessing
-source =
-	src/ocrmypdf
-omit =
-	tests/spoof/*
-
-[report]
-exclude_lines =
-	pragma: no cover
-	def __repr__
-	raise AssertionError
-	raise NotImplementedError
-	if 0:
-	if False:
-	if __name__ == .__main__.:

.docker/Dockerfile

@@ -1,6 +1,6 @@
 # OCRmyPDF
 #
-FROM ubuntu:19.10 as base
+FROM ubuntu:20.04 as base
 
 FROM base as builder
 
@@ -10,8 +10,10 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   build-essential autoconf automake libtool \
   libleptonica-dev \
   zlib1g-dev \
-  python3 \
+  python3-dev \
   python3-distutils \
+  libffi-dev \
+  libqpdf-dev \
   ca-certificates \
   curl \
   git
@@ -24,7 +26,7 @@ RUN \
 # Needs libleptonica-dev, zlib1g-dev
 RUN \
   mkdir jbig2 \
-  && curl -L https://github.com/agl/jbig2enc/archive/0.29.tar.gz | \
+  && curl -L https://github.com/agl/jbig2enc/archive/ea6a40a.tar.gz | \
   tar xz -C jbig2 --strip-components=1 \
   && cd jbig2 \
   && ./autogen.sh && ./configure && make && make install \
@@ -62,7 +64,8 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   tesseract-ocr-fra \
   tesseract-ocr-por \
   tesseract-ocr-spa \
-  unpaper
+  unpaper \
+  && rm -rf /var/lib/apt/lists/*
 
 WORKDIR /app
 

.dockerignore

@@ -1,25 +1,44 @@
+# dotfiles
+.*
+!.coveragerc
+!.dockerignore
+!.git_archival.txt
+!.gitattributes
+!.gitignore
+!.pre-commit-config.yaml
+!.readthedocs.yml
+
+# Dev scratch
 *.ipynb
-*.pdf
-*.pyc
-*.rst
-*.sublime*
 **/*.pyc
-.*/
-!.git/
-.ruffus_history.sqlite
-bin/
-build/
-docs/
-dist/
-htmlcov/
-include/
-lib/
-MANIFEST.in
-ocrmypdf.egg-info/
-staging/
-tests/cache/
-tests/output/
+/*.pdf
+/*.qdf
+/*.png
+/scratch.py
+IDEAS
+log/
 tests/resources/private/
 tmp/
 venv*/
+/debug_tests.py
+*.traineddata
+/private
+
+# Package building
+*.egg-info/
+build/
+dist/
 wheelhouse/
+pip-wheel-metadata/
+
+# Code coverage
+htmlcov/
+
+# Docker specific
+bin/
+docs/
+include/
+lib/
+
+# Docker include .git/
+!.git/

.github/ISSUE_TEMPLATE/1-general-issues.md

@@ -0,0 +1,32 @@
+---
+name: General issues
+about: Installation, packages, dependencies, "nothing works", test suite failures...
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+**Describe the bug**
+What's the problem?
+
+**To Reproduce**
+Steps to reproduce the behavior.
+
+**Expected behavior**
+What did you expected to happen?
+
+**Screenshots**
+If applicable, add screenshots to help explain your problem.
+
+**System (please complete the following information):**
+ - OS:
+ - Python version:
+ - OCRmyPDF version:
+
+**Installation**
+How did you install OCRmyPDF? Did you install it from your operating system's
+package manager, or using pip?
+
+**Additional context**
+Add any other context about the problem here.

.github/ISSUE_TEMPLATE/2-problem-with-a-specific-input-file.md

@@ -0,0 +1,40 @@
+---
+name: Problem with a specific input file
+about: Something went wrong while trying to OCR a specific file
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+**Describe the bug**
+A clear and concise description of what the bug is.
+
+**To Reproduce**
+What command line or API call were you trying to run?
+
+```bash
+ocrmypdf  ...arguments... input.pdf output.pdf
+```
+
+Run with verbosity or higher `-v1` to see more detailed logging. This information may be helpful.
+
+**Example file**
+If your issue is a problem that affects only certain files, and we will require an input file (PDF or image) that demonstrates your issue.
+
+Please provide an input file with no personal or confidential information. At your option you may [GPG-encrypt the file](https://github.com/jbarlow83/OCRmyPDF/wiki) for OCRmyPDF's author only.
+
+Links to files hosted elsewhere are perfectly acceptable. You could also look in ``tests/resources`` and see if any of those files reproduce your issue.
+
+*(Issues without example files usually cannot be resolved. It's like reporting an issue against a web browser without providing a URL.)*
+
+**Expected behavior**
+A clear and concise description of what you expected to happen.
+
+**Screenshots**
+If applicable, add screenshots to help explain your problem.
+
+**System**
+ - OS: [e.g. Linux, Windows, macOS]
+ - OCRmyPDF Version: ``ocrmypdf --version``
+ - How did you install ocrmypdf? Did you use a system package manager, `pip`, or a Docker image?

.github/ISSUE_TEMPLATE/3-feature_request.md

@@ -0,0 +1,20 @@
+---
+name: Feature request
+about: Suggest an idea for this project
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+**Is your feature request related to a problem? Please describe.**
+A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]
+
+**Describe the solution you'd like**
+A clear and concise description of what you want to happen.
+
+**Describe alternatives you've considered**
+A clear and concise description of any alternative solutions or features you've considered.
+
+**Additional context**
+Add any other context or screenshots about the feature request here.

.github/issue_template.md

@@ -1,33 +0,0 @@
-**Describe the issue**
-A clear and concise description of what the issue is.
-
-**To Reproduce**
-What command line were you trying to run?
-
-```bash
-ocrmypdf  ...arguments... input.pdf output.pdf
-```
-
-**Example file**
-Please include an example *input* PDF (or image). The input file is more helpful.
-
-Please check any or all that apply about the test file:
-
-- [ ] This is the input file
-- [ ] The file contains no personal or confidential information
-- [ ] I am the copyright holder for this file
-- [ ] I permit this file to be included in the OCRmyPDF test suite under the CC-BY-SA 4.0 license
-- [ ] I am not the copyright holder, but this file is available under a free software license
-
-Files that are not free for inclusion in this project are quite welcome, but we like to collect free files for our test suite when possible. Please do *not* submit files with confidential information. At your option you may encrypt files for OCRmyPDF's author only.
-
-**Expected behavior**
-A clear and concise description of what you expected to happen. Include screenshots if applicable.
-
-**System:**
-
-- OS: [e.g. Linux, macOS]
-- OCRmyPDF Version: [e.g. v7.4.0]
-
-**Additional context**
-Add any other context about the problem here.

.github/workflows/build.yml

@@ -0,0 +1,275 @@
+name: Test and deploy
+
+on:
+  push:
+    branches:
+      - master
+      - ci
+      - release/*
+    tags:
+      - v*
+    paths-ignore:
+      - README*
+  pull_request:
+
+jobs:
+  test_linux:
+    name: Test ${{ matrix.os }} with Python ${{ matrix.python }}
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-18.04] #, ubuntu-20.04]
+        python: ["3.6"] #, "3.7", "3.8", "3.9"]
+
+    env:
+      OS: ${{ matrix.os }}
+      PYTHON: ${{ matrix.python }}
+
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: "0" # 0=all, needed for setuptools-scm to resolve version tags
+
+      - uses: actions/setup-python@v2
+        name: Install Python
+        with:
+          python-version: ${{ matrix.python }}
+
+      - name: Install common packages
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y --no-install-recommends \
+            curl \
+            ghostscript \
+            img2pdf \
+            libffi-dev \
+            liblept5 \
+            libsm6 libxext6 libxrender-dev \
+            pngquant \
+            poppler-utils \
+            tesseract-ocr \
+            tesseract-ocr-deu \
+            tesseract-ocr-eng \
+            unpaper \
+            zlib1g
+
+      - name: Install Ubuntu 18.04 packages
+        if: matrix.os == 'ubuntu-18.04'
+        run: |
+          sudo apt-get install -y --no-install-recommends \
+            libexempi3
+
+      - name: Install Ubuntu 20.04 packages
+        if: matrix.os == 'ubuntu-20.04'
+        run: |
+          sudo apt-get install -y --no-install-recommends \
+            libexempi8
+
+      - name: Install Python packages
+        run: |
+          python -m pip install -r requirements/main.txt -r requirements/test.txt .
+
+      - name: Report versions
+        run: |
+          tesseract --version
+          gs --version
+          pngquant --version
+          unpaper --version
+          img2pdf --version
+
+      - name: Test
+        run: |
+          python -m pytest --cov-report xml --cov=ocrmypdf --cov=tests/ -n0 tests/
+
+      - name: Upload coverage to Codecov
+        uses: codecov/codecov-action@v1
+        with:
+          files: ./coverage.xml
+          env_vars: OS,PYTHON
+
+  test_macos:
+    name: Test macOS
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [macos-latest]
+        python: ["3.9"]
+
+    env:
+      OS: ${{ matrix.os }}
+      PYTHON: ${{ matrix.python }}
+
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: "0" # 0=all, needed for setuptools-scm to resolve version tags
+
+      - uses: actions/setup-python@v2
+        name: Install Python
+        with:
+          python-version: ${{ matrix.python }}
+
+      - name: Install Homebrew deps
+        run: |
+          brew update
+          brew install \
+            exempi \
+            ghostscript \
+            jbig2enc \
+            leptonica \
+            openjpeg \
+            pngquant \
+            tesseract
+
+      - name: Install Python packages
+        run: |
+          python -m pip install --upgrade pip
+          python -m pip install -r requirements/main.txt -r requirements/test.txt .
+
+      - name: Report versions
+        run: |
+          tesseract --version
+          gs --version
+          pngquant --version
+          img2pdf --version
+
+      - name: Test
+        run: |
+          python -m pytest --cov-report xml --cov=ocrmypdf --cov=tests/ -n0 tests/
+
+      - name: Upload coverage to Codecov
+        uses: codecov/codecov-action@v1
+        with:
+          files: ./coverage.xml
+          env_vars: OS,PYTHON
+
+  test_windows:
+    name: Test Windows
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [windows-latest]
+        python: ["3.9"]
+
+    env:
+      OS: ${{ matrix.os }}
+      PYTHON: ${{ matrix.python }}
+
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: "0" # 0=all, needed for setuptools-scm to resolve version tags
+
+      - uses: actions/setup-python@v2
+        name: Install Python
+        with:
+          python-version: ${{ matrix.python }}
+
+      - name: Install system packages
+        run: |
+          choco install --yes --no-progress --pre tesseract
+          choco install --yes --no-progress ghostscript
+          choco install --yes --no-progress pngquant
+
+      - name: Install Python packages
+        run: |
+          python -m pip install --upgrade pip
+          python -m pip install -r requirements/main.txt -r requirements/test.txt .
+
+      - name: Test
+        run: |
+          python -m pytest --cov-report xml --cov=ocrmypdf --cov=tests/ -n0 tests/
+
+      - name: Upload coverage to Codecov
+        uses: codecov/codecov-action@v1
+        with:
+          files: ./coverage.xml
+          env_vars: OS,PYTHON
+
+  wheel_sdist_linux:
+    name: Build sdist and wheels
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: "0" # 0=all, needed for setuptools-scm to resolve version tags
+
+      - uses: actions/setup-python@v2
+        name: Install Python
+        with:
+          python-version: "3.6"
+
+      - name: Make wheels and sdist
+        run: |
+          python -m pip install --upgrade pip wheel
+          python setup.py sdist
+          python setup.py bdist_wheel
+
+      - uses: actions/upload-artifact@v2
+        with:
+          path: |
+            ./dist/*.whl
+            ./dist/*.tar.gz
+
+  upload_pypi:
+    name: Deploy artifacts to PyPI
+    needs: [wheel_sdist_linux, test_linux, test_macos, test_windows]
+    runs-on: ubuntu-latest
+    if: github.event_name == 'push' && startsWith(github.event.ref, 'refs/tags/v')
+    steps:
+      - uses: actions/download-artifact@v2
+        with:
+          name: artifact
+          path: dist
+
+      - uses: pypa/gh-action-pypi-publish@master
+        with:
+          user: __token__
+          password: ${{ secrets.TOKEN_PYPI }}
+          # repository_url: https://test.pypi.org/legacy/
+
+  docker:
+    name: Build Docker images
+    needs: [wheel_sdist_linux, test_linux, test_macos, test_windows]
+    runs-on: ubuntu-latest
+    steps:
+      - name: Set image tag to release or branch
+        run: echo "DOCKER_IMAGE_TAG=${GITHUB_REF##*/}" >> $GITHUB_ENV
+
+      - name: If master, set to latest
+        run: echo 'DOCKER_IMAGE_TAG=latest' >> $GITHUB_ENV
+        if: env.DOCKER_IMAGE_TAG == 'master'
+
+      - name: Set Docker Hub repository to username
+        run: echo "DOCKER_REPOSITORY=jbarlow83" >> $GITHUB_ENV
+
+      - name: Set image name
+        run: echo "DOCKER_IMAGE_NAME=ocrmypdf" >> $GITHUB_ENV
+
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: "0" # 0=all, needed for setuptools-scm to resolve version tags
+
+      - name: Login to Docker Hub
+        uses: docker/login-action@v1
+        with:
+          username: jbarlow83
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v1
+
+      - name: Set up Docker Buildx
+        id: buildx
+        uses: docker/setup-buildx-action@v1
+
+      - name: Print image tag
+        run: echo "Building image ${DOCKER_REPOSITORY}/${DOCKER_IMAGE_NAME}:${DOCKER_IMAGE_TAG}"
+
+      - name: Build
+        run: |
+          docker buildx build \
+            --push \
+            --platform linux/arm64/v8,linux/amd64  \
+            --tag "${DOCKER_REPOSITORY}/${DOCKER_IMAGE_NAME}:${DOCKER_IMAGE_TAG}" \
+            --file .docker/Dockerfile .

.gitignore

@@ -1,47 +1,44 @@
-# Development environment
-.bash_history
-.pylintrc
-.pytest_cache/
-.ruffus_history.sqlite
-.venv*/
-*.pyc
-*.sublime-*
-*.DS_Store
-.mypy_cache/
+# dotfiles
+.*
+!.coveragerc
+!.dockerignore
+!.git_archival.txt
+!.gitattributes
+!.gitignore
+!.pre-commit-config.yaml
+!.readthedocs.yml
+!.github/
+
+# Dev scratch
+*.ipynb
+**/*.pyc
+/*.pdf
+/*.qdf
+/*.png
+/scratch.py
+IDEAS
+log/
+tests/resources/private/
+tmp/
+venv*/
+/debug_tests.py
+*.traineddata
+/private
+/coverage.xml
 
 # Package building
-.eggs/
 *.egg-info/
 build/
 dist/
 wheelhouse/
 pip-wheel-metadata/
 
+# Code coverage
+htmlcov/
+
 # Automatically generated files
 docs/_build/
 docs/_static/
 docs/_templates/
 docs/Makefile
 ocrmypdf/lib/_*.py
-
-# Code coverage
-.coverage*
-htmlcov/
-
-# Testing
-.ipynb_checkpoints/
-.vscode/
-*.ipynb
-*.profile
-/*.pdf
-/*.qdf
-/*.png
-/scratch.py
-IDEAS
-log/
-tests/output/
-tests/resources/private/
-tmp/
-/debug_tests.py
-*.traineddata
-/private

.pre-commit-config.yaml

@@ -1,6 +1,6 @@
 repos:
   - repo: https://github.com/pre-commit/pre-commit-hooks
-    rev: v2.4.0
+    rev: v3.4.0
     hooks:
       - id: check-case-conflict
       - id: check-merge-conflict
@@ -8,16 +8,16 @@ repos:
       - id: check-yaml
       - id: debug-statements
   - repo: https://github.com/asottile/seed-isort-config
-    rev: v1.9.3
+    rev: v2.2.0
     hooks:
       - id: seed-isort-config
   - repo: https://github.com/pre-commit/mirrors-isort
-    rev: v4.3.21 # pick the isort version you'd like to use from https://github.com/pre-commit/mirrors-isort/releases
+    rev: v5.7.0 # pick the isort version you'd like to use from https://github.com/pre-commit/mirrors-isort/releases
     hooks:
       - id: isort
   - repo: https://github.com/psf/black
-    rev: stable
+    rev: 20.8b1
     hooks:
       - id: black
-        language_version: python3.7
+        language_version: python
         exclude: ^src/ocrmypdf/lib/_leptonica.py

README.md

@@ -1,17 +1,12 @@
 <img src="docs/images/logo.svg" width="240" alt="OCRmyPDF">
 
-[![Build Status][azure]](https://dev.azure.com/jim0585/ocrmypdf/_build/latest?definitionId=2&branchName=master) [![PyPI version][pypi]](https://pypi.org/project/ocrmypdf/) ![Homebrew version][homebrew] ![ReadTheDocs][docs] ![Python versions][pyversions]
+[![Build Status](https://github.com/jbarlow83/OCRmyPDF/actions/workflows/build.yml/badge.svg)](https://github.com/jbarlow83/OCRmyPDF/actions/workflows/build.yml) [![PyPI version][pypi]](https://pypi.org/project/ocrmypdf/) ![Homebrew version][homebrew] ![ReadTheDocs][docs] ![Python versions][pyversions]
 
 [azure]: https://dev.azure.com/jim0585/ocrmypdf/_apis/build/status/jbarlow83.OCRmyPDF?branchName=master
-
 [travis]: https://travis-ci.org/jbarlow83/OCRmyPDF.svg?branch=master "Travis build status"
-
 [pypi]: https://img.shields.io/pypi/v/ocrmypdf.svg "PyPI version"
-
 [homebrew]: https://img.shields.io/homebrew/v/ocrmypdf.svg "Homebrew version"
-
 [docs]: https://readthedocs.org/projects/ocrmypdf/badge/?version=latest "RTD"
-
 [pyversions]: https://img.shields.io/pypi/pyversions/ocrmypdf "Supported Python versions"
 
 OCRmyPDF adds an OCR text layer to scanned PDF files, allowing them to be searched or copy-pasted.
@@ -30,8 +25,7 @@ ocrmypdf                      # it's a scriptable command line program
 
 [See the release notes for details on the latest changes](https://ocrmypdf.readthedocs.io/en/latest/release_notes.html).
 
-Main features
--------------
+## Main features
 
 - Generates a searchable [PDF/A](https://en.wikipedia.org/?title=PDF/A) file from a regular PDF
 - Places OCR text accurately below the image to ease copy / paste
@@ -47,8 +41,7 @@ Main features
 
 For details: please consult the [documentation](https://ocrmypdf.readthedocs.io/en/latest/).
 
-Motivation
-----------
+## Motivation
 
 I searched the web for a free command line tool to OCR PDF files: I found many, but none of them were really satisfying:
 
@@ -62,33 +55,23 @@ I searched the web for a free command line tool to OCR PDF files: I found many,
 
 ...so I decided to develop my own tool.
 
-Installation
-------------
+## Installation
 
 Linux, Windows, macOS and FreeBSD are supported. Docker images are also available.
 
-Users of Debian 9 or later or Ubuntu 16.10 or later may simply
-
-```bash
-apt-get install ocrmypdf
-```
-
-and users of Fedora 29 or later may simply
-
-```bash
-dnf install ocrmypdf
-```
-
-and Homebrew users (macOS, Linux, Windows Subsystem for Linux) may simply
-
-```bash
-brew install ocrmypdf
-```
+| Operating system              | Install command               |
+| ----------------------------- | ------------------------------|
+| Debian, Ubuntu                | ``apt install ocrmypdf``      |
+| Windows Subsystem for Linux   | ``apt install ocrmypdf``      |
+| Fedora                        | ``dnf install ocrmypdf``      |
+| macOS                         | ``brew install ocrmypdf``     |
+| LinuxBrew                     | ``brew install ocrmypdf``     |
+| FreeBSD                       | ``pkg install py37-ocrmypdf`` |
+| Conda                         | ``conda install ocrmypdf``    |
 
 For everyone else, [see our documentation](https://ocrmypdf.readthedocs.io/en/latest/installation.html) for installation steps.
 
-Languages
----------
+## Languages
 
 OCRmyPDF uses Tesseract for OCR, and relies on its language packs. For Linux users, you can often find packages that provide language packs:
 
@@ -101,12 +84,14 @@ apt-get install tesseract-ocr-chi-sim  # Example: Install Chinese Simplified lan
 
 # Arch Linux users
 pacman -S tesseract-data-eng tesseract-data-deu # Example: Install the English and German language packs
+
+# brew macOS users
+brew install tesseract-lang
 ```
 
 You can then pass the `-l LANG` argument to OCRmyPDF to give a hint as to what languages it should search for. Multiple languages can be requested.
 
-Documentation and support
--------------------------
+## Documentation and support
 
 Once OCRmyPDF is installed, the built-in help which explains the command syntax and options can be accessed via:
 
@@ -118,35 +103,35 @@ Our [documentation is served on Read the Docs](https://ocrmypdf.readthedocs.io/e
 
 Please report issues on our [GitHub issues](https://github.com/jbarlow83/OCRmyPDF/issues) page, and follow the issue template for quick response.
 
-Requirements
-------------
+## Requirements
 
 In addition to the required Python version (3.6+), OCRmyPDF requires external program installations of Ghostscript, Tesseract OCR, QPDF, and Leptonica. OCRmyPDF is pure Python, but uses CFFI to portably generate library bindings. OCRmyPDF works on pretty much everything: Linux, macOS, Windows and FreeBSD.
 
-Press & Media
--------------
+## Press & Media
 
 - [Going paperless with OCRmyPDF](https://medium.com/@ikirichenko/going-paperless-with-ocrmypdf-e2f36143f46a)
 - [Converting a scanned document into a compressed searchable PDF with redactions](https://medium.com/@treyharris/converting-a-scanned-document-into-a-compressed-searchable-pdf-with-redactions-63f61c34fe4c)
 - [c't 1-2014, page 59](https://heise.de/-2279695): Detailed presentation of OCRmyPDF v1.0 in the leading German IT magazine c't
 - [heise Open Source, 09/2014: Texterkennung mit OCRmyPDF](https://heise.de/-2356670)
 - [heise Durchsuchbare PDF-Dokumente mit OCRmyPDF erstellen](https://www.heise.de/ratgeber/Durchsuchbare-PDF-Dokumente-mit-OCRmyPDF-erstellen-4607592.html)
+- [Excellent Utilities: OCRmyPDF](https://www.linuxlinks.com/excellent-utilities-ocrmypdf-add-ocr-text-layer-scanned-pdfs/)
 
-Business enquiries
-------------------
+## Business enquiries
 
 OCRmyPDF would not be the software that it is today without companies and users choosing to provide support for feature development and consulting enquiries. We are happy to discuss all enquiries, whether for extending the existing feature set, or integrating OCRmyPDF into a larger system.
 
-License
--------
+## License
 
-The OCRmyPDF software is licensed under the GNU GPLv3. Certain files are covered by other licenses, as noted in their source files.
+The OCRmyPDF software is licensed under the Mozilla Public License 2.0
+(MPL-2.0). This license permits integration of OCRmyPDF with other code,
+included commercial and closed source, but asks you to publish source-level
+modifications you make to OCRmyPDF.
 
-The license for each test file varies, and is noted in tests/resources/README.rst. The documentation is licensed under Creative Commons Attribution-ShareAlike 4.0 (CC-BY-SA 4.0).
+Some components of OCRmyPDF have other licenses, as noted in those files and the
+``debian/copyright`` file. Most files in ``misc/`` use the MIT license, and the
+documentation and test files are generally licensed under Creative Commons
+ShareAlike 4.0 (CC-BY-SA 4.0).
 
-OCRmyPDF versions prior to 6.0 were distributed under the MIT License.
-
-Disclaimer
-----------
+## Disclaimer
 
 The software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

azure-pipelines.yml

@@ -1,251 +0,0 @@
-trigger:
-  tags:
-    include:
-      - v*
-  branches:
-    include:
-      - "*"
-    exclude:
-      - "travis"
-
-stages:
-  - stage: "Test"
-    jobs:
-      - job: Windows
-        pool:
-          vmImage: "vs2017-win2016"
-        strategy:
-          matrix:
-            Python36:
-              python.version: "3.6"
-            Python37:
-              python.version: "3.7"
-            Python38:
-              python.version: "3.8"
-        steps:
-          - task: UsePythonVersion@0
-            inputs:
-              versionSpec: "$(python.version)"
-          - pwsh: |
-              choco install --yes --no-progress --pre tesseract
-              choco install --yes --no-progress python3
-              choco install --yes --no-progress ghostscript
-              choco install --yes --no-progress pngquant
-            displayName: "Install system packages"
-          - pwsh: |
-              refreshenv
-              python -m pip install --upgrade pip wheel
-              python -m pip install -r requirements/main.txt -r requirements/test.txt .
-            displayName: "Install Python packages"
-          - pwsh: |
-              refreshenv
-              $env:pathext += ';.py'
-              # -n auto helps Windows
-              python -m pytest -n auto --junitxml=test.xml --cov=ocrmypdf --cov-report=xml
-            displayName: "Test"
-          - task: PublishTestResults@2
-            inputs:
-              testResultsFiles: "test.xml"
-              testRunTitle: "$(Agent.OS) - $(Build.DefinitionName) - Python $(python.version)"
-            condition: succeededOrFailed()
-      - job: "Ubuntu_1804"
-        pool:
-          vmImage: "ubuntu-18.04"
-        strategy:
-          matrix:
-            Python36:
-              python.version: "3.6"
-            Python37:
-              python.version: "3.7"
-            Python38:
-              python.version: "3.8"
-        steps:
-          - task: UsePythonVersion@0
-            inputs:
-              versionSpec: "$(python.version)"
-          - bash: |
-              sudo apt-get update
-              sudo apt-get install -y --no-install-recommends \
-                python3-software-properties \
-                curl \
-                ghostscript \
-                img2pdf \
-                libexempi3 \
-                libffi-dev \
-                liblept5 \
-                libsm6 libxext6 libxrender-dev \
-                pngquant \
-                poppler-utils \
-                tesseract-ocr \
-                tesseract-ocr-deu \
-                tesseract-ocr-eng \
-                unpaper \
-                zlib1g
-            displayName: "Install system packages"
-          - bash: |
-              curl https://bootstrap.pypa.io/get-pip.py | python3
-              pip3 install -r requirements/main.txt -r requirements/test.txt .
-            displayName: "Install Python packages"
-          - bash: |
-              tesseract --version
-            displayName: "Record versions"
-          - bash: |
-              # -n auto is slower on Linux and breaks on Python 3.8
-              pytest -n0 --junitxml=test.xml --cov=ocrmypdf --cov-report=xml
-            displayName: "Test"
-          - task: PublishTestResults@2
-            inputs:
-              testResultsFiles: "test.xml"
-              testRunTitle: "$(Agent.OS) - $(Build.DefinitionName) - Python $(python.version)"
-            condition: succeededOrFailed()
-      - job: "Ubuntu_1604"
-        pool:
-          vmImage: "ubuntu-16.04"
-        strategy:
-          matrix:
-            Python36:
-              python.version: "3.6"
-        steps:
-          - task: UsePythonVersion@0
-            inputs:
-              versionSpec: "$(python.version)"
-          - bash: |
-              sudo apt-get update
-              sudo apt-get install -y --no-install-recommends \
-                software-properties-common
-              sudo add-apt-repository -y ppa:alex-p/tesseract-ocr
-              sudo apt-get update
-              sudo apt-get install -y --no-install-recommends \
-                ghostscript \
-                img2pdf \
-                libexempi3 \
-                libffi-dev \
-                liblept5 \
-                libsm6 libxext6 libxrender-dev \
-                pngquant \
-                poppler-utils \
-                tesseract-ocr \
-                tesseract-ocr-deu \
-                tesseract-ocr-eng \
-                unpaper \
-                zlib1g
-            displayName: "Install system packages"
-          - bash: |
-              curl https://bootstrap.pypa.io/get-pip.py | python3
-              pip3 install -r requirements/main.txt -r requirements/test.txt .
-            displayName: "Install Python packages"
-          - bash: |
-              tesseract --version
-            displayName: "Record versions"
-          - bash: |
-              # -n auto is slower on Linux and breaks on Python 3.8
-              pytest -n0 --junitxml=test.xml --cov=ocrmypdf --cov-report=xml
-            displayName: "Test"
-          - task: PublishTestResults@2
-            inputs:
-              testResultsFiles: "test.xml"
-              testRunTitle: "$(Agent.OS) - $(Build.DefinitionName) - Python $(python.version)"
-            condition: succeededOrFailed()
-      - job: "macOS_Mojave"
-        pool:
-          vmImage: "macos-10.14"
-        strategy:
-          matrix:
-            Python37:
-              python.version: "3.7"
-            Python38:
-              python.version: "3.8"
-        steps:
-          - task: UsePythonVersion@0
-            inputs:
-              versionSpec: "$(python.version)"
-          - bash: |
-              brew update
-              brew unlink python@2
-              brew install \
-                exempi \
-                ghostscript \
-                jbig2enc \
-                leptonica \
-                openjpeg \
-                pngquant \
-                tesseract \
-                unpaper
-            displayName: "Install system packages"
-          - bash: |
-              pip3 install --upgrade pip
-              pip3 install -r requirements/main.txt -r requirements/test.txt .
-            displayName: "Install Python packages"
-          - bash: |
-              tesseract --version
-            displayName: "Record versions"
-          - bash: pytest -nauto --junitxml=test.xml --cov=ocrmypdf --cov-report=xml
-            displayName: "Test"
-          - task: PublishTestResults@2
-            inputs:
-              testResultsFiles: "test.xml"
-              testRunTitle: "$(Agent.OS) - $(Build.DefinitionName) - Python $(python.version)"
-            condition: succeededOrFailed()
-          - task: PublishCodeCoverageResults@1
-            inputs:
-              codeCoverageTool: Cobertura
-              summaryFileLocation: "$(System.DefaultWorkingDirectory)/**/coverage.xml"
-
-  - stage: "Artifacts"
-    jobs:
-      - job: "sdist_wheel"
-        pool:
-          vmImage: "ubuntu-18.04"
-        steps:
-          - task: UsePythonVersion@0
-            inputs:
-              versionSpec: "3.7"
-          - bash: |
-              python -m pip install --upgrade pip wheel
-              python setup.py sdist bdist_wheel
-          - publish: dist
-            artifact: sdist_wheel
-
-  - stage: "Deploy"
-    jobs:
-      - deployment: "PyPI"
-        pool:
-          vmImage: "ubuntu-18.04"
-        environment: "deploy"
-        strategy:
-          runOnce:
-            deploy:
-              steps:
-                - download: current
-                  artifact: sdist_wheel
-                - script: |
-                    mkdir -p dist
-                    mv $(Pipeline.Workspace)/sdist_wheel/* dist
-                  displayName: "Move dist files"
-                - task: UsePythonVersion@0
-                  inputs:
-                    versionSpec: "3.8"
-                    architecture: x64
-                - script: |
-                    pip install --upgrade twine
-                  displayName: "Generate artifacts"
-                - script: |
-                    cat <<FILE >.pypirc
-                    [distutils]
-                    index-servers =
-                        pypi
-
-                    [pypi]
-                    username: __token__
-                    password: $(TOKEN_PYPI)
-
-                    FILE
-                  displayName: "Generate PyPI auth file"
-                - script: |
-                    python -m twine upload --config-file .pypirc dist/*
-                  displayName: "Upload to PyPI"
-                  condition: and(succeeded(), startsWith(variables['Build.SourceBranch'], 'refs/tags/'))
-                - script: |
-                    curl -X POST -d "token=$(TOKEN_RTD)" https://readthedocs.org/api/v2/webhook/pikepdf/39557/
-                  displayName: "Trigger ReadTheDocs"
-                  condition: and(succeeded(), or(startsWith(variables['Build.SourceBranch'], 'refs/tags/'), startsWith(variables['Build.SourceBranch'], 'refs/heads/master')))

debian/copyright

@@ -2,35 +2,70 @@ Format: https://www.debian.org/doc/packaging-manuals/copyright-format/1.0/
 Upstream-Name: OCRmyPDF
 Upstream-Contact: James R. Barlow <barlow.jim@gmail.com>
 Source: https://github.com/jbarlow83/OCRmyPDF
-Files-Excluded: tests/resources/milk.pdf
 
 Files: *
 Copyright:
- (C) 2013-2017 The OCRmyPDF Authors
- (C) 2013-2016, 2015-2017 2016, 2017, 2017-2018, 2018 James R. Barlow
-License: GPL-3+
+ (C) 2013-2015 Julien Pfefferkorn
+ (C) 2015-2020 James R. Barlow
+ (C) 2019 Martin Wind
+License: MPL-2.0
+
+Files: misc/*
+Copyright:
+ (C) 2020 James R. Barlow
+License: Expat
+
+Files: misc/completion/ocrmypdf.bash
+Copyright:
+ (C) 2019 Frank Pille
+ (C) 2020 Alex Willner
+License: Expat
+
+Files: misc/completion/ocrmypdf.fish
+Copyright:
+ (C) 2020 James R. Barlow
+License: Expat
+
+Files: misc/batch.py
+Copyright:
+ (C) 2016 findingorder: https://github.com/findingorder
+License: Expat
+
+Files: misc/synology.py
+Copyright:
+ (C) github.com/Enantiomerie
+License: Expat
+
+Files: misc/watcher.py
+Copyright:
+ (C) 2019 Ian Alexander: https://github.com/ianalexander
+ (C) 2020 James R. Barlow
+License: Expat
+
+Files: misc/webservice.py
+Copyright: (C) 2019 James R. Barlow
+License: AGPL-3+
 
 Files: docs tests/resources/*
 Copyright: (C) 2013-2018 James R. Barlow
 License: CC-BY-SA-4.0
 
+Files: docs/images/bitmap_vs_svg.svg
+Copyright: (C) 2006 Yug
+License: CC-BY-SA-2.5
+
 Files: src/ocrmypdf/hocrtransform.py
 Copyright: (C) 2010 Jonathan Brinley <jonathanbrinley@gmail.com>
  (C) 2013-14 Julien Pfefferkorn
  (C) 2015-16 James R. Barlow
 License: Expat
 
-Files: src/ocrmypdf/pdfa.py
-Copyright: (C) 2015 James R. Barlow
- (C) 1986-2017 The authors of GhostScript
-License: GPL-3+
-
 Files: src/ocrmypdf/_unicodefun.py
 Copyright: (C) 2014 Armin Ronacher
  (C) 2017 James R. Barlow
 License: BSD-3-clause
 
-Files: tests/spoof/*
+Files: tests/plugins/*
 Copyright: (C) 2016, 2017, 2016-2018 James R. Barlow
 License: Expat
 
@@ -79,15 +114,20 @@ Copyright: held by the contributors to the Wikipedia article "Optical character
  (epson.pdf generated from Wikipedia article as of 2016-09-14)
 License: CC-BY-SA-3.0
 
-Files: tests/resources/typewriter.png tests/resources/2400dpi.pdf tests/resources/3small.pdf
+Files: tests/resources/typewriter.png tests/resources/2400dpi.pdf
 Copyright: (C) 2005 Ellywa
 License: GFDL-1.2+ or CC-BY-SA-1.0 or CC-BY-SA-2.0 or CC-BY-SA-2.5 or CC-BY-SA-3.0
+Comment:
+ Obtained from: https://commons.wikimedia.org/wiki/File:Triumph.typewriter_text_Linzensoep.gif
 
 Files: tests/resources/overlay.pdf
 Copyright: (C) 2017 Max Anderson
 License: Expat
 
-Files: tests/resources/baiona*.png tests/resources/3small.pdf
+Files:
+ tests/resources/baiona*.png
+ tests/resources/baiona*.jpg
+ tests/resources/link.pdf
 Copyright: (C) 2014 Euskaldunaa
 License: CC-BY-SA-4.0
 
@@ -95,6 +135,13 @@ Files: tests/resources/vector.pdf
 Copyright: (C) 2018 Catscratch
 License: Expat
 
+Files: tests/resources/3small.pdf
+Copyright: (C) 2014 Euskaldunaa
+ (C) 2017 James R. Barlow
+ (C) 2005 Ellywa
+License: CC-BY-SA-4.0 and (GFDL-1.2+ or CC-BY-SA-1.0 or CC-BY-SA-2.0 or CC-BY-SA-2.5 or CC-BY-SA-3.0)
+Comment: concatenation of baiona_gray.png, crom.png and typewriter.png/2400dpi.pdf
+
 Files: src/ocrmypdf/data/sRGB.icc
 Copyright:  Kai-Uwe Behrmann <www.behrmann.name>
             Marti Maria <www.littlecms.com>
@@ -107,6 +154,13 @@ Files: debian/*
 Copyright: (C) 2016 Sean Whitton <spwhitton@spwhitton.name>
 License: GPL-3+
 
+License: MPL-2.0
+ This Source Code Form is subject to the terms of the Mozilla Public
+ License, v. 2.0.
+ .
+ On Debian systems the full text of the MPL-2.0 can be found in
+ /usr/share/common-licenses/MPL-2.0.
+
 License: GPL-3+
  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
@@ -124,6 +178,669 @@ License: GPL-3+
  On Debian systems, the complete text of the GNU General
  Public License version 3 can be found in "/usr/share/common-licenses/GPL-3".
 
+License: AGPL-3+
+                     GNU AFFERO GENERAL PUBLIC LICENSE
+                        Version 3, 19 November 2007
+ .
+  Copyright (C) 2007 Free Software Foundation, Inc. <http://fsf.org/>
+  Everyone is permitted to copy and distribute verbatim copies
+  of this license document, but changing it is not allowed.
+ .
+                             Preamble
+ .
+   The GNU Affero General Public License is a free, copyleft license for
+ software and other kinds of works, specifically designed to ensure
+ cooperation with the community in the case of network server software.
+ .
+   The licenses for most software and other practical works are designed
+ to take away your freedom to share and change the works.  By contrast,
+ our General Public Licenses are intended to guarantee your freedom to
+ share and change all versions of a program--to make sure it remains free
+ software for all its users.
+ .
+   When we speak of free software, we are referring to freedom, not
+ price.  Our General Public Licenses are designed to make sure that you
+ have the freedom to distribute copies of free software (and charge for
+ them if you wish), that you receive source code or can get it if you
+ want it, that you can change the software or use pieces of it in new
+ free programs, and that you know you can do these things.
+ .
+   Developers that use our General Public Licenses protect your rights
+ with two steps: (1) assert copyright on the software, and (2) offer
+ you this License which gives you legal permission to copy, distribute
+ and/or modify the software.
+ .
+   A secondary benefit of defending all users' freedom is that
+ improvements made in alternate versions of the program, if they
+ receive widespread use, become available for other developers to
+ incorporate.  Many developers of free software are heartened and
+ encouraged by the resulting cooperation.  However, in the case of
+ software used on network servers, this result may fail to come about.
+ The GNU General Public License permits making a modified version and
+ letting the public access it on a server without ever releasing its
+ source code to the public.
+ .
+   The GNU Affero General Public License is designed specifically to
+ ensure that, in such cases, the modified source code becomes available
+ to the community.  It requires the operator of a network server to
+ provide the source code of the modified version running there to the
+ users of that server.  Therefore, public use of a modified version, on
+ a publicly accessible server, gives the public access to the source
+ code of the modified version.
+ .
+   An older license, called the Affero General Public License and
+ published by Affero, was designed to accomplish similar goals.  This is
+ a different license, not a version of the Affero GPL, but Affero has
+ released a new version of the Affero GPL which permits relicensing under
+ this license.
+ .
+   The precise terms and conditions for copying, distribution and
+ modification follow.
+ .
+                        TERMS AND CONDITIONS
+ .
+   0. Definitions.
+ .
+   "This License" refers to version 3 of the GNU Affero General Public License.
+ .
+   "Copyright" also means copyright-like laws that apply to other kinds of
+ works, such as semiconductor masks.
+ .
+   "The Program" refers to any copyrightable work licensed under this
+ License.  Each licensee is addressed as "you".  "Licensees" and
+ "recipients" may be individuals or organizations.
+ .
+   To "modify" a work means to copy from or adapt all or part of the work
+ in a fashion requiring copyright permission, other than the making of an
+ exact copy.  The resulting work is called a "modified version" of the
+ earlier work or a work "based on" the earlier work.
+ .
+   A "covered work" means either the unmodified Program or a work based
+ on the Program.
+ .
+   To "propagate" a work means to do anything with it that, without
+ permission, would make you directly or secondarily liable for
+ infringement under applicable copyright law, except executing it on a
+ computer or modifying a private copy.  Propagation includes copying,
+ distribution (with or without modification), making available to the
+ public, and in some countries other activities as well.
+ .
+   To "convey" a work means any kind of propagation that enables other
+ parties to make or receive copies.  Mere interaction with a user through
+ a computer network, with no transfer of a copy, is not conveying.
+ .
+   An interactive user interface displays "Appropriate Legal Notices"
+ to the extent that it includes a convenient and prominently visible
+ feature that (1) displays an appropriate copyright notice, and (2)
+ tells the user that there is no warranty for the work (except to the
+ extent that warranties are provided), that licensees may convey the
+ work under this License, and how to view a copy of this License.  If
+ the interface presents a list of user commands or options, such as a
+ menu, a prominent item in the list meets this criterion.
+ .
+   1. Source Code.
+ .
+   The "source code" for a work means the preferred form of the work
+ for making modifications to it.  "Object code" means any non-source
+ form of a work.
+ .
+   A "Standard Interface" means an interface that either is an official
+ standard defined by a recognized standards body, or, in the case of
+ interfaces specified for a particular programming language, one that
+ is widely used among developers working in that language.
+ .
+   The "System Libraries" of an executable work include anything, other
+ than the work as a whole, that (a) is included in the normal form of
+ packaging a Major Component, but which is not part of that Major
+ Component, and (b) serves only to enable use of the work with that
+ Major Component, or to implement a Standard Interface for which an
+ implementation is available to the public in source code form.  A
+ "Major Component", in this context, means a major essential component
+ (kernel, window system, and so on) of the specific operating system
+ (if any) on which the executable work runs, or a compiler used to
+ produce the work, or an object code interpreter used to run it.
+ .
+   The "Corresponding Source" for a work in object code form means all
+ the source code needed to generate, install, and (for an executable
+ work) run the object code and to modify the work, including scripts to
+ control those activities.  However, it does not include the work's
+ System Libraries, or general-purpose tools or generally available free
+ programs which are used unmodified in performing those activities but
+ which are not part of the work.  For example, Corresponding Source
+ includes interface definition files associated with source files for
+ the work, and the source code for shared libraries and dynamically
+ linked subprograms that the work is specifically designed to require,
+ such as by intimate data communication or control flow between those
+ subprograms and other parts of the work.
+ .
+   The Corresponding Source need not include anything that users
+ can regenerate automatically from other parts of the Corresponding
+ Source.
+ .
+   The Corresponding Source for a work in source code form is that
+ same work.
+ .
+   2. Basic Permissions.
+ .
+   All rights granted under this License are granted for the term of
+ copyright on the Program, and are irrevocable provided the stated
+ conditions are met.  This License explicitly affirms your unlimited
+ permission to run the unmodified Program.  The output from running a
+ covered work is covered by this License only if the output, given its
+ content, constitutes a covered work.  This License acknowledges your
+ rights of fair use or other equivalent, as provided by copyright law.
+ .
+   You may make, run and propagate covered works that you do not
+ convey, without conditions so long as your license otherwise remains
+ in force.  You may convey covered works to others for the sole purpose
+ of having them make modifications exclusively for you, or provide you
+ with facilities for running those works, provided that you comply with
+ the terms of this License in conveying all material for which you do
+ not control copyright.  Those thus making or running the covered works
+ for you must do so exclusively on your behalf, under your direction
+ and control, on terms that prohibit them from making any copies of
+ your copyrighted material outside their relationship with you.
+ .
+   Conveying under any other circumstances is permitted solely under
+ the conditions stated below.  Sublicensing is not allowed; section 10
+ makes it unnecessary.
+ .
+   3. Protecting Users' Legal Rights From Anti-Circumvention Law.
+ .
+   No covered work shall be deemed part of an effective technological
+ measure under any applicable law fulfilling obligations under article
+ 11 of the WIPO copyright treaty adopted on 20 December 1996, or
+ similar laws prohibiting or restricting circumvention of such
+ measures.
+ .
+   When you convey a covered work, you waive any legal power to forbid
+ circumvention of technological measures to the extent such circumvention
+ is effected by exercising rights under this License with respect to
+ the covered work, and you disclaim any intention to limit operation or
+ modification of the work as a means of enforcing, against the work's
+ users, your or third parties' legal rights to forbid circumvention of
+ technological measures.
+ .
+   4. Conveying Verbatim Copies.
+ .
+   You may convey verbatim copies of the Program's source code as you
+ receive it, in any medium, provided that you conspicuously and
+ appropriately publish on each copy an appropriate copyright notice;
+ keep intact all notices stating that this License and any
+ non-permissive terms added in accord with section 7 apply to the code;
+ keep intact all notices of the absence of any warranty; and give all
+ recipients a copy of this License along with the Program.
+ .
+   You may charge any price or no price for each copy that you convey,
+ and you may offer support or warranty protection for a fee.
+ .
+   5. Conveying Modified Source Versions.
+ .
+   You may convey a work based on the Program, or the modifications to
+ produce it from the Program, in the form of source code under the
+ terms of section 4, provided that you also meet all of these conditions:
+ .
+     a) The work must carry prominent notices stating that you modified
+     it, and giving a relevant date.
+ .
+     b) The work must carry prominent notices stating that it is
+     released under this License and any conditions added under section
+     7.  This requirement modifies the requirement in section 4 to
+     "keep intact all notices".
+ .
+     c) You must license the entire work, as a whole, under this
+     License to anyone who comes into possession of a copy.  This
+     License will therefore apply, along with any applicable section 7
+     additional terms, to the whole of the work, and all its parts,
+     regardless of how they are packaged.  This License gives no
+     permission to license the work in any other way, but it does not
+     invalidate such permission if you have separately received it.
+ .
+     d) If the work has interactive user interfaces, each must display
+     Appropriate Legal Notices; however, if the Program has interactive
+     interfaces that do not display Appropriate Legal Notices, your
+     work need not make them do so.
+ .
+   A compilation of a covered work with other separate and independent
+ works, which are not by their nature extensions of the covered work,
+ and which are not combined with it such as to form a larger program,
+ in or on a volume of a storage or distribution medium, is called an
+ "aggregate" if the compilation and its resulting copyright are not
+ used to limit the access or legal rights of the compilation's users
+ beyond what the individual works permit.  Inclusion of a covered work
+ in an aggregate does not cause this License to apply to the other
+ parts of the aggregate.
+ .
+   6. Conveying Non-Source Forms.
+ .
+   You may convey a covered work in object code form under the terms
+ of sections 4 and 5, provided that you also convey the
+ machine-readable Corresponding Source under the terms of this License,
+ in one of these ways:
+ .
+     a) Convey the object code in, or embodied in, a physical product
+     (including a physical distribution medium), accompanied by the
+     Corresponding Source fixed on a durable physical medium
+     customarily used for software interchange.
+ .
+     b) Convey the object code in, or embodied in, a physical product
+     (including a physical distribution medium), accompanied by a
+     written offer, valid for at least three years and valid for as
+     long as you offer spare parts or customer support for that product
+     model, to give anyone who possesses the object code either (1) a
+     copy of the Corresponding Source for all the software in the
+     product that is covered by this License, on a durable physical
+     medium customarily used for software interchange, for a price no
+     more than your reasonable cost of physically performing this
+     conveying of source, or (2) access to copy the
+     Corresponding Source from a network server at no charge.
+ .
+     c) Convey individual copies of the object code with a copy of the
+     written offer to provide the Corresponding Source.  This
+     alternative is allowed only occasionally and noncommercially, and
+     only if you received the object code with such an offer, in accord
+     with subsection 6b.
+ .
+     d) Convey the object code by offering access from a designated
+     place (gratis or for a charge), and offer equivalent access to the
+     Corresponding Source in the same way through the same place at no
+     further charge.  You need not require recipients to copy the
+     Corresponding Source along with the object code.  If the place to
+     copy the object code is a network server, the Corresponding Source
+     may be on a different server (operated by you or a third party)
+     that supports equivalent copying facilities, provided you maintain
+     clear directions next to the object code saying where to find the
+     Corresponding Source.  Regardless of what server hosts the
+     Corresponding Source, you remain obligated to ensure that it is
+     available for as long as needed to satisfy these requirements.
+ .
+     e) Convey the object code using peer-to-peer transmission, provided
+     you inform other peers where the object code and Corresponding
+     Source of the work are being offered to the general public at no
+     charge under subsection 6d.
+ .
+   A separable portion of the object code, whose source code is excluded
+ from the Corresponding Source as a System Library, need not be
+ included in conveying the object code work.
+ .
+   A "User Product" is either (1) a "consumer product", which means any
+ tangible personal property which is normally used for personal, family,
+ or household purposes, or (2) anything designed or sold for incorporation
+ into a dwelling.  In determining whether a product is a consumer product,
+ doubtful cases shall be resolved in favor of coverage.  For a particular
+ product received by a particular user, "normally used" refers to a
+ typical or common use of that class of product, regardless of the status
+ of the particular user or of the way in which the particular user
+ actually uses, or expects or is expected to use, the product.  A product
+ is a consumer product regardless of whether the product has substantial
+ commercial, industrial or non-consumer uses, unless such uses represent
+ the only significant mode of use of the product.
+ .
+   "Installation Information" for a User Product means any methods,
+ procedures, authorization keys, or other information required to install
+ and execute modified versions of a covered work in that User Product from
+ a modified version of its Corresponding Source.  The information must
+ suffice to ensure that the continued functioning of the modified object
+ code is in no case prevented or interfered with solely because
+ modification has been made.
+ .
+   If you convey an object code work under this section in, or with, or
+ specifically for use in, a User Product, and the conveying occurs as
+ part of a transaction in which the right of possession and use of the
+ User Product is transferred to the recipient in perpetuity or for a
+ fixed term (regardless of how the transaction is characterized), the
+ Corresponding Source conveyed under this section must be accompanied
+ by the Installation Information.  But this requirement does not apply
+ if neither you nor any third party retains the ability to install
+ modified object code on the User Product (for example, the work has
+ been installed in ROM).
+ .
+   The requirement to provide Installation Information does not include a
+ requirement to continue to provide support service, warranty, or updates
+ for a work that has been modified or installed by the recipient, or for
+ the User Product in which it has been modified or installed.  Access to a
+ network may be denied when the modification itself materially and
+ adversely affects the operation of the network or violates the rules and
+ protocols for communication across the network.
+ .
+   Corresponding Source conveyed, and Installation Information provided,
+ in accord with this section must be in a format that is publicly
+ documented (and with an implementation available to the public in
+ source code form), and must require no special password or key for
+ unpacking, reading or copying.
+ .
+   7. Additional Terms.
+ .
+   "Additional permissions" are terms that supplement the terms of this
+ License by making exceptions from one or more of its conditions.
+ Additional permissions that are applicable to the entire Program shall
+ be treated as though they were included in this License, to the extent
+ that they are valid under applicable law.  If additional permissions
+ apply only to part of the Program, that part may be used separately
+ under those permissions, but the entire Program remains governed by
+ this License without regard to the additional permissions.
+ .
+   When you convey a copy of a covered work, you may at your option
+ remove any additional permissions from that copy, or from any part of
+ it.  (Additional permissions may be written to require their own
+ removal in certain cases when you modify the work.)  You may place
+ additional permissions on material, added by you to a covered work,
+ for which you have or can give appropriate copyright permission.
+ .
+   Notwithstanding any other provision of this License, for material you
+ add to a covered work, you may (if authorized by the copyright holders of
+ that material) supplement the terms of this License with terms:
+ .
+     a) Disclaiming warranty or limiting liability differently from the
+     terms of sections 15 and 16 of this License; or
+ .
+     b) Requiring preservation of specified reasonable legal notices or
+     author attributions in that material or in the Appropriate Legal
+     Notices displayed by works containing it; or
+ .
+     c) Prohibiting misrepresentation of the origin of that material, or
+     requiring that modified versions of such material be marked in
+     reasonable ways as different from the original version; or
+ .
+     d) Limiting the use for publicity purposes of names of licensors or
+     authors of the material; or
+ .
+     e) Declining to grant rights under trademark law for use of some
+     trade names, trademarks, or service marks; or
+ .
+     f) Requiring indemnification of licensors and authors of that
+     material by anyone who conveys the material (or modified versions of
+     it) with contractual assumptions of liability to the recipient, for
+     any liability that these contractual assumptions directly impose on
+     those licensors and authors.
+ .
+   All other non-permissive additional terms are considered "further
+ restrictions" within the meaning of section 10.  If the Program as you
+ received it, or any part of it, contains a notice stating that it is
+ governed by this License along with a term that is a further
+ restriction, you may remove that term.  If a license document contains
+ a further restriction but permits relicensing or conveying under this
+ License, you may add to a covered work material governed by the terms
+ of that license document, provided that the further restriction does
+ not survive such relicensing or conveying.
+ .
+   If you add terms to a covered work in accord with this section, you
+ must place, in the relevant source files, a statement of the
+ additional terms that apply to those files, or a notice indicating
+ where to find the applicable terms.
+ .
+   Additional terms, permissive or non-permissive, may be stated in the
+ form of a separately written license, or stated as exceptions;
+ the above requirements apply either way.
+ .
+   8. Termination.
+ .
+   You may not propagate or modify a covered work except as expressly
+ provided under this License.  Any attempt otherwise to propagate or
+ modify it is void, and will automatically terminate your rights under
+ this License (including any patent licenses granted under the third
+ paragraph of section 11).
+ .
+   However, if you cease all violation of this License, then your
+ license from a particular copyright holder is reinstated (a)
+ provisionally, unless and until the copyright holder explicitly and
+ finally terminates your license, and (b) permanently, if the copyright
+ holder fails to notify you of the violation by some reasonable means
+ prior to 60 days after the cessation.
+ .
+   Moreover, your license from a particular copyright holder is
+ reinstated permanently if the copyright holder notifies you of the
+ violation by some reasonable means, this is the first time you have
+ received notice of violation of this License (for any work) from that
+ copyright holder, and you cure the violation prior to 30 days after
+ your receipt of the notice.
+ .
+   Termination of your rights under this section does not terminate the
+ licenses of parties who have received copies or rights from you under
+ this License.  If your rights have been terminated and not permanently
+ reinstated, you do not qualify to receive new licenses for the same
+ material under section 10.
+ .
+   9. Acceptance Not Required for Having Copies.
+ .
+   You are not required to accept this License in order to receive or
+ run a copy of the Program.  Ancillary propagation of a covered work
+ occurring solely as a consequence of using peer-to-peer transmission
+ to receive a copy likewise does not require acceptance.  However,
+ nothing other than this License grants you permission to propagate or
+ modify any covered work.  These actions infringe copyright if you do
+ not accept this License.  Therefore, by modifying or propagating a
+ covered work, you indicate your acceptance of this License to do so.
+ .
+   10. Automatic Licensing of Downstream Recipients.
+ .
+   Each time you convey a covered work, the recipient automatically
+ receives a license from the original licensors, to run, modify and
+ propagate that work, subject to this License.  You are not responsible
+ for enforcing compliance by third parties with this License.
+ .
+   An "entity transaction" is a transaction transferring control of an
+ organization, or substantially all assets of one, or subdividing an
+ organization, or merging organizations.  If propagation of a covered
+ work results from an entity transaction, each party to that
+ transaction who receives a copy of the work also receives whatever
+ licenses to the work the party's predecessor in interest had or could
+ give under the previous paragraph, plus a right to possession of the
+ Corresponding Source of the work from the predecessor in interest, if
+ the predecessor has it or can get it with reasonable efforts.
+ .
+   You may not impose any further restrictions on the exercise of the
+ rights granted or affirmed under this License.  For example, you may
+ not impose a license fee, royalty, or other charge for exercise of
+ rights granted under this License, and you may not initiate litigation
+ (including a cross-claim or counterclaim in a lawsuit) alleging that
+ any patent claim is infringed by making, using, selling, offering for
+ sale, or importing the Program or any portion of it.
+ .
+   11. Patents.
+ .
+   A "contributor" is a copyright holder who authorizes use under this
+ License of the Program or a work on which the Program is based.  The
+ work thus licensed is called the contributor's "contributor version".
+ .
+   A contributor's "essential patent claims" are all patent claims
+ owned or controlled by the contributor, whether already acquired or
+ hereafter acquired, that would be infringed by some manner, permitted
+ by this License, of making, using, or selling its contributor version,
+ but do not include claims that would be infringed only as a
+ consequence of further modification of the contributor version.  For
+ purposes of this definition, "control" includes the right to grant
+ patent sublicenses in a manner consistent with the requirements of
+ this License.
+ .
+   Each contributor grants you a non-exclusive, worldwide, royalty-free
+ patent license under the contributor's essential patent claims, to
+ make, use, sell, offer for sale, import and otherwise run, modify and
+ propagate the contents of its contributor version.
+ .
+   In the following three paragraphs, a "patent license" is any express
+ agreement or commitment, however denominated, not to enforce a patent
+ (such as an express permission to practice a patent or covenant not to
+ sue for patent infringement).  To "grant" such a patent license to a
+ party means to make such an agreement or commitment not to enforce a
+ patent against the party.
+ .
+   If you convey a covered work, knowingly relying on a patent license,
+ and the Corresponding Source of the work is not available for anyone
+ to copy, free of charge and under the terms of this License, through a
+ publicly available network server or other readily accessible means,
+ then you must either (1) cause the Corresponding Source to be so
+ available, or (2) arrange to deprive yourself of the benefit of the
+ patent license for this particular work, or (3) arrange, in a manner
+ consistent with the requirements of this License, to extend the patent
+ license to downstream recipients.  "Knowingly relying" means you have
+ actual knowledge that, but for the patent license, your conveying the
+ covered work in a country, or your recipient's use of the covered work
+ in a country, would infringe one or more identifiable patents in that
+ country that you have reason to believe are valid.
+ .
+   If, pursuant to or in connection with a single transaction or
+ arrangement, you convey, or propagate by procuring conveyance of, a
+ covered work, and grant a patent license to some of the parties
+ receiving the covered work authorizing them to use, propagate, modify
+ or convey a specific copy of the covered work, then the patent license
+ you grant is automatically extended to all recipients of the covered
+ work and works based on it.
+ .
+   A patent license is "discriminatory" if it does not include within
+ the scope of its coverage, prohibits the exercise of, or is
+ conditioned on the non-exercise of one or more of the rights that are
+ specifically granted under this License.  You may not convey a covered
+ work if you are a party to an arrangement with a third party that is
+ in the business of distributing software, under which you make payment
+ to the third party based on the extent of your activity of conveying
+ the work, and under which the third party grants, to any of the
+ parties who would receive the covered work from you, a discriminatory
+ patent license (a) in connection with copies of the covered work
+ conveyed by you (or copies made from those copies), or (b) primarily
+ for and in connection with specific products or compilations that
+ contain the covered work, unless you entered into that arrangement,
+ or that patent license was granted, prior to 28 March 2007.
+ .
+   Nothing in this License shall be construed as excluding or limiting
+ any implied license or other defenses to infringement that may
+ otherwise be available to you under applicable patent law.
+ .
+   12. No Surrender of Others' Freedom.
+ .
+   If conditions are imposed on you (whether by court order, agreement or
+ otherwise) that contradict the conditions of this License, they do not
+ excuse you from the conditions of this License.  If you cannot convey a
+ covered work so as to satisfy simultaneously your obligations under this
+ License and any other pertinent obligations, then as a consequence you may
+ not convey it at all.  For example, if you agree to terms that obligate you
+ to collect a royalty for further conveying from those to whom you convey
+ the Program, the only way you could satisfy both those terms and this
+ License would be to refrain entirely from conveying the Program.
+ .
+   13. Remote Network Interaction; Use with the GNU General Public License.
+ .
+   Notwithstanding any other provision of this License, if you modify the
+ Program, your modified version must prominently offer all users
+ interacting with it remotely through a computer network (if your version
+ supports such interaction) an opportunity to receive the Corresponding
+ Source of your version by providing access to the Corresponding Source
+ from a network server at no charge, through some standard or customary
+ means of facilitating copying of software.  This Corresponding Source
+ shall include the Corresponding Source for any work covered by version 3
+ of the GNU General Public License that is incorporated pursuant to the
+ following paragraph.
+ .
+   Notwithstanding any other provision of this License, you have
+ permission to link or combine any covered work with a work licensed
+ under version 3 of the GNU General Public License into a single
+ combined work, and to convey the resulting work.  The terms of this
+ License will continue to apply to the part which is the covered work,
+ but the work with which it is combined will remain governed by version
+ 3 of the GNU General Public License.
+ .
+   14. Revised Versions of this License.
+ .
+   The Free Software Foundation may publish revised and/or new versions of
+ the GNU Affero General Public License from time to time.  Such new versions
+ will be similar in spirit to the present version, but may differ in detail to
+ address new problems or concerns.
+ .
+   Each version is given a distinguishing version number.  If the
+ Program specifies that a certain numbered version of the GNU Affero General
+ Public License "or any later version" applies to it, you have the
+ option of following the terms and conditions either of that numbered
+ version or of any later version published by the Free Software
+ Foundation.  If the Program does not specify a version number of the
+ GNU Affero General Public License, you may choose any version ever published
+ by the Free Software Foundation.
+ .
+   If the Program specifies that a proxy can decide which future
+ versions of the GNU Affero General Public License can be used, that proxy's
+ public statement of acceptance of a version permanently authorizes you
+ to choose that version for the Program.
+ .
+   Later license versions may give you additional or different
+ permissions.  However, no additional obligations are imposed on any
+ author or copyright holder as a result of your choosing to follow a
+ later version.
+ .
+   15. Disclaimer of Warranty.
+ .
+   THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
+ APPLICABLE LAW.  EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
+ HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY
+ OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO,
+ THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM
+ IS WITH YOU.  SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF
+ ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
+ .
+   16. Limitation of Liability.
+ .
+   IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+ WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
+ THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
+ GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
+ USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+ DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
+ PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
+ EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
+ SUCH DAMAGES.
+ .
+   17. Interpretation of Sections 15 and 16.
+ .
+   If the disclaimer of warranty and limitation of liability provided
+ above cannot be given local legal effect according to their terms,
+ reviewing courts shall apply local law that most closely approximates
+ an absolute waiver of all civil liability in connection with the
+ Program, unless a warranty or assumption of liability accompanies a
+ copy of the Program in return for a fee.
+ .
+                      END OF TERMS AND CONDITIONS
+ .
+             How to Apply These Terms to Your New Programs
+ .
+   If you develop a new program, and you want it to be of the greatest
+ possible use to the public, the best way to achieve this is to make it
+ free software which everyone can redistribute and change under these terms.
+ .
+   To do so, attach the following notices to the program.  It is safest
+ to attach them to the start of each source file to most effectively
+ state the exclusion of warranty; and each file should have at least
+ the "copyright" line and a pointer to where the full notice is found.
+ .
+     <one line to give the program's name and a brief idea of what it does.>
+     Copyright (C) <year>  <name of author>
+ .
+     This program is free software: you can redistribute it and/or modify
+     it under the terms of the GNU Affero General Public License as published by
+     the Free Software Foundation, either version 3 of the License, or
+     (at your option) any later version.
+ .
+     This program is distributed in the hope that it will be useful,
+     but WITHOUT ANY WARRANTY; without even the implied warranty of
+     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+     GNU Affero General Public License for more details.
+ .
+     You should have received a copy of the GNU Affero General Public License
+     along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ .
+ Also add information on how to contact you by electronic and paper mail.
+ .
+   If your software can interact with users remotely through a computer
+ network, you should also make sure that it provides a way for users to
+ get its source.  For example, if your program is a web application, its
+ interface could display a "Source" link that leads users to an archive
+ of the code.  There are many ways you could offer source, and different
+ solutions will be better for different programs; see section 13 for the
+ specific requirements.
+ .
+   You should also get your employer (if you work as a programmer) or school,
+ if any, to sign a "copyright disclaimer" for the program, if necessary.
+ For more information on this, and how to apply and follow the GNU AGPL, see
+ <http://www.gnu.org/licenses/>.
+
 License: Expat
  Permission is hereby granted, free of charge, to any person obtaining
  a copy of this software and associated documentation files (the

docs/advanced.rst

@@ -125,8 +125,7 @@ include:
 .. envvar:: OMP_THREAD_LIMIT
 
    Controls the number of threads Tesseract will use. OCRmyPDF will
-   manage this environment if it is not already set. (Currently, it will
-   set it to 1 because this gives the best results in testing.)
+   manage this environment variable if it is not already set.
 
 For example, if you have a development build of Tesseract don't wish to
 use the system installation, you can launch OCRmyPDF as follows:
@@ -148,7 +147,8 @@ In addition to tesseract, OCRmyPDF uses the following external binaries:
 
 -  ``gs`` (Ghostscript)
 -  ``unpaper``
--  ``qpdf``
+-  ``pngquant``
+-  ``jbig2``
 
 In each case OCRmyPDF will search the ``PATH`` environment variable to
 locate the binaries.
@@ -314,7 +314,7 @@ message is:
 .. code-block:: none
 
     Temporary working files retained at:
-    /tmp/com.github.ocrmypdf.u20wpz07
+    /tmp/ocrmypdf.io.u20wpz07
 
 The organization of this folder is an implementation detail and subject
 to change between releases. However the general organization is that

docs/api.rst

@@ -20,7 +20,8 @@ and largely have the same functions.
 
     import ocrmypdf
 
-    ocrmypdf.ocr('input.pdf', 'output.pdf', deskew=True)
+    if __name__ == '__main__':  # To ensure correct behavior on Windows and macOS
+        ocrmypdf.ocr('input.pdf', 'output.pdf', deskew=True)
 
 With a few exceptions, all of the command line arguments are available
 and may be passed as equivalent keywords.
@@ -35,21 +36,37 @@ The :func:`ocrmypdf.ocr` function runs OCRmyPDF similar to command line
 execution. To do this, it will:
 
 - create a monitoring thread
-- create worker processes (forking itself)
-- manage the signal flags of worker processes
+- create worker processes (on Linux, forking itself; on Windows and macOS, by
+  spawning)
+- manage the signal flags of its worker processes
 - execute other subprocesses (forking and executing other programs)
 
 The Python process that calls ``ocrmypdf.ocr()`` must be sufficiently
-privileged to perform these actions. If it is not, ``ocrmypdf()`` will
-fail.
+privileged to perform these actions.
 
 There is no currently no option to manage how jobs are scheduled other
 than the argument ``jobs=`` which will limit the number of worker
 processes.
 
-Forking a child process to call ``ocrmypdf.ocr()`` is suggested. That
+Creating a child process to call ``ocrmypdf.ocr()`` is suggested. That
 way your application will survive and remain interactive even if
-OCRmyPDF does not.
+OCRmyPDF fails for any reason.
+
+Programs that call ``ocrmypdf.ocr()`` should also install a SIGBUS signal
+handler (except on Windows), to raise an exception if access to a memory
+mapped file fails. OCRmyPDF may use memory mapping.
+
+``ocrmypdf.ocr()`` will take a threading lock to prevent multiple runs of itself
+in the same Python interpreter process. This is not thread-safe, because of how
+OCRmyPDF's plugins and Python's library import system work. If you need to parallelize
+OCRmyPDF, use processes.
+
+.. warning::
+
+    On Windows and macOS, the script that calls ``ocrmypdf.ocr()`` must be
+    protected by an "ifmain" guard (``if __name__ == '__main__'``). If you do
+    not take at least one of these steps, process semantics will prevent
+    OCRmyPDF from working correctly.
 
 Logging
 -------
@@ -97,8 +114,4 @@ Reference
     :members:
     :undoc-members:
 
-.. autoclass:: ocrmypdf.ExitCode
-    :members:
-    :undoc-members:
-
 .. autofunction:: ocrmypdf.configure_logging

docs/apiref.rst

@@ -0,0 +1,55 @@
+=============
+API Reference
+=============
+
+This page summarizes the rest of the public API. Generally speaking this
+should mainly of interest to plugin developers.
+
+ocrmypdf
+========
+
+.. autoclass:: ocrmypdf.PageContext
+    :members:
+
+.. autoclass:: ocrmypdf.PdfContext
+    :members:
+
+ocrmypdf.exceptions
+===================
+
+.. automodule:: ocrmypdf.exceptions
+    :members:
+    :undoc-members:
+
+ocrmypdf.helpers
+================
+
+.. automodule:: ocrmypdf.helpers
+    :members:
+    :noindex: deprecated
+
+    .. autodecorator:: deprecated
+
+ocrmypdf.hocrtransform
+======================
+
+.. automodule:: ocrmypdf.hocrtransform
+    :members:
+
+ocrmypdf.pdfa
+=============
+
+.. automodule:: ocrmypdf.pdfa
+    :members:
+
+ocrmypdf.quality
+================
+
+.. automodule:: ocrmypdf.quality
+    :members:
+
+ocrmypdf.subprocess
+===================
+
+.. automodule:: ocrmypdf.subprocess
+    :members:

docs/batch.rst

@@ -127,7 +127,7 @@ Users may need to customize the script to meet their requirements.
     "OCR_ON_SUCCESS_DELETE", "This will delete the input file if the exit code is 0 (OK)"
     "OCR_OUTPUT_DIRECTORY_YEAR_MONTH", "This will place files in the output in ``{output}/{year}/{month}/{filename}``"
     "OCR_DESKEW", "Apply deskew to crooked input PDFs"
-    "OCR_JSON_SETTINGS", "A JSON string specifying any other arguments for ``ocrmypdf.ocr``"
+    "OCR_JSON_SETTINGS", "A JSON string specifying any other arguments for ``ocrmypdf.ocr``, e.g. ``'OCR_JSON_SETTINGS={""rotate_pages"": true}'``."
     "OCR_POLL_NEW_FILE_SECONDS", "Polling interval"
     "OCR_LOGLEVEL", "Level of log messages to report"
 

docs/conf.py

@@ -1,5 +1,4 @@
 #!/usr/bin/env python3
-# -*- coding: utf-8 -*-
 #
 # ocrmypdf documentation build configuration file, created by
 # sphinx-quickstart on Sun Sep  4 14:29:43 2016.
@@ -21,6 +20,8 @@
 # import sys
 # sys.path.insert(0, os.path.abspath('.'))
 
+"""isort:skip_file"""
+
 # -- General configuration ------------------------------------------------
 
 # If your documentation needs a minimal Sphinx version, state it here.
@@ -32,6 +33,8 @@
 # ones.
 extensions = ['sphinx.ext.napoleon']
 
+napoleon_use_rtype = False
+
 # Add any paths that contain templates here, relative to this directory.
 templates_path = ['_templates']
 
@@ -51,7 +54,7 @@ master_doc = 'index'
 # General information about the project.
 project = 'ocrmypdf'
 copyright = (
-    '2019, James R. Barlow. Licensed under Creative Commons Attribution-ShareAlike 4.0.'
+    '2020, James R. Barlow. Licensed under Creative Commons Attribution-ShareAlike 4.0.'
 )
 author = 'James R. Barlow'
 
@@ -90,6 +93,7 @@ from pkg_resources import get_distribution, DistributionNotFound
 release = get_distribution('ocrmypdf').version
 version = '.'.join(release.split('.')[:2])
 
+
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.
 #
@@ -174,7 +178,7 @@ html_theme_options = {'display_version': False}
 # The name of an image file (relative to this directory) to place at the top
 # of the sidebar.
 #
-# html_logo = None
+# html_logo = "images/logo.svg"  # looks bad
 
 # The name of an image file (relative to this directory) to use as a favicon of
 # the docs.  This file should be a Windows icon file (.ico) being 16x16 or 32x32

docs/contributing.rst

@@ -32,7 +32,8 @@ If you are proposing a change that will require a new Python dependency, we
 prefer dependencies that are already packaged by Debian or Red Hat. This makes
 life much easier for our downstream package maintainers.
 
-Python dependencies must also be GPLv3 compatible.
+Python dependencies must also be license-compatible. GPLv3 or AGPLv3 are likely
+incompatible with the project's license, but LGPLv3 is compatible.
 
 New non-Python dependencies
 ===========================
@@ -55,3 +56,12 @@ of that platform.
 
 Packager maintainers, please ensure that the command line completion scripts in
 ``misc/`` are installed.
+
+Copyright and license
+=====================
+
+For contributions over 10 lines of code, please include your name to list of
+copyright holders for that file. The core program is licensed under MPL-2.0,
+test files and documentation under CC-BY-SA 4.0, and miscellaneous files under
+MIT. Please contribute code only that you wrote and you have the permission to
+contribute or license to us.

docs/cookbook.rst

@@ -56,7 +56,11 @@ portrait pages.
     ocrmypdf --rotate-pages myfile.pdf myfile.pdf
 
 You can increase (decrease) the parameter ``--rotate-pages-threshold``
-to make page rotation more (less) aggressive.
+to make page rotation more (less) aggressive. The threshold number is the ratio
+of how confidence the OCR engine is that the document image should be changed,
+compared to kept the same. A value of ``15.0`` is the default, and is fairly
+conservative. A value of ``2.0`` will produce more rotations, and more false
+positives.
 
 If the page is "just a little off horizontal", like a crooked picture,
 then you want ``--deskew``. ``--rotate-pages`` is for when the cardinal

docs/docker.rst

@@ -1,3 +1,5 @@
+.. _docker:
+
 =====================
 OCRmyPDF Docker image
 =====================
@@ -90,10 +92,8 @@ Docker volume:
 
 .. code-block:: bash
 
-   docker run --rm -v $(pwd):/data ocrmypdf /data/input.pdf /data/output.pdf
-
-(However, when done this way, ``output.pdf`` may be owned by the root
-user.)
+   alias docker_ocrmypdf='docker run --rm  -i --user "$(id -u):$(id -g)" --workdir /data -v "$PWD:/data" ocrmypdf'
+   docker_ocrmypdf /data/input.pdf /data/output.pdf
 
 .. _docker-lang-packs:
 
@@ -165,8 +165,7 @@ complete. This may entail setting a long timeout; this interface is more
 useful for internal HTTP API calls.
 
 Unlike the rest of OCRmyPDF, this web service is licensed under the
-Affero GPLv3 (AGPLv3) since Ghostscript, a dependency of OCRmyPDF, is
-also licensed in this way.
+Affero GPLv3 (AGPLv3) since Ghostscript is also licensed in this way.
 
 In addition to the above, please read our
 :ref:`general remarks on using OCRmyPDF as a service <ocr-service>`.

docs/errors.rst

@@ -22,14 +22,20 @@ As the error message suggests, your options are:
 -  ``ocrmypdf --skip-text`` to skip OCR and other processing on any
    pages that contain text. Text pages will be copied into the output
    PDF without modification.
+-  ``ocrmypdf --redo-ocr`` to scan the file for any existing OCR
+   (non-printing text), remove it, and do OCR again. This is one way
+   to take advantage of improvements in OCR accuracy. Printable vector
+   text is excluded from OCR, so this can be used on files that contain
+   a mix of digital and scanned files.
+
 
 Input file 'filename' is not a valid PDF
 ========================================
 
-OCRmyPDF passes files through qpdf, a program that fixes errors in PDFs,
-before it tries to work on them. In most cases this happens because the
-PDF is corrupt and truncated (incomplete file copying) and not much can
-be done.
+OCRmyPDF checks files with pikepdf, a library that in turn uses libqpdf to fixes
+errors in PDFs, before it tries to work on them. In most cases this happens
+because the PDF is corrupt and truncated (incomplete file copying) and not much
+can be done.
 
 You can try rewriting the file with Ghostscript:
 

docs/index.rst

@@ -1,7 +1,7 @@
 OCRmyPDF documentation
 ======================
 
-OCRmyPDF adds an optical charcter recognition (OCR) text layer to scanned PDF
+OCRmyPDF adds an optical character recognition (OCR) text layer to scanned PDF
 files, allowing them to be searched.
 
 PDF is the best format for storing and exchanging scanned documents.
@@ -26,7 +26,8 @@ image processing and OCR to existing PDFs.
    docker
    advanced
    batch
-   security
+   performance
+   pdfsecurity
    errors
 
 .. toctree::
@@ -34,6 +35,8 @@ image processing and OCR to existing PDFs.
    :maxdepth: 2
 
    api
+   plugins
+   apiref
    contributing
 
 Indices and tables

docs/installation.rst

@@ -8,20 +8,28 @@ Installing OCRmyPDF
 |latest|
 
 The easiest way to install OCRmyPDF is to follow the steps for your operating
-system/platform, although sometimes this version may be out of date. This
-installation guide provides information allowing you to compare the current
-version to the one provided by your platform.
+system/platform. This version may be out of date, however.
 
-If you want to use the latest version of OCRmyPDF and all of its optional
-dependencies, the easiest way to get that is install the Homebrew package. Homebrew
-is best known as a macOS package manger, but also works for
-`Linux and Windows Subsystem for Linux <https://docs.brew.sh/Homebrew-on-Linux>`__.
-After Homebrew is installed, simply run ``brew install ocrmypdf``.
+These platforms have one-liner installs:
 
-You can also use the more detailed procedures here to manually install OCRmyPDF
-from source or with the ``pip`` package manager for binary wheels. The reason
-for these varied steps is that OCRmyPDF requires third-party executables that are
-not part of Python.
++-------------------------------+-------------------------------+
+| Debian, Ubuntu                | ``apt install ocrmypdf``      |
++-------------------------------+-------------------------------+
+| Windows Subsystem for Linux   | ``apt install ocrmypdf``      |
++-------------------------------+-------------------------------+
+| Fedora                        | ``dnf install ocrmypdf``      |
++-------------------------------+-------------------------------+
+| macOS                         | ``brew install ocrmypdf``     |
++-------------------------------+-------------------------------+
+| LinuxBrew                     | ``brew install ocrmypdf``     |
++-------------------------------+-------------------------------+
+| FreeBSD                       | ``pkg install py37-ocrmypdf`` |
++-------------------------------+-------------------------------+
+| Conda (WSL, macOS, Linux)     | ``conda install ocrmypdf``    |
++-------------------------------+-------------------------------+
+
+More detailed procedures are outlined below. If you want to do a manual
+install, or install a more recent version than your platform provides, read on.
 
 .. contents:: Platform-specific steps
     :depth: 2
@@ -45,14 +53,11 @@ Debian and Ubuntu 18.04 or newer
 .. |ubu-1804| image:: https://repology.org/badge/version-for-repo/ubuntu_18_04/ocrmypdf.svg
     :alt: Ubuntu 18.04 LTS
 
-.. |ubu-1810| image:: https://repology.org/badge/version-for-repo/ubuntu_18_10/ocrmypdf.svg
-    :alt: Ubuntu 18.10
+.. |ubu-2004| image:: https://repology.org/badge/version-for-repo/ubuntu_20_04/ocrmypdf.svg
+    :alt: Ubuntu 20.04 LTS
 
-.. |ubu-1904| image:: https://repology.org/badge/version-for-repo/ubuntu_19_04/ocrmypdf.svg
-    :alt: Ubuntu 19.04
-
-.. |ubu-1910| image:: https://repology.org/badge/version-for-repo/ubuntu_19_10/ocrmypdf.svg
-    :alt: Ubuntu 19.10
+.. |ubu-2010| image:: https://repology.org/badge/version-for-repo/ubuntu_20_10/ocrmypdf.svg
+    :alt: Ubuntu 20.10
 
 +-----------------------------------------------+
 | **OCRmyPDF versions in Debian & Ubuntu**      |
@@ -61,10 +66,10 @@ Debian and Ubuntu 18.04 or newer
 +-----------------------------------------------+
 | |deb-stable| |deb-testing| |deb-unstable|     |
 +-----------------------------------------------+
-| |ubu-1804| |ubu-1810| |ubu-1904| |ubu-1910|   |
+| |ubu-1804| |ubu-2004| |ubu-2010|              |
 +-----------------------------------------------+
 
-Users of Debian 9 ("stretch") or later or Ubuntu 18.04 or later, including users
+Users of Debian 9 ("stretch") or later, or Ubuntu 18.04 or later, including users
 of Windows Subsystem for Linux, may simply
 
 .. code-block:: bash
@@ -90,14 +95,14 @@ For full details on version availability for your platform, check the
    automatically detect it (specifically the ``jbig2`` binary) on the
    ``PATH``. To add JBIG2 encoding, see :ref:`jbig2`.
 
-Fedora 29 or newer
-------------------
+Fedora
+------
 
-.. |fedora-29| image:: https://repology.org/badge/version-for-repo/fedora_29/ocrmypdf.svg
-    :alt: Fedora 29
+.. |fedora-32| image:: https://repology.org/badge/version-for-repo/fedora_32/ocrmypdf.svg
+    :alt: Fedora 32
 
-.. |fedora-30| image:: https://repology.org/badge/version-for-repo/fedora_30/ocrmypdf.svg
-    :alt: Fedora 30
+.. |fedora-33| image:: https://repology.org/badge/version-for-repo/fedora_33/ocrmypdf.svg
+    :alt: Fedora 33
 
 .. |fedora-rawhide| image:: https://repology.org/badge/version-for-repo/fedora_rawhide/ocrmypdf.svg
     :alt: Fedore Rawhide
@@ -107,7 +112,7 @@ Fedora 29 or newer
 +-----------------------------------------------+
 | |latest|                                      |
 +-----------------------------------------------+
-| |fedora-29| |fedora-30| |fedora-rawhide|      |
+| |fedora-32| |fedora-33| |fedora-rawhide|      |
 +-----------------------------------------------+
 
 Users of Fedora 29 or later may simply
@@ -133,15 +138,50 @@ from sources <#installing-head-revision-from-sources>`__.
 
 .. _ubuntu-lts-latest:
 
-Installing the latest version on Ubuntu 18.04 LTS
+Installing the latest version on Ubuntu 20.04 LTS
 -------------------------------------------------
 
-Ubuntu 18.04 includes ocrmypdf 6.1.2 - you can install that with ``apt``, but
-it is quite old now. To install a more recent version, first install several
-system dependencies:
+Ubuntu 20.04 includes ocrmypdf 9.6.0 - you can install that with ``apt``. To
+install a more recent version, uninstall the system-provided version of
+ocrmypdf, and install the following dependencies:
 
 .. code-block:: bash
 
+    sudo apt-get -y remove ocrmypdf  # remove system ocrmypdf, if installed
+    sudo apt-get -y update
+    sudo apt-get -y install \
+        ghostscript \
+        icc-profiles-free \
+        liblept5 \
+        libxml2 \
+        pngquant \
+        python3-pip \
+        tesseract-ocr \
+        zlib1g
+
+To install ocrmypdf for the system:
+
+.. code-block:: bash
+
+    pip3 install ocrmypdf
+
+To install for the current user only:
+
+.. code-block:: bash
+
+    export PATH=$HOME/.local/bin:$PATH
+    pip3 install --user ocrmypdf
+
+Ubuntu 18.04 LTS
+----------------
+
+Ubuntu 18.04 includes ocrmypdf 6.1.2 - you can install that with ``apt``, but
+it is quite old now. To install a more recent version, uninstall the old version
+of ocrmypdf, and install the following dependencies:
+
+.. code-block:: bash
+
+    sudo apt-get -y remove ocrmypdf
     sudo apt-get -y update
     sudo apt-get -y install \
         ghostscript \
@@ -155,7 +195,8 @@ system dependencies:
         python3-reportlab \
         qpdf \
         tesseract-ocr \
-        zlib1g
+        zlib1g \
+        unpaper
 
 We will need a newer version of ``pip`` then was available for Ubuntu 18.04:
 
@@ -236,68 +277,6 @@ environment variable contains ``$HOME/.local/bin``.
 
 To add JBIG2 encoding, see :ref:`jbig2`.
 
-Ubuntu 14.04 LTS
-----------------
-
-Installing on Ubuntu 14.04 LTS (trusty) is more difficult than some
-other options, because of its age. Several backports are required. For
-explanations of some steps of this procedure, see the similar steps for
-Ubuntu 16.04.
-
-Install system dependencies:
-
-.. code-block:: bash
-
-    sudo apt-get update
-    sudo apt-get install \
-        software-properties-common python-software-properties \
-        zlib1g-dev \
-        libexempi3 \
-        libjpeg-dev \
-        libffi-dev \
-        pngquant \
-        qpdf
-
-We will need backports of Ghostscript 9.16, libav-11 (for unpaper 6.1),
-Tesseract 4.00 (alpha), and Python 3.6. This will replace Ghostscript
-and Tesseract 3.x on your system. Python 3.6 will be installed alongside
-the system Python 3.4.
-
-If you prefer to not modify your system in this matter, consider using a
-Docker container.
-
-.. code-block:: bash
-
-    sudo add-apt-repository ppa:vshn/ghostscript -y
-    sudo add-apt-repository ppa:heyarje/libav-11 -y
-    sudo add-apt-repository ppa:alex-p/tesseract-ocr -y
-    sudo add-apt-repository ppa:jonathonf/python-3.6 -y
-
-    sudo apt-get update
-
-    sudo apt-get install \
-        python3.6-dev \
-        ghostscript \
-        tesseract-ocr \
-        tesseract-ocr-eng \
-        libavformat56 libavcodec56 libavutil54 \
-        wget
-
-Now we need to install ``pip`` and let it install ocrmypdf:
-
-.. code-block:: bash
-
-    curl https://bootstrap.pypa.io/ez_setup.py -o - | python3.6 && python3.6 -m easy_install pip
-    pip3.6 install ocrmypdf
-
-The optional dependency ``unpaper`` is only available at 0.4.2 in Ubuntu 14.04,
-and no backports are available. Previously the author maintained a backported
-.deb package for unpaper 6.1, but since Ubuntu 14.04 is now end of life, this is
-not supported. As such, ``unpaper`` is not available on Ubuntu 14.04 or must by
-compiled by hand.
-
-To add JBIG2 encoding, see :ref:`jbig2`.
-
 Arch Linux (AUR)
 ----------------
 
@@ -326,20 +305,7 @@ standard tooling needed to build packages, such as a compiler and binary tools.
 
    sudo pacman -S base-devel
 
-The OCRmyPDF package depends on `the python-pdfminer.six AUR package
-<https://aur.archlinux.org/packages/python-pdfminer.six/>`__.  Dependencies on
-AUR packages are not automatically resolved, so this package must be manually
-installed first.
-
-.. code-block:: bash
-
-   curl -O https://aur.archlinux.org/cgit/aur.git/snapshot/python-pdfminer.six.tar.gz
-   tar xvzf python-pdfminer.six.tar.gz
-   cd python-pdfminer.six
-   makepkg -sri
-
-With that complete you can then repeat the same series of steps for the
-OCRmyPDF package.
+Now you are ready to install the OCRmyPDF package.
 
 .. code-block:: bash
 
@@ -373,11 +339,10 @@ page.
     fine without it but will produce larger output files. The encoder is
     available from `the jbig2enc-git AUR package
     <https://aur.archlinux.org/packages/jbig2enc-git/>`__ and may be installed
-    using the same series of steps as for the installation of the pdfminer.six
-    and OCRmyPDF AUR packages. Alternatively, it may be built manually from
-    source following the instructions in `Installing the JBIG2 encoder
-    <jbig2>`__.  If JBIG2 is installed, OCRmyPDF 7.0.0 and later will
-    automatically detect it.
+    using the same series of steps as for the installation OCRmyPDF AUR
+    package. Alternatively, it may be built manually from source following the
+    instructions in `Installing the JBIG2 encoder <jbig2>`__.  If JBIG2 is
+    installed, OCRmyPDF 7.0.0 and later will automatically detect it.
 
 Alpine Linux
 ------------
@@ -392,6 +357,48 @@ To install OCRmyPDF for Alpine Linux:
 
     apk add ocrmypdf
 
+Mageia 7
+--------
+
+There is no OS-level packaging available for Mageia, so you must install the
+dependencies:
+
+.. code-block:: bash
+
+    # As root user
+    urpmi.update -a
+    urpmi \
+        ghostscript \
+        icc-profiles-openicc \
+        jbig2dec \
+        lib64leptonica5 \
+        pngquant \
+        python3-pip \
+        python3-cffi \
+        python3-distutils-extra \
+        python3-pkg-resources \
+        python3-reportlab \
+        qpdf \
+        tesseract \
+        tesseract-osd \
+        tesseract-eng \
+        tesseract-fra
+
+To install ocrmypdf for the system:
+
+.. code-block:: bash
+
+    # As root user
+    pip3 install ocrmypdf
+    ldconfig
+
+Or, to install for the current user only:
+
+.. code-block:: bash
+
+    export PATH=$HOME/.local/bin:$PATH
+    pip3 install --user ocrmypdf
+
 Other Linux packages
 --------------------
 
@@ -442,7 +449,10 @@ languages you can optionally install them all:
 Manual installation on macOS
 ----------------------------
 
-These instructions probably work on all macOS supported by Homebrew.
+These instructions probably work on all macOS supported by Homebrew, and are
+for installing a more current version of OCRmyPDF than is available from
+Homebrew. Note that the Homebrew versions usually track the release versions
+fairly closely.
 
 If it's not already present, `install Homebrew <http://brew.sh/>`__.
 
@@ -453,14 +463,8 @@ Update Homebrew:
     brew update
 
 Install or upgrade the required Homebrew packages, if any are missing.
-To do this, download the ``Brewfile`` that lists all of the dependencies
-to the current directory, and run ``brew bundle`` to process them
-(installing or upgrading as needed). ``Brewfile`` is a plain text file.
-
-.. code-block:: bash
-
-    wget https://github.com/jbarlow83/OCRmyPDF/raw/master/.travis/Brewfile
-    brew bundle
+To do this, use ``brew edit ocrmypdf`` to obtain a recent list of Homebrew
+dependencies. You could also check the ``.workflows/build.yml``.
 
 This will include the English, French, German and Spanish language
 packs. If you need other languages you can optionally install them all:
@@ -495,6 +499,130 @@ The command line program should now be available:
 
     ocrmypdf --help
 
+Installing on Windows
+=====================
+
+Native Windows
+--------------
+
+.. note::
+
+    Administrator privileges will be required for some of these steps.
+
+You must install the following for Windows:
+
+* Python 3.7 (64-bit) or later
+* Tesseract 4.0 or later
+* Ghostscript 9.50 or later
+
+Using the `Chocolatey <https://chocolatey.org/>`_ package manager, install the
+following when running in an Administrator command prompt:
+
+* ``choco install python3``
+* ``choco install --pre tesseract``
+* ``choco install ghostscript``
+* ``choco install pngquant`` (optional)
+
+The commands above will install Python 3.x (latest version), Tesseract, Ghostscript
+and pngquant. Chocolatey may also need to install the Windows Visual C++ Runtime
+DLLs or other Windows patches, and may require a reboot.
+
+You may then use ``pip`` to install ocrmypdf. (This can performed by a user or
+Administrator.):
+
+* ``pip install ocrmypdf``
+
+Chocolatey automatically selects appropriate versions of these applications. If you
+are installing them manually, please install 64-bit versions of all applications for
+64-bit Windows, or 32-bit versions of all applications for 32-bit Windows. Mixing
+the "bitness" of these programs will lead to errors.
+
+OCRmyPDF will check the Windows Registry and standard locations in your Program Files
+for third party software it needs (specifically, Tesseract and Ghostscript). To
+override the versions OCRmyPDF selects, you can modify the ``PATH`` environment
+variable. `Follow these directions <https://www.computerhope.com/issues/ch000549.htm#dospath>`_
+to change the PATH.
+
+.. warning::
+
+    As of early 2021, users have reported problems with the Microsoft Store version of
+    Python and OCRmyPDF. These issues affect many other third party Python packages.
+    Please download Python from Python.org or Chocolatey instead, and do not use the
+    Microsoft Store version.
+
+Windows Subsystem for Linux
+---------------------------
+
+#. Install Ubuntu 18.04 for Windows Subsystem for Linux, if not already installed.
+#. Follow the procedure to install :ref:`OCRmyPDF on Ubuntu 18.04 <ubuntu-lts-latest>`.
+#. Open the Windows command prompt and create a symlink:
+
+.. code-block:: powershell
+
+    wsl sudo ln -s  /home/$USER/.local/bin/ocrmypdf /usr/local/bin/ocrmypdf
+
+Then confirm that the expected version from PyPI (|latest|) is installed:
+
+.. code-block:: powershell
+
+    wsl ocrmypdf --version
+
+You can then run OCRmyPDF in the Windows command prompt or Powershell, prefixing
+``wsl``, and call it from Windows programs or batch files.
+
+Cygwin64
+--------
+
+First install the the following prerequisite Cygwin packages using ``setup-x86_64.exe``::
+
+    python36 (or later)
+    python3?-devel
+    python3?-pip
+    python3?-lxml
+    python3?-imaging
+
+       (where 3? means match the version of python3 you installed)
+
+    gcc-g++
+    ghostscript (<=9.50 or >=9.52-2 see note below)
+    libexempi3
+    libexempi-devel
+    libffi6
+    libffi-devel
+    pngquant
+    qpdf
+    libqpdf-devel
+    tesseract-ocr
+    tesseract-ocr-devel
+
+.. note::
+
+    The Cygwin package for Ghostscript in versions 9.52 and
+    9.52-1 contained a bug that caused an exception to occur when
+    ocrmypdf invoked gs.  Make sure you have either 9.50 (or earlier)
+    or 9.52-2 (or later).
+
+Then open a Cygwin terminal (i.e. ``mintty``), run the following commands. Note
+that if you are using the version of ``pip`` that was installed with the Cygwin
+Python package, the command name will be ``pip3``.  If you have since updated
+``pip`` (with, for instance ``pip3 install --upgrade pip``) the the command is
+likely just ``pip`` instead of ``pip3``:
+
+.. code-block:: bash
+
+    pip3 install wheel
+    pip3 install ocrmypdf
+
+The optional dependency "unpaper" that is currently not available under Cygwin.
+Without it, certain options such as ``--clean`` will produce an error message.
+However, the OCR-to-text-layer functionality is available.
+
+Docker
+------
+
+You can also :ref:`Install the Docker <docker>` container on Windows. Ensure that
+your command prompt can run the docker "hello world" container.
+
 Installing on FreeBSD
 =====================
 
@@ -518,78 +646,7 @@ Installing the Docker image
 For some users, installing the Docker image will be easier than
 installing all of OCRmyPDF's dependencies.
 
-See `OCRmyPDF Docker Image <docker>`__ for more information.
-
-Installing on Windows
-=====================
-
-.. warning::
-
-    Native Windows support is new. Consider it "beta" software. Some
-    functionality is missing or may be more difficult to enable. If you need a
-    production-ready solution, use Windows Subsystem for Linux or a Docker
-    image.
-
-.. note::
-
-    Administrator privileges will be required for some of these steps.
-
-You must install the following for Windows:
-
-* Python 3.7 (64-bit)
-* Tesseract 4.0 or later
-* Ghostscript 9.50 or later
-
-You can install these with the Chocolatey package manager:
-
-* ``choco install python3``
-* ``choco install --pre tesseract``
-* ``choco install ghostscript``
-
-Also consider adding:
-
-* ``choco install pngquant``
-
-Windows 10 64-bit and 64-bit versions of applications are recommended. Earlier
-versions of Windows and 32-bit versions of these programs are not tested, and not
-supported at this time.
-
-OCRmyPDF will check for Tesseract-OCR and Ghostscript in your Program Files folder.
-If they are in some other location, you may need to modify the ``PATH``
-environment variable so Tesseract, Ghostscript, and other any optional executables can
-be found. You can enter it in the command line or
-`follow these directions <https://www.computerhope.com/issues/ch000549.htm#dospath>`_
-to make the change persistent and system-wide.
-
-You may then use pip to install ocrmypdf:
-
-* ``pip install ocrmypdf``
-
-Installing on Windows Subsystem for Linux
-=========================================
-
-#. Install Ubuntu 18.04 for Windows Subsystem for Linux, if not already installed.
-#. Follow the procedure to install :ref:`OCRmyPDF on Ubuntu 18.04 <ubuntu-lts-latest>`.
-#. Open the Windows command prompt and create a symlink:
-
-.. code-block:: powershell
-
-    wsl sudo ln -s  /home/$USER/.local/bin/ocrmypdf /usr/local/bin/ocrmypdf
-
-Then confirm that the expected version from PyPI (|latest|) is installed:
-
-.. code-block:: powershell
-
-    wsl ocrmypdf --version
-
-You can then run OCRmyPDF in the Windows command prompt or Powershell, prefixing
-``wsl``, and call it from Windows programs or batch files.
-
-Docker
-^^^^^^
-
-You can also :ref:`Install the Docker <docker-install>` container on Windows. Ensure that
-your command prompt can run the docker "hello world" container.
+See :ref:`docker` for more information.
 
 Installing with Python pip
 ==========================
@@ -597,7 +654,22 @@ Installing with Python pip
 OCRmyPDF is delivered by PyPI because it is a convenient way to install
 the latest version. However, PyPI and ``pip`` cannot address the fact
 that ``ocrmypdf`` depends on certain non-Python system libraries and
-programs being instsalled.
+programs being installed.
+
+.. warning::
+
+    Debian and Ubuntu users: unfortunately, Debian and Ubuntu customize
+    Python in non-standard ways, and the nature of these customizations
+    varies from release to release. This can make for a frustrating
+    user experience. The instructions below work on almost all platforms that
+    have Python installed, except for Debian and Ubuntu, where you may need
+    to take additional steps. For best results on Debian and Ubuntu, use the
+    ``apt`` packages; or if these are too old, run
+    ``apt install python3-pip python3-venv``, create a virtual environment,
+    and install OCRmyPDF in that environment.
+
+    `See here for more inforation on Debian-Python issues
+    <https://gist.github.com/tiran/2dec9e03c6f901814f6d1e8dad09528e>`__.
 
 For best results, first install `your platform's
 version <https://repology.org/metapackage/ocrmypdf/versions>`__ of
@@ -625,6 +697,13 @@ instead use this for a system wide installation:
 
     pip3 install ocrmypdf
 
+.. note::
+
+    AArch64 (ARM64) users: this process will be difficult because most
+    Python packages are not available as binary wheels for your platform.
+    You're probably better off using a platform install on Debian, Ubuntu,
+    or Fedora.
+
 Requirements for pip and HEAD install
 -------------------------------------
 

docs/introduction.rst

@@ -186,6 +186,11 @@ Ghostscript also imposes some limitations:
 -  Ghostscript's PDF/A conversion removes any XMP metadata that is not
    one of the standard XMP metadata namespaces for PDFs. In particular,
    PRISM Metdata is removed.
+-  Ghostscript's PDF/A conversion seems to remove or deactivate
+   hyperlinks and other active content.
+
+You can use ``--output-type pdf`` to disable PDF/A conversion and produce
+a standard, non-archival PDF.
 
 Regarding OCRmyPDF itself:
 

docs/languages.rst

@@ -70,4 +70,7 @@ derived Docker image as
 Windows users
 =============
 
-The Tesseract installer provided by Chocolatey already includes 100 languages.
+The Tesseract installer provided by Chocolatey currently includes only English language. 
+To install other languages, download the respective language pack (``.traineddata`` file) 
+from https://github.com/tesseract-ocr/tessdata/ and place it in 
+``C:\\Program Files\\Tesseract-OCR\\tessdata`` (or wherever Tesseract OCR is installed).

docs/pdfsecurity.rst

@@ -64,11 +64,11 @@ malicious user could upload a chosen PDF. In particular, it is not
 necessarily secure against PDF malware or PDFs that cause denial of
 service. OCRmyPDF relies on Ghostscript, and therefore, if deployed
 online one should be prepared to comply with Ghostscript's Affero GPL
-license, OCRmyPDF's GPL license, and any other licenses.
+license, and any other licenses.
 
 Setting aside these concerns, a side effect of OCRmyPDF is it may
 incidentally sanitize PDFs that contain certain types of malware. It
-runs ``qpdf`` to repair the PDF, which could correct malformed PDF
+repairs the PDF with pikepdf/libqpdf, which could correct malformed PDF
 structures that are part of an attack. When PDF/A output is selected
 (the default), the input PDF is partially reconstructed by Ghostscript.
 When ``--force-ocr`` is used, all pages are rasterized and reconverted
@@ -144,10 +144,9 @@ set, the document cannot be viewed without the password.
 Either way, OCRmyPDF does not remove passwords from PDFs and exits with
 an error on encountering them.
 
-``qpdf``, one of OCRmyPDF's dependencies, can remove passwords. If the
-owner and user password are set, a password is required for ``qpdf``. If
-only the owner password is set, then the password can be stripped, even
-if one does not have the owner password.
+``qpdf`` can remove passwords. If the owner and user password are set, a
+password is required for ``qpdf``. If only the owner password is set, then the
+password can be stripped, even if one does not have the owner password.
 
 After OCR is applied, password protection is not permitted on PDF/A
 documents but the file can be converted to regular PDF.

docs/performance.rst

@@ -0,0 +1,22 @@
+===========
+Performance
+===========
+
+Some users have noticed that current versions of OCRmyPDF do not run as quickly
+as some older versions (specifically 6.x and older). This is because OCRmyPDF
+added image optimization as a postprocessing step, and it is enabled by default.
+
+Speed
+=====
+
+If running OCRmyPDF quickly is your main goal, you can use settings such as:
+
+* ``--optimize 0`` to disable file size optimization
+* ``--output-type pdf`` to disable PDF/A generation
+* ``--fast-web-view 0`` to disable fast web view optimization
+* ``--skip-big`` to skip large images, if some pages have large images
+
+You can also avoid:
+
+* ``--force-ocr``
+* Image preprocessing

docs/plugins.rst

@@ -2,23 +2,199 @@
 Plugins
 =======
 
-You can use plugins to customize the behavior of OCRmyPDF at certain
-points of interest.
+    The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
+    NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED",  "MAY", and
+    "OPTIONAL" in this document are to be interpreted as described in
+    RFC 2119.
 
-Currently, it is possible to: - override the decision for whether or not
-to perform OCR on a particular file - modify the image is about to be
-sent for OCR
+You can use plugins to customize the behavior of OCRmyPDF at certain points of
+interest.
 
-How plugins are imported
-========================
+Currently, it is possible to:
 
-Plugins are imported on demand, by the OCRmyPDF worker process that
-needs to use them. As such, plugins cannot share state with each other,
-and will be imported many times, once for each worker process.
+- add new command line arguments
+- override the decision for whether or not to perform OCR on a particular file
+- modify the image is about to be sent for OCR
+- modify the page image before it is converted to PDF
+- replace the Tesseract OCR with another OCR engine that has similar behavior
+- replace Ghostscript with another PDF to image converter (rasterizer) or
+  PDF/A generator
 
-Plugins currently cannot override the same hook.
+OCRmyPDF plugins are based on the Python ``pluggy`` package and conform to its
+conventions. Note that: plugins installed with as setuptools entrypoints are
+not checked currently, because OCRmyPDF assumes you may not want to enable
+plugins for all files.
 
-How plugins are invoked
-=======================
+Script plugins
+==============
 
-Plugins may be called from the command line:
+Script plugins may be called from the command line, by specifying the name of a file.
+Script plugins may be convenient for informal or "one-off" plugins, when a certain
+batch of files needs a special processing step for example.
+
+.. code-block:: bash
+
+    ocrmypdf --plugin ocrmypdf_example_plugin.py input.pdf output.pdf
+
+Multiple plugins may be installed by issuing the ``--plugin`` argument multiple times.
+
+Packaged plugins
+================
+
+Installed plugins may be installed into the same virtual environment as OCRmyPDF
+is installed into. They may be invoked using Python standard module naming.
+If you are intending to distribute a plugin, please package it.
+
+.. code-block:: bash
+
+    ocrmypdf --plugin ocrmypdf_fancypants.pockets.contents input.pdf output.pdf
+
+OCRmyPDF does not automatically import plugins, because the assumption is that
+plugins affect different files differently and you may not want them activated
+all the time. The command line or ``ocrmypdf.ocr(plugin='...')`` must call
+for them.
+
+Third parties that wish to distribute packages for ocrmypdf should package them
+as packaged plugins, and these modules should begin with the name ``ocrmypdf_``
+similar to ``pytest`` packages such as ``pytest-cov`` (the package) and
+``pytest_cov`` (the module).
+
+.. note::
+
+    We strongly recommend plugin authors name their plugins with the prefix
+    ``ocrmypdf-`` (for the package name on PyPI) and ``ocrmypdf_`` (for the
+    module), just like pytest plugins.
+
+Setuptools plugins
+==================
+
+You can also create a plugin that OCRmyPDF will always automatically load if both are
+installed in the same virtual environment, using a setuptools entrypoint.
+
+Your package's ``setup.py`` would need to contain the following, for a plugin
+named ``ocrmypdf-exampleplugin``:
+
+.. code-block:: python
+
+    # sample ./setup.py file
+    from setuptools import setup
+
+    setup(
+        name="ocrmypdf-exampleplugin",
+        packages=["exampleplugin"],
+        # the following makes a plugin available to pytest
+        entry_points={"ocrmypdf": ["exampleplugin = exampleplugin.pluginmodule"]},
+    )
+
+Plugin requirements
+===================
+
+OCRmyPDF generally uses multiple worker processes. When a new worker is started,
+Python will import all plugins again, including all plugins that were imported earlier.
+This means that the global state of a plugin in one worker will not be shared with
+other workers. As such, plugin hook implementations should be stateless, relying
+only on their inputs. Hook implementations may use their input parameters to
+to obtain a reference to shared state prepared by another hook implementation.
+Plugins must expect that other instances of the plugin will be running
+simultaneously.
+
+The ``context`` object that is passed to many hooks can be used to share information
+about a file being worked on. Plugins must write private, plugin-specific data to
+a subfolder named ``{options.work_folder}/ocrmypdf-plugin-name``. Plugins MAY
+read and write files in ``options.work_folder``, but should be aware that their
+semantics are subject to change.
+
+OCRmyPDF will delete ``options.work_folder`` when it has finished OCRing
+a file, unless invoked with ``--keep-temporary-files``.
+
+The documentation for some plugin hooks contain a detailed description of the
+execution context in which they will be called.
+
+Plugins should be prepared to work whether executed in worker threads or worker
+processes. Generally, OCRmyPDF uses processes, but has a semi-hidden threaded
+argument that simplifies debugging.
+
+
+Plugin hooks
+============
+
+A plugin may provide the following hooks. Hooks must be decorated with
+``ocrmypdf.hookimpl``, for example:
+
+.. code-block:: python
+
+    from ocrmpydf import hookimpl
+
+    @hookimpl
+    def add_options(parser):
+        pass
+
+The following is a complete list of hooks that are available, and when
+they are called.
+
+.. _firstresult:
+
+**Note on firstresult hooks**
+
+If multiple plugins install implementations for this hook, they will be called in
+the reverse of the order in which they are installed (i.e., last plugin wins).
+When each hook implementation is called in order, the first implementation that
+returns a value other than ``None`` will "win" and prevent execution of all other
+hooks. As such, you cannot "chain" a series of plugin filters together in this
+way. Instead, a single hook implementation should be responsible for any such
+chaining operations.
+
+Custom command line arguments
+-----------------------------
+
+.. autofunction:: ocrmypdf.pluginspec.add_options
+
+.. autofunction:: ocrmypdf.pluginspec.check_options
+
+Execution and progress reporting
+--------------------------------
+
+.. autoclass: ocrmypdf.pluginspec.Executor
+    :members:
+
+.. autofunction:: ocrmypdf.pluginspec.get_logging_console
+
+.. autofunction:: ocrmypdf.pluginspec.get_executor
+
+.. autofunction:: ocrmypdf.pluginspec.get_progressbar_class
+
+Applying special behavior before processing
+-------------------------------------------
+
+.. autofunction:: ocrmypdf.pluginspec.validate
+
+PDF page to image
+-----------------
+
+.. autofunction:: ocrmypdf.pluginspec.rasterize_pdf_page
+
+Modifying intermediate images
+-----------------------------
+
+.. autofunction:: ocrmypdf.pluginspec.filter_ocr_image
+
+.. autofunction:: ocrmypdf.pluginspec.filter_page_image
+
+.. autofunction:: ocrmypdf.pluginspec.filter_pdf_page
+
+OCR engine
+----------
+
+.. autofunction:: ocrmypdf.pluginspec.get_ocr_engine
+
+.. autoclass:: ocrmypdf.pluginspec.OcrEngine
+    :members:
+
+    .. automethod:: __str__
+
+.. autoclass:: ocrmypdf.pluginspec.OrientationConfidence
+
+PDF/A production
+----------------
+
+.. autofunction:: ocrmypdf.pluginspec.generate_pdfa

docs/release_notes.rst

@@ -5,14 +5,472 @@ Release notes
 OCRmyPDF uses `semantic versioning <http://semver.org/>`__ for its
 command line interface and its public API.
 
-The ``ocrmypdf`` package may now be imported. The public API may be
-useful in scripts that launch OCRmyPDF processes or that wish to use
-some of its features for working with PDFs.
+OCRmyPDF's output messages are not considered part of the stable interface -
+that is, output messages may be improved at any release level, so parsing them
+may be unreliable. Use the API to depend on precise behavior.
 
-Note that it is licensed under GPLv3, so scripts that
-``import ocrmypdf`` and are released publicly should probably also be
-licensed under GPLv3.
+The public API may be useful in scripts that launch OCRmyPDF processes or that
+wish to use some of its features for working with PDFs.
 
+v12.0.0
+=======
+
+**Breaking changes**
+
+-  Due to recent security issues in pikepdf, Pillow and reportlab, we now require
+   newer versions of these libraries and some of their dependencies. (If necessary,
+   package maintainers may override these versions at their discretion; lower
+   versions will often work.)
+-  We now use the "LeaveColorUnchanged" color conversion strategy when directing
+   Ghostscript to create a PDF/A. Generally this is faster than performing a
+   color conversion, which is not always necessary.
+-  OCR text is now packaged in a Form XObject. This makes it easier to isolate
+   OCR from other document content. However, some poor implemented PDF text
+   extraction algorithms may fail to find the text.
+-  Many API functions have stricter parameter checking or expect keyword arguments
+   were they previously did not.
+-  Some deprecated functions in ``ocrmypdf.optimize`` were removed.
+-  The ``ocrmypdf.leptonica`` module is now deprecated.
+-  Continuous integration moved to GitHub Actions.
+-  We no longer depend on ``pytest_helpers_namespace`` for testing.
+
+**New features**
+
+-  New plugin hook: ``get_progressbar_class``, for progress reporting,
+   allowing developers to replace the standard console progress bar with some
+   other mechanism, such as updating a GUI progress bar.
+-  New plugin hook: ``get_executor``, for replacing the concurrency model.
+   This is primarily to support execution on AWS Lambda, which does not support
+   standard Python ``multiprocessing`` due to its lack of shared memory.
+-  New plugin hook: ``get_logging_console``, for replacing the standard
+   way OCRmyPDF outputs its messages.
+-  New plugin hook: ``filter_pdf_page``, for modifying individual PDF
+   pages produced by OCRmyPDF.
+-  We now generate an ARM64-compatible Docker image alongside the x64 image.
+   Thanks to @andkrause for contributing the change and @0x326 for review comments.
+
+v11.7.3
+=======
+
+-  Exclude CCITT Group 3 images from being optimized. Some libraries
+   OCRmyPDF uses do not seem to handle this obscure compression format properly.
+   You may get errors or possible corrupted output images without this fix.
+
+v11.7.2
+=======
+
+-  Updated pinned versions in main.txt, primarily to upgrade Pillow to 8.1.2, due
+   to recently disclosed security vulnerabilities in that software.
+-  The ``--sidecar`` parameter now causes an exception if set to the same file as
+   the input or output PDF.
+
+v11.7.1
+=======
+
+-  Some exceptions while attempting image optimization were only logged at the debug
+   level, causing them to be suppressed. These errors are now logged appropriately.
+-  Improved the error message related to ``--unpaper-args``.
+-  Updated documentation to mention the new conda distribution.
+
+v11.7.0
+=======
+
+-  We now support using ``--sidecar`` in conjunction with ``--pages``; these arguments
+   used to be mutually exclusive. (#735)
+-  Fixed a possible issue with PDF/A-1b generation. Acrobat complained that our PDFs use
+   object streams. More robust PDF/A validators like veraPDF don't consider this a
+   problem, but we'll honor Acrobat's objection from here on. This may increase file
+   size of PDF/A-1b files. PDF/A-2b files will not be affected.
+
+v11.6.2
+=======
+
+-  Fixed a regression where the wrong page orientation would be produced when using
+   arguments such as ``--deskew --rotate-pages`` (#730).
+
+v11.6.1
+=======
+
+-  Fixed an issue with attempting optimize unusually narrow-width images by excluding
+   these images from optimization (#732).
+-  Remove an obsolete compatibility shim for a version of pikepdf that is no longer
+   supported.
+
+v11.6.0
+=======
+
+-  OCRmyPDF will now automatically register plugins from the same virtual environment
+   with an appropriate setuptools entrypoint.
+-  Refactor the plugin manager to remove unnecessary complications and make plugin
+   registration more automatic.
+-  ``PageContext`` and ``PdfContext`` are now formally part of the API, as they
+   should have been, since they were part of ``ocrmypdf.pluginspec``.
+
+v11.5.0
+=======
+
+-  Fixed an issue where the output page size might differ by a fractional amount
+   due to rounding, when ``--force-ocr`` was used and the page contained objects
+   with multiple resolutions.
+-  When determining the resolution at which to rasterize a page, we now consider
+   printed text on the page as requiring a higher resolution. This fixes issues
+   with certain pages being rendered with unacceptably low resolution text, but
+   may increase output file sizes in some workflows where low resolution text
+   is acceptable.
+-  Added a workaround to fix an exception that occurs when trying to
+   ``import ocrmypdf.leptonica`` on Apple ARM silicon (or potentially, other
+   platforms that do not permit write+executable memory).
+
+v11.4.5
+=======
+
+-  Fixed an issue where files may not be closed when the API is used.
+-  Improved ``setup.cfg`` with better settings for test coverage.
+
+v11.4.4
+=======
+
+-  Fixed ``AttributeError: 'NoneType' object has no attribute 'userunit'``, issue #700,
+   related to OCRmyPDF not properly forwarded an error message from pdfminer.six.
+-  Adjusted typing of some arguments.
+-  ``ocrmypdf.ocr`` now takes a ``threading.Lock`` for reasons outlined in the
+   documentation.
+
+v11.4.3
+=======
+
+-  Removed a redundant debug message.
+-  Test suite now asserts that most patched functions are called when they should be.
+-  Test suite now skips a test that fails on two particular versions of piekpdf.
+
+v11.4.2
+=======
+
+-  Fixed support for Cygwin, hopefully.
+-  watcher.py: Fixed an issue with the OCR_LOGLEVEL not being interpreted.
+
+v11.4.1
+=======
+
+-  Fixed an issue where invalid pages ranges passed using the ``pages`` argument,
+   such as "1-0" would cause unhandled exceptions.
+-  Accepted a user-contributed to the Synology demo script in misc/synology.py.
+-  Clarified documentation about change of temporary file location ``ocrmypdf.io``.
+-  Fixed Python wheel tag which was incorrectly set to py35 even though we long
+   since dropped support for Python 3.5.
+
+v11.4.0
+=======
+
+-  When looking for Tesseract and Ghostscript, we now check the Windows Registry to
+   see if their installers registered the location of their executables. This should
+   help Windows users who have installed these programs to non-standard
+   locations.
+-  We now report on the progress of PDF/A conversion, since this operation is
+   sometimes slow.
+-  Improved command line completions.
+-  The prefix of the temporary folder OCRmyPDF creates has been changed from
+   ``com.github.ocrmypdf`` to ``ocrmypdf.io``. Scripts that chose to depend on this
+   prefix may need to be adjusted. (This has always been an implementation detail so is
+   not considered part of the semantic versioning "contract".)
+-  Fixed issue #692, where a particular file with malformed fonts would flood an
+   internal message cue by generating so many debug messages.
+-  Fixed an exception on processing hOCR files with no page record. Tesseract
+   is not known to generate such files.
+
+v11.3.4
+=======
+
+-  Fixed an error message 'called readLinearizationData for file that is not
+   linearized' that may occur when pikepdf 2.1.0 is used. (Upgrading to pikepdf
+   2.1.1 also fixes the issue.)
+-  File watcher now automatically includes ``.PDF`` in addition to ``.pdf`` to
+   better support case sensitive file systems.
+-  Some documentation and comment improvements.
+
+v11.3.3
+=======
+
+-  If unpaper outputs non-UTF-8 data, quietly fix this rather than choke on the
+   conversion. (Possibly addresses #671.)
+
+v11.3.2
+=======
+
+-  Explicitly require pikepdf 2.0.0 or newer when running on Python 3.9. (There are
+   concerns about the stability of pybind11 2.5.x with Python 3.9, which is used in
+   pikepdf 1.x.)
+-  Fixed another issue related to page rotation.
+-  Fixed an issue where image marked as image masks were not properly considered
+   as optimization candidates.
+-  On some systems, unpaper seems to be unable to process the PNGs we offer it
+   as input. We now convert the input to PNM format, which unpaper always accepts.
+   Fixes #665 and #667.
+-  DPI sent to unpaper is now rounded to a more reasonable number of decimal digits.
+-  Debug and error messages from unpaper were being suppressed.
+-  Some documentation tweaks.
+
+v11.3.1
+=======
+
+-  Declare support for new versions: pdfminer.six 20201018 and pikepdf 2.x
+-  Fix warning related to ``--pdfa-image-compression`` that appears at the wrong
+   time.
+
+v11.3.0
+=======
+
+-  The "OCR" step is describing as "Image processing" in the output messages when
+   OCR is disabled, to better explain the application's behavior.
+-  Debug logs are now only created when run as a command line, and not when OCR
+   is performed for an API call. It is the calling application's responsibility
+   to set up logging.
+-  For PDFs with a low number of pages, we gathered information about the input PDF
+   in a thread rather than process (when there are more pages). When run as a
+   thread, we did not close the file handle to the working PDF, leaking one file
+   handle per call of ``ocrmypdf.ocr``.
+-  Fixed an issue where debug messages send by child worker processes did not match
+   the log settings of parent process, causing messages to be dropped. This affected
+   macOS and Windows only where the parent process is not forked.
+-  Fixed the hookspec of rasterize_pdf_page to remove default parameters that
+   were not handled in an expected way by pluggy.
+-  Fixed another issue with automatic page rotation (#658) due to the issue above.
+
+v11.2.1
+=======
+
+-  Fixed an issue where optimization of a 1-bit image with a color palette or
+   associated ICC that was optimized to JBIG2 could have its colors inverted.
+
+v11.2.0
+=======
+
+-  Fixed an issue with optimizing PNG-type images that had soft masks or image masks.
+   This is a regression introduced in (or about) v11.1.0.
+-  Improved type checking of the ``plugins`` parameter for the ``ocrmypdf.ocr``
+   API call.
+
+v11.1.2
+=======
+
+-  Fixed hOCR renderer writing the text in roughly reverse order. This should not
+   affect reasonably smart PDF readers that properly locate the position of all
+   text, but may confuse those that rely on the order of objects in the content
+   stream. (#642)
+
+v11.1.1
+=======
+
+-  We now avoid using named temporary files when using pngquant allowing containerized
+   pngquant installs to be used.
+-  Clarified an error message.
+-  Highest number of 1's in a release ever!
+
+v11.1.0
+=======
+
+-  Fixed page rotation issues: #634, #589.
+-  Fixed some cases where optimization created an invalid image such as a
+   1-bit "RGB" image: #629, #620.
+-  Page numbers are now displayed in debug logs when pages are being grafted.
+-  ocrmypdf.optimize.rewrite_png and ocrmypdf.optimize.rewrite_png_as_g4 were
+   marked deprecated. Strictly speaking these should have been internal APIs,
+   but they were never hidden.
+-  As a precaution, pikepdf mmap-based file access has been disabled due to a
+   rare race condition that causes a crash when certain objects are deallocated.
+   The problem is likely in pikepdf's dependency pybind11.
+-  Extended the example plugin to demonstrate conversion to mono.
+
+v11.0.2
+=======
+
+-  Fixed issue #612, TypeError exception. Fixed by eliminating unnecessary repair of
+   input PDF metadata in memory.
+
+v11.0.1
+=======
+
+-  Blacklist pdfminer.six 20200720, which has a regression fixed in 20200726.
+-  Approve img2pdf 0.4 as it passes tests.
+-  Clarify that the GPL-3 portion of pdfa.py was removed with the changes in v11.0.0;
+   the debian/copyright file did not properly annotate this change.
+
+v11.0.0
+=======
+
+-  Project license changed to Mozilla Public License 2.0. Some miscellaneous
+   code is now under MIT license and non-code content/media remains under
+   CC-BY-SA 4.0. License changed with approval of all people who were found
+   to have contributed to GPLv3 licensed sections of the project. (#600)
+-  Because the license changed, this is being treated as a major version number
+   change; however, there are no known breaking changes in functional behavior
+   or API compared to v10.x.
+
+v10.3.3
+=======
+
+-  Fixed a "KeyError: 'dpi'" error message when using ``--threshold`` on an image.
+   (#607)
+
+v10.3.2
+=======
+
+-  Fixed a case where we reported "no reason" for a file size increase, when we
+   could determine the reason.
+-  Enabled support for pdfminer.six 20200726.
+
+v10.3.1
+=======
+
+-  Fixed a number of test suite failures with pdfminer.six older than veresion 20200402.
+-  Enabled support for pdfminer.six 20200720.
+
+v10.3.0
+=======
+
+-  Fixed an issue where we would consider images that were already JBIG2-encoded
+   for optimization, potentially producing a less optimized image than the original.
+   We do not believe this issue would ever cause an image to loss fidelity.
+-  Where available, pikepdf memory mapping is now used. This improves performance.
+-  When Leptonica 1.79+ is installed, use its new error handling API to avoid
+   a "messy" redirection of stderr which was necessary to capture its error
+   messages.
+-  For older versions of Leptonica, added a new thread level lock. This fixes a
+   possible race condition in handling error conditions in Leptonica (although
+   there is no evidence it ever caused issues in practice).
+-  Documentation improvements and more type hinting.
+
+v10.2.1
+=======
+
+-  Disabled calculation of text box order with pdfminer. We never needed this result
+   and it is expensive to calculate on files with complex pre-existing text.
+-  Fixed plugin manager to accept ``Path(plugin)`` as a path to a plugin.
+-  Fixed some typing errors.
+-  Documentation improvements.
+
+v10.2.0
+=======
+
+-  Update Docker image to use Ubuntu 20.04.
+-  Fixed issue PDF/A acquires title "Untitled" after conversion. (#582)
+-  Fixed a problem where, when using ``--pdf-renderer hocr``, some text would
+   be missing from the output when using a more recent version of Tesseract.
+   Tesseract began adding more detailed markup about the semantics of text
+   that our HOCR transform did not recognize, so it ignored them. This option is
+   not the default. If necessary ``--redo-ocr`` also redoing OCR to fix such issues.
+-  Fixed an error in Python 3.9 beta, due to removal of deprecated
+   ``Element.getchildren()``. (#584)
+-  Implemented support using the API with ``BytesIO`` and other file stream objects.
+   (#545)
+
+v10.1.1
+=======
+
+-  Fixed ``OMP_THREAD_LIMIT`` set to invalid value error messages on some input
+   files. (The error was harmless, apart from less than optimal performance in
+   some cases.)
+
+v10.1.0
+=======
+
+-  Previously, we ``--clean-final`` would cause an unpaper-cleaned page image to
+   be produced twice, which was necessary in some cases but not in general. We
+   now take this optimization opportunity and reuse the image if possible.
+-  We now provide PNG files as input to unpaper, since it accepts them, instead
+   of generating PPM files which can be very large. This can improve performance
+   and temporary disk usage.
+-  Documentation updated for plugins.
+
+v10.0.1
+=======
+
+-  Fixed regression when ``-l lang1+lang2`` is used from command line.
+
+v10.0.0
+=======
+
+**Breaking changes**
+
+-  Support for pdfminer.six version 20181108 has been dropped, along with a
+   monkeypatch that made this version work.
+-  Output messages are now displayed in color (when supported by the terminal)
+   and prefixes describing the severity of the message are removed. As such
+   programs that parse OCRmyPDF's log message will need to be revised. (Please
+   consider using OCRmyPDF as a library instead.)
+-  The minimum version for certain dependencies has increased.
+-  Many API changes; see developer changes.
+-  The Python libraries pluggy and coloredlogs are now required.
+
+**New features and improvements**
+
+-  PDF page scanning is now parallelized across CPUs, speeding up this phase
+   dramatically for files with a high page counts.
+-  PDF page scanning is optimized, addressing some performance regressions.
+-  PDF page scanning is no longer run on pages that are not selected when the
+   ``--pages`` argument is used.
+-  PDF page scanning is now independent of Ghostscript, ending our past reliance
+   on this occasionally unstable feature in Ghostscript.
+-  A plugin architecture has been added, currently allowing one to more easily
+   use a different OCR engine or PDF renderer from Tesseract and Ghostscript,
+   respectively. A plugin can also override some decisions, such changing
+   the OCR settings after initial scanning.
+-  Colored log messages.
+
+**Developer changes**
+
+-  The test spoofing mechanism, used to test correct handling of failures in
+   Tesseract and Ghostscript, has been removed in favor of using plugins for
+   testing. The spoofing mechanism was fairly complex and required many special
+   hacks for Windows.
+-  Code describing the resolution in DPI of images was refactored into a
+   ``ocrmypdf.helpers.Resolution`` class.
+-  The module ``ocrmypdf._exec`` is now private to OCRmyPDF.
+-  The ``ocrmypdf.hocrtransform`` module has been updated to follow PEP8 naming
+   conventions.
+-  Ghostscript is no longer used for finding the location of text in PDFs, and
+   APIs related to this feature have been removed.
+-  Lots of internal reorganization to support plugins.
+
+v9.8.2
+======
+
+-  Fixed an issue where OCRmyPDF would ignore text inside Form XObject when
+   making certain decisions about whether a document already had text.
+-  Fixed file size increase warning to take overhead of small files into account.
+-  Added instructions for installing on Cygwin.
+
+v9.8.1
+======
+
+-  Fixed an issue where unexpected files in the ``%PROGRAMFILES%\gs`` directory
+   (Windows) caused an exception.
+-  Mark pdfminer.six 20200517 as supported.
+-  If jbig2enc is missing and optimization is requested, a warning is issued
+   instead of an error, which was the intended behavior.
+-  Documentation updates.
+
+v9.8.0
+======
+
+-  Fixed issue where only the first PNG (FlateDecode) image in a file would be
+   considered for optimization. File sizes should be improved from here on.
+-  Fixed a startup crash when the chosen language was Japanese (#543).
+-  Added options to configure polling and log level to watcher.py.
+
+v9.7.2
+======
+
+-  Fixed an issue with ``ocrmypdf.ocr(...language=)`` not accepting a list of
+   languages as documented.
+-  Updated setup.py to confirm that pdfminer.six version 20200402 is supported.
+
+v9.7.1
+======
+
+-  Fixed version check failing when used with qpdf 10.0.0.
+-  Added some missing type annotations.
+-  Updated documentation to warn about need for "ifmain" guard and Windows.
 
 v9.7.0
 ======
@@ -207,7 +665,7 @@ v9.0.0
 
 -  Added a high level API for applications that want to integrate OCRmyPDF.
    Special thanks to Martin Wind (@mawi1988) whose made significant contributions
-   to this effort. OCRmyPDF is GPLv3-licensed.
+   to this effort.
 -  Added progress bars for long-running steps. ■■■■■■■□□
 -  We now create linearized ("fast web view") PDFs by default. The new parameter
    ``--fast-web-view`` provides control over when this feature is applied.
@@ -834,8 +1292,8 @@ v6.1.0
 v6.0.0
 ======
 
--  The software license has been changed to GPLv3. Test resource files
-   and some individual sources may have other licenses.
+-  The software license has been changed to GPLv3 [it has since changed again].
+   Test resource files and some individual sources may have other licenses.
 -  OCRmyPDF now depends on
    `PyMuPDF <https://pymupdf.readthedocs.io/en/latest/installation/>`__.
    Including PyMuPDF is the primary reason for the change to GPLv3.

misc/batch.py

@@ -1,5 +1,23 @@
 #!/usr/bin/env python3
-# Original version by DeliciousPickle@github; modified
+# Copyright 2016 findingorder: https://github.com/findingorder
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
 
 # This script must be edited to meet your needs.
 

misc/completion/ocrmypdf.bash

@@ -1,5 +1,26 @@
 # ocrmypdf completion                                     -*- shell-script -*-
 
+# Copyright 2019 Frank Pille
+# Copyright 2020 Alex Willner
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
 set -o errexit
 
 _ocrmypdf()

misc/completion/ocrmypdf.fish

@@ -1,3 +1,23 @@
+# Copyright 2020 James R. Barlow
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
 complete -c ocrmypdf -x -n '__fish_is_first_arg' -l version
 complete -c ocrmypdf -x -n '__fish_is_first_arg' -s h -s "?" -l help
 
@@ -39,7 +59,8 @@ complete -c ocrmypdf -x -l output-type -a '(__fish_ocrmypdf_output_type)' -d "se
 
 function __fish_ocrmypdf_pdf_renderer
     echo -e "auto\t"(_ "auto select PDF renderer")
-    echo -e "hocr\t"(_ "use hocr renderer")
+    echo -e "hocr\t"(_ "use hOCR renderer")
+    echo -e "hocrdebug\t"(_ "uses hOCR renderer in debug mode, showing recognized text")
     echo -e "sandwich\t"(_ "use sandwich renderer")
 end
 complete -c ocrmypdf -x -l pdf-renderer -a '(__fish_ocrmypdf_pdf_renderer)' -d "select PDF renderer options"
@@ -115,4 +136,4 @@ complete -c ocrmypdf -r -l user-words -d "specify location of user words file"
 complete -c ocrmypdf -r -l user-patterns -d "specify location of user patterns file"
 complete -c ocrmypdf -x -l fast-web-view -d "if file size if above this amount in MB, linearize PDF"
 
-complete -c ocrmypdf -x -a "(__fish_complete_suffix .pdf)"
+complete -c ocrmypdf -x -a "(__fish_complete_suffix .pdf; __fish_complete_suffix .PDF; __fish_complete_suffix .jpg; __fish_complete_suffix .png)"

misc/docker-compose.example.yml

@@ -9,7 +9,7 @@ services:
       - "/media/scan:/input"
       - "/mnt/scan:/output"
     environment:
-      - OCR_OUTPUT_DIRECTORY_YEAR_MONT=0
+      - OCR_OUTPUT_DIRECTORY_YEAR_MONTH=0
     user: "<SET TO YOUR USER ID>:<SET TO YOUR GROUP ID>"
     entrypoint: python3
     command: watcher.py

misc/example_plugin.py

@@ -0,0 +1,84 @@
+# © 2020 James R Barlow: https://github.com/jbarlow83
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+"""
+An example of an OCRmyPDF plugin.
+
+This plugin adds two new command line arguments
+    --grayscale-ocr: converts the image to grayscale before performing OCR on it
+        (This is occasionally useful for images whose color confounds OCR. It only
+        affects the image shown to OCR. The image is not saved.)
+    --mono-page: converts pages all pages in the output file to black and white
+
+To use this from the command line:
+    ocrmypdf --plugin path/to/example_plugin.py --mono-page input.pdf output.pdf
+
+To use this as an API:
+    import ocrmypdf
+    ocrmypdf.ocr('input.pdf', 'output.pdf',
+        plugins=['path/to/example_plugin.py'], mono_page=True
+    )
+"""
+
+import logging
+
+from PIL import Image
+
+from ocrmypdf import hookimpl
+
+log = logging.getLogger(__name__)
+
+
+@hookimpl
+def add_options(parser):
+    parser.add_argument('--grayscale-ocr', action='store_true')
+    parser.add_argument('--mono-page', action='store_true')
+
+
+@hookimpl
+def prepare(options):
+    pass
+
+
+@hookimpl
+def validate(pdfinfo, options):
+    pass
+
+
+@hookimpl
+def filter_ocr_image(page, image):
+    if page.options.grayscale_ocr:
+        log.info("graying")
+        return image.convert('L')
+    return image
+
+
+@hookimpl
+def filter_page_image(page, image_filename):
+    if page.options.mono_page:
+        with Image.open(image_filename) as im:
+            im = im.convert('1')
+            im.save(image_filename)
+        return image_filename
+    else:
+        output = image_filename.with_suffix('.jpg')
+        with Image.open(image_filename) as im:
+            im.save(output)
+        return output

misc/synology.py

@@ -1,5 +1,23 @@
 #!/bin/env python3
-# Contributed by github.com/Enantiomerie
+# Copyright 2017 github.com/Enantiomerie
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
 
 # This script must be edited to meet your needs.
 
@@ -61,8 +79,10 @@ for dir_name, subdirs, file_list in os.walk(start_dir):
                 stdout=output_file,
                 stderr=subprocess.PIPE,
                 check=False,
+                text=True,
+                errors='ignore',
             )
-        logging.info(proc.stderr.read())
+        logging.info(proc.stderr)
         os.chmod(full_path_ocr, 0o664)
         os.chmod(full_path, 0o664)
         full_path_ocr_archive = sys.argv[2]

misc/watcher.py

@@ -1,18 +1,23 @@
 # Copyright (C) 2019 Ian Alexander: https://github.com/ianalexander
 # Copyright (C) 2020 James R Barlow: https://github.com/jbarlow83
 #
-# This program is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
 #
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
 #
-# You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
 
 import json
 import logging
@@ -25,6 +30,7 @@ from pathlib import Path
 import pikepdf
 from watchdog.events import PatternMatchingEventHandler
 from watchdog.observers import Observer
+from watchdog.observers.polling import PollingObserver
 
 import ocrmypdf
 
@@ -32,13 +38,14 @@ import ocrmypdf
 
 INPUT_DIRECTORY = os.getenv('OCR_INPUT_DIRECTORY', '/input')
 OUTPUT_DIRECTORY = os.getenv('OCR_OUTPUT_DIRECTORY', '/output')
-OUTPUT_DIRECTORY_YEAR_MONTH = bool(os.getenv('OCR_OUTPUT_DIRECTORY_YEAR_MONTH', False))
-ON_SUCCESS_DELETE = bool(os.getenv('OCR_ON_SUCCESS_DELETE', False))
-DESKEW = bool(os.getenv('OCR_DESKEW', False))
+OUTPUT_DIRECTORY_YEAR_MONTH = bool(os.getenv('OCR_OUTPUT_DIRECTORY_YEAR_MONTH', ''))
+ON_SUCCESS_DELETE = bool(os.getenv('OCR_ON_SUCCESS_DELETE', ''))
+DESKEW = bool(os.getenv('OCR_DESKEW', ''))
 OCR_JSON_SETTINGS = json.loads(os.getenv('OCR_JSON_SETTINGS', '{}'))
-POLL_NEW_FILE_SECONDS = os.getenv('OCR_POLL_NEW_FILE_SECONDS', 1)
-LOGLEVEL = os.environ.get('OCR_LOGLEVEL', 'INFO').upper()
-PATTERNS = ['*.pdf']
+POLL_NEW_FILE_SECONDS = int(os.getenv('OCR_POLL_NEW_FILE_SECONDS', '1'))
+USE_POLLING = bool(os.getenv('OCR_USE_POLLING', ''))
+LOGLEVEL = os.getenv('OCR_LOGLEVEL', 'INFO')
+PATTERNS = ['*.pdf', '*.PDF']
 
 log = logging.getLogger('ocrmypdf-watcher')
 
@@ -110,8 +117,14 @@ class HandleObserverEvent(PatternMatchingEventHandler):
 
 def main():
     ocrmypdf.configure_logging(
-        verbosity=ocrmypdf.Verbosity.default, manage_root_logger=True
+        verbosity=(
+            ocrmypdf.Verbosity.default
+            if LOGLEVEL != 'DEBUG'
+            else ocrmypdf.Verbosity.debug
+        ),
+        manage_root_logger=True,
     )
+    log.setLevel(LOGLEVEL)
     log.info(
         f"Starting OCRmyPDF watcher with config:\n"
         f"Input Directory: {INPUT_DIRECTORY}\n"
@@ -126,7 +139,8 @@ def main():
         f"DESKEW: {DESKEW}\n"
         f"ARGS: {OCR_JSON_SETTINGS}\n"
         f"POLL_NEW_FILE_SECONDS: {POLL_NEW_FILE_SECONDS}\n"
-        f"LOGLEVEL: {LOGLEVEL}\n"
+        f"USE_POLLING: {USE_POLLING}\n"
+        f"LOGLEVEL: {LOGLEVEL}"
     )
 
     if 'input_file' in OCR_JSON_SETTINGS or 'output_file' in OCR_JSON_SETTINGS:
@@ -134,7 +148,10 @@ def main():
         sys.exit(1)
 
     handler = HandleObserverEvent(patterns=PATTERNS)
-    observer = Observer()
+    if USE_POLLING:
+        observer = PollingObserver()
+    else:
+        observer = Observer()
     observer.schedule(handler, INPUT_DIRECTORY, recursive=True)
     observer.start()
     try:

pyproject.toml

@@ -10,8 +10,7 @@ build-backend = "setuptools.build_meta"
 
 [tool.black]
 line-length = 88
-target-version = ["py36",
-"py37", "py38"]
+target-version = ["py36", "py37", "py38"]
 skip-string-normalization = true
 include = '\.pyi?$'
 exclude = '''

requirements/dev.txt

@@ -1,2 +0,0 @@
-twine >= 1.8.1
-coverage >= 4.5

requirements/main.txt

@@ -1,10 +1,12 @@
 # requirements.txt can be used to replicate the developer's build environment
 # setup.py lists a separate set of requirements that are looser to simplify
 # installation
-cffi == 1.14.0
-img2pdf == 0.3.3
-pdfminer.six == 20200124
-pikepdf == 1.10.2
-Pillow == 7.0.0
-reportlab == 3.5.34
-tqdm == 4.42.1
+cffi == 1.14.5
+coloredlogs == 15.0  # technically optional
+img2pdf == 0.4.0
+pdfminer.six == 20201018
+pikepdf == 2.10.0
+pluggy == 0.13.1
+Pillow == 8.1.2
+reportlab == 3.5.66
+tqdm == 4.59.0

requirements/test.txt

@@ -1,7 +1,6 @@
-pytest >= 5.0.0
-pytest-helpers-namespace >= 2019.1.8
-pytest-xdist >= 1.31.0
-pytest-cov >= 2.8.0
+pytest >= 6.0.0
+pytest-xdist >= 2.2.0
+pytest-cov >= 2.11.1
 python-xmp-toolkit == 2.0.1  # requires apt-get install libexempi3
                      # or brew install exempi
 #PyMuPDF == 1.13.4    # optional

requirements/watcher.txt

@@ -1 +1 @@
-watchdog >= 0.8.2, < 1.0
+watchdog == 1.0.2

setup.cfg

@@ -1,5 +1,5 @@
 [bdist_wheel]
-python-tag = py35
+python-tag = py36
 
 [aliases]
 test=pytest
@@ -15,6 +15,8 @@ filterwarnings =
 	ignore:.*XMLParser.*:DeprecationWarning
 markers =
 	slow
+addopts =
+	-n auto
 
 [isort]
 multi_line_output=3
@@ -23,7 +25,32 @@ force_grid_wrap=0
 use_parentheses=True
 line_length=88
 known_first_party = ocrmypdf
-known_third_party = PIL,_cffi_backend,cffi,flask,gs,img2pdf,pdfminer,pikepdf,pkg_resources,pytest,reportlab,setuptools,sphinx_rtd_theme,tqdm,watchdog,werkzeug
+known_third_party = PIL,_cffi_backend,cffi,flask,img2pdf,pdfminer,pikepdf,pkg_resources,pluggy,pytest,reportlab,setuptools,sphinx_rtd_theme,tqdm,watchdog,werkzeug
 
 [metadata]
 license_file = LICENSE
+
+[coverage:paths]
+source =
+	src/ocrmypdf
+
+[coverage:run]
+branch = true
+parallel = true
+concurrency = multiprocessing
+
+[coverage:report]
+# Regexes for lines to exclude from consideration
+exclude_lines =
+    # Have to re-enable the standard pragma
+    pragma: no cover
+
+    # Don't complain if tests don't hit defensive assertion code:
+    raise AssertionError
+    raise NotImplementedError
+
+    # Don't complain if non-runnable code isn't run:
+    if 0:
+	if False:
+    if __name__ == .__main__.:
+	if TYPE_CHECKING:

setup.py

@@ -2,20 +2,10 @@
 # -*- coding: utf-8 -*-
 # © 2015 James R. Barlow: github.com/jbarlow83
 #
-# This file is part of OCRmyPDF.
-#
-# OCRmyPDF is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# OCRmyPDF is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with OCRmyPDF.  If not, see <http://www.gnu.org/licenses/>.
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
 
 from __future__ import print_function, unicode_literals
 
@@ -27,26 +17,6 @@ if sys.version_info < (3, 6):
     print("Python 3.6 or newer is required", file=sys.stderr)
     sys.exit(1)
 
-
-# pylint: disable=w0613
-
-
-command = next((arg for arg in sys.argv[1:] if not arg.startswith('-')), '')
-if command.startswith('install') or command in [
-    'check',
-    'test',
-    'nosetests',
-    'easy_install',
-]:
-    forced = '--force' in sys.argv
-    if forced:
-        print("The argument --force is deprecated. Please discontinue use.")
-
-
-if 'upload' in sys.argv[1:]:
-    print('Use twine to upload the package - setup.py upload is insecure')
-    sys.exit(1)
-
 tests_require = open('requirements/test.txt', encoding='utf-8').read().splitlines()
 
 
@@ -62,7 +32,7 @@ setup(
     long_description_content_type='text/markdown',
     url='https://github.com/jbarlow83/OCRmyPDF',
     author='James R. Barlow',
-    author_email='jim@purplerock.ca',
+    author_email='james@purplerock.ca',
     packages=find_packages('src', exclude=["tests", "tests.*"]),
     package_dir={'': 'src'},
     keywords=['PDF', 'OCR', 'optical character recognition', 'PDF/A', 'scanning'],
@@ -70,12 +40,13 @@ setup(
         "Programming Language :: Python :: 3.6",
         "Programming Language :: Python :: 3.7",
         "Programming Language :: Python :: 3.8",
+        "Programming Language :: Python :: 3.9",
         "Development Status :: 5 - Production/Stable",
         "Environment :: Console",
         "Intended Audience :: End Users/Desktop",
         "Intended Audience :: Science/Research",
         "Intended Audience :: System Administrators",
-        "License :: OSI Approved :: GNU General Public License v3 (GPLv3)",
+        "License :: OSI Approved :: Mozilla Public License 2.0 (MPL 2.0)",
         "Operating System :: MacOS :: MacOS X",
         "Operating System :: Microsoft :: Windows :: Windows 10",
         "Operating System :: POSIX",
@@ -88,25 +59,26 @@ setup(
     python_requires=' >= 3.6',
     setup_requires=[  # can be removed whenever we can drop pip 9 support
         'cffi >= 1.9.1',  # to build the leptonica module
-        'pytest-runner',  # to enable python setup.py test
         'setuptools_scm',  # so that version will work
         'setuptools_scm_git_archive',  # enable version from github tarballs
     ],
     use_scm_version={'version_scheme': 'post-release'},
     cffi_modules=['src/ocrmypdf/lib/compile_leptonica.py:ffibuilder'],
     install_requires=[
-        'chardet >= 3.0.4, < 4',  # unlisted requirement of pdfminer.six 20181108
         'cffi >= 1.9.1',  # must be a setup and install requirement
-        'img2pdf >= 0.3.0, < 0.4',  # pure Python, so track HEAD closely
-        'pdfminer.six >= 20181108, <= 20200124',
-        'pikepdf >= 1.8.1, < 2',
-        'Pillow >= 6.2.0',
-        'reportlab >= 3.3.0',  # oldest released version with sane image handling
+        'coloredlogs >= 14.0',  # strictly optional
+        'img2pdf >= 0.3.0, < 0.5',  # pure Python, so track HEAD closely
+        'pdfminer.six >= 20191110, != 20200720, <= 20201018',
+        "pikepdf >= 2.10.0",
+        'Pillow >= 8.1.2',
+        'pluggy >= 0.13.0, < 1.0',
+        'reportlab >= 3.5.66',
+        'setuptools',
         'tqdm >= 4',
     ],
     tests_require=tests_require,
     entry_points={'console_scripts': ['ocrmypdf = ocrmypdf.__main__:run']},
-    package_data={'ocrmypdf': ['data/sRGB.icc']},
+    package_data={'ocrmypdf': ['data/sRGB.icc', 'py.typed']},
     include_package_data=True,
     zip_safe=False,
     project_urls={

src/ocrmypdf/RELEASE.md

@@ -0,0 +1,35 @@
+# Release checklist
+
+## Patch release
+
+- Check `pytest`
+
+- Update release notes
+
+## Minor release
+
+## Major release
+
+- Run `pre-commit autoupdate`
+
+- Check README.md
+
+- Check setup.py
+
+    - Are classifiers up to date?
+    - Is `python_requires` correct?
+    - Python 3.6 is EOL on December 2021-12. Could drop support then.
+    - Can we tighten any `install_requires` dependencies?
+
+- Search for old version shims we can remove
+
+    - "shim"
+    - ` pikepdf.__version__`
+
+- Search for deprecation: search all files for deprec*, etc.
+
+- Check requirements/*
+
+- Delete `tests/cache`, do `pytest --runslow`, and update cache.
+
+- Do `pytest --cov-report html`

src/ocrmypdf/__init__.py

@@ -1,24 +1,18 @@
 # © 2017 James R. Barlow: github.com/jbarlow83
 #
-# This file is part of OCRmyPDF.
-#
-# OCRmyPDF is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# OCRmyPDF is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with OCRmyPDF.  If not, see <http://www.gnu.org/licenses/>.
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
-from . import helpers, hocrtransform, leptonica, pdfa, pdfinfo
-from ._version import PROGRAM_NAME, __version__
-from .api import Verbosity, configure_logging, ocr
-from .exceptions import (
+
+from pluggy import HookimplMarker as _HookimplMarker
+
+from ocrmypdf import helpers, hocrtransform, leptonica, pdfa, pdfinfo
+from ocrmypdf._concurrent import Executor
+from ocrmypdf._jobcontext import PageContext, PdfContext
+from ocrmypdf._version import PROGRAM_NAME, __version__
+from ocrmypdf.api import Verbosity, configure_logging, ocr
+from ocrmypdf.exceptions import (
     BadArgsError,
     DpiError,
     EncryptedPdfError,
@@ -33,3 +27,6 @@ from .exceptions import (
     TesseractConfigError,
     UnsupportedImageFormatError,
 )
+from ocrmypdf.pluginspec import OcrEngine, OrientationConfidence
+
+hookimpl = _HookimplMarker('ocrmypdf')

src/ocrmypdf/__main__.py

@@ -1,36 +1,38 @@
 #!/usr/bin/env python3
 # © 2015-19 James R. Barlow: github.com/jbarlow83
 #
-# This file is part of OCRmyPDF.
-#
-# OCRmyPDF is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# OCRmyPDF is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with OCRmyPDF.  If not, see <http://www.gnu.org/licenses/>.
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
 
 import logging
 import os
+import signal
 import sys
+from multiprocessing import set_start_method
 
-from . import __version__
-from ._jobcontext import make_logger
-from ._sync import run_pipeline
-from ._validation import check_closed_streams, check_options
-from .api import Verbosity, configure_logging
-from .cli import parser
-from .exceptions import BadArgsError, ExitCode, MissingDependencyError
+from ocrmypdf import __version__
+from ocrmypdf._plugin_manager import get_parser_options_plugins
+from ocrmypdf._sync import run_pipeline
+from ocrmypdf._validation import check_closed_streams, check_options
+from ocrmypdf.api import Verbosity, configure_logging
+from ocrmypdf.exceptions import (
+    BadArgsError,
+    ExitCode,
+    InputFileError,
+    MissingDependencyError,
+)
+
+log = logging.getLogger('ocrmypdf')
+
+
+def sigbus(*args):
+    raise InputFileError("Lost access to the input file")
 
 
 def run(args=None):
-    options = parser.parse_args(args=args)
+    _parser, options, plugin_manager = get_parser_options_plugins(args=args)
 
     if not check_closed_streams(options):
         return ExitCode.bad_args
@@ -45,12 +47,14 @@ def run(args=None):
         verbosity = Verbosity.quiet
         options.progress_bar = False
     configure_logging(
-        verbosity, progress_bar_friendly=options.progress_bar, manage_root_logger=True
+        verbosity,
+        progress_bar_friendly=options.progress_bar,
+        manage_root_logger=True,
+        plugin_manager=plugin_manager,
     )
-    log = make_logger('ocrmypdf')
-    log.debug('ocrmypdf ' + __version__)
+    log.debug('ocrmypdf %s', __version__)
     try:
-        check_options(options)
+        check_options(options, plugin_manager)
     except ValueError as e:
         log.error(e)
         return ExitCode.bad_args
@@ -61,9 +65,14 @@ def run(args=None):
         log.error(e)
         return ExitCode.missing_dependency
 
-    result = run_pipeline(options=options)
+    if hasattr(signal, 'SIGBUS'):
+        signal.signal(signal.SIGBUS, sigbus)
+
+    result = run_pipeline(options=options, plugin_manager=plugin_manager)
     return result
 
 
 if __name__ == '__main__':
+    if sys.platform == 'darwin' and sys.version_info < (3, 8):
+        set_start_method('spawn')  # see python bpo-33725
     sys.exit(run())

src/ocrmypdf/_concurrent.py

@@ -0,0 +1,133 @@
+# © 2020 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import threading
+from abc import ABC, abstractmethod
+from typing import Callable, Iterable, Optional
+
+
+def _task_noop(*_args, **_kwargs):
+    return
+
+
+class NullProgressBar:
+    def __init__(self, **kwargs):
+        pass
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_value, traceback):
+        return False
+
+    def update(self, _arg=None):
+        return
+
+
+class Executor(ABC):
+    pool_lock = threading.Lock()
+    pbar_class = NullProgressBar
+
+    def __init__(self, *, pbar_class=None):
+        if pbar_class:
+            self.pbar_class = pbar_class
+
+    def __call__(
+        self,
+        *,
+        use_threads: bool,
+        max_workers: int,
+        tqdm_kwargs: dict,
+        worker_initializer: Optional[Callable] = None,
+        task: Optional[Callable] = None,
+        task_arguments: Optional[Iterable] = None,
+        task_finished: Optional[Callable] = None,
+    ) -> None:
+        """
+        Set up parallel execution and progress reporting.
+
+        Args:
+            use_threads: If ``False``, the workload is the sort that will benefit from
+                running in a multiprocessing context (for example, it uses Python
+                heavily, and parallelizing it with threads is not expected to be
+                performant).
+            max_workers: The maximum number of workers that should be run.
+            tdqm_kwargs: Arguments to set up the progress bar.
+            worker_initializer: Called when a worker is initialized, in the worker's
+                execution context. If the child workers are processes, it must be
+                possible to marshall/pickle the worker initializer.
+                ``functools.partial`` can be used to bind parameters.
+            task: Called when the worker starts a new task, in the worker's execution
+                context. Must be possible to marshall to the worker.
+            task_finished: Called when a worker finishes a task, in the parent's
+                context.
+            task_arguments: An iterable that generates a group of parameters for each
+                task. This runs in the parent's context, but the parameters must be
+                marshallable to the worker.
+        """
+
+        if not task_arguments:
+            return  # Nothing to do!
+        if not worker_initializer:
+            worker_initializer = _task_noop
+        if not task_finished:
+            task_finished = _task_noop
+        if not task:
+            task = _task_noop
+
+        with self.pool_lock:
+            self._execute(
+                use_threads=use_threads,
+                max_workers=max_workers,
+                tqdm_kwargs=tqdm_kwargs,
+                worker_initializer=worker_initializer,
+                task=task,
+                task_arguments=task_arguments,
+                task_finished=task_finished,
+            )
+
+    @abstractmethod
+    def _execute(
+        self,
+        *,
+        use_threads: bool,
+        max_workers: int,
+        tqdm_kwargs: dict,
+        worker_initializer: Callable,
+        task: Callable,
+        task_arguments: Iterable,
+        task_finished: Callable,
+    ):
+        """Custom executors should override this method."""
+
+
+def setup_executor(plugin_manager) -> Executor:
+    pbar_class = plugin_manager.hook.get_progressbar_class()
+    return plugin_manager.hook.get_executor(progressbar_class=pbar_class)
+
+
+class SerialExecutor(Executor):
+    """Implements a purely sequential executor using the parallel protocol.
+
+    The current process/thread will be the worker that executes all tasks
+    in order. As such, ``worker_initializer`` will never be called.
+    """
+
+    def _execute(
+        self,
+        *,
+        use_threads: bool,
+        max_workers: int,
+        tqdm_kwargs: dict,
+        worker_initializer: Callable,
+        task: Callable,
+        task_arguments: Iterable,
+        task_finished: Callable,
+    ):  # pylint: disable=unused-argument
+        with self.pbar_class(**tqdm_kwargs) as pbar:
+            for args in task_arguments:
+                result = task(args)
+                task_finished(result, pbar)

src/ocrmypdf/_exec/__init__.py

@@ -0,0 +1,8 @@
+# © 2020 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+"""Manage third party executables"""

src/ocrmypdf/_exec/ghostscript.py

@@ -0,0 +1,270 @@
+# © 2017 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+"""Interface to Ghostscript executable"""
+
+import logging
+import os
+import re
+from io import BytesIO
+from os import fspath
+from pathlib import Path
+from shutil import which
+from subprocess import PIPE, CalledProcessError
+from typing import Optional
+
+from PIL import Image
+
+from ocrmypdf.exceptions import MissingDependencyError, SubprocessOutputError
+from ocrmypdf.helpers import Resolution
+from ocrmypdf.subprocess import get_version, run, run_polling_stderr
+
+log = logging.getLogger(__name__)
+
+missing_gs_error = """
+---------------------------------------------------------------------
+This error normally occurs when ocrmypdf find can't Ghostscript.
+Please ensure Ghostscript is installed and its location is added to
+the system PATH environment variable.
+
+For details see:
+    https://ocrmypdf.readthedocs.io/en/latest/installation.html
+---------------------------------------------------------------------
+"""
+
+_gswin = None
+if os.name == 'nt':
+    _gswin = which('gswin64c')
+    if not _gswin:
+        _gswin = which('gswin32c')
+        if not _gswin:
+            raise MissingDependencyError(missing_gs_error)
+    _gswin = Path(_gswin).stem
+
+GS = _gswin if _gswin else 'gs'
+del _gswin
+
+
+def version():
+    return get_version(GS)
+
+
+def jpeg_passthrough_available() -> bool:
+    """Returns True if the installed version of Ghostscript supports JPEG passthru
+
+    Prior to 9.23, Ghostscript decoded and re-encoded JPEGs internally. In 9.23
+    it gained the ability to keep JPEGs unmodified. However, the 9.23
+    implementation was buggy and would deletes the last two bytes of images in
+    some cases, as reported here.
+    https://bugs.ghostscript.com/show_bug.cgi?id=699216
+
+    The issue was fixed for 9.24, hence that is the first version we consider
+    the feature available. (Ghostscript 9.24 has its own problems is blacklisted.)
+    """
+    return version() >= '9.24'
+
+
+def _gs_error_reported(stream) -> bool:
+    return True if re.search(r'error', stream, flags=re.IGNORECASE) else False
+
+
+def rasterize_pdf(
+    input_file: os.PathLike,
+    output_file: os.PathLike,
+    *,
+    raster_device: str,
+    raster_dpi: Resolution,
+    pageno: int = 1,
+    page_dpi: Optional[Resolution] = None,
+    rotation: Optional[int] = None,
+    filter_vector: bool = False,
+):
+    """Rasterize one page of a PDF at resolution raster_dpi in canvas units."""
+    raster_dpi = raster_dpi.round(6)
+    if not page_dpi:
+        page_dpi = raster_dpi
+
+    args_gs = (
+        [
+            GS,
+            '-dQUIET',
+            '-dSAFER',
+            '-dBATCH',
+            '-dNOPAUSE',
+            f'-sDEVICE={raster_device}',
+            f'-dFirstPage={pageno}',
+            f'-dLastPage={pageno}',
+            f'-r{raster_dpi.x:f}x{raster_dpi.y:f}',
+        ]
+        + (['-dFILTERVECTOR'] if filter_vector else [])
+        + [
+            '-o',
+            '-',
+            '-sstdout=%stderr',
+            '-dAutoRotatePages=/None',  # Probably has no effect on raster
+            '-f',
+            fspath(input_file),
+        ]
+    )
+
+    try:
+        p = run(args_gs, stdout=PIPE, stderr=PIPE, check=True)
+    except CalledProcessError as e:
+        log.error(e.stderr.decode(errors='replace'))
+        raise SubprocessOutputError('Ghostscript rasterizing failed')
+    else:
+        stderr = p.stderr.decode(errors='replace')
+        if _gs_error_reported(stderr):
+            log.error(stderr)
+
+    with Image.open(BytesIO(p.stdout)) as im:
+        if rotation is not None:
+            log.debug("Rotating output by %i", rotation)
+            # rotation is a clockwise angle and Image.ROTATE_* is
+            # counterclockwise so this cancels out the rotation
+            if rotation == 90:
+                im = im.transpose(Image.ROTATE_90)
+            elif rotation == 180:
+                im = im.transpose(Image.ROTATE_180)
+            elif rotation == 270:
+                im = im.transpose(Image.ROTATE_270)
+            if rotation % 180 == 90:
+                page_dpi = page_dpi.flip_axis()
+        im.save(fspath(output_file), dpi=page_dpi)
+
+
+class GhostscriptFollower:
+    re_process = re.compile(r"Processing pages \d+ through (\d+).")
+    re_page = re.compile(r"Page (\d+)")
+
+    def __init__(self, progressbar_class):
+        self.count = 0
+        self.progressbar_class = progressbar_class
+        self.progressbar = None
+
+    def __call__(self, line):
+        if not self.progressbar_class:
+            return
+        if not self.progressbar:
+            m = self.re_process.match(line.strip())
+            if m:
+                self.count = int(m.group(1))
+                self.progressbar = self.progressbar_class(
+                    total=self.count, desc="PDF/A conversion", unit='page'
+                )
+                return
+        else:
+            m = self.re_page.match(line.strip())
+            if m:
+                self.progressbar.update()
+
+
+def generate_pdfa(
+    pdf_pages,
+    output_file: os.PathLike,
+    *,
+    compression: str,
+    pdf_version: str = '1.5',
+    pdfa_part: str = '2',
+    progressbar_class=None,
+):
+    # Ghostscript's compression is all or nothing. We can either force all images
+    # to JPEG, force all to Flate/PNG, or let it decide how to encode the images.
+    # In most case it's best to let it decide.
+    compression_args = []
+    if compression == 'jpeg':
+        compression_args = [
+            "-dAutoFilterColorImages=false",
+            "-dColorImageFilter=/DCTEncode",
+            "-dAutoFilterGrayImages=false",
+            "-dGrayImageFilter=/DCTEncode",
+        ]
+    elif compression == 'lossless':
+        compression_args = [
+            "-dAutoFilterColorImages=false",
+            "-dColorImageFilter=/FlateEncode",
+            "-dAutoFilterGrayImages=false",
+            "-dGrayImageFilter=/FlateEncode",
+        ]
+    else:
+        compression_args = [
+            "-dAutoFilterColorImages=true",
+            "-dAutoFilterGrayImages=true",
+        ]
+
+    strategy = 'LeaveColorUnchanged'
+    # Older versions of Ghostscript expect a leading slash in
+    # sColorConversionStrategy, newer ones should not have it. See Ghostscript
+    # git commit fe1c025d.
+    strategy = ('/' + strategy) if version() < '9.19' else strategy
+
+    if version() == '9.23':
+        # 9.23: added JPEG passthrough as a new feature, but with a bug that
+        # incorrectly formats some images. Fixed as of 9.24. So we disable this
+        # feature for 9.23.
+        # https://bugs.ghostscript.com/show_bug.cgi?id=699216
+        compression_args.append('-dPassThroughJPEGImages=false')
+
+    # nb no need to specify ProcessColorModel when ColorConversionStrategy
+    # is set; see:
+    # https://bugs.ghostscript.com/show_bug.cgi?id=699392
+    args_gs = (
+        [
+            GS,
+            "-dBATCH",
+            "-dNOPAUSE",
+            "-dSAFER",
+            "-dCompatibilityLevel=" + str(pdf_version),
+            "-sDEVICE=pdfwrite",
+            "-dAutoRotatePages=/None",
+            "-sColorConversionStrategy=" + strategy,
+        ]
+        + compression_args
+        + [
+            "-dJPEGQ=95",
+            "-dPDFA=" + pdfa_part,
+            "-dPDFACompatibilityPolicy=1",
+            "-o",
+            "-",
+            "-sstdout=%stderr",
+        ]
+    )
+    args_gs.extend(fspath(s) for s in pdf_pages)  # Stringify Path objs
+
+    try:
+        with Path(output_file).open('wb') as output:
+            p = run_polling_stderr(
+                args_gs,
+                stdout=output,
+                stderr=PIPE,
+                check=True,
+                text=True,
+                encoding='utf-8',
+                errors='replace',
+                callback=GhostscriptFollower(progressbar_class),
+            )
+    except CalledProcessError as e:
+        # Ghostscript does not change return code when it fails to create
+        # PDF/A - check PDF/A status elsewhere
+        log.error(e.stderr)
+        raise SubprocessOutputError('Ghostscript PDF/A rendering failed') from e
+    else:
+        stderr = p.stderr
+        # If there is an error we log the whole stderr, except for filtering
+        # duplicates.
+        if _gs_error_reported(stderr):
+            last_part = None
+            repcount = 0
+            for part in stderr.split('****'):
+                if part != last_part:
+                    if repcount > 1:
+                        log.error(f"(previous error message repeated {repcount} times)")
+                        repcount = 0
+                    log.error(part)
+                else:
+                    repcount += 1
+                last_part = part

src/ocrmypdf/_exec/jbig2enc.py

@@ -1,30 +1,18 @@
 # © 2018 James R. Barlow: github.com/jbarlow83
 #
-# This file is part of OCRmyPDF.
-#
-# OCRmyPDF is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# OCRmyPDF is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with OCRmyPDF.  If not, see <http://www.gnu.org/licenses/>.
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
 
 """Interface to jbig2 executable"""
 
-from functools import lru_cache
 from subprocess import PIPE
 
-from ..exceptions import MissingDependencyError
-from . import get_version, run
+from ocrmypdf.exceptions import MissingDependencyError
+from ocrmypdf.subprocess import get_version, run
 
 
-@lru_cache(maxsize=1)
 def version():
     return get_version('jbig2', regex=r'jbig2enc (\d+(\.\d+)*).*')
 
@@ -53,9 +41,17 @@ def convert_group(*, cwd, infiles, out_prefix):
     return proc
 
 
+def convert_group_mp(args):
+    return convert_group(cwd=args[0], infiles=args[1], out_prefix=args[2])
+
+
 def convert_single(*, cwd, infile, outfile):
     args = ['jbig2', '-p', infile]
     with open(outfile, 'wb') as fstdout:
         proc = run(args, cwd=cwd, stdout=fstdout, stderr=PIPE)
     proc.check_returncode()
     return proc
+
+
+def convert_single_mp(args):
+    return convert_single(cwd=args[0], infile=args[1], outfile=args[2])

src/ocrmypdf/_exec/pngquant.py

@@ -0,0 +1,65 @@
+# © 2018 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+"""Interface to pngquant executable"""
+
+from contextlib import contextmanager
+from io import BytesIO
+from pathlib import Path
+from subprocess import PIPE
+
+from PIL import Image
+
+from ocrmypdf.exceptions import MissingDependencyError
+from ocrmypdf.subprocess import get_version, run
+
+
+def version():
+    return get_version('pngquant', regex=r'(\d+(\.\d+)*).*')
+
+
+def available():
+    try:
+        version()
+    except MissingDependencyError:
+        return False
+    return True
+
+
+@contextmanager
+def input_as_png(input_file: Path):
+    if not input_file.name.endswith('.png'):
+        with Image.open(input_file) as im:
+            bio = BytesIO()
+            im.save(bio, format='png')
+            bio.seek(0)
+            yield bio
+    else:
+        with open(input_file, 'rb') as f:
+            yield f
+
+
+def quantize(input_file: Path, output_file: Path, quality_min: int, quality_max: int):
+    with input_as_png(input_file) as input_stream:
+        args = [
+            'pngquant',
+            '--force',
+            '--skip-if-larger',
+            '--quality',
+            f'{quality_min}-{quality_max}',
+            '--',  # pngquant: stop processing arguments
+            '-',  # pngquant: stream input and output
+        ]
+        result = run(args, stdin=input_stream, stdout=PIPE, stderr=PIPE, check=False)
+
+    if result.returncode == 0:
+        # input_file could be the same as output_file, so we defer the write
+        output_file.write_bytes(result.stdout)
+
+
+def quantize_mp(args):
+    return quantize(*args)

src/ocrmypdf/_exec/tesseract.py

@@ -1,37 +1,33 @@
 # © 2017 James R. Barlow: github.com/jbarlow83
 #
-# This file is part of OCRmyPDF.
-#
-# OCRmyPDF is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# OCRmyPDF is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with OCRmyPDF.  If not, see <http://www.gnu.org/licenses/>.
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
 
 """Interface to Tesseract executable"""
 
 import logging
 import os
+import re
 import shutil
 from collections import namedtuple
-from contextlib import suppress
+from distutils.version import StrictVersion
 from os import fspath
+from pathlib import Path
 from subprocess import PIPE, STDOUT, CalledProcessError, TimeoutExpired
+from typing import List, Optional
 
-from ..exceptions import (
+from PIL import Image
+
+from ocrmypdf.exceptions import (
     MissingDependencyError,
     SubprocessOutputError,
     TesseractConfigError,
 )
-from ..helpers import page_number, safe_symlink
-from . import get_version, run
+from ocrmypdf.subprocess import get_version, run
+
+log = logging.getLogger(__name__)
 
 OrientationConfidence = namedtuple('OrientationConfidence', ('angle', 'confidence'))
 
@@ -59,52 +55,39 @@ class TesseractLoggerAdapter(logging.LoggerAdapter):
         return '[tesseract] %s' % (msg), kwargs
 
 
-def version(tesseract_env=None):
-    return get_version('tesseract', regex=r'tesseract\s(.+)', env=tesseract_env)
+class TesseractVersion(StrictVersion):
+    version_re = re.compile(
+        r'''
+        ^(\d+) \. (\d+) (\. (\d+))?  # groups: 1/major, 2/minor, 3/[skip], 4/patch
+        [-]?  # optional hyphen separator
+        (?:(alpha|beta|rc|dev)[.\-\ ]?(\d+)?)?  # 5/prerelease, 6/prerelease_num
+        $
+        ''',
+        re.VERBOSE | re.ASCII,
+    )
+
+    def parse(self, vstring):
+        try:
+            super().parse(vstring)
+        except TypeError as e:
+            if 'int() argument must be a string' in str(e):
+                super().parse(vstring + '0')
 
 
-def v4(tesseract_env=None):
-    "Is this Tesseract v4.0?"
-    return version(tesseract_env) >= '4'
+def version():
+    return get_version('tesseract', regex=r'tesseract\s(.+)')
 
 
-def has_textonly_pdf(tesseract_env=None, langs=None):
-    """Does Tesseract have textonly_pdf capability?
-
-    Available in v4.00.00alpha since January 2017. Best to
-    parse the parameter list.
-    """
-    args_tess = tess_base_args(langs, engine_mode=None) + ['--print-parameters', 'pdf']
-    params = ''
-    try:
-        proc = run(
-            args_tess,
-            check=True,
-            universal_newlines=True,
-            stdout=PIPE,
-            stderr=STDOUT,
-            env=tesseract_env,
-        )
-        params = proc.stdout
-    except CalledProcessError as e:
-        raise MissingDependencyError(
-            "Could not --print-parameters from tesseract"
-        ) from e
-    if 'textonly_pdf' in params:
-        return True
-    return False
-
-
-def has_user_words(tesseract_env=None):
+def has_user_words():
     """Does Tesseract have --user-words capability?
 
     Not available in 4.0, but available in 4.1. Also available in 3.x, but
     we no longer support 3.x.
     """
-    return version(tesseract_env) >= '4.1'
+    return version() >= '4.1'
 
 
-def languages(tesseract_env=None):
+def get_languages():
     def lang_error(output):
         msg = (
             "Tesseract failed to report available languages.\n"
@@ -118,11 +101,11 @@ def languages(tesseract_env=None):
     try:
         proc = run(
             args_tess,
-            universal_newlines=True,
+            text=True,
             stdout=PIPE,
             stderr=STDOUT,
+            logs_errors_to_stdout=True,
             check=True,
-            env=tesseract_env,
         )
         output = proc.stdout
     except CalledProcessError as e:
@@ -131,11 +114,11 @@ def languages(tesseract_env=None):
     for line in output.splitlines():
         if line.startswith('Error'):
             raise MissingDependencyError(lang_error(output))
-    header, *rest = output.splitlines()
+    _header, *rest = output.splitlines()
     return set(lang.strip() for lang in rest)
 
 
-def tess_base_args(langs, engine_mode):
+def tess_base_args(langs: List[str], engine_mode: Optional[int]) -> List[str]:
     args = ['tesseract']
     if langs:
         args.extend(['-l', '+'.join(langs)])
@@ -144,7 +127,7 @@ def tess_base_args(langs, engine_mode):
     return args
 
 
-def get_orientation(input_file, engine_mode, timeout: float, log, tesseract_env=None):
+def get_orientation(input_file: Path, engine_mode: Optional[int], timeout: float):
     args_tesseract = tess_base_args(['osd'], engine_mode) + [
         '--psm',
         '0',
@@ -153,19 +136,13 @@ def get_orientation(input_file, engine_mode, timeout: float, log, tesseract_env=
     ]
 
     try:
-        p = run(
-            args_tesseract,
-            stdout=PIPE,
-            stderr=STDOUT,
-            timeout=timeout,
-            check=True,
-            env=tesseract_env,
-        )
+        p = run(args_tesseract, stdout=PIPE, stderr=STDOUT, timeout=timeout, check=True)
         stdout = p.stdout
     except TimeoutExpired:
         return OrientationConfidence(angle=0, confidence=0.0)
     except CalledProcessError as e:
-        tesseract_log_output(log, e.output, input_file)
+        tesseract_log_output(e.stdout)
+        tesseract_log_output(e.stderr)
         if (
             b'Too few characters. Skipping this page' in e.output
             or b'Image too large' in e.output
@@ -187,15 +164,17 @@ def get_orientation(input_file, engine_mode, timeout: float, log, tesseract_env=
         return oc
 
 
-def tesseract_log_output(mainlog, stdout, input_file):
-    log = TesseractLoggerAdapter(
-        mainlog, extra=mainlog.extra if hasattr(mainlog, 'extra') else None
+def tesseract_log_output(stream):
+    tlog = TesseractLoggerAdapter(
+        log, extra=log.extra if hasattr(log, 'extra') else None
     )
 
+    if not stream:
+        return
     try:
-        text = stdout.decode()
+        text = stream.decode()
     except UnicodeDecodeError:
-        text = stdout.decode('utf-8', 'ignore')
+        text = stream.decode('utf-8', 'ignore')
 
     lines = text.splitlines()
     for line in lines:
@@ -204,67 +183,59 @@ def tesseract_log_output(mainlog, stdout, input_file):
         elif line.startswith("Warning in pixReadMem"):
             continue
         elif 'diacritics' in line:
-            log.warning("lots of diacritics - possibly poor OCR")
+            tlog.warning("lots of diacritics - possibly poor OCR")
         elif line.startswith('OSD: Weak margin'):
-            log.warning("unsure about page orientation")
+            tlog.warning("unsure about page orientation")
         elif 'Error in pixScanForForeground' in line:
             pass  # Appears to be spurious/problem with nonwhite borders
         elif 'Error in boxClipToRectangle' in line:
             pass  # Always appears with pixScanForForeground message
         elif 'parameter not found: ' in line.lower():
-            log.error(line.strip())
+            tlog.error(line.strip())
             problem = line.split('found: ')[1]
             raise TesseractConfigError(problem)
         elif 'error' in line.lower() or 'exception' in line.lower():
-            log.error(line.strip())
+            tlog.error(line.strip())
         elif 'warning' in line.lower():
-            log.warning(line.strip())
+            tlog.warning(line.strip())
         elif 'read_params_file' in line.lower():
-            log.error(line.strip())
+            tlog.error(line.strip())
         else:
-            log.info(line.strip())
+            tlog.info(line.strip())
 
 
-def page_timedout(log, input_file, timeout):
+def page_timedout(timeout):
     if timeout == 0:
         return
-    prefix = f"{(page_number(input_file)):4d}: [tesseract] "
-    log.warning(prefix + " took too long to OCR - skipping")
+    log.warning("[tesseract] took too long to OCR - skipping")
 
 
-def _generate_null_hocr(output_hocr, output_sidecar, image):
+def _generate_null_hocr(output_hocr, output_text, image):
     """Produce a .hocr file that reports no text detected on a page that is
     the same size as the input image."""
-    from PIL import Image
-
     with Image.open(image) as im:
         w, h = im.size
 
-    with open(output_hocr, 'w', encoding="utf-8") as f:
-        f.write(HOCR_TEMPLATE.format(w, h))
-    with open(output_sidecar, 'w', encoding='utf-8') as f:
-        f.write('[skipped page]')
+    output_hocr.write_text(HOCR_TEMPLATE.format(w, h), encoding='utf-8')
+    output_text.write_text('[skipped page]', encoding='utf-8')
 
 
 def generate_hocr(
-    input_file,
-    output_files,
-    language: list,
-    engine_mode,
-    tessconfig: list,
+    *,
+    input_file: Path,
+    output_hocr: Path,
+    output_text: Path,
+    languages: List[str],
+    engine_mode: int,
+    tessconfig: List[str],
     timeout: float,
     pagesegmode: int,
     user_words,
     user_patterns,
-    tesseract_env,
-    log,
 ):
+    prefix = output_hocr.with_suffix('')
 
-    output_hocr = next(o for o in output_files if fspath(o).endswith('.hocr'))
-    output_sidecar = next(o for o in output_files if fspath(o).endswith('.txt'))
-    prefix = os.path.splitext(output_hocr)[0]
-
-    args_tesseract = tess_base_args(language, engine_mode)
+    args_tesseract = tess_base_args(languages, engine_mode)
 
     if pagesegmode is not None:
         args_tesseract.extend(['--psm', str(pagesegmode)])
@@ -275,94 +246,70 @@ def generate_hocr(
     if user_patterns:
         args_tesseract.extend(['--user-patterns', user_patterns])
 
-    # Reminder: test suite tesseract spoofers will break after any changes
+    # Reminder: test suite tesseract test plugins will break after any changes
     # to the number of order parameters here
     args_tesseract.extend([input_file, prefix, 'hocr', 'txt'] + tessconfig)
     try:
-        p = run(
-            args_tesseract,
-            stdout=PIPE,
-            stderr=STDOUT,
-            timeout=timeout,
-            check=True,
-            env=tesseract_env,
-        )
+        p = run(args_tesseract, stdout=PIPE, stderr=STDOUT, timeout=timeout, check=True)
         stdout = p.stdout
     except TimeoutExpired:
         # Generate a HOCR file with no recognized text if tesseract times out
         # Temporary workaround to hocrTransform not being able to function if
         # it does not have a valid hOCR file.
-        page_timedout(log, input_file, timeout)
-        _generate_null_hocr(output_hocr, output_sidecar, input_file)
+        page_timedout(timeout)
+        _generate_null_hocr(output_hocr, output_text, input_file)
     except CalledProcessError as e:
-        tesseract_log_output(log, e.output, input_file)
+        tesseract_log_output(e.output)
         if b'Image too large' in e.output:
-            _generate_null_hocr(output_hocr, output_sidecar, input_file)
+            _generate_null_hocr(output_hocr, output_text, input_file)
             return
 
         raise SubprocessOutputError() from e
     else:
-        tesseract_log_output(log, stdout, input_file)
+        tesseract_log_output(stdout)
         # The sidecar text file will get the suffix .txt; rename it to
         # whatever caller wants it named
-        if os.path.exists(prefix + '.txt'):
-            shutil.move(prefix + '.txt', output_sidecar)
+        if prefix.with_suffix('.txt').exists():
+            shutil.move(prefix.with_suffix('.txt'), output_text)
 
 
-def use_skip_page(text_only, skip_pdf, output_pdf, output_text):
-    with open(output_text, 'w') as f:
-        f.write('[skipped page]')
+def use_skip_page(output_pdf, output_text):
+    output_text.write_text('[skipped page]', encoding='utf-8')
 
-    if skip_pdf and not text_only:
-        # Substitute a "skipped page"
-        with suppress(FileNotFoundError):
-            os.remove(output_pdf)  # In case it was partially created
-        safe_symlink(skip_pdf, output_pdf)
-        return
-
-    # Or normally, just write a 0 byte file to the output to indicate a skip
-    with open(output_pdf, 'wb') as out:
-        out.write(b'')
+    # A 0 byte file to the output to indicate a skip
+    output_pdf.write_bytes(b'')
 
 
 def generate_pdf(
     *,
-    input_image,
-    skip_pdf=None,
-    output_pdf,
-    output_text,
-    language: list,
-    engine_mode,
-    text_only: bool,
-    tessconfig: list,
+    input_file: Path,
+    output_pdf: Path,
+    output_text: Path,
+    languages: List[str],
+    engine_mode: int,
+    tessconfig: List[str],
     timeout: float,
     pagesegmode: int,
     user_words,
     user_patterns,
-    tesseract_env,
-    log,
 ):
     """Use Tesseract to render a PDF.
 
-    input_image -- image to analyze
-    skip_pdf -- if we time out, use this file as output
+    input_file -- image to analyze
     output_pdf -- file to generate
     output_text -- OCR text file
-    language -- list of languages to consider
+    languages -- list of languages to consider
     engine_mode -- engine mode argument for tess v4
-    text_only -- enable tesseract text only mode?
     tessconfig -- tesseract configuration
     timeout -- timeout (seconds)
-    log -- logger object
     """
 
-    args_tesseract = tess_base_args(language, engine_mode)
+    args_tesseract = tess_base_args(languages, engine_mode)
 
     if pagesegmode is not None:
         args_tesseract.extend(['--psm', str(pagesegmode)])
 
-    if text_only and has_textonly_pdf(tesseract_env, language):
-        args_tesseract.extend(['-c', 'textonly_pdf=1'])
+    args_tesseract.extend(['-c', 'textonly_pdf=1'])
 
     if user_words:
         args_tesseract.extend(['--user-words', user_words])
@@ -372,30 +319,23 @@ def generate_pdf(
 
     prefix = os.path.splitext(output_pdf)[0]  # Tesseract appends suffixes
 
-    # Reminder: test suite tesseract spoofers might break after any changes
+    # Reminder: test suite tesseract test plugins might break after any changes
     # to the number of order parameters here
 
-    args_tesseract.extend([input_image, prefix, 'pdf', 'txt'] + tessconfig)
+    args_tesseract.extend([input_file, prefix, 'pdf', 'txt'] + tessconfig)
     try:
-        p = run(
-            args_tesseract,
-            stdout=PIPE,
-            stderr=STDOUT,
-            timeout=timeout,
-            check=True,
-            env=tesseract_env,
-        )
+        p = run(args_tesseract, stdout=PIPE, stderr=STDOUT, timeout=timeout, check=True)
         stdout = p.stdout
         if os.path.exists(prefix + '.txt'):
             shutil.move(prefix + '.txt', output_text)
     except TimeoutExpired:
-        page_timedout(log, input_image, timeout)
-        use_skip_page(text_only, skip_pdf, output_pdf, output_text)
+        page_timedout(timeout)
+        use_skip_page(output_pdf, output_text)
     except CalledProcessError as e:
-        tesseract_log_output(log, e.output, input_image)
+        tesseract_log_output(e.output)
         if b'Image too large' in e.output:
-            use_skip_page(text_only, skip_pdf, output_pdf, output_text)
+            use_skip_page(output_pdf, output_text)
             return
         raise SubprocessOutputError() from e
     else:
-        tesseract_log_output(log, stdout, input_image)
+        tesseract_log_output(stdout)

src/ocrmypdf/_exec/unpaper.py

@@ -0,0 +1,134 @@
+# © 2015 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+# unpaper documentation:
+# https://github.com/Flameeyes/unpaper/blob/master/doc/basic-concepts.md
+
+"""Interface to unpaper executable"""
+
+import logging
+import os
+import shlex
+from decimal import Decimal
+from pathlib import Path
+from subprocess import PIPE, STDOUT
+from tempfile import TemporaryDirectory
+from typing import List, Optional, Tuple, Union
+
+from PIL import Image
+
+from ocrmypdf.exceptions import MissingDependencyError, SubprocessOutputError
+from ocrmypdf.subprocess import get_version
+from ocrmypdf.subprocess import run as external_run
+
+DecFloat = Union[Decimal, float]
+
+log = logging.getLogger(__name__)
+
+
+def version() -> str:
+    return get_version('unpaper')
+
+
+def _setup_unpaper_io(tmpdir: Path, input_file: Path) -> Tuple[Path, Path]:
+    SUFFIXES = {'1': '.pbm', 'L': '.pgm', 'RGB': '.ppm'}
+    with Image.open(input_file) as im:
+        im_modified = False
+        if im.mode not in SUFFIXES:
+            log.info("Converting image to other colorspace")
+            try:
+                if im.mode == 'P' and len(im.getcolors()) == 2:
+                    im = im.convert(mode='1')
+                else:
+                    im = im.convert(mode='RGB')
+            except IOError as e:
+                raise MissingDependencyError(
+                    "Could not convert image with type " + im.mode
+                ) from e
+            else:
+                im_modified = True
+        try:
+            suffix = SUFFIXES[im.mode]
+        except KeyError:
+            raise MissingDependencyError(
+                "Failed to convert image to a supported format."
+            ) from None
+
+        if im_modified or input_file.suffix != '.pnm':
+            input_pnm = tmpdir / 'input.pnm'
+            im.save(input_pnm, format='PPM')
+        else:
+            # No changes, PNG input, just use the file we already have
+            input_pnm = input_file
+        output_pnm = tmpdir / f'output{suffix}'
+    return input_pnm, output_pnm
+
+
+def run(
+    input_file: Path, output_file: Path, *, dpi: DecFloat, mode_args: List[str]
+) -> None:
+    args_unpaper = ['unpaper', '-v', '--dpi', str(round(dpi, 6))] + mode_args
+
+    with TemporaryDirectory() as tmpdir:
+        input_pnm, output_pnm = _setup_unpaper_io(Path(tmpdir), input_file)
+
+        # To prevent any shenanigans from accepting arbitrary parameters in
+        # --unpaper-args, we:
+        # 1) run with cwd set to a tmpdir with only unpaper's files
+        # 2) forbid the use of '/' in arguments, to prevent changing paths
+        # 3) append absolute paths for the input and output file
+        # This should ensure that a user cannot clobber some other file with
+        # their unpaper arguments (whether intentionally or otherwise)
+        args_unpaper.extend([os.fspath(input_pnm), os.fspath(output_pnm)])
+        external_run(
+            args_unpaper,
+            close_fds=True,
+            check=True,
+            stderr=STDOUT,  # unpaper writes logging output to stdout and stderr
+            stdout=PIPE,  # and cannot send file output to stdout
+            cwd=tmpdir,
+            logs_errors_to_stdout=True,
+        )
+        try:
+            with Image.open(output_pnm) as imout:
+                imout.save(output_file, dpi=(dpi, dpi))
+        except (FileNotFoundError, OSError):
+            raise SubprocessOutputError(
+                "unpaper: failed to produce the expected output file. "
+                + " Called with: "
+                + str(args_unpaper)
+            ) from None
+
+
+def validate_custom_args(args: str) -> List[str]:
+    unpaper_args = shlex.split(args)
+    if any(('/' in arg or arg == '.' or arg == '..') for arg in unpaper_args):
+        raise ValueError('No filenames allowed in --unpaper-args')
+    return unpaper_args
+
+
+def clean(
+    input_file: Path,
+    output_file: Path,
+    *,
+    dpi: DecFloat,
+    unpaper_args: Optional[List[str]] = None,
+):
+    default_args = [
+        '--layout',
+        'none',
+        '--mask-scan-size',
+        '100',  # don't blank out narrow columns
+        '--no-border-align',  # don't align visible content to borders
+        '--no-mask-center',  # don't center visible content within page
+        '--no-grayfilter',  # don't remove light gray areas
+        '--no-blackfilter',  # don't remove solid black areas
+        '--no-deskew',  # don't deskew
+    ]
+    if not unpaper_args:
+        unpaper_args = default_args
+    run(input_file, output_file, dpi=dpi, mode_args=unpaper_args)

src/ocrmypdf/_graft.py

@@ -1,46 +1,44 @@
 # © 2018 James R. Barlow: github.com/jbarlow83
 #
-# This file is part of OCRmyPDF.
-#
-# OCRmyPDF is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# OCRmyPDF is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with OCRmyPDF.  If not, see <http://www.gnu.org/licenses/>.
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
-import os
+
+import logging
+import uuid
 from contextlib import suppress
 from pathlib import Path
+from typing import Optional
 
 import pikepdf
+from pikepdf.objects import Dictionary, Name
 
+log = logging.getLogger(__name__)
 MAX_REPLACE_PAGES = 100
 
 
-def _update_page_resources(*, page, font, font_key, procset):
-    """Update this page's fonts with a reference to the Glyphless font"""
+def _ensure_dictionary(obj, name):
+    if name not in obj:
+        obj[name] = Dictionary({})
+    return obj[name]
 
-    if '/Resources' not in page:
-        page['/Resources'] = pikepdf.Dictionary({})
-    resources = page['/Resources']
-    try:
-        fonts = resources['/Font']
-    except KeyError:
-        fonts = pikepdf.Dictionary({})
+
+def _update_resources(*, obj, font, font_key, procset):
+    """Update this obj's fonts with a reference to the Glyphless font.
+
+    obj can be a page or Form XObject.
+    """
+
+    resources = _ensure_dictionary(obj, Name.Resources)
+    fonts = _ensure_dictionary(resources, Name.Font)
     if font_key is not None and font_key not in fonts:
         fonts[font_key] = font
-    resources['/Font'] = fonts
 
     # Reassign /ProcSet to one that just lists everything - ProcSet is
     # obsolete and doesn't matter but recommended for old viewer support
-    resources['/ProcSet'] = procset
+    if procset:
+        resources['/ProcSet'] = procset
 
 
 def strip_invisible_text(pdf, page):
@@ -88,99 +86,10 @@ def strip_invisible_text(pdf, page):
     page.Contents = pikepdf.Stream(pdf, content_stream)
 
 
-def _graft_text_layer(
-    *, pdf_base, page_num, text, font, font_key, procset, rotation, strip_old_text, log
-):
-    """Insert the text layer from text page 0 on to pdf_base at page_num"""
-
-    log.debug("Grafting")
-    if Path(text).stat().st_size == 0:
-        return
-
-    # This is a pointer indicating a specific page in the base file
-    pdf_text = pikepdf.open(text)
-    pdf_text_contents = pdf_text.pages[0].Contents.read_bytes()
-
-    base_page = pdf_base.pages.p(page_num)
-
-    # The text page always will be oriented up by this stage but the original
-    # content may have a rotation applied. Wrap the text stream with a rotation
-    # so it will be oriented the same way as the rest of the page content.
-    # (Previous versions OCRmyPDF rotated the content layer to match the text.)
-    mediabox = [float(pdf_text.pages[0].MediaBox[v]) for v in range(4)]
-    wt, ht = mediabox[2] - mediabox[0], mediabox[3] - mediabox[1]
-
-    mediabox = [float(base_page.MediaBox[v]) for v in range(4)]
-    wp, hp = mediabox[2] - mediabox[0], mediabox[3] - mediabox[1]
-
-    translate = pikepdf.PdfMatrix().translated(-wt / 2, -ht / 2)
-    untranslate = pikepdf.PdfMatrix().translated(wp / 2, hp / 2)
-    corner = pikepdf.PdfMatrix().translated(mediabox[0], mediabox[1])
-    # -rotation because the input is a clockwise angle and this formula
-    # uses CCW
-    rotation = -rotation % 360
-    rotate = pikepdf.PdfMatrix().rotated(rotation)
-
-    # Because of rounding of DPI, we might get a text layer that is not
-    # identically sized to the target page. Scale to adjust. Normally this
-    # is within 0.998.
-    if rotation in (90, 270):
-        wt, ht = ht, wt
-    scale_x = wp / wt
-    scale_y = hp / ht
-
-    # log.debug('%r', scale_x, scale_y)
-    scale = pikepdf.PdfMatrix().scaled(scale_x, scale_y)
-
-    # Translate the text so it is centered at (0, 0), rotate it there, adjust
-    # for a size different between initial and text PDF, then untranslate, and
-    # finally move the lower left corner to match the mediabox
-    ctm = translate @ rotate @ scale @ untranslate @ corner
-
-    pdf_text_contents = b'q %s cm\n' % ctm.encode() + pdf_text_contents + b'\nQ\n'
-
-    new_text_layer = pikepdf.Stream(pdf_base, pdf_text_contents)
-
-    if strip_old_text:
-        strip_invisible_text(pdf_base, base_page)
-
-    base_page.page_contents_add(new_text_layer, prepend=True)
-
-    _update_page_resources(
-        page=base_page, font=font, font_key=font_key, procset=procset
-    )
-    pdf_text.close()
-
-
-def _find_font(text, pdf_base):
-    """Copy a font from the filename text into pdf_base"""
-
-    font, font_key = None, None
-    possible_font_names = ('/f-0-0', '/F1')
-    try:
-        with pikepdf.open(text) as pdf_text:
-            try:
-                pdf_text_fonts = pdf_text.pages[0].Resources.get('/Font', {})
-            except (AttributeError, IndexError, KeyError):
-                return None, None
-            for f in possible_font_names:
-                pdf_text_font = pdf_text_fonts.get(f, None)
-                if pdf_text_font is not None:
-                    font_key = f
-                    break
-            if pdf_text_font:
-                font = pdf_base.copy_foreign(pdf_text_font)
-            return font, font_key
-    except (FileNotFoundError, pikepdf.PdfError):
-        # PdfError occurs if a 0-length file is written e.g. due to OCR timeout
-        return None, None
-
-
 class OcrGrafter:
     def __init__(self, context):
         self.context = context
-        self.log = context.log
-        self.path_base = Path(context.origin).resolve()
+        self.path_base = context.origin
 
         self.pdf_base = pikepdf.open(self.path_base)
         self.font, self.font_key = None, None
@@ -195,10 +104,16 @@ class OcrGrafter:
         self.emplacements = 1
         self.interim_count = 0
 
-    def graft_page(self, page_result):
-        pageno, image, text, _sidecar, autorotate_correction = page_result
-        if text and not self.font:
-            self.font, self.font_key = _find_font(text, self.pdf_base)
+    def graft_page(
+        self,
+        *,
+        pageno: int,
+        image: Optional[Path],
+        textpdf: Optional[Path],
+        autorotate_correction: int,
+    ):
+        if textpdf and not self.font:
+            self.font, self.font_key = self._find_font(textpdf)
 
         emplaced_page = False
         content_rotation = self.pdfinfo[pageno].rotation
@@ -206,7 +121,7 @@ class OcrGrafter:
         if path_image is not None and path_image != self.path_base:
             # We are updating the old page with a rasterized PDF of the new
             # page (without changing objgen, to preserve references)
-            self.log.debug("Emplacement update")
+            log.debug("Emplacement update")
             with pikepdf.open(image) as pdf_image:
                 self.emplacements += 1
                 foreign_image_page = pdf_image.pages[0]
@@ -216,60 +131,67 @@ class OcrGrafter:
                 del self.pdf_base.pages[-1]
             emplaced_page = True
 
+        # Calculate if the text is misaligned compared to the content
         if emplaced_page:
             content_rotation = autorotate_correction
         text_rotation = autorotate_correction
         text_misaligned = (text_rotation - content_rotation) % 360
-        self.log.debug(
-            f"Rotations for page {pageno}: [text, auto, misalign, content] = "
-            f"{text_rotation}, {autorotate_correction}, "
-            f"{text_misaligned}, {content_rotation}"
+        log.debug(
+            f"Text rotation: (text, autorotate, content) -> text misalignment = "
+            f"({text_rotation}, {autorotate_correction}, {content_rotation}) -> {text_misaligned}"
         )
 
-        if text and self.font:
-            # Graft the text layer onto this page, whether new or old
+        if textpdf and self.font:
+            # Graft the text layer onto this page, whether new or old, possibly
+            # rotating the text layer by the amount is misaligned.
             strip_old = self.context.options.redo_ocr
-            _graft_text_layer(
-                pdf_base=self.pdf_base,
+            self._graft_text_layer(
                 page_num=pageno + 1,
-                text=text,
+                textpdf=textpdf,
                 font=self.font,
                 font_key=self.font_key,
-                rotation=text_misaligned,
+                text_rotation=text_misaligned,
                 procset=self.procset,
                 strip_old_text=strip_old,
-                log=self.log,
             )
 
-        # Correct the rotation if applicable
-        self.pdf_base.pages[pageno].Rotate = (
-            content_rotation - autorotate_correction
-        ) % 360
-
+        # Correct the overall page rotation if needed, now that the text and content
+        # are aligned
+        page_rotation = (content_rotation - autorotate_correction) % 360
+        self.pdf_base.pages[pageno].Rotate = page_rotation
+        log.debug(
+            f"Page rotation: (content, auto) -> page = "
+            f"({content_rotation}, {autorotate_correction}) -> {page_rotation}"
+        )
         if self.emplacements % MAX_REPLACE_PAGES == 0:
             self.save_and_reload()
 
     def save_and_reload(self):
-        # Periodically save and reload the Pdf object. This will keep a
-        # lid on our memory usage for very large files. Attach the font to
-        # page 1 even if page 1 doesn't use it, so we have a way to get it
-        # back.
+        """Save and reload the Pdf.
+
+        This will keep a lid on our memory usage for very large files. Attach
+        the font to page 1 even if page 1 doesn't use it, so we have a way to get it
+        back.
+        """
+
         page0 = self.pdf_base.pages[0]
-        _update_page_resources(
-            page=page0, font=self.font, font_key=self.font_key, procset=self.procset
+        _update_resources(
+            obj=page0, font=self.font, font_key=self.font_key, procset=self.procset
         )
 
         # We cannot read and write the same file, that will corrupt it
         # but we don't to keep more copies than we need to. Delete intermediates.
-        # {interim_count} is the opened file we were updateing
+        # {interim_count} is the opened file we were updating
         # {interim_count - 1} can be deleted
         # {interim_count + 1} is the new file will produce and open
-        old_file = self.output_file + f'_working{self.interim_count - 1}.pdf'
+        old_file = self.output_file.with_suffix(f'.working{self.interim_count - 1}.pdf')
         if not self.context.options.keep_temporary_files:
             with suppress(FileNotFoundError):
-                os.unlink(old_file)
+                old_file.unlink()
 
-        next_file = self.output_file + f'_working{self.interim_count + 1}.pdf'
+        next_file = self.output_file.with_suffix(
+            f'.working{self.interim_count + 1}.pdf'
+        )
         self.pdf_base.save(next_file)
         self.pdf_base.close()
 
@@ -282,3 +204,111 @@ class OcrGrafter:
         self.pdf_base.save(self.output_file)
         self.pdf_base.close()
         return self.output_file
+
+    def _find_font(self, text):
+        """Copy a font from the filename text into pdf_base"""
+
+        font, font_key = None, None
+        possible_font_names = ('/f-0-0', '/F1')
+        try:
+            with pikepdf.open(text) as pdf_text:
+                try:
+                    pdf_text_fonts = pdf_text.pages[0].Resources.get('/Font', {})
+                except (AttributeError, IndexError, KeyError):
+                    return None, None
+                pdf_text_font = None
+                for f in possible_font_names:
+                    pdf_text_font = pdf_text_fonts.get(f, None)
+                    if pdf_text_font is not None:
+                        font_key = f
+                        break
+                if pdf_text_font:
+                    font = self.pdf_base.copy_foreign(pdf_text_font)
+                return font, font_key
+        except (FileNotFoundError, pikepdf.PdfError):
+            # PdfError occurs if a 0-length file is written e.g. due to OCR timeout
+            return None, None
+
+    def _graft_text_layer(
+        self,
+        *,
+        page_num: int,
+        textpdf: Path,
+        font: pikepdf.Object,
+        font_key: pikepdf.Object,
+        procset: pikepdf.Object,
+        text_rotation: int,
+        strip_old_text: bool,
+    ):
+        """Insert the text layer from text page 0 on to pdf_base at page_num"""
+
+        log.debug("Grafting")
+        if Path(textpdf).stat().st_size == 0:
+            return
+
+        # This is a pointer indicating a specific page in the base file
+        with pikepdf.open(textpdf) as pdf_text:
+            pdf_text_contents = pdf_text.pages[0].Contents.read_bytes()
+
+            base_page = self.pdf_base.pages.p(page_num)
+
+            # The text page always will be oriented up by this stage but the original
+            # content may have a rotation applied. Wrap the text stream with a rotation
+            # so it will be oriented the same way as the rest of the page content.
+            # (Previous versions OCRmyPDF rotated the content layer to match the text.)
+            mediabox = [float(pdf_text.pages[0].MediaBox[v]) for v in range(4)]
+            wt, ht = mediabox[2] - mediabox[0], mediabox[3] - mediabox[1]
+
+            mediabox = [float(base_page.MediaBox[v]) for v in range(4)]
+            wp, hp = mediabox[2] - mediabox[0], mediabox[3] - mediabox[1]
+
+            translate = pikepdf.PdfMatrix().translated(-wt / 2, -ht / 2)
+            untranslate = pikepdf.PdfMatrix().translated(wp / 2, hp / 2)
+            corner = pikepdf.PdfMatrix().translated(mediabox[0], mediabox[1])
+            # -rotation because the input is a clockwise angle and this formula
+            # uses CCW
+            text_rotation = -text_rotation % 360
+            rotate = pikepdf.PdfMatrix().rotated(text_rotation)
+
+            # Because of rounding of DPI, we might get a text layer that is not
+            # identically sized to the target page. Scale to adjust. Normally this
+            # is within 0.998.
+            if text_rotation in (90, 270):
+                wt, ht = ht, wt
+            scale_x = wp / wt
+            scale_y = hp / ht
+
+            # log.debug('%r', scale_x, scale_y)
+            scale = pikepdf.PdfMatrix().scaled(scale_x, scale_y)
+
+            # Translate the text so it is centered at (0, 0), rotate it there, adjust
+            # for a size different between initial and text PDF, then untranslate, and
+            # finally move the lower left corner to match the mediabox
+            ctm = translate @ rotate @ scale @ untranslate @ corner
+
+            base_resources = _ensure_dictionary(base_page, Name.Resources)
+            base_xobjs = _ensure_dictionary(base_resources, Name.XObject)
+            text_xobj_name = Name('/' + str(uuid.uuid4()))
+            xobj = self.pdf_base.make_stream(pdf_text_contents)
+            base_xobjs[text_xobj_name] = xobj
+            xobj.Type = Name.XObject
+            xobj.Subtype = Name.Form
+            xobj.FormType = 1
+            xobj.BBox = mediabox
+            _update_resources(
+                obj=xobj, font=font, font_key=font_key, procset=[Name.PDF]
+            )
+
+            pdf_draw_xobj = (
+                (b'q %s cm\n' % ctm.encode()) + (b'%s Do\n' % text_xobj_name) + b'\nQ\n'
+            )
+            new_text_layer = pikepdf.Stream(self.pdf_base, pdf_draw_xobj)
+
+            if strip_old_text:
+                strip_invisible_text(self.pdf_base, base_page)
+
+            base_page.page_contents_add(new_text_layer, prepend=True)
+
+            _update_resources(
+                obj=base_page, font=font, font_key=font_key, procset=procset
+            )

src/ocrmypdf/_jobcontext.py

@@ -1,124 +1,103 @@
 # © 2018 James R. Barlow: github.com/jbarlow83
 #
-# This file is part of OCRmyPDF.
-#
-# OCRmyPDF is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# OCRmyPDF is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with OCRmyPDF.  If not, see <http://www.gnu.org/licenses/>.
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
 
-import logging
 import os
 import shutil
 import sys
+from argparse import Namespace
+from copy import copy
+from pathlib import Path
+from typing import Iterator
+
+from pluggy import PluginManager
+
+from ocrmypdf.pdfinfo import PdfInfo
+from ocrmypdf.pdfinfo.info import PageInfo
 
 
-class PicklableLoggerMixin:
-    def __init__(self):
-        self._log = None
+class PdfContext:
+    """Holds the context for a particular run of the pipeline."""
 
-    @property
-    def log(self):
-        if not self._log:
-            self._log = self.get_logger()
-        return self._log
+    options: Namespace  #: The specified options for processing this PDF.
+    origin: Path  #: The filename of the original input file.
+    pdfinfo: PdfInfo  #: Detailed data for this PDF.
+    plugin_manager: PluginManager  #: PluginManager for processing the current PDF.
 
-    def __getstate__(self):
-        # Python 3.6 is incapable of pickling a logger and marshalling it to another
-        # process (threading._RLock error), so we disconnect it before pickling,
-        # and create a new logger in the worker process.
-        state = self.__dict__.copy()
-        state['_log'] = None
-        return state
-
-
-class PDFContext(PicklableLoggerMixin):
-    """Holds our context for a particular run of the pipeline"""
-
-    def __init__(self, options, work_folder, origin, pdfinfo):
-        PicklableLoggerMixin.__init__(self)
+    def __init__(
+        self,
+        options: Namespace,
+        work_folder: Path,
+        origin: Path,
+        pdfinfo: PdfInfo,
+        plugin_manager,
+    ):
         self.options = options
         self.work_folder = work_folder
         self.origin = origin
         self.pdfinfo = pdfinfo
-        if options:
-            self.name = os.path.basename(options.input_file)
-        else:
-            self.name = 'origin.pdf'
-        if self.name == '-':
-            self.name = 'stdin'
+        self.plugin_manager = plugin_manager
 
-    def get_logger(self):
-        return make_logger(self.options, filename=self.name)
+    def get_path(self, name: str) -> Path:
+        """Generate a ``Path`` for an intermediate file involved in processing.
 
-    def get_path(self, name):
-        return os.path.join(self.work_folder, name)
+        The path will be in a temporary folder that is common for all processing
+        of this particular PDF.
+        """
+        return self.work_folder / name
 
-    def get_page_contexts(self):
+    def get_page_contexts(self) -> Iterator['PageContext']:
+        """Get all ``PageContext`` for this PDF."""
         npages = len(self.pdfinfo)
         for n in range(npages):
             yield PageContext(self, n)
 
 
-class PageContext(PicklableLoggerMixin):
-    """Holds our context for a page
+class PageContext:
+    """Holds our context for a page.
 
-    Must be pickable, so only store intrinsic/simple data elements
+    Must be pickable, so stores only intrinsic/simple data elements or those
+    capable of their serializing themselves via ``__getstate__``.
     """
 
-    def __init__(self, pdf_context, pageno):
-        PicklableLoggerMixin.__init__(self)
+    options: Namespace  #: The specified options for processing this PDF.
+    origin: Path  #: The filename of the original input file.
+    pageno: int  #: This page number (zero-based).
+    pageinfo: PageInfo  #: Information on this page.
+    plugin_manager: PluginManager  #: PluginManager for processing the current PDF.
+
+    def __init__(self, pdf_context: PdfContext, pageno):
         self.work_folder = pdf_context.work_folder
         self.origin = pdf_context.origin
         self.options = pdf_context.options
-        self.name = pdf_context.name
         self.pageno = pageno
         self.pageinfo = pdf_context.pdfinfo[pageno]
-        self._log = None
+        self.plugin_manager = pdf_context.plugin_manager
 
-    def get_logger(self):
-        return make_logger(self.options, filename=self.name, page=self.pageno + 1)
+    def get_path(self, name: str) -> Path:
+        """Generate a ``Path`` for a file that is part of processing this page.
 
-    def get_path(self, name):
-        return os.path.join(self.work_folder, "%06d_%s" % (self.pageno + 1, name))
+        The path will be based in a common temporary folder and have a prefix based
+        on the page number.
+        """
+        return self.work_folder / ("%06d_%s" % (self.pageno + 1, name))
+
+    def __getstate__(self):
+        state = self.__dict__.copy()
+
+        state['options'] = copy(self.options)
+        if not isinstance(state['options'].input_file, (str, bytes, os.PathLike)):
+            state['options'].input_file = 'stream'
+        if not isinstance(state['options'].output_file, (str, bytes, os.PathLike)):
+            state['options'].output_file = 'stream'
+        return state
 
 
-def cleanup_working_files(work_folder, options):
+def cleanup_working_files(work_folder: Path, options: Namespace):
     if options.keep_temporary_files:
         print(f"Temporary working files retained at:\n{work_folder}", file=sys.stderr)
     else:
         shutil.rmtree(work_folder, ignore_errors=True)
-
-
-class LogNameAdapter(logging.LoggerAdapter):
-    def process(self, msg, kwargs):
-        # return '[%s] %s' % (self.extra['input_filename'], msg), kwargs
-        return '%s' % (msg,), kwargs
-
-
-class LogNamePageAdapter(logging.LoggerAdapter):
-    def process(self, msg, kwargs):
-        return (
-            #'[%s:%05u] %s' % (self.extra['input_filename'], self.extra['page'], msg),
-            '%4u: %s' % (self.extra['page'], msg),
-            kwargs,
-        )
-
-
-def make_logger(options=None, prefix='ocrmypdf', filename=None, page=None):
-    log = logging.getLogger(prefix)
-    if filename and page:
-        adapter = LogNamePageAdapter(log, dict(input_filename=filename, page=page))
-    elif filename:
-        adapter = LogNameAdapter(log, dict(input_filename=filename))
-    else:
-        adapter = log
-    return adapter

src/ocrmypdf/_logging.py

@@ -0,0 +1,50 @@
+# © 2020 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+import logging
+import sys
+from contextlib import suppress
+
+from tqdm import tqdm
+
+
+class PageNumberFilter(logging.Filter):
+    def filter(self, record):
+        pageno = getattr(record, 'pageno', None)
+        if isinstance(pageno, int):
+            record.pageno = f'{pageno:5d} '
+        elif pageno is None:
+            record.pageno = ''
+        return True
+
+
+class TqdmConsole:
+    """Wrapper to log messages in a way that is compatible with tqdm progress bar
+
+    This routes log messages through tqdm so that it can print them above the
+    progress bar, and then refresh the progress bar, rather than overwriting
+    it which looks messy.
+
+    For some reason Python 3.6 prints extra empty messages from time to time,
+    so we suppress those.
+    """
+
+    def __init__(self, file):
+        self.file = file
+        self.py36 = sys.version_info[0:2] == (3, 6)
+
+    def write(self, msg):
+        # When no progress bar is active, tqdm.write() routes to print()
+        if self.py36:
+            if msg.strip() != '':
+                tqdm.write(msg.rstrip(), end='\n', file=self.file)
+        else:
+            tqdm.write(msg.rstrip(), end='\n', file=self.file)
+
+    def flush(self):
+        with suppress(AttributeError):
+            self.file.flush()

src/ocrmypdf/_pipeline.py

@@ -1,67 +1,64 @@
 # © 2016 James R. Barlow: github.com/jbarlow83
 #
-# This file is part of OCRmyPDF.
-#
-# OCRmyPDF is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# OCRmyPDF is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with OCRmyPDF.  If not, see <http://www.gnu.org/licenses/>.
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
+
+import logging
 import os
 import re
 import sys
+from contextlib import suppress
 from datetime import datetime, timezone
 from pathlib import Path
 from shutil import copyfileobj
+from typing import Dict, Iterable, Optional
 
 import img2pdf
 import pikepdf
 from pikepdf.models.metadata import encode_pdf_date
-from PIL import Image
+from PIL import Image, ImageColor, ImageDraw
 
-from . import leptonica
-from ._version import PROGRAM_NAME
-from ._version import __version__ as VERSION
-from .exceptions import (
+from ocrmypdf import leptonica
+from ocrmypdf._concurrent import Executor
+from ocrmypdf._exec import unpaper
+from ocrmypdf._jobcontext import PageContext, PdfContext
+from ocrmypdf._version import PROGRAM_NAME
+from ocrmypdf._version import __version__ as VERSION
+from ocrmypdf.exceptions import (
     DpiError,
     EncryptedPdfError,
     InputFileError,
     PriorOcrFoundError,
     UnsupportedImageFormatError,
 )
-from .exec import ghostscript, tesseract
-from .helpers import safe_symlink
-from .hocrtransform import HocrTransform
-from .optimize import optimize
-from .pdfa import generate_pdfa_ps
-from .pdfinfo import Colorspace, Encoding, PdfInfo
+from ocrmypdf.helpers import Resolution, safe_symlink
+from ocrmypdf.hocrtransform import HocrTransform
+from ocrmypdf.optimize import optimize
+from ocrmypdf.pdfa import generate_pdfa_ps
+from ocrmypdf.pdfinfo import Colorspace, Encoding, PdfInfo
+
+log = logging.getLogger(__name__)
 
 VECTOR_PAGE_DPI = 400
 
 
-def triage_image_file(input_file, output_file, options, log):
+def triage_image_file(input_file, output_file, options):
     log.info("Input file is not a PDF, checking if it is an image...")
     try:
         im = Image.open(input_file)
     except EnvironmentError as e:
         # Recover the original filename
-        log.error(str(e).replace(input_file, options.input_file))
+        log.error(str(e).replace(str(input_file), str(options.input_file)))
         raise UnsupportedImageFormatError() from e
 
     with im:
         log.info("Input file is an image")
         if 'dpi' in im.info:
             if im.info['dpi'] <= (96, 96) and not options.image_dpi:
-                log.info("Image size: (%d, %d)" % im.size)
-                log.info("Image resolution: (%d, %d)" % im.info['dpi'])
+                log.info("Image size: (%d, %d)", *im.size)
+                log.info("Image resolution: (%d, %d)", *im.info['dpi'])
                 log.error(
                     "Input file is an image, but the resolution (DPI) is "
                     "not credible.  Estimate the resolution at which the "
@@ -69,7 +66,7 @@ def triage_image_file(input_file, output_file, options, log):
                 )
                 raise DpiError()
         elif not options.image_dpi:
-            log.info("Image size: (%d, %d)" % im.size)
+            log.info("Image size: (%d, %d)", *im.size)
             log.error(
                 "Input file is an image, but has no resolution (DPI) "
                 "in its metadata.  Estimate the resolution at which "
@@ -96,11 +93,14 @@ def triage_image_file(input_file, output_file, options, log):
         layout_fun = img2pdf.default_layout_fun
         if options.image_dpi:
             layout_fun = img2pdf.get_fixed_dpi_layout_fun(
-                (options.image_dpi, options.image_dpi)
+                Resolution(options.image_dpi, options.image_dpi)
             )
         with open(output_file, 'wb') as outf:
             img2pdf.convert(
-                input_file, layout_fun=layout_fun, with_pdfrw=False, outputstream=outf
+                os.fspath(input_file),
+                layout_fun=layout_fun,
+                with_pdfrw=False,
+                outputstream=outf,
             )
         log.info("Successfully converted to PDF, processing...")
     except img2pdf.ImageOpenError as e:
@@ -124,7 +124,7 @@ def _pdf_guess_version(input_file, search_window=1024):
     return ''
 
 
-def triage(original_filename, input_file, output_file, options, log):
+def triage(original_filename, input_file, output_file, options):
     try:
         if _pdf_guess_version(input_file):
             if options.image_dpi:
@@ -137,26 +137,38 @@ def triage(original_filename, input_file, output_file, options, log):
             return output_file
     except EnvironmentError as e:
         log.debug(f"Temporary file was at: {input_file}")
-        msg = str(e).replace(input_file, original_filename)
+        msg = str(e).replace(str(input_file), original_filename)
         raise InputFileError(msg) from e
 
-    triage_image_file(input_file, output_file, options, log)
+    triage_image_file(input_file, output_file, options)
     return output_file
 
 
-def get_pdfinfo(input_file, detailed_page_analysis=False, progbar=False):
+def get_pdfinfo(
+    input_file,
+    *,
+    executor: Executor,
+    detailed_analysis=False,
+    progbar=False,
+    max_workers=None,
+    check_pages=None,
+) -> PdfInfo:
     try:
         return PdfInfo(
-            input_file, detailed_page_analysis=detailed_page_analysis, progbar=progbar
+            input_file,
+            detailed_analysis=detailed_analysis,
+            progbar=progbar,
+            max_workers=max_workers,
+            check_pages=check_pages,
+            executor=executor,
         )
-    except pikepdf.PasswordError:
-        raise EncryptedPdfError()
-    except pikepdf.PdfError:
-        raise InputFileError()
+    except pikepdf.PasswordError as e:
+        raise EncryptedPdfError() from e
+    except pikepdf.PdfError as e:
+        raise InputFileError() from e
 
 
-def validate_pdfinfo_options(context):
-    log = context.log
+def validate_pdfinfo_options(context: PdfContext):
     pdfinfo = context.pdfinfo
     options = context.options
 
@@ -194,54 +206,60 @@ def validate_pdfinfo_options(context):
                     "form and all filled form fields. The output PDF will be "
                     "'flattened' and will no longer be fillable."
                 )
+    context.plugin_manager.hook.validate(pdfinfo=pdfinfo, options=options)
+
+
+def _vector_page_dpi(pageinfo):
+    return VECTOR_PAGE_DPI if pageinfo.has_vector or pageinfo.has_text else 0.0
 
 
 def get_page_dpi(pageinfo, options):
     "Get the DPI when nonsquare DPI is tolerable"
     xres = max(
-        pageinfo.xres or VECTOR_PAGE_DPI,
-        options.oversample or 0,
-        VECTOR_PAGE_DPI if pageinfo.has_vector else 0,
+        pageinfo.dpi.x or VECTOR_PAGE_DPI,
+        options.oversample or 0.0,
+        _vector_page_dpi(pageinfo),
     )
     yres = max(
-        pageinfo.yres or VECTOR_PAGE_DPI,
+        pageinfo.dpi.y or VECTOR_PAGE_DPI,
         options.oversample or 0,
-        VECTOR_PAGE_DPI if pageinfo.has_vector else 0,
+        _vector_page_dpi(pageinfo),
     )
-    return (float(xres), float(yres))
+    return Resolution(float(xres), float(yres))
 
 
-def get_page_square_dpi(pageinfo, options):
+def get_page_square_dpi(pageinfo, options) -> Resolution:
     "Get the DPI when we require xres == yres, scaled to physical units"
-    xres = pageinfo.xres or 0
-    yres = pageinfo.yres or 0
-    userunit = pageinfo.userunit or 1
-    return float(
+    xres = pageinfo.dpi.x or 0.0
+    yres = pageinfo.dpi.y or 0.0
+    userunit = float(pageinfo.userunit) or 1.0
+    units = float(
         max(
             (xres * userunit) or VECTOR_PAGE_DPI,
             (yres * userunit) or VECTOR_PAGE_DPI,
-            VECTOR_PAGE_DPI if pageinfo.has_vector else 0,
-            options.oversample or 0,
+            _vector_page_dpi(pageinfo),
+            options.oversample or 0.0,
         )
     )
+    return Resolution(units, units)
 
 
-def get_canvas_square_dpi(pageinfo, options):
+def get_canvas_square_dpi(pageinfo, options) -> Resolution:
     """Get the DPI when we require xres == yres, in Postscript units"""
-    return float(
+    units = float(
         max(
-            (pageinfo.xres) or VECTOR_PAGE_DPI,
-            (pageinfo.yres) or VECTOR_PAGE_DPI,
-            VECTOR_PAGE_DPI if pageinfo.has_vector else 0,
-            options.oversample or 0,
+            (pageinfo.dpi.x) or VECTOR_PAGE_DPI,
+            (pageinfo.dpi.y) or VECTOR_PAGE_DPI,
+            _vector_page_dpi(pageinfo),
+            options.oversample or 0.0,
         )
     )
+    return Resolution(units, units)
 
 
-def is_ocr_required(page_context):
+def is_ocr_required(page_context: PageContext):
     pageinfo = page_context.pageinfo
     options = page_context.options
-    log = page_context.log
 
     ocr_required = True
 
@@ -251,14 +269,15 @@ def is_ocr_required(page_context):
     elif pageinfo.has_text:
         if not options.force_ocr and not (options.skip_text or options.redo_ocr):
             raise PriorOcrFoundError(
-                "page already has text! - aborting (use --force-ocr to force OCR)"
+                "page already has text! - aborting (use --force-ocr to force OCR; "
+                " see also help for the arguments --skip-text and --redo-ocr"
             )
         elif options.force_ocr:
             log.info("page already has text! - rasterizing text and running OCR anyway")
             ocr_required = True
         elif options.redo_ocr:
             if pageinfo.has_corrupt_text:
-                log.warn(
+                log.warning(
                     "some text on this page cannot be mapped to characters: "
                     "consider using --force-ocr instead"
                 )
@@ -285,7 +304,7 @@ def is_ocr_required(page_context):
             )
         elif options.force_ocr:
             # Warn the user they might not want to do this
-            log.warn(
+            log.warning(
                 "page has no images - "
                 "all vector content will be "
                 f"rasterized at {VECTOR_PAGE_DPI} DPI, losing some resolution and likely "
@@ -305,31 +324,31 @@ def is_ocr_required(page_context):
         pixel_count = pageinfo.width_pixels * pageinfo.height_pixels
         if pixel_count > (options.skip_big * 1_000_000):
             ocr_required = False
-            log.warn(
+            log.warning(
                 "page too big, skipping OCR "
                 f"({(pixel_count / 1_000_000):.1f} MPixels > {options.skip_big:.1f} MPixels --skip-big)"
             )
     return ocr_required
 
 
-def rasterize_preview(input_file, page_context):
+def rasterize_preview(input_file: Path, page_context: PageContext):
     output_file = page_context.get_path('rasterize_preview.jpg')
     canvas_dpi = get_canvas_square_dpi(page_context.pageinfo, page_context.options)
     page_dpi = get_page_square_dpi(page_context.pageinfo, page_context.options)
-    ghostscript.rasterize_pdf(
-        input_file,
-        output_file,
-        xres=canvas_dpi,
-        yres=canvas_dpi,
+    page_context.plugin_manager.hook.rasterize_pdf_page(
+        input_file=input_file,
+        output_file=output_file,
         raster_device='jpeggray',
-        log=page_context.log,
-        page_dpi=(page_dpi, page_dpi),
+        raster_dpi=canvas_dpi,
         pageno=page_context.pageinfo.pageno + 1,
+        page_dpi=page_dpi,
+        rotation=0,
+        filter_vector=False,
     )
     return output_file
 
 
-def describe_rotation(page_context, orient_conf, correction):
+def describe_rotation(page_context: PageContext, orient_conf, correction: int):
     """
     Describe the page rotation we are going to perform.
     """
@@ -358,34 +377,28 @@ def describe_rotation(page_context, orient_conf, correction):
     return f"{facing}, confidence {orient_conf.confidence:.2f} - {action}"
 
 
-def get_orientation_correction(preview, page_context):
-    """
-    Work out orientation correct for each page.
+def get_orientation_correction(preview: Path, page_context: PageContext):
+    """Work out orientation correct for each page.
 
     We ask Ghostscript to draw a preview page, which will rasterize with the
-    current /Rotate applied, and then ask Tesseract which way the page is
+    current /Rotate applied, and then ask OCR which way the page is
     oriented. If the value of /Rotate is correct (e.g., a user already
-    manually fixed rotation), then Tesseract will say the page is pointing
+    manually fixed rotation), then OCR will say the page is pointing
     up and the correction is zero. Otherwise, the orientation found by
-    Tesseract represents the clockwise rotation, or the counterclockwise
+    OCR represents the clockwise rotation, or the counterclockwise
     correction to rotation.
 
     When we draw the real page for OCR, we rotate it by the CCW correction,
     which points it (hopefully) upright. _graft.py takes care of the orienting
     the image and text layers.
-
     """
 
-    orient_conf = tesseract.get_orientation(
-        preview,
-        engine_mode=page_context.options.tesseract_oem,
-        timeout=page_context.options.tesseract_timeout,
-        log=page_context.log,
-        tesseract_env=page_context.options.tesseract_env,
+    orient_conf = page_context.plugin_manager.hook.get_ocr_engine().get_orientation(
+        preview, page_context.options
     )
 
     correction = orient_conf.angle % 360
-    page_context.log.info(describe_rotation(page_context, orient_conf, correction))
+    log.info(describe_rotation(page_context, orient_conf, correction))
     if (
         orient_conf.confidence >= page_context.options.rotate_pages_threshold
         and correction != 0
@@ -396,7 +409,11 @@ def get_orientation_correction(preview, page_context):
 
 
 def rasterize(
-    input_file, page_context, correction=0, output_tag='', remove_vectors=None
+    input_file: Path,
+    page_context: PageContext,
+    correction: int = 0,
+    output_tag: str = '',
+    remove_vectors=None,
 ):
     colorspaces = ['pngmono', 'pnggray', 'png256', 'png16m']
     device_idx = 0
@@ -426,21 +443,19 @@ def rasterize(
 
     device = colorspaces[device_idx]
 
-    page_context.log.debug(f"Rasterize with {device}")
+    log.debug(f"Rasterize with {device}, rotation {correction}")
 
     # Produce the page image with square resolution or else deskew and OCR
     # will not work properly.
     canvas_dpi = get_canvas_square_dpi(pageinfo, page_context.options)
     page_dpi = get_page_square_dpi(pageinfo, page_context.options)
 
-    ghostscript.rasterize_pdf(
-        input_file,
-        output_file,
-        xres=canvas_dpi,
-        yres=canvas_dpi,
+    page_context.plugin_manager.hook.rasterize_pdf_page(
+        input_file=input_file,
+        output_file=output_file,
         raster_device=device,
-        log=page_context.log,
-        page_dpi=(page_dpi, page_dpi),
+        raster_dpi=canvas_dpi,
+        page_dpi=page_dpi,
         pageno=pageinfo.pageno + 1,
         rotation=correction,
         filter_vector=remove_vectors,
@@ -448,39 +463,36 @@ def rasterize(
     return output_file
 
 
-def preprocess_remove_background(input_file, page_context):
+def preprocess_remove_background(input_file: Path, page_context: PageContext):
     if any(image.bpc > 1 for image in page_context.pageinfo.images):
         output_file = page_context.get_path('pp_rm_bg.png')
         leptonica.remove_background(input_file, output_file)
         return output_file
     else:
-        page_context.log.info("background removal skipped on mono page")
+        log.info("background removal skipped on mono page")
         return input_file
 
 
-def preprocess_deskew(input_file, page_context):
+def preprocess_deskew(input_file: Path, page_context: PageContext):
     output_file = page_context.get_path('pp_deskew.png')
     dpi = get_page_square_dpi(page_context.pageinfo, page_context.options)
-    leptonica.deskew(input_file, output_file, dpi)
+    leptonica.deskew(input_file, output_file, dpi.x)
     return output_file
 
 
-def preprocess_clean(input_file, page_context):
-    from .exec import unpaper
-
+def preprocess_clean(input_file: Path, page_context: PageContext):
     output_file = page_context.get_path('pp_clean.png')
     dpi = get_page_square_dpi(page_context.pageinfo, page_context.options)
     unpaper.clean(
         input_file,
         output_file,
-        dpi,
-        page_context.log,
-        page_context.options.unpaper_args,
+        dpi=dpi.x,
+        unpaper_args=page_context.options.unpaper_args,
     )
     return output_file
 
 
-def create_ocr_image(image, page_context):
+def create_ocr_image(image: Path, page_context: PageContext):
     """Create the image we send for OCR. May not be the same as the display
     image depending on preprocessing. This image will never be shown to the
     user."""
@@ -488,15 +500,11 @@ def create_ocr_image(image, page_context):
     output_file = page_context.get_path('ocr.png')
     options = page_context.options
     with Image.open(image) as im:
-        from PIL import ImageColor
-        from PIL import ImageDraw
-
         white = ImageColor.getcolor('#ffffff', im.mode)
         # pink = ImageColor.getcolor('#ff0080', im.mode)
         draw = ImageDraw.ImageDraw(im)
 
-        xres, yres = im.info['dpi']
-        page_context.log.debug('resolution %r %r' % (xres, yres))
+        log.debug('resolution %r', im.info['dpi'])
 
         if not options.force_ocr:
             # Do not mask text areas when forcing OCR, because we need to OCR
@@ -512,46 +520,50 @@ def create_ocr_image(image, page_context):
                 # without regard whatever resolution is in pageinfo (may differ or
                 # be None)
                 bbox = [float(v) for v in textarea]
-                xscale, yscale = float(xres) / 72.0, float(yres) / 72.0
+                xyscale = tuple(float(coord) / 72.0 for coord in im.info['dpi'])
                 pixcoords = [
-                    bbox[0] * xscale,
-                    im.height - bbox[3] * yscale,
-                    bbox[2] * xscale,
-                    im.height - bbox[1] * yscale,
+                    bbox[0] * xyscale[0],
+                    im.height - bbox[3] * xyscale[1],
+                    bbox[2] * xyscale[0],
+                    im.height - bbox[1] * xyscale[1],
                 ]
                 pixcoords = [int(round(c)) for c in pixcoords]
-                page_context.log.debug('blanking %r', pixcoords)
+                log.debug('blanking %r', pixcoords)
                 draw.rectangle(pixcoords, fill=white)
                 # draw.rectangle(pixcoords, outline=pink)
 
         if options.threshold:
             pix = leptonica.Pix.frompil(im)
             pix = pix.masked_threshold_on_background_norm()
-            im = pix.topil()
+            im_pix = pix.topil()
+            im_pix.info['dpi'] = im.info['dpi']
+            im = im_pix
 
         del draw
+
+        filter_im = page_context.plugin_manager.hook.filter_ocr_image(
+            page=page_context, image=im
+        )
+        if filter_im is not None:
+            im = filter_im
+
         # Pillow requires integer DPI
-        dpi = round(xres), round(yres)
+        dpi = tuple(round(coord) for coord in im.info['dpi'])
         im.save(output_file, dpi=dpi)
     return output_file
 
 
-def ocr_tesseract_hocr(input_file, page_context):
+def ocr_engine_hocr(input_file: Path, page_context: PageContext):
     hocr_out = page_context.get_path('ocr_hocr.hocr')
     hocr_text_out = page_context.get_path('ocr_hocr.txt')
     options = page_context.options
-    tesseract.generate_hocr(
+
+    ocr_engine = page_context.plugin_manager.hook.get_ocr_engine()
+    ocr_engine.generate_hocr(
         input_file=input_file,
-        output_files=[hocr_out, hocr_text_out],
-        language=options.language,
-        engine_mode=options.tesseract_oem,
-        tessconfig=options.tesseract_config,
-        timeout=options.tesseract_timeout,
-        pagesegmode=options.tesseract_pagesegmode,
-        user_words=options.user_words,
-        user_patterns=options.user_patterns,
-        tesseract_env=options.tesseract_env,
-        log=page_context.log,
+        output_hocr=hocr_out,
+        output_text=hocr_text_out,
+        options=options,
     )
     return (hocr_out, hocr_text_out)
 
@@ -561,24 +573,28 @@ def should_visible_page_image_use_jpg(pageinfo):
     return pageinfo.images and all(im.enc == Encoding.jpeg for im in pageinfo.images)
 
 
-def create_visible_page_jpg(image, page_context):
+def create_visible_page_jpg(image: Path, page_context: PageContext) -> Path:
     output_file = page_context.get_path('visible.jpg')
     with Image.open(image) as im:
         # At this point the image should be a .png, but deskew, unpaper
         # might have removed the DPI information. In this case, fall back to
         # square DPI used to rasterize. When the preview image was
         # rasterized, it was also converted to square resolution, which is
-        # what we want to give tesseract, so keep it square.
-        fallback_dpi = get_page_square_dpi(page_context.pageinfo, page_context.options)
-        dpi = im.info.get('dpi', (fallback_dpi, fallback_dpi))
+        # what we want to give to the OCR engine, so keep it square.
+        if 'dpi' in im.info:
+            dpi = Resolution(*im.info['dpi'])
+        else:
+            # Fallback to page-implied DPI
+            dpi = get_page_square_dpi(page_context.pageinfo, page_context.options)
 
         # Pillow requires integer DPI
-        dpi = round(dpi[0]), round(dpi[1])
-        im.save(output_file, format='JPEG', dpi=dpi)
+        im.save(output_file, format='JPEG', dpi=dpi.to_int())
     return output_file
 
 
-def create_pdf_page_from_image(image, page_context):
+def create_pdf_page_from_image(
+    image: Path, page_context: PageContext, orientation_correction
+):
     # We rasterize a square DPI version of each page because most image
     # processing tools don't support rectangular DPI. Use the square DPI as it
     # accurately describes the image. It would be possible to resample the image
@@ -586,57 +602,65 @@ def create_pdf_page_from_image(image, page_context):
     # except that the hocr renderer does not understand non-square DPI. The
     # sandwich renderer would be fine.
     output_file = page_context.get_path('visible.pdf')
-    dpi = get_page_square_dpi(page_context.pageinfo, page_context.options)
-    layout_fun = img2pdf.get_fixed_dpi_layout_fun((dpi, dpi))
+
+    pageinfo = page_context.pageinfo
+    pagesize = 72.0 * float(pageinfo.width_inches), 72.0 * float(pageinfo.height_inches)
+    effective_rotation = (pageinfo.rotation - orientation_correction) % 360
+    if effective_rotation % 180 == 90:
+        pagesize = pagesize[1], pagesize[0]
 
     # This create a single page PDF
     with open(image, 'rb') as imfile, open(output_file, 'wb') as pdf:
-        page_context.log.debug('convert')
+        log.debug('convert')
+
+        layout_fun = img2pdf.get_layout_fun(pagesize)
         img2pdf.convert(
             imfile, with_pdfrw=False, layout_fun=layout_fun, outputstream=pdf
         )
-        page_context.log.debug('convert done')
+        log.debug('convert done')
+
+    output_file = page_context.plugin_manager.hook.filter_pdf_page(
+        page=page_context, image_filename=image, output_pdf=output_file
+    )
+
     return output_file
 
 
-def render_hocr_page(hocr, page_context):
+def render_hocr_page(hocr: Path, page_context: PageContext):
+    options = page_context.options
     output_file = page_context.get_path('ocr_hocr.pdf')
-    dpi = get_page_square_dpi(page_context.pageinfo, page_context.options)
-    hocrtransform = HocrTransform(hocr, dpi)
+    dpi = get_page_square_dpi(page_context.pageinfo, options)
+    debug_mode = options.pdf_renderer == 'hocrdebug'
+
+    hocrtransform = HocrTransform(hocr_filename=hocr, dpi=dpi.x)  # square
     hocrtransform.to_pdf(
-        output_file,
-        imageFileName=None,
-        showBoundingboxes=False,
-        invisibleText=True,
-        interwordSpaces=True,
+        out_filename=output_file,
+        image_filename=None,
+        show_bounding_boxes=False if not debug_mode else True,
+        invisible_text=True if not debug_mode else False,
+        interword_spaces=True,
     )
     return output_file
 
 
-def ocr_tesseract_textonly_pdf(input_image, page_context):
+def ocr_engine_textonly_pdf(input_image: Path, page_context: PageContext):
     output_pdf = page_context.get_path('ocr_tess.pdf')
     output_text = page_context.get_path('ocr_tess.txt')
     options = page_context.options
-    tesseract.generate_pdf(
-        input_image=input_image,
-        skip_pdf=None,
+
+    ocr_engine = page_context.plugin_manager.hook.get_ocr_engine()
+    ocr_engine.generate_pdf(
+        input_file=input_image,
         output_pdf=output_pdf,
         output_text=output_text,
-        language=options.language,
-        engine_mode=options.tesseract_oem,
-        text_only=True,
-        tessconfig=options.tesseract_config,
-        timeout=options.tesseract_timeout,
-        pagesegmode=options.tesseract_pagesegmode,
-        user_words=options.user_words,
-        user_patterns=options.user_patterns,
-        tesseract_env=options.tesseract_env,
-        log=page_context.log,
+        options=options,
     )
     return (output_pdf, output_text)
 
 
-def get_docinfo(base_pdf, options):
+def get_docinfo(base_pdf: pikepdf.Pdf, context: PdfContext) -> Dict[str, str]:
+    options = context.options
+
     def from_document_info(key):
         try:
             s = base_pdf.docinfo[key]
@@ -648,7 +672,6 @@ def get_docinfo(base_pdf, options):
         k: from_document_info(k)
         for k in ('/Title', '/Author', '/Keywords', '/Subject', '/CreationDate')
     }
-    renderer_tag = 'OCR'
     if options is not None:
         if options.title:
             pdfmark['/Title'] = options.title
@@ -659,29 +682,21 @@ def get_docinfo(base_pdf, options):
         if options.subject:
             pdfmark['/Subject'] = options.subject
 
-        if options.pdf_renderer == 'sandwich':
-            renderer_tag = 'OCR-PDF'
+    creator_tag = context.plugin_manager.hook.get_ocr_engine().creator_tag(options)
 
-    pdfmark['/Creator'] = (
-        f'{PROGRAM_NAME} {VERSION} / ' f'Tesseract {renderer_tag} {tesseract.version()}'
-    )
+    pdfmark['/Creator'] = f'{PROGRAM_NAME} {VERSION} / {creator_tag}'
     pdfmark['/Producer'] = f'pikepdf {pikepdf.__version__}'
-    if 'OCRMYPDF_CREATOR' in os.environ:
-        pdfmark['/Creator'] = os.environ['OCRMYPDF_CREATOR']
-    if 'OCRMYPDF_PRODUCER' in os.environ:
-        pdfmark['/Producer'] = os.environ['OCRMYPDF_PRODUCER']
-
     pdfmark['/ModDate'] = encode_pdf_date(datetime.now(timezone.utc))
     return pdfmark
 
 
-def generate_postscript_stub(context):
+def generate_postscript_stub(context: PdfContext):
     output_file = context.get_path('pdfa.ps')
     generate_pdfa_ps(output_file)
     return output_file
 
 
-def convert_to_pdfa(input_pdf, input_ps_stub, context):
+def convert_to_pdfa(input_pdf: Path, input_ps_stub: Path, context: PdfContext):
     options = context.options
     input_pdfinfo = context.pdfinfo
     fix_docinfo_file = context.get_path('fix_docinfo.pdf')
@@ -697,7 +712,7 @@ def convert_to_pdfa(input_pdf, input_ps_stub, context):
         try:
             len(pdf_file.docinfo)
         except TypeError:
-            context.log.error(
+            log.error(
                 "File contains a malformed DocumentInfo block - continuing anyway"
             )
         else:
@@ -711,26 +726,49 @@ def convert_to_pdfa(input_pdf, input_ps_stub, context):
         else:
             safe_symlink(input_pdf, fix_docinfo_file)
 
-    ghostscript.generate_pdfa(
+    context.plugin_manager.hook.generate_pdfa(
         pdf_version=input_pdfinfo.min_version,
-        pdf_pages=[fix_docinfo_file, input_ps_stub],
+        pdf_pages=[fix_docinfo_file],
+        pdfmark=input_ps_stub,
         output_file=output_file,
         compression=options.pdfa_image_compression,
-        log=context.log,
         pdfa_part=options.output_type[-1],  # is pdfa-1, pdfa-2, or pdfa-3
+        progressbar_class=(
+            context.plugin_manager.hook.get_progressbar_class()
+            if options.progress_bar
+            else None
+        ),
     )
 
     return output_file
 
 
-def should_linearize(working_file, context):
+def should_linearize(working_file: Path, context: PdfContext):
     filesize = os.stat(working_file).st_size
     if filesize > (context.options.fast_web_view * 1_000_000):
         return True
     return False
 
 
-def metadata_fixup(working_file, context):
+def get_pdf_save_settings(output_type: str):
+    if output_type == 'pdfa-1':
+        # Trigger recompression to ensure object streams are removed, because
+        # Acrobat complains about them in PDF/A-1b validation.
+        return dict(
+            preserve_pdfa=True,
+            compress_streams=True,
+            stream_decode_level=pikepdf.StreamDecodeLevel.generalized,
+            object_stream_mode=pikepdf.ObjectStreamMode.disable,
+        )
+    else:
+        return dict(
+            preserve_pdfa=True,
+            compress_streams=True,
+            object_stream_mode=(pikepdf.ObjectStreamMode.generate),
+        )
+
+
+def metadata_fixup(working_file: Path, context: PdfContext):
     output_file = context.get_path('metafix.pdf')
     options = context.options
 
@@ -738,25 +776,21 @@ def metadata_fixup(working_file, context):
         if not missing:
             return
         if options.output_type.startswith('pdfa'):
-            context.log.warning(
+            log.warning(
                 "Some input metadata could not be copied because it is not "
                 "permitted in PDF/A. You may wish to examine the output "
                 "PDF's XMP metadata."
             )
-            context.log.debug(
-                "The following metadata fields were not copied: %r", missing
-            )
+            log.debug("The following metadata fields were not copied: %r", missing)
         else:
-            context.log.error(
+            log.error(
                 "Some input metadata could not be copied."
                 "You may wish to examine the output PDF's XMP metadata."
             )
-            context.log.info(
-                "The following metadata fields were not copied: %r", missing
-            )
+            log.info("The following metadata fields were not copied: %r", missing)
 
     with pikepdf.open(context.origin) as original, pikepdf.open(working_file) as pdf:
-        docinfo = get_docinfo(original, options)
+        docinfo = get_docinfo(original, context)
         with pdf.open_metadata() as meta:
             meta.load_from_docinfo(docinfo, delete_missing=False, raise_failure=False)
             # If xmp:CreateDate is missing, set it to the modify date to
@@ -764,15 +798,21 @@ def metadata_fixup(working_file, context):
             if 'xmp:CreateDate' not in meta:
                 meta['xmp:CreateDate'] = meta.get('xmp:ModifyDate', '')
 
-            meta_original = original.open_metadata()
-            missing = set(meta_original.keys()) - set(meta.keys())
-            report_on_metadata(missing)
+            with original.open_metadata(
+                set_pikepdf_as_editor=False, update_docinfo=False, strict=False
+            ) as meta_original:
+                if meta.get('dc:title') == 'Untitled':
+                    # Ghostscript likes to set title to Untitled if omitted from input.
+                    # Reverse this, because PDF/A TechNote 0003:Metadata in PDF/A-1
+                    # and the XMP Spec do not make this recommendation.
+                    if 'dc:title' not in meta_original:
+                        del meta['dc:title']
+                missing = set(meta_original.keys()) - set(meta.keys())
+                report_on_metadata(missing)
 
         pdf.save(
             output_file,
-            compress_streams=True,
-            preserve_pdfa=True,
-            object_stream_mode=pikepdf.ObjectStreamMode.generate,
+            **get_pdf_save_settings(options.output_type),
             linearize=(  # Don't linearize if optimize() will be linearizing too
                 should_linearize(working_file, context)
                 if options.optimize == 0
@@ -783,47 +823,68 @@ def metadata_fixup(working_file, context):
     return output_file
 
 
-def optimize_pdf(input_file, context):
+def optimize_pdf(input_file: Path, context: PdfContext, executor: Executor):
     output_file = context.get_path('optimize.pdf')
     save_settings = dict(
-        compress_streams=True,
-        preserve_pdfa=True,
-        object_stream_mode=pikepdf.ObjectStreamMode.generate,
         linearize=should_linearize(input_file, context),
+        **get_pdf_save_settings(context.options.output_type),
     )
-    optimize(input_file, output_file, context, save_settings)
+    optimize(input_file, output_file, context, save_settings, executor)
     return output_file
 
 
-def merge_sidecars(txt_files, context):
+def enumerate_compress_ranges(iterable):
+    skipped_from, index = None, None
+    for index, txt_file in enumerate(iterable):
+        index += 1
+        if txt_file:
+            if skipped_from is not None:
+                yield (skipped_from, index - 1), None
+                skipped_from = None
+            yield (index, index), txt_file
+        else:
+            if skipped_from is None:
+                skipped_from = index
+    if skipped_from is not None:
+        yield (skipped_from, index), None
+
+
+def merge_sidecars(txt_files: Iterable[Optional[Path]], context: PdfContext):
     output_file = context.get_path('sidecar.txt')
     with open(output_file, 'w', encoding="utf-8") as stream:
-        for page_num, txt_file in enumerate(txt_files):
-            if page_num != 0:
+        for (frm, to), txt_file in enumerate_compress_ranges(txt_files):
+            if frm != 1:
                 stream.write('\f')  # Form feed between pages
             if txt_file:
                 with open(txt_file, 'r', encoding="utf-8") as in_:
                     txt = in_.read()
-                    # Tesseract v4 alpha started adding form feeds in
-                    # commit aa6eb6b
-                    # No obvious way to detect what binaries will do this, so
-                    # for consistency just ignore its form feeds and insert our
-                    # own
+                    # Some OCR engines (e.g. Tesseract v4 alpha) add form feeds
+                    # between pages, and some do not. For consistency, we ignore
+                    # any added by the OCR engine and them on our own.
                     if txt.endswith('\f'):
                         stream.write(txt[:-1])
                     else:
                         stream.write(txt)
             else:
-                stream.write(f'[OCR skipped on page {(page_num + 1)}]')
+                if frm != to:
+                    pages = f'{frm}-{to}'
+                else:
+                    pages = f'{frm}'
+                stream.write(f'[OCR skipped on page(s) {pages}]')
     return output_file
 
 
-def copy_final(input_file, output_file, context):
-    context.log.debug('%s -> %s', input_file, output_file)
+def copy_final(input_file, output_file, _context: PdfContext):
+    log.debug('%s -> %s', input_file, output_file)
     with open(input_file, 'rb') as input_stream:
         if output_file == '-':
             copyfileobj(input_stream, sys.stdout.buffer)
             sys.stdout.flush()
+        elif hasattr(output_file, 'writable'):
+            output_stream = output_file
+            copyfileobj(input_stream, output_stream)
+            with suppress(AttributeError):
+                output_stream.flush()
         else:
             # At this point we overwrite the output_file specified by the user
             # use copyfileobj because then we use open() to create the file and

src/ocrmypdf/_plugin_manager.py

@@ -0,0 +1,113 @@
+# © 2020 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+import argparse
+import importlib
+import importlib.util
+import pkgutil
+import sys
+from pathlib import Path
+from typing import List, Tuple, Union
+
+import pluggy
+
+import ocrmypdf.builtin_plugins
+from ocrmypdf import pluginspec
+from ocrmypdf.cli import get_parser, plugins_only_parser
+
+
+class OcrmypdfPluginManager(pluggy.PluginManager):
+    """pluggy.PluginManager that can fork.
+
+    Capable of reconstructing itself in child workers.
+
+    Arguments:
+        setup_func: callback that initializes the plugin manager with all
+            standard plugins
+    """
+
+    def __init__(
+        self,
+        *args,
+        plugins: List[Union[str, Path]],
+        builtins: bool = True,
+        **kwargs,
+    ):
+        self.__init_args = args
+        self.__init_kwargs = kwargs
+        self.__plugins = plugins
+        self.__builtins = builtins
+        super().__init__(*args, **kwargs)
+        self.setup_plugins()
+
+    def __getstate__(self):
+        state = dict(
+            init_args=self.__init_args,
+            plugins=self.__plugins,
+            builtins=self.__builtins,
+            init_kwargs=self.__init_kwargs,
+        )
+        return state
+
+    def __setstate__(self, state):
+        self.__init__(
+            *state['init_args'],
+            plugins=state['plugins'],
+            builtins=state['builtins'],
+            **state['init_kwargs'],
+        )
+
+    def setup_plugins(self):
+        self.add_hookspecs(pluginspec)
+
+        # 1. Register builtins
+        if self.__builtins:
+            for module in sorted(
+                pkgutil.iter_modules(ocrmypdf.builtin_plugins.__path__)
+            ):
+                name = f'ocrmypdf.builtin_plugins.{module.name}'
+                module = importlib.import_module(name)
+                self.register(module)
+
+        # 2. Register setuptools plugins
+        self.load_setuptools_entrypoints('ocrmypdf')
+
+        # 3. Register plugins specified on command line
+        for name in self.__plugins:
+            if isinstance(name, Path) or name.endswith('.py'):
+                # Import by filename
+                module_name = Path(name).stem
+                spec = importlib.util.spec_from_file_location(module_name, name)
+                module = importlib.util.module_from_spec(spec)
+                sys.modules[module_name] = module
+                spec.loader.exec_module(module)
+            else:
+                # Import by dotted module name
+                module = importlib.import_module(name)
+            self.register(module)
+
+
+def get_plugin_manager(plugins: List[Union[str, Path]], builtins=True):
+    pm = OcrmypdfPluginManager(
+        project_name='ocrmypdf',
+        plugins=plugins,
+        builtins=builtins,
+    )
+    return pm
+
+
+def get_parser_options_plugins(
+    args,
+) -> Tuple[argparse.ArgumentParser, argparse.Namespace, pluggy.PluginManager]:
+    pre_options, _unused = plugins_only_parser.parse_known_args(args=args)
+    plugin_manager = get_plugin_manager(pre_options.plugins)
+
+    parser = get_parser()
+    plugin_manager.hook.add_options(parser=parser)  # pylint: disable=no-member
+
+    options = parser.parse_args(args=args)
+    return parser, options, plugin_manager

src/ocrmypdf/_sync.py

@@ -1,37 +1,27 @@
 # © 2016 James R. Barlow: github.com/jbarlow83
 #
-# This file is part of OCRmyPDF.
-#
-# OCRmyPDF is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# OCRmyPDF is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with OCRmyPDF.  If not, see <http://www.gnu.org/licenses/>.
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
 
 import logging
 import logging.handlers
-import multiprocessing
 import os
-import signal
 import sys
 import threading
-from collections import namedtuple
+from functools import partial
 from pathlib import Path
 from tempfile import mkdtemp
+from typing import List, NamedTuple, Optional, Tuple
 
 import PIL
-from tqdm import tqdm
 
-from ._graft import OcrGrafter
-from ._jobcontext import PDFContext, cleanup_working_files, make_logger
-from ._pipeline import (
+from ocrmypdf._concurrent import Executor, setup_executor
+from ocrmypdf._graft import OcrGrafter
+from ocrmypdf._jobcontext import PageContext, PdfContext, cleanup_working_files
+from ocrmypdf._logging import PageNumberFilter
+from ocrmypdf._pipeline import (
     convert_to_pdfa,
     copy_final,
     create_ocr_image,
@@ -43,8 +33,8 @@ from ._pipeline import (
     is_ocr_required,
     merge_sidecars,
     metadata_fixup,
-    ocr_tesseract_hocr,
-    ocr_tesseract_textonly_pdf,
+    ocr_engine_hocr,
+    ocr_engine_textonly_pdf,
     optimize_pdf,
     preprocess_clean,
     preprocess_deskew,
@@ -56,22 +46,57 @@ from ._pipeline import (
     triage,
     validate_pdfinfo_options,
 )
-from ._validation import (
+from ocrmypdf._plugin_manager import get_plugin_manager
+from ocrmypdf._validation import (
     check_requested_output_file,
     create_input_file,
     report_output_file_size,
 )
-from .exceptions import ExitCode, ExitCodeException
-from .exec import qpdf
-from .helpers import available_cpu_count
-from .pdfa import file_claims_pdfa
-
-PageResult = namedtuple(
-    'PageResult', 'pageno, pdf_page_from_image, ocr, text, orientation_correction'
+from ocrmypdf.exceptions import ExitCode, ExitCodeException
+from ocrmypdf.helpers import (
+    NeverRaise,
+    available_cpu_count,
+    check_pdf,
+    pikepdf_enable_mmap,
+    samefile,
 )
+from ocrmypdf.pdfa import file_claims_pdfa
+
+log = logging.getLogger(__name__)
 
 
-def preprocess(page_context, image, remove_background, deskew, clean):
+class PageResult(NamedTuple):  # pylint: disable=inherit-non-class
+    pageno: int
+    pdf_page_from_image: Optional[Path]
+    ocr: Optional[Path]
+    text: Optional[Path]
+    orientation_correction: int
+
+
+tls = threading.local()
+tls.pageno = None
+
+
+old_factory = logging.getLogRecordFactory()
+
+
+def record_factory(*args, **kwargs):
+    record = old_factory(*args, **kwargs)
+    if hasattr(tls, 'pageno'):
+        record.pageno = tls.pageno
+    return record
+
+
+logging.setLogRecordFactory(record_factory)
+
+
+def preprocess(
+    page_context: PageContext,
+    image: Path,
+    remove_background: bool,
+    deskew: bool,
+    clean: bool,
+) -> Path:
     if remove_background:
         image = preprocess_remove_background(image, page_context)
     if deskew:
@@ -81,54 +106,55 @@ def preprocess(page_context, image, remove_background, deskew, clean):
     return image
 
 
-def exec_page_sync(page_context):
+def make_intermediate_images(
+    page_context: PageContext, orientation_correction: int
+) -> Tuple[Path, Optional[Path]]:
     options = page_context.options
-    orientation_correction = 0
-    pdf_page_from_image_out = None
-    ocr_out = None
-    text_out = None
-    if is_ocr_required(page_context):
-        if options.rotate_pages:
-            # Rasterize
-            rasterize_preview_out = rasterize_preview(page_context.origin, page_context)
-            orientation_correction = get_orientation_correction(
-                rasterize_preview_out, page_context
-            )
 
-        rasterize_out = rasterize(
-            page_context.origin,
+    ocr_image = preprocess_out = None
+    rasterize_out = rasterize(
+        page_context.origin,
+        page_context,
+        correction=orientation_correction,
+        remove_vectors=False,
+    )
+
+    if not any([options.clean, options.clean_final, options.remove_vectors]):
+        ocr_image = preprocess_out = preprocess(
             page_context,
-            correction=orientation_correction,
-            remove_vectors=False,
+            rasterize_out,
+            options.remove_background,
+            options.deskew,
+            clean=False,
         )
-
-        if not any([options.clean, options.clean_final, options.remove_vectors]):
-            ocr_image = preprocess_out = preprocess(
+    else:
+        if not options.lossless_reconstruction:
+            preprocess_out = preprocess(
                 page_context,
                 rasterize_out,
                 options.remove_background,
                 options.deskew,
-                clean=False,
+                clean=options.clean_final,
+            )
+        if options.remove_vectors:
+            rasterize_ocr_out = rasterize(
+                page_context.origin,
+                page_context,
+                correction=orientation_correction,
+                remove_vectors=True,
+                output_tag='_ocr',
             )
         else:
-            if not options.lossless_reconstruction:
-                preprocess_out = preprocess(
-                    page_context,
-                    rasterize_out,
-                    options.remove_background,
-                    options.deskew,
-                    clean=options.clean_final,
-                )
-            if options.remove_vectors:
-                rasterize_ocr_out = rasterize(
-                    page_context.origin,
-                    page_context,
-                    correction=orientation_correction,
-                    remove_vectors=True,
-                    output_tag='_ocr',
-                )
-            else:
-                rasterize_ocr_out = rasterize_out
+            rasterize_ocr_out = rasterize_out
+
+        if (
+            preprocess_out
+            and rasterize_ocr_out == rasterize_out
+            and options.clean == options.clean_final
+        ):
+            # Optimization: image for OCR is identical to presentation image
+            ocr_image = preprocess_out
+        else:
             ocr_image = preprocess(
                 page_context,
                 rasterize_ocr_out,
@@ -136,28 +162,57 @@ def exec_page_sync(page_context):
                 options.deskew,
                 clean=options.clean,
             )
+    return ocr_image, preprocess_out
 
-        ocr_image_out = create_ocr_image(ocr_image, page_context)
 
-        pdf_page_from_image_out = None
-        if not options.lossless_reconstruction:
-            visible_image_out = preprocess_out
-            if should_visible_page_image_use_jpg(page_context.pageinfo):
-                visible_image_out = create_visible_page_jpg(
-                    visible_image_out, page_context
-                )
-            pdf_page_from_image_out = create_pdf_page_from_image(
-                visible_image_out, page_context
-            )
+def exec_page_sync(page_context: PageContext):
+    options = page_context.options
+    tls.pageno = page_context.pageno + 1
 
-        if options.pdf_renderer == 'hocr':
-            (hocr_out, text_out) = ocr_tesseract_hocr(ocr_image_out, page_context)
-            ocr_out = render_hocr_page(hocr_out, page_context)
+    if not is_ocr_required(page_context):
+        return PageResult(
+            pageno=page_context.pageno,
+            pdf_page_from_image=None,
+            ocr=None,
+            text=None,
+            orientation_correction=0,
+        )
 
-        if options.pdf_renderer == 'sandwich':
-            (ocr_out, text_out) = ocr_tesseract_textonly_pdf(
-                ocr_image_out, page_context
-            )
+    orientation_correction = 0
+    if options.rotate_pages:
+        # Rasterize
+        rasterize_preview_out = rasterize_preview(page_context.origin, page_context)
+        orientation_correction = get_orientation_correction(
+            rasterize_preview_out, page_context
+        )
+
+    ocr_image, preprocess_out = make_intermediate_images(
+        page_context, orientation_correction
+    )
+    ocr_image_out = create_ocr_image(ocr_image, page_context)
+
+    pdf_page_from_image_out = None
+    if not options.lossless_reconstruction:
+        assert preprocess_out
+        visible_image_out = preprocess_out
+        if should_visible_page_image_use_jpg(page_context.pageinfo):
+            visible_image_out = create_visible_page_jpg(visible_image_out, page_context)
+        filtered_image = page_context.plugin_manager.hook.filter_page_image(
+            page=page_context, image_filename=visible_image_out
+        )
+        if filtered_image:
+            visible_image_out = filtered_image
+        pdf_page_from_image_out = create_pdf_page_from_image(
+            visible_image_out, page_context, orientation_correction
+        )
+
+    if options.pdf_renderer.startswith('hocr'):
+        (hocr_out, text_out) = ocr_engine_hocr(ocr_image_out, page_context)
+        ocr_out = render_hocr_page(hocr_out, page_context)
+    elif options.pdf_renderer == 'sandwich':
+        (ocr_out, text_out) = ocr_engine_textonly_pdf(ocr_image_out, page_context)
+    else:
+        raise NotImplementedError(f"pdf_renderer {options.pdf_renderer}")
 
     return PageResult(
         pageno=page_context.pageno,
@@ -168,235 +223,162 @@ def exec_page_sync(page_context):
     )
 
 
-def post_process(pdf_file, context):
+def post_process(pdf_file, context: PdfContext, executor: Executor):
     pdf_out = pdf_file
     if context.options.output_type.startswith('pdfa'):
         ps_stub_out = generate_postscript_stub(context)
         pdf_out = convert_to_pdfa(pdf_out, ps_stub_out, context)
 
     pdf_out = metadata_fixup(pdf_out, context)
-    return optimize_pdf(pdf_out, context)
+    return optimize_pdf(pdf_out, context, executor)
 
 
-def worker_init(queue, max_pixels):
-    """Initialize a process pool worker"""
-
-    # Ignore SIGINT (our parent process will kill us gracefully)
-    signal.signal(signal.SIGINT, signal.SIG_IGN)
-
-    # Reconfigure the root logger for this process to send all messages to a queue
-    h = logging.handlers.QueueHandler(queue)
-    root = logging.getLogger()
-    root.handlers = []
-    root.addHandler(h)
-
+def worker_init(max_pixels: int):
     # In Windows, child process will not inherit our change to this value in
-    # the parent process, so ensure workers get it set
+    # the parent process, so ensure workers get it set. Not needed when running
+    # threaded, but harmless to set again.
     PIL.Image.MAX_IMAGE_PIXELS = max_pixels
+    pikepdf_enable_mmap()
 
 
-def worker_thread_init(_queue, max_pixels):
-    # This is probably not needed since threads should all see the same memory,
-    # but done for consistency.
-    PIL.Image.MAX_IMAGE_PIXELS = max_pixels
-
-
-def log_listener(queue):
-    """Listen to the worker processes and forward the messages to logging
-
-    For simplicity this is a thread rather than a process. Only one process
-    should actually write to sys.stderr or whatever we're using, so if this is
-    made into a process the main application needs to be directed to it.
-
-    See https://docs.python.org/3/howto/logging-cookbook.html#logging-to-a-single-file-from-multiple-processes
-    """
-
-    while True:
-        try:
-            record = queue.get()
-            if record is None:
-                break
-            logger = logging.getLogger(record.name)
-            logger.handle(record)
-        except Exception:
-            import traceback
-
-            print("Logging problem", file=sys.stderr)
-            traceback.print_exc(file=sys.stderr)
-
-
-def exec_concurrent(context):
+def exec_concurrent(context: PdfContext, executor: Executor):
     """Execute the pipeline concurrently"""
 
     # Run exec_page_sync on every page context
-    max_workers = min(len(context.pdfinfo), context.options.jobs)
+    options = context.options
+    max_workers = min(len(context.pdfinfo), options.jobs)
     if max_workers > 1:
-        context.log.info("Start processing %d pages concurrently", max_workers)
+        log.info("Start processing %d pages concurrently", max_workers)
 
-    # Tesseract 4.x can be multithreaded, and we also run multiple workers. We want
-    # to manage how many threads it uses to avoid creating total threads than cores.
-    # Performance testing shows we're better off
-    # parallelizing ocrmypdf and forcing Tesseract to be single threaded, which we
-    # get by setting the envvar OMP_THREAD_LIMIT to 1. But if the page count of the
-    # input file is small, then we allow Tesseract to use threads, subject to the
-    # constraint: (ocrmypdf workers) * (tesseract threads) <= max_workers.
-    # As of Tesseract 4.1, 3 threads is the most effective on a 4 core/8 thread system.
-    tess_threads = min(3, context.options.jobs // max_workers)
-    if context.options.tesseract_env is None:
-        context.options.tesseract_env = os.environ.copy()
-    context.options.tesseract_env.setdefault('OMP_THREAD_LIMIT', str(tess_threads))
-    try:
-        tess_threads = int(context.options.tesseract_env['OMP_THREAD_LIMIT'])
-    except ValueError:  # OMP_THREAD_LIMIT initialized to non-numeric
-        context.log.error("Environment variable OMP_THREAD_LIMIT is not numeric")
-    if tess_threads > 1:
-        context.log.info("Using Tesseract OpenMP thread limit %d", tess_threads)
-
-    if context.options.use_threads:
-        from multiprocessing.dummy import Pool
-
-        initializer = worker_thread_init
-    else:
-        Pool = multiprocessing.Pool
-        initializer = worker_init
-
-    sidecars = [None] * len(context.pdfinfo)
+    sidecars: List[Optional[Path]] = [None] * len(context.pdfinfo)
     ocrgraft = OcrGrafter(context)
 
-    log_queue = multiprocessing.Queue(-1)
-    listener = threading.Thread(target=log_listener, args=(log_queue,))
-    listener.start()
-    with tqdm(
-        total=(2 * len(context.pdfinfo)),
-        desc='OCR',
-        unit='page',
-        unit_scale=0.5,
-        disable=not context.options.progress_bar,
-    ) as pbar:
-        pool = Pool(
-            processes=max_workers,
-            initializer=initializer,
-            initargs=(log_queue, PIL.Image.MAX_IMAGE_PIXELS),
-        )
+    def update_page(result: PageResult, pbar):
         try:
-            results = pool.imap_unordered(exec_page_sync, context.get_page_contexts())
-            while True:
-                try:
-                    page_result = results.next()
-                    sidecars[page_result.pageno] = page_result.text
-                    pbar.update()
-                    ocrgraft.graft_page(page_result)
-                    pbar.update()
-                except StopIteration:
-                    break
-        except KeyboardInterrupt:
-            # Terminate pool so we exit instantly
-            pool.terminate()
-            # Don't try listener.join() here, will deadlock
-            raise
-        except Exception:
-            if not os.environ.get("PYTEST_CURRENT_TEST", ""):
-                # Unless inside pytest, exit immediately because no one wants
-                # to wait for child processes to finalize results that will be
-                # thrown away. Inside pytest, we want child processes to exit
-                # cleanly so that they output an error messages or coverage data
-                # we need from them.
-                pool.terminate()
-            raise
+            tls.pageno = result.pageno + 1
+            sidecars[result.pageno] = result.text
+            pbar.update()
+            ocrgraft.graft_page(
+                pageno=result.pageno,
+                image=result.pdf_page_from_image,
+                textpdf=result.ocr,
+                autorotate_correction=result.orientation_correction,
+            )
+            pbar.update()
         finally:
-            # Terminate log listener
-            log_queue.put_nowait(None)
-            pool.close()
-            pool.join()
+            tls.pageno = None
 
-    listener.join()
+    executor(
+        use_threads=options.use_threads,
+        max_workers=max_workers,
+        tqdm_kwargs=dict(
+            total=(2 * len(context.pdfinfo)),
+            desc='OCR' if options.tesseract_timeout > 0 else 'Image processing',
+            unit='page',
+            unit_scale=0.5,
+            disable=not options.progress_bar,
+        ),
+        worker_initializer=partial(worker_init, PIL.Image.MAX_IMAGE_PIXELS),
+        task=exec_page_sync,
+        task_arguments=context.get_page_contexts(),
+        task_finished=update_page,
+    )
 
     # Output sidecar text
-    if context.options.sidecar:
+    if options.sidecar:
         text = merge_sidecars(sidecars, context)
         # Copy text file to destination
-        copy_final(text, context.options.sidecar, context)
+        copy_final(text, options.sidecar, context)
 
     # Merge layers to one single pdf
     pdf = ocrgraft.finalize()
 
     # PDF/A and metadata
-    pdf = post_process(pdf, context)
+    log.info("Postprocessing...")
+    pdf = post_process(pdf, context, executor)
 
     # Copy PDF file to destination
-    copy_final(pdf, context.options.output_file, context)
+    copy_final(pdf, options.output_file, context)
 
 
-class NeverRaise(Exception):
-    """An exception that is never raised"""
+def configure_debug_logging(log_filename: Path, prefix: str = ''):
+    """
+    Create a debug log file at a specified location.
 
-    pass  # pylint: disable=unnecessary-pass
-
-
-def samefile(f1, f2):
-    if os.name == 'nt':
-        return f1 == f2
-    else:
-        return os.path.samefile(f1, f2)
-
-
-def configure_debug_logging(log_filename, prefix=''):
+    Arguments:
+        log_filename: Where to the put the log file.
+        prefix: The logging domain prefix that should be sent to the log.
+    """
     log_file_handler = logging.FileHandler(log_filename, delay=True)
     log_file_handler.setLevel(logging.DEBUG)
     formatter = logging.Formatter(
-        '[%(asctime)s] - %(name)s - %(levelname)7s - %(message)s'
+        '[%(asctime)s] - %(name)s - %(levelname)7s -%(pageno)s %(message)s'
     )
     log_file_handler.setFormatter(formatter)
+    log_file_handler.addFilter(PageNumberFilter())
     logging.getLogger(prefix).addHandler(log_file_handler)
     return log_file_handler
 
 
-def run_pipeline(options, api=False):
-    log = make_logger(options, __name__)
-
+def run_pipeline(options, *, plugin_manager, api=False):
     # Any changes to options will not take effect for options that are already
     # bound to function parameters in the pipeline. (For example
     # options.input_file, options.pdf_renderer are already bound.)
     if not options.jobs:
         options.jobs = available_cpu_count()
+    if not plugin_manager:
+        plugin_manager = get_plugin_manager(options.plugins)
 
-    work_folder = mkdtemp(prefix="com.github.ocrmypdf.")
+    work_folder = Path(mkdtemp(prefix="ocrmypdf.io."))
     debug_log_handler = None
-    if (options.keep_temporary_files or options.verbose >= 1) and not os.environ.get(
-        'PYTEST_CURRENT_TEST', ''
+    if (
+        (options.keep_temporary_files or options.verbose >= 1)
+        and not os.environ.get('PYTEST_CURRENT_TEST', '')
+        and not api
     ):
-        debug_log_handler = configure_debug_logging(Path(work_folder) / "debug.log")
+        # Debug log for command line interface only with verbose output
+        # See https://github.com/pytest-dev/pytest/issues/5502 for why we skip this
+        # when pytest is running
+        debug_log_handler = configure_debug_logging(
+            Path(work_folder) / "debug.log"
+        )  # pragma: no cover
 
+    pikepdf_enable_mmap()
+
+    executor = setup_executor(plugin_manager)
     try:
         check_requested_output_file(options)
         start_input_file, original_filename = create_input_file(options, work_folder)
 
         # Triage image or pdf
         origin_pdf = triage(
-            original_filename,
-            start_input_file,
-            os.path.join(work_folder, 'origin.pdf'),
-            options,
-            log,
+            original_filename, start_input_file, work_folder / 'origin.pdf', options
         )
 
         # Gather pdfinfo and create context
         pdfinfo = get_pdfinfo(
             origin_pdf,
-            detailed_page_analysis=options.redo_ocr,
+            executor=executor,
+            detailed_analysis=options.redo_ocr,
             progbar=options.progress_bar,
+            max_workers=options.jobs if not options.use_threads else 1,  # To help debug
+            check_pages=options.pages,
         )
 
-        context = PDFContext(options, work_folder, origin_pdf, pdfinfo)
+        context = PdfContext(options, work_folder, origin_pdf, pdfinfo, plugin_manager)
 
         # Validate options are okay for this pdf
         validate_pdfinfo_options(context)
 
         # Execute the pipeline
-        exec_concurrent(context)
+        exec_concurrent(context, executor)
 
         if options.output_file == '-':
             log.info("Output sent to stdout")
+        elif (
+            hasattr(options.output_file, 'writable') and options.output_file.writable()
+        ):
+            log.info("Output written to stream")
         elif samefile(options.output_file, os.devnull):
             pass  # Say nothing when sending to dev null
         else:
@@ -412,7 +394,7 @@ def run_pipeline(options, api=False):
                         pdfa_info['conformance'],
                     )
                     return ExitCode.pdfa_conversion_failed
-            if not qpdf.check(options.output_file, log):
+            if not check_pdf(options.output_file):
                 log.warning('Output file: The generated PDF is INVALID')
                 return ExitCode.invalid_output_pdf
             report_output_file_size(options, start_input_file, options.output_file)
@@ -429,7 +411,7 @@ def run_pipeline(options, api=False):
         else:
             log.error(type(e).__name__)
         return e.exit_code
-    except (Exception if not api else NeverRaise) as e:
+    except (Exception if not api else NeverRaise) as e:  # pylint: disable=broad-except
         log.exception("An exception occurred while executing the pipeline")
         return ExitCode.other_error
     finally:

src/ocrmypdf/_validation.py

@@ -1,48 +1,38 @@
 #!/usr/bin/env python3
 # © 2015-17 James R. Barlow: github.com/jbarlow83
 #
-# This file is part of OCRmyPDF.
-#
-# OCRmyPDF is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# OCRmyPDF is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with OCRmyPDF.  If not, see <http://www.gnu.org/licenses/>.
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 
 import locale
 import logging
 import os
 import sys
+import unicodedata
 from pathlib import Path
 from shutil import copyfileobj
+from typing import List, Set, Tuple, Union
 
+import pikepdf
 import PIL
 
-from ._unicodefun import verify_python3_env
-from .exceptions import (
+from ocrmypdf._exec import jbig2enc, pngquant, unpaper
+from ocrmypdf._unicodefun import verify_python3_env
+from ocrmypdf.exceptions import (
     BadArgsError,
     InputFileError,
     MissingDependencyError,
     OutputFileAccessError,
 )
-from .exec import (
-    check_external_program,
-    ghostscript,
-    jbig2enc,
-    pngquant,
-    qpdf,
-    tesseract,
-    unpaper,
+from ocrmypdf.helpers import (
+    is_file_writable,
+    is_iterable_notstr,
+    monotonic,
+    safe_symlink,
 )
-from .helpers import is_file_writable, is_iterable_notstr, monotonic, safe_symlink
+from ocrmypdf.subprocess import check_external_program
 
 # -------------
 # External dependencies
@@ -67,37 +57,28 @@ def check_platform():
         )
 
 
-def check_options_languages(options):
-    if not options.language:
-        options.language = [DEFAULT_LANGUAGE]
+def check_options_languages(options, ocr_engine_languages):
+    if not options.languages:
+        options.languages = {DEFAULT_LANGUAGE}
         system_lang = locale.getlocale()[0]
         if system_lang and not system_lang.startswith('en'):
             log.debug("No language specified; assuming --language %s", DEFAULT_LANGUAGE)
-
-    # Support v2.x "eng+deu" language syntax
-    if '+' in options.language[0]:
-        options.language = options.language[0].split('+')
-
-    languages = set(options.language)
-    if not languages.issubset(tesseract.languages()):
+    if not ocr_engine_languages:
+        return
+    if not options.languages.issubset(ocr_engine_languages):
         msg = (
-            "The installed version of tesseract does not have language "
-            "data for the following requested languages: \n"
+            f"OCR engine does not have language data for the following "
+            "requested languages: \n"
         )
-        for lang in languages - tesseract.languages():
+        for lang in options.languages - ocr_engine_languages:
             msg += lang + '\n'
         raise MissingDependencyError(msg)
 
 
 def check_options_output(options):
-    # We have these constraints to check for.
-    # 1. Ghostscript < 9.20 mangles multibyte Unicode
-    # 2. hocr doesn't work on non-Latin languages (so don't select it)
+    is_latin = options.languages.issubset(HOCR_OK_LANGS)
 
-    languages = set(options.language)
-    is_latin = languages.issubset(HOCR_OK_LANGS)
-
-    if options.pdf_renderer == 'hocr' and not is_latin:
+    if options.pdf_renderer.startswith('hocr') and not is_latin:
         msg = (
             "The 'hocr' PDF renderer is known to cause problems with one "
             "or more of the languages in your document.  Use "
@@ -105,37 +86,6 @@ def check_options_output(options):
         )
         log.warning(msg)
 
-    if ghostscript.version() < '9.20' and options.output_type != 'pdf' and not is_latin:
-        # https://bugs.ghostscript.com/show_bug.cgi?id=696874
-        # Ghostscript < 9.20 fails to encode multibyte characters properly
-        msg = (
-            "The installed version of Ghostscript does not work correctly "
-            "with the OCR languages you specified. Use --output-type pdf or "
-            "upgrade to Ghostscript 9.20 or later to avoid this issue."
-        )
-        msg += f"Found Ghostscript {ghostscript.version()}"
-        log.warning(msg)
-
-    # Decide on what renderer to use
-    if options.pdf_renderer == 'auto':
-        options.pdf_renderer = 'sandwich'
-
-    if options.pdf_renderer == 'sandwich' and not tesseract.has_textonly_pdf(
-        options.tesseract_env, languages
-    ):
-        raise MissingDependencyError(
-            "You are using an alpha version of Tesseract 4.0 that does not support "
-            "the textonly_pdf parameter. We don't support versions this old."
-        )
-
-    if options.output_type == 'pdfa':
-        options.output_type = 'pdfa-2'
-
-    if options.output_type == 'pdfa-3' and ghostscript.version() < '9.19':
-        raise MissingDependencyError(
-            "--output-type pdfa-3 requires Ghostscript 9.19 or later"
-        )
-
     lossless_reconstruction = False
     if not any(
         (
@@ -162,6 +112,10 @@ def check_options_sidecar(options):
                 "--sidecar filename must be specified when output file is stdout."
             )
         options.sidecar = options.output_file + '.txt'
+    if options.sidecar == options.input_file or options.sidecar == options.output_file:
+        raise BadArgsError(
+            "--sidecar file must be different from the input and output files"
+        )
 
 
 def check_options_preprocessing(options):
@@ -183,13 +137,13 @@ def check_options_preprocessing(options):
                     options.unpaper_args
                 )
         except Exception as e:
-            raise BadArgsError(str(e))
+            raise BadArgsError("--unpaper-args: " + str(e)) from e
 
 
-def _pages_from_ranges(ranges):
+def _pages_from_ranges(ranges: str) -> Set[int]:
     if is_iterable_notstr(ranges):
         return set(ranges)
-    pages = []
+    pages: List[int] = []
     page_groups = ranges.replace(' ', '').split(',')
     for g in page_groups:
         if not g:
@@ -200,9 +154,18 @@ def _pages_from_ranges(ranges):
             pages.append(int(g) - 1)
         else:
             try:
-                pages.extend(range(int(start) - 1, int(end)))
+                new_pages = list(range(int(start) - 1, int(end)))
+                if not new_pages:
+                    raise BadArgsError(f"invalid page subrange '{start}-{end}'")
+                pages.extend(new_pages)
             except ValueError:
-                raise BadArgsError("invalid page range")
+                raise BadArgsError("invalid page range") from None
+
+    if not pages:
+        raise BadArgsError(
+            f"The string of page ranges '{ranges}' did not contain any recognizable "
+            f"page ranges."
+        )
 
     if not monotonic(pages):
         log.warning(
@@ -225,8 +188,6 @@ def check_options_ocr_behavior(options):
     )
     if exclusive_options >= 2:
         raise BadArgsError("Choose only one of --force-ocr, --skip-text, --redo-ocr.")
-    if options.pages and options.sidecar:
-        raise BadArgsError("--pages and --sidecar are mutually exclusive")
     if options.pages:
         options.pages = _pages_from_ranges(options.pages)
 
@@ -263,25 +224,16 @@ def check_options_optimizing(options):
 
 
 def check_options_advanced(options):
-    if options.pdfa_image_compression != 'auto' and options.output_type.startswith(
+    if options.pdfa_image_compression != 'auto' and not options.output_type.startswith(
         'pdfa'
     ):
         log.warning(
-            "--pdfa-image-compression argument has no effect when "
-            "--output-type is not 'pdfa', 'pdfa-1', or 'pdfa-2'"
-        )
-    if not tesseract.has_user_words(options.tesseract_env) and (
-        options.user_words or options.user_patterns
-    ):
-        log.warning(
-            "Tesseract 4.0 ignores --user-words and --user-patterns, so these "
-            "arguments have no effect."
+            "--pdfa-image-compression argument only applies when "
+            "--output-type is one of 'pdfa', 'pdfa-1', or 'pdfa-2'"
         )
 
 
 def check_options_metadata(options):
-    import unicodedata
-
     docinfo = [options.title, options.author, options.keywords, options.subject]
     for s in (m for m in docinfo if m):
         for c in s:
@@ -300,9 +252,9 @@ def check_options_pillow(options):
         PIL.Image.MAX_IMAGE_PIXELS = None
 
 
-def check_options(options):
+def _check_options(options, plugin_manager, ocr_engine_languages):
     check_platform()
-    check_options_languages(options)
+    check_options_languages(options, ocr_engine_languages)
     check_options_metadata(options)
     check_options_output(options)
     check_options_sidecar(options)
@@ -311,7 +263,12 @@ def check_options(options):
     check_options_optimizing(options)
     check_options_advanced(options)
     check_options_pillow(options)
-    check_dependency_versions(options)
+    plugin_manager.hook.check_options(options=options)
+
+
+def check_options(options, plugin_manager):
+    ocr_engine_languages = plugin_manager.hook.get_ocr_engine().languages(options)
+    _check_options(options, plugin_manager, ocr_engine_languages)
 
 
 def check_closed_streams(options):  # pragma: no cover
@@ -362,28 +319,25 @@ def check_closed_streams(options):  # pragma: no cover
     return True
 
 
-def log_page_orientations(pdfinfo):
-    direction = {0: 'n', 90: 'e', 180: 's', 270: 'w'}
-    orientations = []
-    for n, page in enumerate(pdfinfo):
-        angle = page.rotation or 0
-        if angle != 0:
-            orientations.append('{0}{1}'.format(n + 1, direction.get(angle, '')))
-    if orientations:
-        log.info('Page orientations detected: %s', ' '.join(orientations))
-
-
-def create_input_file(options, work_folder):
+def create_input_file(options, work_folder: Path) -> Tuple[Path, str]:
     if options.input_file == '-':
         # stdin
         log.info('reading file from standard input')
-        target = os.path.join(work_folder, 'stdin')
+        target = work_folder / 'stdin'
         with open(target, 'wb') as stream_buffer:
             copyfileobj(sys.stdin.buffer, stream_buffer)
-        return target, "<stdin>"
+        return target, "stdin"
+    elif hasattr(options.input_file, 'readable'):
+        if not options.input_file.readable():
+            raise InputFileError("Input file stream is not readable")
+        log.info('reading file from input stream')
+        target = work_folder / 'stream'
+        with open(target, 'wb') as stream_buffer:
+            copyfileobj(options.input_file, stream_buffer)
+        return target, "stream"
     else:
         try:
-            target = os.path.join(work_folder, 'origin')
+            target = work_folder / 'origin'
             safe_symlink(options.input_file, target)
             return target, os.fspath(options.input_file)
         except FileNotFoundError:
@@ -398,6 +352,9 @@ def check_requested_output_file(options):
                 "is connected to a terminal.  Please redirect stdout to a "
                 "file."
             )
+    elif hasattr(options.output_file, 'writable'):
+        if not options.output_file.writable():
+            raise OutputFileAccessError("Output stream is not writable")
     elif not is_file_writable(options.output_file):
         raise OutputFileAccessError(
             f"Output file location ({options.output_file}) is not a writable file."
@@ -410,8 +367,15 @@ def report_output_file_size(options, input_file, output_file):
         input_size = Path(input_file).stat().st_size
     except FileNotFoundError:
         return  # Outputting to stream or something
+    with pikepdf.open(output_file) as p:
+        # Overhead constants obtained by estimating amount of data added by OCR
+        # PDF/A conversion, and possible XMP metadata addition, with compression
+        FILE_OVERHEAD = 4000
+        OCR_PER_PAGE_OVERHEAD = 3000
+        reasonable_overhead = FILE_OVERHEAD + OCR_PER_PAGE_OVERHEAD * len(p.pages)
     ratio = output_size / input_size
-    if ratio < 1.35 or input_size < 25000:
+    reasonable_ratio = output_size / (input_size + reasonable_overhead)
+    if reasonable_ratio < 1.35 or input_size < 25000:
         return  # Seems fine
 
     reasons = []
@@ -441,6 +405,10 @@ def report_output_file_size(options, input_file, output_file):
                     f"The optional dependency '{name}' was not found, so some image "
                     f"optimizations could not be attempted."
                 )
+    if options.output_type.startswith('pdfa'):
+        reasons.append("PDF/A conversion was enabled. (Try `--output-type pdf`.)")
+    if options.plugins:
+        reasons.append("Plugins were used.")
 
     if reasons:
         explanation = "Possible reasons for this include:\n" + '\n'.join(reasons) + "\n"
@@ -451,31 +419,3 @@ def report_output_file_size(options, input_file, output_file):
         f"The output file size is {ratio:.2f}× larger than the input file.\n"
         f"{explanation}"
     )
-
-
-def check_dependency_versions(options):
-    check_external_program(
-        program='tesseract',
-        package={'linux': 'tesseract-ocr'},
-        version_checker=tesseract.version,
-        need_version='4.0.0',  # using backport for Travis CI
-    )
-    check_external_program(
-        program='gs',
-        package='ghostscript',
-        version_checker=ghostscript.version,
-        need_version='9.15',  # limited by Travis CI / Ubuntu 14.04 backports
-    )
-    gs_version = ghostscript.version()
-    if gs_version in ('9.24', '9.51'):
-        raise MissingDependencyError(
-            f"Ghostscript {gs_version} contains serious regressions and is not "
-            "supported. Please upgrade to a newer version, or downgrade to the "
-            "previous version."
-        )
-    check_external_program(
-        program='qpdf',
-        package='qpdf',
-        version_checker=qpdf.version,
-        need_version='8.0.2',
-    )

src/ocrmypdf/_version.py

@@ -1,19 +1,8 @@
 # © 2017 James R. Barlow: github.com/jbarlow83
 #
-# This file is part of OCRmyPDF.
-#
-# OCRmyPDF is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# OCRmyPDF is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with OCRmyPDF.  If not, see <http://www.gnu.org/licenses/>.
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 
 import pkg_resources

src/ocrmypdf/api.py

@@ -1,61 +1,40 @@
 # © 2019 James R. Barlow: github.com/jbarlow83
 #
-# This file is part of OCRmyPDF.
-#
-# OCRmyPDF is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# OCRmyPDF is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with OCRmyPDF.  If not, see <http://www.gnu.org/licenses/>.
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
 
 import logging
 import os
 import sys
-from contextlib import suppress
+import threading
 from enum import IntEnum
+from io import IOBase
 from pathlib import Path
-from typing import Dict, List
+from typing import AnyStr, BinaryIO, Iterable, Optional, Union
+from warnings import warn
 
-from tqdm import tqdm
+from ocrmypdf._logging import (  # pylint: disable=unused-import
+    PageNumberFilter,
+    TqdmConsole,
+)
+from ocrmypdf._plugin_manager import get_plugin_manager
+from ocrmypdf._sync import run_pipeline
+from ocrmypdf._validation import check_options
+from ocrmypdf.cli import ArgumentParser, get_parser
+from ocrmypdf.helpers import is_iterable_notstr
 
-from ._sync import run_pipeline
-from ._validation import check_options
-from .cli import parser
+try:
+    import coloredlogs
+except ModuleNotFoundError:
+    coloredlogs = None
 
 
-class TqdmConsole:
-    """Wrapper to log messages in a way that is compatible with tqdm progress bar
+StrPath = Union[os.PathLike, AnyStr]
+PathOrIO = Union[BinaryIO, StrPath]
 
-    This routes log messages through tqdm so that it can print them above the
-    progress bar, and then refresh the progress bar, rather than overwriting
-    it which looks messy.
-
-    For some reason Python 3.6 prints extra empty messages from time to time,
-    so we suppress those.
-    """
-
-    def __init__(self, file):
-        self.file = file
-        self.py36 = sys.version_info[0:2] == (3, 6)
-
-    def write(self, msg):
-        # When no progress bar is active, tqdm.write() routes to print()
-        if self.py36:
-            if msg.strip() != '':
-                tqdm.write(msg.rstrip(), end='\n', file=self.file)
-        else:
-            tqdm.write(msg.rstrip(), end='\n', file=self.file)
-
-    def flush(self):
-        with suppress(AttributeError):
-            self.file.flush()
+_api_lock = threading.Lock()
 
 
 class Verbosity(IntEnum):
@@ -67,39 +46,62 @@ class Verbosity(IntEnum):
     debug_all = 2  #: More detailed debugging from ocrmypdf and dependent modules
 
 
-def configure_logging(verbosity, progress_bar_friendly=True, manage_root_logger=False):
+def configure_logging(
+    verbosity: Verbosity,
+    *,
+    progress_bar_friendly: bool = True,
+    manage_root_logger: bool = False,
+    plugin_manager=None,
+):
     """Set up logging.
 
-    Library users may wish to use this function if they want their log output to be
-    similar to ocrmypdf command line interface. If not used, the external application
-    should configure logging on its own.
+    Before calling :func:`ocrmypdf.ocr()`, you can use this function to
+    configure logging if you want ocrmypdf's output to look like the ocrmypdf
+    command line interface. It will register log handlers, log filters, and
+    formatters, configure color logging to standard error, and adjust the log
+    levels of third party libraries. Details of this are fine-tuned and subject
+    to change. The ``verbosity`` argument is equivalent to the argument
+    ``--verbose`` and applies those settings. If you have a wrapper
+    script for ocrmypdf and you want it to be very similar to ocrmypdf, use this
+    function; if you are using ocrmypdf as part of an application that manages
+    its own logging, you probably do not want this function.
 
-    ocrmypdf will perform all of its logging under the ``"ocrmypdf"`` logging namespace.
-    In addition, ocrmypdf imports pdfminer, which logs under ``"pdfminer"``. A library
-    user may wish to configure both; note that pdfminer is extremely chatty at the log
-    level ``logging.INFO``.
+    If this function is not called, ocrmypdf will not configure logging, and it
+    is up to the caller of ``ocrmypdf.ocr()`` to set up logging as it wishes using
+    the Python standard library's logging module. If this function is called,
+    the caller may of course make further adjustments to logging.
 
-    Library users may perform additional configuration afterwards.
+    Regardless of whether this function is called, ocrmypdf will perform all of
+    its logging under the ``"ocrmypdf"`` logging namespace. In addition,
+    ocrmypdf imports pdfminer, which logs under ``"pdfminer"``. A library user
+    may wish to configure both; note that pdfminer is extremely chatty at the
+    log level ``logging.INFO``.
+
+    This function does not set up the ``debug.log`` log file that the command
+    line interface does at certain verbosity levels. Applications should configure
+    their own debug logging.
 
     Args:
-        verbosity (Verbosity): Verbosity level.
-        progress_bar_friendly (bool): Install the TqdmConsole log handler, which is
-            compatible with the tqdm progress bar; without this log messages will
-            overwrite the progress bar
-        manage_root_logger (bool): Configure the process's root logger, to ensure
-            all log output is sent through
+        verbosity: Verbosity level.
+        progress_bar_friendly: If True (the default), install a custom log handler
+            that is compatible with progress bars and colored output.
+        manage_root_logger: Configure the process's root logger.
+        plugin_manager: The plugin manager, used for obtaining the custom log handler.
 
     Returns:
         The toplevel logger for ocrmypdf (or the root logger, if we are managing it).
     """
 
     prefix = '' if manage_root_logger else 'ocrmypdf'
+
     log = logging.getLogger(prefix)
     log.setLevel(logging.DEBUG)
 
-    if progress_bar_friendly:
-        console = logging.StreamHandler(stream=TqdmConsole(sys.stderr))
-    else:
+    console = None
+    if plugin_manager and progress_bar_friendly:
+        console = plugin_manager.hook.get_logging_console()
+
+    if not console:
         console = logging.StreamHandler(stream=sys.stderr)
 
     if verbosity < 0:
@@ -109,9 +111,25 @@ def configure_logging(verbosity, progress_bar_friendly=True, manage_root_logger=
     else:
         console.setLevel(logging.INFO)
 
-    formatter = logging.Formatter('%(levelname)7s - %(message)s')
+    console.addFilter(PageNumberFilter())
+
     if verbosity >= 2:
-        formatter = logging.Formatter('%(name)s - %(levelname)7s - %(message)s')
+        fmt = '%(levelname)7s %(name)s -%(pageno)s %(message)s'
+    else:
+        fmt = '%(pageno)s%(message)s'
+
+    use_colors = progress_bar_friendly
+    if not coloredlogs:
+        use_colors = False
+    if use_colors:
+        if os.name == 'nt':
+            use_colors = coloredlogs.enable_ansi_support()
+        if use_colors:
+            use_colors = coloredlogs.terminal_supports_colors()
+    if use_colors:
+        formatter = coloredlogs.ColoredFormatter(fmt=fmt)
+    else:
+        formatter = logging.Formatter(fmt=fmt)
 
     console.setFormatter(formatter)
     log.addHandler(console)
@@ -128,7 +146,9 @@ def configure_logging(verbosity, progress_bar_friendly=True, manage_root_logger=
     return log
 
 
-def create_options(*, input_file, output_file, **kwargs):
+def create_options(
+    *, input_file: PathOrIO, output_file: PathOrIO, parser: ArgumentParser, **kwargs
+):
     cmdline = []
     deferred = []
 
@@ -138,7 +158,7 @@ def create_options(*, input_file, output_file, **kwargs):
 
         # These arguments with special handling for which we bypass
         # argparse
-        if arg in {'tesseract_env', 'progress_bar'}:
+        if arg in {'progress_bar', 'plugins'}:
             deferred.append((arg, val))
             continue
 
@@ -150,6 +170,12 @@ def create_options(*, input_file, output_file, **kwargs):
                 cmdline.append(f"--{cmd_style_arg}")
             continue
 
+        if is_iterable_notstr(val):
+            for elem in val:
+                cmdline.append(f"--{cmd_style_arg}")
+                cmdline.append(elem)
+            continue
+
         # We have a parameter
         cmdline.append(f"--{cmd_style_arg}")
         if isinstance(val, (int, float)):
@@ -161,29 +187,36 @@ def create_options(*, input_file, output_file, **kwargs):
         else:
             raise TypeError(f"{arg}: {val} ({type(val)})")
 
-    cmdline.append(str(input_file))
-    cmdline.append(str(output_file))
+    if isinstance(input_file, (BinaryIO, IOBase)):
+        cmdline.append('stream://input_file')
+    else:
+        cmdline.append(os.fspath(input_file))
+    if isinstance(output_file, (BinaryIO, IOBase)):
+        cmdline.append('stream://output_file')
+    else:
+        cmdline.append(os.fspath(output_file))
 
-    parser.api_mode = True
+    parser._api_mode = True
     options = parser.parse_args(cmdline)
     for keyword, val in deferred:
         setattr(options, keyword, val)
 
-    # If we are running a Tesseract spoof, ensure it knows what the input file is
-    if os.environ.get('PYTEST_CURRENT_TEST') and options.tesseract_env:
-        options.tesseract_env['_OCRMYPDF_TEST_INFILE'] = os.fspath(input_file)
+    if options.input_file == 'stream://input_file':
+        options.input_file = input_file
+    if options.output_file == 'stream://output_file':
+        options.output_file = output_file
 
     return options
 
 
 def ocr(  # pylint: disable=unused-argument
-    input_file: os.PathLike,
-    output_file: os.PathLike,
+    input_file: PathOrIO,
+    output_file: PathOrIO,
     *,
-    language: List[str] = None,
+    language: Iterable[str] = None,
     image_dpi: int = None,
     output_type=None,
-    sidecar: os.PathLike = None,
+    sidecar: Optional[StrPath] = None,
     jobs: int = None,
     use_threads: bool = None,
     title: str = None,
@@ -210,7 +243,7 @@ def ocr(  # pylint: disable=unused-argument
     jbig2_page_group_size: int = None,
     pages: str = None,
     max_image_mpixels: float = None,
-    tesseract_config: List[str] = None,
+    tesseract_config: Iterable[str] = None,
     tesseract_pagesegmode: int = None,
     tesseract_oem: int = None,
     pdf_renderer=None,
@@ -220,9 +253,11 @@ def ocr(  # pylint: disable=unused-argument
     user_words: os.PathLike = None,
     user_patterns: os.PathLike = None,
     fast_web_view: float = None,
+    plugins: Iterable[StrPath] = None,
+    plugin_manager=None,
     keep_temporary_files: bool = None,
     progress_bar: bool = None,
-    tesseract_env: Dict[str, str] = None,
+    **kwargs,
 ):
     """Run OCRmyPDF on one PDF or image.
 
@@ -230,10 +265,24 @@ def ocr(  # pylint: disable=unused-argument
     A few specific arguments are discussed here:
 
     Args:
-        use_threads (bool): Use worker threads instead of processes. This reduces
+        use_threads: Use worker threads instead of processes. This reduces
             performance but may make debugging easier since it is easier to set
             breakpoints.
-        tesseract_env (dict): Override environment variables for Tesseract
+        input_file: If a :class:`pathlib.Path`, ``str`` or ``bytes``, this is
+            interpreted as file system path to the input file. If the object
+            appears to be a readable stream (with methods such as ``.read()``
+            and ``.seek()``), the object will be read in its entirety and saved to
+            a temporary file. If ``input_file`` is  ``"-"``, standard input will be
+            read.
+        output_file: If a :class:`pathlib.Path`, ``str`` or ``bytes``, this is
+            interpreted as file system path to the output file. If the object
+            appears to be a writable stream (with methods such as ``.write()`` and
+            ``.seek()``), the output will be written to this stream. If
+            ``output_file`` is ``"-"``, the output will be written to ``sys.stdout``
+            (provided that standard output does not seem to be a terminal device).
+            When a stream is used as output, whether via a writable object or
+            ``"-"``, some final validation steps are not performed (we do not read
+            back the stream after it is written).
     Raises:
         ocrmypdf.PdfMergeFailedError: If the input PDF is malformed, preventing merging
             with the OCR layer.
@@ -257,7 +306,35 @@ def ocr(  # pylint: disable=unused-argument
     Returns:
         :class:`ocrmypdf.ExitCode`
     """
+    if plugins and plugin_manager:
+        raise ValueError("plugins= and plugin_manager are mutually exclusive")
 
-    options = create_options(**locals())
-    check_options(options)
-    return run_pipeline(options, api=True)
+    if not plugins:
+        plugins = []
+    elif isinstance(plugins, (str, Path)):
+        plugins = [plugins]
+    else:
+        plugins = list(plugins)
+
+    # No new variable names should be assigned until these two steps are run
+    create_options_kwargs = {k: v for k, v in locals().items() if k != 'kwargs'}
+    create_options_kwargs.update(kwargs)
+
+    parser = get_parser()
+    create_options_kwargs['parser'] = parser
+
+    with _api_lock:
+        # We can't allow multiple ocrmypdf.ocr() threads to run in parallel, because
+        # they might install different plugins, and generally speaking we have areas
+        # of code that use global state.
+
+        if not plugin_manager:
+            plugin_manager = get_plugin_manager(plugins)
+        plugin_manager.hook.add_options(parser=parser)  # pylint: disable=no-member
+
+        if 'verbose' in kwargs:
+            warn("ocrmypdf.ocr(verbose=) is ignored. Use ocrmypdf.configure_logging().")
+
+        options = create_options(**create_options_kwargs)
+        check_options(options, plugin_manager)
+        return run_pipeline(options=options, plugin_manager=plugin_manager, api=True)

src/ocrmypdf/builtin_plugins/__init__.py

@@ -0,0 +1,9 @@
+# © 2020 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# This file exists only mark builtin_plugins as a package.
+# The plugin manager will not load it, so anything defined here may not be
+# processed as a module.

src/ocrmypdf/builtin_plugins/concurrency.py

@@ -0,0 +1,172 @@
+# © 2020 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# © 2020 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+import logging
+import logging.handlers
+import multiprocessing
+import os
+import queue
+import signal
+import sys
+import threading
+from contextlib import suppress
+from multiprocessing import Pool as ProcessPool
+from multiprocessing.pool import ThreadPool
+from typing import Callable, Iterable, Union
+
+from tqdm import tqdm
+
+from ocrmypdf import Executor, hookimpl
+from ocrmypdf._logging import TqdmConsole
+from ocrmypdf.exceptions import InputFileError
+from ocrmypdf.helpers import remove_all_log_handlers
+
+Queue = Union[multiprocessing.Queue, queue.Queue]
+
+
+def log_listener(q: Queue):
+    """Listen to the worker processes and forward the messages to logging
+
+    For simplicity this is a thread rather than a process. Only one process
+    should actually write to sys.stderr or whatever we're using, so if this is
+    made into a process the main application needs to be directed to it.
+
+    See https://docs.python.org/3/howto/logging-cookbook.html#logging-to-a-single-file-from-multiple-processes
+    """
+
+    while True:
+        try:
+            record = q.get()
+            if record is None:
+                break
+            logger = logging.getLogger(record.name)
+            logger.handle(record)
+        except Exception:  # pylint: disable=broad-except
+            import traceback  # pylint: disable=import-outside-toplevel
+
+            print("Logging problem", file=sys.stderr)
+            traceback.print_exc(file=sys.stderr)
+
+
+def process_sigbus(*args):
+    raise InputFileError("A worker process lost access to an input file")
+
+
+def process_init(q: Queue, user_init: Callable[[], None], loglevel):
+    """Initialize a process pool worker"""
+
+    # Ignore SIGINT (our parent process will kill us gracefully)
+    signal.signal(signal.SIGINT, signal.SIG_IGN)
+
+    # Install SIGBUS handler (so our parent process can abort somewhat gracefully)
+    with suppress(AttributeError):  # Windows and Cygwin do not have SIGBUS
+        # Windows and Cygwin do not have pthread_sigmask or SIGBUS
+        signal.signal(signal.SIGBUS, process_sigbus)
+
+    # Remove any log handlers that belong to the parent process
+    root = logging.getLogger()
+    remove_all_log_handlers(root)
+
+    # Set up our single log handler to forward messages to the parent
+    root.setLevel(loglevel)
+    root.addHandler(logging.handlers.QueueHandler(q))
+
+    user_init()
+    return
+
+
+def thread_init(_queue: Queue, user_init: Callable[[], None], _loglevel):
+    # As a thread, block SIGBUS so the main thread deals with it...
+    with suppress(AttributeError):
+        signal.pthread_sigmask(signal.SIG_BLOCK, {signal.SIGBUS})
+
+    user_init()
+    return
+
+
+class StandardExecutor(Executor):
+    def _execute(
+        self,
+        *,
+        use_threads: bool,
+        max_workers: int,
+        tqdm_kwargs: dict,
+        worker_initializer: Callable,
+        task: Callable,
+        task_arguments: Iterable,
+        task_finished: Callable,
+    ):
+        if use_threads:
+            log_queue = queue.Queue(-1)
+            pool_class = ThreadPool
+            initializer = thread_init
+        else:
+            log_queue = multiprocessing.Queue(-1)
+            pool_class = ProcessPool
+            initializer = process_init
+
+        # Regardless of whether we use_threads for worker processes, the log_listener
+        # must be a thread. Make sure we create the listener after the worker pool,
+        # so that it does not get forked into the workers.
+        listener = threading.Thread(target=log_listener, args=(log_queue,))
+        listener.start()
+
+        with self.pbar_class(**tqdm_kwargs) as pbar:
+            pool = pool_class(
+                processes=max_workers,
+                initializer=initializer,
+                initargs=(log_queue, worker_initializer, logging.getLogger("").level),
+            )
+            try:
+                results = pool.imap_unordered(task, task_arguments)
+                for result in results:
+                    if task_finished:
+                        task_finished(result, pbar)
+                    else:
+                        pbar.update()
+            except KeyboardInterrupt:
+                # Terminate pool so we exit instantly
+                pool.terminate()
+                # Don't try listener.join() here, will deadlock
+                raise
+            except Exception:
+                if not os.environ.get("PYTEST_CURRENT_TEST", ""):
+                    # Unless inside pytest, exit immediately because no one wants
+                    # to wait for child processes to finalize results that will be
+                    # thrown away. Inside pytest, we want child processes to exit
+                    # cleanly so that they output an error messages or coverage data
+                    # we need from them.
+                    pool.terminate()
+                raise
+            finally:
+                # Terminate log listener
+                log_queue.put_nowait(None)
+                pool.close()
+                pool.join()
+
+        listener.join()
+
+
+@hookimpl
+def get_executor(progressbar_class):
+    return StandardExecutor(pbar_class=progressbar_class)
+
+
+@hookimpl
+def get_progressbar_class():
+    return tqdm
+
+
+@hookimpl
+def get_logging_console():
+    return logging.StreamHandler(stream=TqdmConsole(sys.stderr))

src/ocrmypdf/builtin_plugins/default_filters.py

@@ -0,0 +1,14 @@
+# © 2021 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+from ocrmypdf import hookimpl
+
+
+@hookimpl
+def filter_pdf_page(
+    page, image_filename, output_pdf
+):  # pylint: disable=unused-argument
+    return output_pdf

src/ocrmypdf/builtin_plugins/ghostscript.py

@@ -0,0 +1,99 @@
+# © 2020 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+import logging
+
+from ocrmypdf import hookimpl
+from ocrmypdf._exec import ghostscript
+from ocrmypdf._validation import HOCR_OK_LANGS
+from ocrmypdf.exceptions import MissingDependencyError
+from ocrmypdf.subprocess import check_external_program
+
+log = logging.getLogger(__name__)
+
+
+@hookimpl
+def check_options(options):
+    gs_version = ghostscript.version()
+    check_external_program(
+        program='gs',
+        package='ghostscript',
+        version_checker=gs_version,
+        need_version='9.15',  # limited by Travis CI / Ubuntu 14.04 backports
+    )
+    if gs_version in ('9.24', '9.51'):
+        raise MissingDependencyError(
+            f"Ghostscript {gs_version} contains serious regressions and is not "
+            "supported. Please upgrade to a newer version, or downgrade to the "
+            "previous version."
+        )
+
+    # We have these constraints to check for.
+    # 1. Ghostscript < 9.20 mangles multibyte Unicode
+    # 2. hocr doesn't work on non-Latin languages (so don't select it)
+    is_latin = options.languages.issubset(HOCR_OK_LANGS)
+    if gs_version < '9.20' and options.output_type != 'pdf' and not is_latin:
+        # https://bugs.ghostscript.com/show_bug.cgi?id=696874
+        # Ghostscript < 9.20 fails to encode multibyte characters properly
+        log.warning(
+            f"The installed version of Ghostscript ({gs_version}) does not work "
+            "correctly with the OCR languages you specified. Use --output-type pdf or "
+            "upgrade to Ghostscript 9.20 or later to avoid this issue."
+        )
+
+    if options.output_type == 'pdfa':
+        options.output_type = 'pdfa-2'
+
+    if options.output_type == 'pdfa-3' and ghostscript.version() < '9.19':
+        raise MissingDependencyError(
+            "--output-type pdfa-3 requires Ghostscript 9.19 or later"
+        )
+
+
+@hookimpl
+def rasterize_pdf_page(
+    input_file,
+    output_file,
+    raster_device,
+    raster_dpi,
+    pageno,
+    page_dpi,
+    rotation,
+    filter_vector,
+):
+    ghostscript.rasterize_pdf(
+        input_file,
+        output_file,
+        raster_device=raster_device,
+        raster_dpi=raster_dpi,
+        pageno=pageno,
+        page_dpi=page_dpi,
+        rotation=rotation,
+        filter_vector=filter_vector,
+    )
+    return output_file
+
+
+@hookimpl
+def generate_pdfa(
+    pdf_pages,
+    pdfmark,
+    output_file,
+    compression,
+    pdf_version,
+    pdfa_part,
+    progressbar_class,
+):
+    ghostscript.generate_pdfa(
+        pdf_pages=[*pdf_pages, pdfmark],
+        output_file=output_file,
+        compression=compression,
+        pdf_version=pdf_version,
+        pdfa_part=pdfa_part,
+        progressbar_class=progressbar_class,
+    )
+    return output_file

src/ocrmypdf/builtin_plugins/tesseract_ocr.py

@@ -0,0 +1,179 @@
+# © 2020 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+import logging
+import os
+
+from ocrmypdf import hookimpl
+from ocrmypdf._exec import tesseract
+from ocrmypdf.cli import numeric
+from ocrmypdf.exceptions import MissingDependencyError
+from ocrmypdf.helpers import clamp
+from ocrmypdf.pluginspec import OcrEngine
+from ocrmypdf.subprocess import check_external_program
+
+log = logging.getLogger(__name__)
+
+
+@hookimpl
+def add_options(parser):
+    tess = parser.add_argument_group("Tesseract", "Advanced control of Tesseract OCR")
+    tess.add_argument(
+        '--tesseract-config',
+        action='append',
+        metavar='CFG',
+        default=[],
+        help="Additional Tesseract configuration files -- see documentation",
+    )
+    tess.add_argument(
+        '--tesseract-pagesegmode',
+        action='store',
+        type=int,
+        metavar='PSM',
+        choices=range(0, 14),
+        help="Set Tesseract page segmentation mode (see tesseract --help)",
+    )
+    tess.add_argument(
+        '--tesseract-oem',
+        action='store',
+        type=int,
+        metavar='MODE',
+        choices=range(0, 4),
+        help=(
+            "Set Tesseract 4.0 OCR engine mode: "
+            "0 - original Tesseract only; "
+            "1 - neural nets LSTM only; "
+            "2 - Tesseract + LSTM; "
+            "3 - default."
+        ),
+    )
+    tess.add_argument(
+        '--tesseract-timeout',
+        default=180.0,
+        type=numeric(float, 0),
+        metavar='SECONDS',
+        help='Give up on OCR after the timeout, but copy the preprocessed page '
+        'into the final output',
+    )
+    tess.add_argument(
+        '--user-words',
+        metavar='FILE',
+        help="Specify the location of the Tesseract user words file. This is a "
+        "list of words Tesseract should consider while performing OCR in "
+        "addition to its standard language dictionaries. This can improve "
+        "OCR quality especially for specialized and technical documents.",
+    )
+    tess.add_argument(
+        '--user-patterns',
+        metavar='FILE',
+        help="Specify the location of the Tesseract user patterns file.",
+    )
+
+
+@hookimpl
+def check_options(options):
+    check_external_program(
+        program='tesseract',
+        package={'linux': 'tesseract-ocr'},
+        version_checker=tesseract.version,
+        need_version='4.0.0-beta.1',  # using backport for Travis CI
+        version_parser=tesseract.TesseractVersion,
+    )
+
+    # Decide on what renderer to use
+    if options.pdf_renderer == 'auto':
+        options.pdf_renderer = 'sandwich'
+
+    if not tesseract.has_user_words() and (options.user_words or options.user_patterns):
+        log.warning(
+            "Tesseract 4.0 ignores --user-words and --user-patterns, so these "
+            "arguments have no effect."
+        )
+    if options.tesseract_pagesegmode in (0, 2):
+        log.warning(
+            "The --tesseract-pagesegmode argument you select will disable OCR. "
+            "This may cause processing to fail."
+        )
+
+
+@hookimpl
+def validate(pdfinfo, options):
+    # Tesseract 4.x can be multithreaded, and we also run multiple workers. We want
+    # to manage how many threads it uses to avoid creating total threads than cores.
+    # Performance testing shows we're better off
+    # parallelizing ocrmypdf and forcing Tesseract to be single threaded, which we
+    # get by setting the envvar OMP_THREAD_LIMIT to 1. But if the page count of the
+    # input file is small, then we allow Tesseract to use threads, subject to the
+    # constraint: (ocrmypdf workers) * (tesseract threads) <= max_workers.
+    # As of Tesseract 4.1, 3 threads is the most effective on a 4 core/8 thread system.
+    if not os.environ.get('OMP_THREAD_LIMIT', '').isnumeric():
+        tess_threads = clamp(options.jobs // len(pdfinfo), 1, 3)
+        os.environ['OMP_THREAD_LIMIT'] = str(tess_threads)
+    else:
+        tess_threads = int(os.environ['OMP_THREAD_LIMIT'])
+    log.debug("Using Tesseract OpenMP thread limit %d", tess_threads)
+
+
+class TesseractOcrEngine(OcrEngine):
+    @staticmethod
+    def version():
+        return tesseract.version()
+
+    @staticmethod
+    def creator_tag(options):
+        tag = '-PDF' if options.pdf_renderer == 'sandwich' else ''
+        return f"Tesseract OCR{tag} {TesseractOcrEngine.version()}"
+
+    def __str__(self):
+        return f"Tesseract OCR {TesseractOcrEngine.version()}"
+
+    @staticmethod
+    def languages(options):
+        return tesseract.get_languages()
+
+    @staticmethod
+    def get_orientation(input_file, options):
+        return tesseract.get_orientation(
+            input_file,
+            engine_mode=options.tesseract_oem,
+            timeout=options.tesseract_timeout,
+        )
+
+    @staticmethod
+    def generate_hocr(input_file, output_hocr, output_text, options):
+        tesseract.generate_hocr(
+            input_file=input_file,
+            output_hocr=output_hocr,
+            output_text=output_text,
+            languages=options.languages,
+            engine_mode=options.tesseract_oem,
+            tessconfig=options.tesseract_config,
+            timeout=options.tesseract_timeout,
+            pagesegmode=options.tesseract_pagesegmode,
+            user_words=options.user_words,
+            user_patterns=options.user_patterns,
+        )
+
+    @staticmethod
+    def generate_pdf(input_file, output_pdf, output_text, options):
+        tesseract.generate_pdf(
+            input_file=input_file,
+            output_pdf=output_pdf,
+            output_text=output_text,
+            languages=options.languages,
+            engine_mode=options.tesseract_oem,
+            tessconfig=options.tesseract_config,
+            timeout=options.tesseract_timeout,
+            pagesegmode=options.tesseract_pagesegmode,
+            user_words=options.user_words,
+            user_patterns=options.user_patterns,
+        )
+
+
+@hookimpl
+def get_ocr_engine():
+    return TesseractOcrEngine()

src/ocrmypdf/cli.py

@@ -1,29 +1,20 @@
 # © 2015-19 James R. Barlow: github.com/jbarlow83
 #
-# This file is part of OCRmyPDF.
-#
-# OCRmyPDF is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# OCRmyPDF is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with OCRmyPDF.  If not, see <http://www.gnu.org/licenses/>.
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
 
 import argparse
+from typing import Optional, Type, TypeVar
 
-from ._version import PROGRAM_NAME as _PROGRAM_NAME
-from ._version import __version__ as _VERSION
+from ocrmypdf._version import PROGRAM_NAME as _PROGRAM_NAME
+from ocrmypdf._version import __version__ as _VERSION
 
-__all__ = ['parser']
+T = TypeVar('T')
 
 
-def numeric(basetype, min_=None, max_=None):
+def numeric(basetype: Type[T], min_: Optional[T] = None, max_: Optional[T] = None):
     """Validator for numeric params"""
     min_ = basetype(min_) if min_ is not None else None
     max_ = basetype(max_) if max_ is not None else None
@@ -47,30 +38,46 @@ class ArgumentParser(argparse.ArgumentParser):
 
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
-        self.api_mode = False
+        self._api_mode = False
 
     def error(self, message):
-        if not self.api_mode:
+        if not self._api_mode:
             super().error(message)
             return
         raise ValueError(message)
 
 
-parser = ArgumentParser(
-    prog=_PROGRAM_NAME,
-    fromfile_prefix_chars='@',
-    formatter_class=argparse.RawDescriptionHelpFormatter,
-    description="""\
+class LanguageSetAction(argparse.Action):
+    def __init__(self, option_strings, dest, default=None, **kwargs):
+        if default is None:
+            default = set()
+        super().__init__(option_strings, dest, default=default, **kwargs)
+
+    def __call__(self, parser, namespace, values, option_string=None):
+        dest = getattr(namespace, self.dest)
+        if '+' in values:
+            dest.update(lang for lang in values.split('+'))
+        else:
+            dest.add(values)
+
+
+def get_parser():
+    parser = ArgumentParser(
+        prog=_PROGRAM_NAME,
+        allow_abbrev=True,
+        fromfile_prefix_chars='@',
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+        description="""\
 Generates a searchable PDF or PDF/A from a regular PDF.
 
 OCRmyPDF rasterizes each page of the input PDF, optionally corrects page
 rotation and performs image processing, runs the Tesseract OCR engine on the
 image, and then creates a PDF from the OCR information.
 """,
-    epilog="""\
+        epilog="""\
 OCRmyPDF attempts to keep the output file at about the same size.  If a file
-contains losslessly compressed images, and output file will be losslessly
-compressed as well.
+contains losslessly compressed images, and images in the output file will be
+losslessly compressed as well.
 
 PDF is a page description file that attempts to preserve a layout exactly.
 A PDF can contain vector objects (such as text or lines) and raster objects
@@ -89,9 +96,8 @@ all objects on the page and produce an image-only PDF as output.
 
 If you are concerned about long-term archiving of PDFs, use the default option
 --output-type pdfa which converts the PDF to a standardized PDF/A-2b.  This
-converts images to sRGB colorspace, removes some features from the PDF such
-as Javascript or forms. If you want to minimize the number of changes made to
-your PDF, use --output-type pdf.
+removes some features from the PDF such as Javascript or forms. If you want to
+minimize the number of changes made to your PDF, use --output-type pdf.
 
 If OCRmyPDF is given an image file as input, it will attempt to convert the
 image to a PDF before processing.  For more control over the conversion of
@@ -99,8 +105,7 @@ images to PDF, use the Python package img2pdf or other image to PDF software.
 
 For example, this command uses img2pdf to convert all .png files beginning
 with the 'page' prefix to a PDF, fitting each image on A4-sized paper, and
-sending the result to OCRmyPDF through a pipe.  img2pdf is a dependency of
-ocrmypdf so it is already installed.
+sending the result to OCRmyPDF through a pipe.
 
     img2pdf --pagesize A4 page*.png | ocrmypdf - myfile.pdf
 
@@ -108,386 +113,374 @@ Online documentation is located at:
     https://ocrmypdf.readthedocs.io/en/latest/introduction.html
 
 """,
-)
+    )
 
-parser.add_argument(
-    'input_file',
-    metavar="input_pdf_or_image",
-    help="PDF file containing the images to be OCRed (or '-' to read from "
-    "standard input)",
+    parser.add_argument(
+        'input_file',
+        metavar="input_pdf_or_image",
+        help="PDF file containing the images to be OCRed (or '-' to read from "
+        "standard input)",
+    )
+    parser.add_argument(
+        'output_file',
+        metavar="output_pdf",
+        help="Output searchable PDF file (or '-' to write to standard output). "
+        "Existing files will be ovewritten. If same as input file, the "
+        "input file will be updated only if processing is successful.",
+    )
+    parser.add_argument(
+        '-l',
+        '--language',
+        dest='languages',
+        action=LanguageSetAction,
+        help="Language(s) of the file to be OCRed (see tesseract --list-langs for "
+        "all language packs installed in your system). Use -l eng+deu for "
+        "multiple languages.",
+    )
+    parser.add_argument(
+        '--image-dpi',
+        metavar='DPI',
+        type=int,
+        help="For input image instead of PDF, use this DPI instead of file's.",
+    )
+    parser.add_argument(
+        '--output-type',
+        choices=['pdfa', 'pdf', 'pdfa-1', 'pdfa-2', 'pdfa-3'],
+        default='pdfa',
+        help="Choose output type. 'pdfa' creates a PDF/A-2b compliant file for "
+        "long term archiving (default, recommended) but may not suitable "
+        "for users who want their file altered as little as possible. 'pdfa' "
+        "also has problems with full Unicode text. 'pdf' attempts to "
+        "preserve file contents as much as possible. 'pdf-a1' creates a "
+        "PDF/A1-b file. 'pdf-a2' is equivalent to 'pdfa'. 'pdf-a3' creates a "
+        "PDF/A3-b file.",
+    )
+
+    # Use null string '\0' as sentinel to indicate the user supplied no argument,
+    # since that is the only invalid character for filepaths on all platforms
+    # bool('\0') is True in Python
+    parser.add_argument(
+        '--sidecar',
+        nargs='?',
+        const='\0',
+        default=None,
+        metavar='FILE',
+        help="Generate sidecar text files that contain the same text recognized "
+        "by Tesseract. This may be useful for building a OCR text database. "
+        "If FILE is omitted, the sidecar file be named {output_file}.txt; the next "
+        "argument must NOT be the name of the input PDF. "
+        "If FILE is set to '-', the sidecar is written to stdout (a "
+        "convenient way to preview OCR quality). The output file and sidecar "
+        "may not both use stdout at the same time.",
+    )
+
+    parser.add_argument(
+        '--version',
+        action='version',
+        version=_VERSION,
+        help="Print program version and exit",
+    )
+
+    jobcontrol = parser.add_argument_group("Job control options")
+    jobcontrol.add_argument(
+        '-j',
+        '--jobs',
+        metavar='N',
+        type=numeric(int, 0, 256),
+        help="Use up to N CPU cores simultaneously (default: use all).",
+    )
+    jobcontrol.add_argument(
+        '-q', '--quiet', action='store_true', help="Suppress INFO messages"
+    )
+    jobcontrol.add_argument(
+        '-v',
+        '--verbose',
+        type=numeric(int, 0, 2),
+        default=0,
+        const=1,
+        nargs='?',
+        help="Print more verbose messages for each additional verbose level. Use "
+        "`-v 1` typically for much more detailed logging. Higher numbers "
+        "are probably only useful in debugging.",
+    )
+    jobcontrol.add_argument(
+        '--no-progress-bar',
+        action='store_false',
+        dest='progress_bar',
+        help=argparse.SUPPRESS,
+    )
+    jobcontrol.add_argument(
+        '--use-threads', action='store_true', help=argparse.SUPPRESS
+    )
+
+    metadata = parser.add_argument_group(
+        "Metadata options",
+        "Set output PDF/A metadata (default: copy input document's metadata)",
+    )
+    metadata.add_argument(
+        '--title', type=str, help="Set document title (place multiple words in quotes)"
+    )
+    metadata.add_argument('--author', type=str, help="Set document author")
+    metadata.add_argument(
+        '--subject', type=str, help="Set document subject description"
+    )
+    metadata.add_argument('--keywords', type=str, help="Set document keywords")
+
+    preprocessing = parser.add_argument_group(
+        "Image preprocessing options",
+        "Options to improve the quality of the final PDF and OCR",
+    )
+    preprocessing.add_argument(
+        '-r',
+        '--rotate-pages',
+        action='store_true',
+        help="Automatically rotate pages based on detected text orientation",
+    )
+    preprocessing.add_argument(
+        '--remove-background',
+        action='store_true',
+        help="Attempt to remove background from gray or color pages, setting it "
+        "to white ",
+    )
+    preprocessing.add_argument(
+        '-d',
+        '--deskew',
+        action='store_true',
+        help="Deskew each page before performing OCR",
+    )
+    preprocessing.add_argument(
+        '-c',
+        '--clean',
+        action='store_true',
+        help="Clean pages from scanning artifacts before performing OCR, and send "
+        "the cleaned page to OCR, but do not include the cleaned page in "
+        "the output",
+    )
+    preprocessing.add_argument(
+        '-i',
+        '--clean-final',
+        action='store_true',
+        help="Clean page as above, and incorporate the cleaned image in the final "
+        "PDF.  Might remove desired content.",
+    )
+    preprocessing.add_argument(
+        '--unpaper-args',
+        type=str,
+        default=None,
+        help="A quoted string of arguments to pass to unpaper. Requires --clean. "
+        "Example: --unpaper-args '--layout double'.",
+    )
+    preprocessing.add_argument(
+        '--oversample',
+        metavar='DPI',
+        type=numeric(int, 0, 5000),
+        default=0,
+        help="Oversample images to at least the specified DPI, to improve OCR "
+        "results slightly",
+    )
+    preprocessing.add_argument(
+        '--remove-vectors',
+        action='store_true',
+        help="EXPERIMENTAL. Mask out any vector objects in the PDF so that they "
+        "will not be included in OCR. This can eliminate false characters.",
+    )
+    preprocessing.add_argument(
+        '--threshold',
+        action='store_true',
+        help=(
+            "EXPERIMENTAL. Threshold image to 1bpp before sending it to Tesseract "
+            "for OCR. Can improve OCR quality compared to Tesseract's thresholder."
+        ),
+    )
+
+    ocrsettings = parser.add_argument_group("OCR options", "Control how OCR is applied")
+    ocrsettings.add_argument(
+        '-f',
+        '--force-ocr',
+        action='store_true',
+        help="Rasterize any text or vector objects on each page, apply OCR, and "
+        "save the rastered output (this rewrites the PDF)",
+    )
+    ocrsettings.add_argument(
+        '-s',
+        '--skip-text',
+        action='store_true',
+        help="Skip OCR on any pages that already contain text, but include the "
+        "page in final output; useful for PDFs that contain a mix of "
+        "images, text pages, and/or previously OCRed pages",
+    )
+    ocrsettings.add_argument(
+        '--redo-ocr',
+        action='store_true',
+        help="Attempt to detect and remove the hidden OCR layer from files that "
+        "were previously OCRed with OCRmyPDF or another program. Apply OCR "
+        "to text found in raster images. Existing visible text objects will "
+        "not be changed. If there is no existing OCR, OCR will be added.",
+    )
+    ocrsettings.add_argument(
+        '--skip-big',
+        type=numeric(float, 0, 5000),
+        metavar='MPixels',
+        help="Skip OCR on pages larger than the specified amount of megapixels, "
+        "but include skipped pages in final output",
+    )
+
+    optimizing = parser.add_argument_group(
+        "Optimization options", "Control how the PDF is optimized after OCR"
+    )
+    optimizing.add_argument(
+        '-O',
+        '--optimize',
+        type=int,
+        choices=range(0, 4),
+        default=1,
+        help=(
+            "Control how PDF is optimized after processing:"
+            "0 - do not optimize; "
+            "1 - do safe, lossless optimizations (default); "
+            "2 - do some lossy optimizations; "
+            "3 - do aggressive lossy optimizations (including lossy JBIG2)"
+        ),
+    )
+    optimizing.add_argument(
+        '--jpeg-quality',
+        type=numeric(int, 0, 100),
+        default=0,
+        metavar='Q',
+        help=(
+            "Adjust JPEG quality level for JPEG optimization. "
+            "100 is best quality and largest output size; "
+            "1 is lowest quality and smallest output; "
+            "0 uses the default."
+        ),
+    )
+    optimizing.add_argument(
+        '--jpg-quality',
+        type=numeric(int, 0, 100),
+        default=0,
+        metavar='Q',
+        dest='jpeg_quality',
+        help=argparse.SUPPRESS,  # Alias for --jpeg-quality
+    )
+    optimizing.add_argument(
+        '--png-quality',
+        type=numeric(int, 0, 100),
+        default=0,
+        metavar='Q',
+        help=(
+            "Adjust PNG quality level to use when quantizing PNGs. "
+            "Values have same meaning as with --jpeg-quality"
+        ),
+    )
+    optimizing.add_argument(
+        '--jbig2-lossy',
+        action='store_true',
+        help=(
+            "Enable JBIG2 lossy mode (better compression, not suitable for some "
+            "use cases - see documentation)."
+        ),
+    )
+    optimizing.add_argument(
+        '--jbig2-page-group-size',
+        type=numeric(int, 1, 10000),
+        default=0,
+        metavar='N',
+        # Adjust number of pages to consider at once for JBIG2 compression
+        help=argparse.SUPPRESS,
+    )
+
+    advanced = parser.add_argument_group(
+        "Advanced", "Advanced options to control OCRmyPDF"
+    )
+    advanced.add_argument(
+        '--pages',
+        type=str,
+        help=(
+            "Limit OCR to the specified pages (ranges or comma separated), "
+            "skipping others"
+        ),
+    )
+    advanced.add_argument(
+        '--max-image-mpixels',
+        action='store',
+        type=numeric(float, 0),
+        metavar='MPixels',
+        help="Set maximum number of pixels to unpack before treating an image as a "
+        "decompression bomb",
+        default=128.0,
+    )
+    advanced.add_argument(
+        '--pdf-renderer',
+        choices=['auto', 'hocr', 'sandwich', 'hocrdebug'],
+        default='auto',
+        help="Choose OCR PDF renderer - the default option is to let OCRmyPDF "
+        "choose.  See documentation for discussion.",
+    )
+    advanced.add_argument(
+        '--rotate-pages-threshold',
+        default=14.0,
+        type=numeric(float, 0, 1000),
+        metavar='CONFIDENCE',
+        help="Only rotate pages when confidence is above this value (arbitrary "
+        "units reported by tesseract)",
+    )
+    advanced.add_argument(
+        '--pdfa-image-compression',
+        choices=['auto', 'jpeg', 'lossless'],
+        default='auto',
+        help="Specify how to compress images in the output PDF/A. 'auto' lets "
+        "OCRmyPDF decide.  'jpeg' changes all grayscale and color images to "
+        "JPEG compression.  'lossless' uses PNG-style lossless compression "
+        "for all images.  Monochrome images are always compressed using a "
+        "lossless codec.  Compression settings "
+        "are applied to all pages, including those for which OCR was "
+        "skipped.  Not supported for --output-type=pdf ; that setting "
+        "preserves the original compression of all images.",
+    )
+    advanced.add_argument(
+        '--fast-web-view',
+        type=numeric(float, 0),
+        default=1.0,
+        metavar="MEGABYTES",
+        help="If the size of file is more than this threshold (in MB), then "
+        "linearize the PDF for fast web viewing. This allows the PDF to be "
+        "displayed before it is fully downloaded in web browsers, but increases "
+        "the space required slightly. By default we skip this for small files "
+        "which do not benefit. If the threshold is 0 it will be apply to all files. "
+        "Set the threshold very high to disable.",
+    )
+    advanced.add_argument(
+        '--plugin',
+        dest='plugins',
+        action='append',
+        default=[],
+        help="Name of plugin to import. Argument may be issued multiple times to "
+        "import multiple plugins. Plugins may be specified as module names in "
+        "Python syntax, provided they are installed in the same Python (virtual) "
+        "environment as ocrmypdf; or you may give the path to the Python file that "
+        "contains the plugin. Plugins must conform to the specification in the "
+        "OCRmyPDF documentation.",
+    )
+
+    debugging = parser.add_argument_group(
+        "Debugging", "Arguments to help with troubleshooting and debugging"
+    )
+    debugging.add_argument(
+        '-k',
+        '--keep-temporary-files',
+        action='store_true',
+        help="Keep temporary files (helpful for debugging)",
+    )
+    return parser
+
+
+plugins_only_parser = ArgumentParser(
+    prog=_PROGRAM_NAME, fromfile_prefix_chars='@', add_help=False, allow_abbrev=False
 )
-parser.add_argument(
-    'output_file',
-    metavar="output_pdf",
-    help="Output searchable PDF file (or '-' to write to standard output). "
-    "Existing files will be ovewritten. If same as input file, the "
-    "input file will be updated only if processing is successful.",
-)
-parser.add_argument(
-    '-l',
-    '--language',
+plugins_only_parser.add_argument(
+    '--plugin',
+    dest='plugins',
     action='append',
-    help="Language(s) of the file to be OCRed (see tesseract --list-langs for "
-    "all language packs installed in your system). Use -l eng+deu for "
-    "multiple languages.",
-)
-parser.add_argument(
-    '--image-dpi',
-    metavar='DPI',
-    type=int,
-    help="For input image instead of PDF, use this DPI instead of file's.",
-)
-parser.add_argument(
-    '--output-type',
-    choices=['pdfa', 'pdf', 'pdfa-1', 'pdfa-2', 'pdfa-3'],
-    default='pdfa',
-    help="Choose output type. 'pdfa' creates a PDF/A-2b compliant file for "
-    "long term archiving (default, recommended) but may not suitable "
-    "for users who want their file altered as little as possible. 'pdfa' "
-    "also has problems with full Unicode text. 'pdf' attempts to "
-    "preserve file contents as much as possible. 'pdf-a1' creates a "
-    "PDF/A1-b file. 'pdf-a2' is equivalent to 'pdfa'. 'pdf-a3' creates a "
-    "PDF/A3-b file.",
-)
-
-# Use null string '\0' as sentinel to indicate the user supplied no argument,
-# since that is the only invalid character for filepaths on all platforms
-# bool('\0') is True in Python
-parser.add_argument(
-    '--sidecar',
-    nargs='?',
-    const='\0',
-    default=None,
-    metavar='FILE',
-    help="Generate sidecar text files that contain the same text recognized "
-    "by Tesseract. This may be useful for building a OCR text database. "
-    "If FILE is omitted, the sidecar file be named {output_file}.txt "
-    "If FILE is set to '-', the sidecar is written to stdout (a "
-    "convenient way to preview OCR quality). The output file and sidecar "
-    "may not both use stdout at the same time.",
-)
-
-parser.add_argument(
-    '--version',
-    action='version',
-    version=_VERSION,
-    help="Print program version and exit",
-)
-
-jobcontrol = parser.add_argument_group("Job control options")
-jobcontrol.add_argument(
-    '-j',
-    '--jobs',
-    metavar='N',
-    type=numeric(int, 0, 256),
-    help="Use up to N CPU cores simultaneously (default: use all).",
-)
-jobcontrol.add_argument(
-    '-q', '--quiet', action='store_true', help="Suppress INFO messages"
-)
-jobcontrol.add_argument(
-    '-v',
-    '--verbose',
-    type=numeric(int, 0, 2),
-    default=0,
-    const=1,
-    nargs='?',
-    help="Print more verbose messages for each additional verbose level. Use "
-    "`-v 1` typically for much more detailed logging. Higher numbers "
-    "are probably only useful in debugging.",
-)
-jobcontrol.add_argument(
-    '--no-progress-bar',
-    action='store_false',
-    dest='progress_bar',
-    help=argparse.SUPPRESS,
-)
-jobcontrol.add_argument('--use-threads', action='store_true', help=argparse.SUPPRESS)
-
-metadata = parser.add_argument_group(
-    "Metadata options",
-    "Set output PDF/A metadata (default: copy input document's metadata)",
-)
-metadata.add_argument(
-    '--title', type=str, help="Set document title (place multiple words in quotes)"
-)
-metadata.add_argument('--author', type=str, help="Set document author")
-metadata.add_argument('--subject', type=str, help="Set document subject description")
-metadata.add_argument('--keywords', type=str, help="Set document keywords")
-
-preprocessing = parser.add_argument_group(
-    "Image preprocessing options",
-    "Options to improve the quality of the final PDF and OCR",
-)
-preprocessing.add_argument(
-    '-r',
-    '--rotate-pages',
-    action='store_true',
-    help="Automatically rotate pages based on detected text orientation",
-)
-preprocessing.add_argument(
-    '--remove-background',
-    action='store_true',
-    help="Attempt to remove background from gray or color pages, setting it "
-    "to white ",
-)
-preprocessing.add_argument(
-    '-d', '--deskew', action='store_true', help="Deskew each page before performing OCR"
-)
-preprocessing.add_argument(
-    '-c',
-    '--clean',
-    action='store_true',
-    help="Clean pages from scanning artifacts before performing OCR, and send "
-    "the cleaned page to OCR, but do not include the cleaned page in "
-    "the output",
-)
-preprocessing.add_argument(
-    '-i',
-    '--clean-final',
-    action='store_true',
-    help="Clean page as above, and incorporate the cleaned image in the final "
-    "PDF.  Might remove desired content.",
-)
-preprocessing.add_argument(
-    '--unpaper-args',
-    type=str,
-    default=None,
-    help="A quoted string of arguments to pass to unpaper. Requires --clean. "
-    "Example: --unpaper-args '--layout double'.",
-)
-preprocessing.add_argument(
-    '--oversample',
-    metavar='DPI',
-    type=numeric(int, 0, 5000),
-    default=0,
-    help="Oversample images to at least the specified DPI, to improve OCR "
-    "results slightly",
-)
-preprocessing.add_argument(
-    '--remove-vectors',
-    action='store_true',
-    help="EXPERIMENTAL. Mask out any vector objects in the PDF so that they "
-    "will not be included in OCR. This can eliminate false characters.",
-)
-preprocessing.add_argument(
-    '--threshold',
-    action='store_true',
-    help="EXPERIMENTAL. Threshold image to 1bpp before sending it to Tesseract for OCR. Can "
-    "improve OCR quality compared to Tesseract's thresholder.",
-)
-
-ocrsettings = parser.add_argument_group("OCR options", "Control how OCR is applied")
-ocrsettings.add_argument(
-    '-f',
-    '--force-ocr',
-    action='store_true',
-    help="Rasterize any text or vector objects on each page, apply OCR, and "
-    "save the rastered output (this rewrites the PDF)",
-)
-ocrsettings.add_argument(
-    '-s',
-    '--skip-text',
-    action='store_true',
-    help="Skip OCR on any pages that already contain text, but include the "
-    "page in final output; useful for PDFs that contain a mix of "
-    "images, text pages, and/or previously OCRed pages",
-)
-ocrsettings.add_argument(
-    '--redo-ocr',
-    action='store_true',
-    help="Attempt to detect and remove the hidden OCR layer from files that "
-    "were previously OCRed with OCRmyPDF or another program. Apply OCR "
-    "to text found in raster images. Existing visible text objects will "
-    "not be changed. If there is no existing OCR, OCR will be added.",
-)
-ocrsettings.add_argument(
-    '--skip-big',
-    type=numeric(float, 0, 5000),
-    metavar='MPixels',
-    help="Skip OCR on pages larger than the specified amount of megapixels, "
-    "but include skipped pages in final output",
-)
-
-optimizing = parser.add_argument_group(
-    "Optimization options", "Control how the PDF is optimized after OCR"
-)
-optimizing.add_argument(
-    '-O',
-    '--optimize',
-    type=int,
-    choices=range(0, 4),
-    default=1,
-    help=(
-        "Control how PDF is optimized after processing:"
-        "0 - do not optimize; "
-        "1 - do safe, lossless optimizations (default); "
-        "2 - do some lossy optimizations; "
-        "3 - do aggressive lossy optimizations (including lossy JBIG2)"
-    ),
-)
-optimizing.add_argument(
-    '--jpeg-quality',
-    type=numeric(int, 0, 100),
-    default=0,
-    metavar='Q',
-    help=(
-        "Adjust JPEG quality level for JPEG optimization. "
-        "100 is best quality and largest output size; "
-        "1 is lowest quality and smallest output; "
-        "0 uses the default."
-    ),
-)
-optimizing.add_argument(
-    '--jpg-quality',
-    type=numeric(int, 0, 100),
-    default=0,
-    metavar='Q',
-    dest='jpeg_quality',
-    help=argparse.SUPPRESS,  # Alias for --jpeg-quality
-)
-optimizing.add_argument(
-    '--png-quality',
-    type=numeric(int, 0, 100),
-    default=0,
-    metavar='Q',
-    help=(
-        "Adjust PNG quality level to use when quantizing PNGs. "
-        "Values have same meaning as with --jpeg-quality"
-    ),
-)
-optimizing.add_argument(
-    '--jbig2-lossy',
-    action='store_true',
-    help=(
-        "Enable JBIG2 lossy mode (better compression, not suitable for some "
-        "use cases - see documentation)."
-    ),
-)
-optimizing.add_argument(
-    '--jbig2-page-group-size',
-    type=numeric(int, 1, 10000),
-    default=0,
-    metavar='N',
-    # Adjust number of pages to consider at once for JBIG2 compression
-    help=argparse.SUPPRESS,
-)
-
-advanced = parser.add_argument_group(
-    "Advanced", "Advanced options to control Tesseract's OCR behavior"
-)
-advanced.add_argument(
-    '--pages',
-    type=str,
-    help="Limit OCR to the specified pages (ranges or comma separated), skipping others",
-)
-advanced.add_argument(
-    '--max-image-mpixels',
-    action='store',
-    type=numeric(float, 0),
-    metavar='MPixels',
-    help="Set maximum number of pixels to unpack before treating an image as a "
-    "decompression bomb",
-    default=128.0,
-)
-advanced.add_argument(
-    '--tesseract-config',
-    action='append',
-    metavar='CFG',
     default=[],
-    help="Additional Tesseract configuration files -- see documentation",
+    help="Name of plugin to import.",
 )
-advanced.add_argument(
-    '--tesseract-pagesegmode',
-    action='store',
-    type=int,
-    metavar='PSM',
-    choices=range(0, 14),
-    help="Set Tesseract page segmentation mode (see tesseract --help)",
-)
-advanced.add_argument(
-    '--tesseract-oem',
-    action='store',
-    type=int,
-    metavar='MODE',
-    choices=range(0, 4),
-    help=(
-        "Set Tesseract 4.0 OCR engine mode: "
-        "0 - original Tesseract only; "
-        "1 - neural nets LSTM only; "
-        "2 - Tesseract + LSTM; "
-        "3 - default."
-    ),
-)
-advanced.add_argument(
-    '--pdf-renderer',
-    choices=['auto', 'hocr', 'sandwich'],
-    default='auto',
-    help="Choose OCR PDF renderer - the default option is to let OCRmyPDF "
-    "choose.  See documentation for discussion.",
-)
-advanced.add_argument(
-    '--tesseract-timeout',
-    default=180.0,
-    type=numeric(float, 0),
-    metavar='SECONDS',
-    help='Give up on OCR after the timeout, but copy the preprocessed page '
-    'into the final output',
-)
-advanced.add_argument(
-    '--rotate-pages-threshold',
-    default=14.0,
-    type=numeric(float, 0, 1000),
-    metavar='CONFIDENCE',
-    help="Only rotate pages when confidence is above this value (arbitrary "
-    "units reported by tesseract)",
-)
-advanced.add_argument(
-    '--pdfa-image-compression',
-    choices=['auto', 'jpeg', 'lossless'],
-    default='auto',
-    help="Specify how to compress images in the output PDF/A. 'auto' lets "
-    "OCRmyPDF decide.  'jpeg' changes all grayscale and color images to "
-    "JPEG compression.  'lossless' uses PNG-style lossless compression "
-    "for all images.  Monochrome images are always compressed using a "
-    "lossless codec.  Compression settings "
-    "are applied to all pages, including those for which OCR was "
-    "skipped.  Not supported for --output-type=pdf ; that setting "
-    "preserves the original compression of all images.",
-)
-advanced.add_argument(
-    '--user-words',
-    metavar='FILE',
-    help="Specify the location of the Tesseract user words file. This is a "
-    "list of words Tesseract should consider while performing OCR in "
-    "addition to its standard language dictionaries. This can improve "
-    "OCR quality especially for specialized and technical documents.",
-)
-advanced.add_argument(
-    '--user-patterns',
-    metavar='FILE',
-    help="Specify the location of the Tesseract user patterns file.",
-)
-advanced.add_argument(
-    '--fast-web-view',
-    type=numeric(float, 0),
-    default=1.0,
-    metavar="MEGABYTES",
-    help="If the size of file is more than this threshold (in MB), then "
-    "linearize the PDF for fast web viewing. This allows the PDF to be "
-    "displayed before it is fully downloaded in web browsers, but increases "
-    "the space required slightly. By default we skip this for small files "
-    "which do not benefit. If the threshold is 0 it will be apply to all files. "
-    "Set the threshold very high to disable.",
-)
-
-debugging = parser.add_argument_group(
-    "Debugging", "Arguments to help with troubleshooting and debugging"
-)
-debugging.add_argument(
-    '-k',
-    '--keep-temporary-files',
-    action='store_true',
-    help="Keep temporary files (helpful for debugging)",
-)
-debugging.add_argument('--tesseract-env', type=str, help=argparse.SUPPRESS)

src/ocrmypdf/exceptions.py

@@ -1,19 +1,8 @@
 # © 2016 James R. Barlow: github.com/jbarlow83
 #
-# This file is part of OCRmyPDF.
-#
-# OCRmyPDF is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# OCRmyPDF is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with OCRmyPDF.  If not, see <http://www.gnu.org/licenses/>.
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 
 from enum import IntEnum

src/ocrmypdf/exec/__init__.py

@@ -1,278 +0,0 @@
-# © 2016 James R. Barlow: github.com/jbarlow83
-#
-# This file is part of OCRmyPDF.
-#
-# OCRmyPDF is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# OCRmyPDF is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with OCRmyPDF.  If not, see <http://www.gnu.org/licenses/>.
-
-"""Wrappers to manage subprocess calls"""
-
-import logging
-import os
-import re
-import shutil
-import sys
-from collections.abc import Mapping
-from functools import lru_cache
-from subprocess import PIPE, STDOUT, CalledProcessError
-from subprocess import run as subprocess_run
-
-from ..exceptions import ExitCode, MissingDependencyError
-
-log = logging.getLogger(__name__)
-
-
-def _get_program(args, env=None):
-    program = args[0]
-    test_path = env.get('_OCRMYPDF_TEST_PATH', '')
-    if test_path:
-        program = shutil.which(program, path=test_path)
-    return program
-
-
-def run(args, *, env=None, **kwargs):
-    """Wrapper around subprocess.run()
-
-    The main purpose of this wrapper is to allow us to substitute the main program
-    for a spoof in the test suite. The hidden variable _OCRMYPDF_TEST_PATH replaces
-    the main PATH as a location to check for programs to run.
-
-    Secondly we have to account for behavioral differences in Windows in particular.
-    Creating symbolic links in Windows requires administrator privileges and
-    may not work if for some reason we're using a FAT file system or the temporary
-    folder is on a different drive from the working folder. The test suite
-    works around this by creating shim Python scripts that perform the same function
-    as a symbolic link, but those shims require support on this side, to ensure
-    we call them with Python.
-
-    """
-    if not env:
-        env = os.environ
-
-    # Search in spoof path if necessary
-    program = _get_program(args, env)
-
-    # If we are running a .py on Windows, ensure we call it with this Python
-    # (to support test suite shims)
-    if os.name == 'nt' and program.lower().endswith('.py'):
-        args = [sys.executable, program] + args[1:]
-    else:
-        args = [program] + args[1:]
-
-    if os.name == 'nt':
-        paths = os.pathsep.join(os.get_exec_path(env))
-        if not shutil.which(args[0], path=paths):
-            shimmed_path = shim_paths_with_program_files(env)
-            new_args0 = shutil.which(args[0], path=shimmed_path)
-            if new_args0:
-                args[0] = new_args0
-
-    process_log = log.getChild(os.path.basename(program))
-    process_log.debug("Running: %s", args)
-    if sys.version_info < (3, 7) and os.name == 'nt':
-        # Can't use close_fds=True on Windows with Python 3.6 or older
-        # https://bugs.python.org/issue19575, etc.
-        kwargs['close_fds'] = False
-    proc = subprocess_run(args, env=env, **kwargs)
-    if process_log.isEnabledFor(logging.DEBUG):
-        try:
-            stderr = proc.stderr.decode('utf-8', 'replace')
-        except AttributeError:
-            stderr = proc.stderr
-        if stderr:
-            process_log.debug("stderr = %s", stderr)
-    return proc
-
-
-def get_version(program, *, version_arg='--version', regex=r'(\d+(\.\d+)*)', env=None):
-    """Get the version of the specified program"""
-    args_prog = [program, version_arg]
-    try:
-        proc = run(
-            args_prog,
-            close_fds=True,
-            universal_newlines=True,
-            stdout=PIPE,
-            stderr=STDOUT,
-            check=True,
-            env=env,
-        )
-        output = proc.stdout
-    except FileNotFoundError as e:
-        raise MissingDependencyError(
-            f"Could not find program '{program}' on the PATH"
-        ) from e
-    except CalledProcessError as e:
-        if e.returncode != 0:
-            raise MissingDependencyError(
-                f"Ran program '{program}' but it exited with an error:\n{e.output}"
-            ) from e
-        raise MissingDependencyError(
-            f"Could not find program '{program}' on the PATH"
-        ) from e
-    try:
-        version = re.match(regex, output.strip()).group(1)
-    except AttributeError as e:
-        raise MissingDependencyError(
-            f"The program '{program}' did not report its version. "
-            f"Message was:\n{output}"
-        )
-
-    return version
-
-
-def shim_paths_with_program_files(env=None):
-    if not env:
-        env = os.environ
-    program_files = env.get('PROGRAMFILES', '')
-    if not program_files:
-        return env.get('PATH', '')
-    paths = []
-    try:
-        for dirname in os.listdir(program_files):
-            if dirname.lower() == 'tesseract-ocr':
-                paths.append(os.path.join(program_files, dirname))
-            elif dirname.lower() == 'gs':
-                try:
-                    latest_gs = max(
-                        os.listdir(os.path.join(program_files, dirname)),
-                        key=lambda d: float(d[2:]),
-                    )
-                except (FileNotFoundError, NotADirectoryError):
-                    continue
-                paths.append(os.path.join(program_files, dirname, latest_gs, 'bin'))
-    except EnvironmentError:
-        pass
-    paths.extend(path for path in os.get_exec_path(env) if path not in set(paths))
-    return os.pathsep.join(paths)
-
-
-missing_program = '''
-The program '{program}' could not be executed or was not found on your
-system PATH.
-'''
-
-missing_optional_program = '''
-The program '{program}' could not be executed or was not found on your
-system PATH.  This program is required when you use the
-{required_for} arguments.  You could try omitting these arguments, or install
-the package.
-'''
-
-missing_recommend_program = '''
-The program '{program}' could not be executed or was not found on your
-system PATH.  This program is recommended when using the {required_for} arguments,
-but not required, so we will proceed.  For best results, install the program.
-'''
-
-old_version = '''
-OCRmyPDF requires '{program}' {need_version} or higher.  Your system appears
-to have {found_version}.  Please update this program.
-'''
-
-old_version_required_for = '''
-OCRmyPDF requires '{program}' {need_version} or higher when run with the
-{required_for} arguments.  If you omit these arguments, OCRmyPDF may be able to
-proceed.  For best results, install the program.
-'''
-
-osx_install_advice = '''
-If you have homebrew installed, try these command to install the missing
-package:
-    brew install {package}
-'''
-
-linux_install_advice = '''
-On systems with the aptitude package manager (Debian, Ubuntu), try these
-commands:
-    sudo apt-get update
-    sudo apt-get install {package}
-
-On RPM-based systems (Red Hat, Fedora), search for instructions on
-installing the RPM for {program}.
-'''
-
-windows_install_advice = '''
-If not already installed, install the Chocolatey package manager. Then use
-a command prompt to install the missing package:
-    choco install {package}
-'''
-
-
-def _get_platform():
-    if sys.platform.startswith('freebsd'):
-        return 'freebsd'
-    elif sys.platform.startswith('linux'):
-        return 'linux'
-    elif sys.platform.startswith('win'):
-        return 'windows'
-    return sys.platform
-
-
-def _error_trailer(program, package, **kwargs):
-    if isinstance(package, Mapping):
-        package = package.get(_get_platform(), program)
-
-    if _get_platform() == 'darwin':
-        log.info(osx_install_advice.format(**locals()))
-    elif _get_platform() == 'linux':
-        log.info(linux_install_advice.format(**locals()))
-    elif _get_platform() == 'windows':
-        log.info(windows_install_advice.format(**locals()))
-
-
-def _error_missing_program(program, package, required_for, recommended):
-    if required_for:
-        log.error(missing_optional_program.format(**locals()))
-    elif recommended:
-        log.info(missing_recommend_program.format(**locals()))
-    else:
-        log.error(missing_program.format(**locals()))
-    _error_trailer(**locals())
-
-
-def _error_old_version(program, package, need_version, found_version, required_for):
-    if required_for:
-        log.error(old_version_required_for.format(**locals()))
-    else:
-        log.error(old_version.format(**locals()))
-    _error_trailer(**locals())
-
-
-def check_external_program(
-    *,
-    program,
-    package,
-    version_checker,
-    need_version,
-    required_for=None,
-    recommended=False,
-    **kwargs,  # To consume log parameter
-):
-    if kwargs:
-        if not 'log' in kwargs:
-            log.warning('check_external_program(log=...) is deprecated')
-    try:
-        found_version = version_checker()
-    except (CalledProcessError, FileNotFoundError, MissingDependencyError):
-        _error_missing_program(program, package, required_for, recommended)
-        if not recommended:
-            raise MissingDependencyError()
-        return
-
-    if found_version < need_version:
-        _error_old_version(program, package, need_version, found_version, required_for)
-        if not recommended:
-            raise MissingDependencyError()
-
-    log.debug('Found %s %s', program, found_version)

src/ocrmypdf/exec/ghostscript.py

@@ -1,343 +0,0 @@
-# © 2017 James R. Barlow: github.com/jbarlow83
-#
-# This file is part of OCRmyPDF.
-#
-# OCRmyPDF is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# OCRmyPDF is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with OCRmyPDF.  If not, see <http://www.gnu.org/licenses/>.
-
-"""Interface to Ghostscript executable"""
-
-import logging
-import os
-import re
-import warnings
-from contextlib import suppress
-from functools import lru_cache
-from io import BytesIO
-from os import fspath
-from pathlib import Path
-from shutil import which
-from subprocess import PIPE, CalledProcessError
-
-from PIL import Image
-
-from ..exceptions import MissingDependencyError, SubprocessOutputError
-from . import get_version, run
-
-gslog = logging.getLogger()
-
-GS = 'gs'
-if os.name == 'nt':
-    GS = which('gswin64c')
-    if not GS:
-        GS = which('gswin32c')
-        if not GS:
-            raise MissingDependencyError(
-                """
-                ---------------------------------------------------------------------
-                This error normally occurs when ocrmypdf can't Ghostscript.  Please
-                ensure Ghostscript is installed and its location is added to the
-                system PATH environment variable.
-
-                For details see:
-                    https://ocrmypdf.readthedocs.io/en/latest/installation.html
-                ---------------------------------------------------------------------
-                """
-            )
-    GS = Path(GS).stem
-
-
-@lru_cache(maxsize=1)
-def version():
-    return get_version(GS)
-
-
-def jpeg_passthrough_available():
-    """Returns True if the installed version of Ghostscript supports JPEG passthru
-
-    Prior to 9.23, Ghostscript decode and re-encoded JPEGs internally. In 9.23
-    it gained the ability to keep JPEGs unmodified. However, the 9.23
-    implementation was buggy and would deletes the last two bytes of images in
-    some cases, as reported here.
-    https://bugs.ghostscript.com/show_bug.cgi?id=699216
-
-    The issue was fixed for 9.24, hence that is the first version we consider
-    the feature available. (However, we don't use 9.24 at all, so the first
-    version that allows JPEG passthrough is 9.25.
-
-    """
-    return version() >= '9.24'
-
-
-def _gs_error_reported(stream):
-    return re.search(r'error', stream, flags=re.IGNORECASE)
-
-
-def extract_text(input_file, pageno=1):
-    """Use the txtwrite device to get text layout information out
-
-    For details on options of -dTextFormat see
-    https://www.ghostscript.com/doc/current/VectorDevices.htm#TXT
-
-    Format is like
-    <page>
-    <line>
-    <span bbox="left top right bottom" font="..." size="...">
-    <char bbox="...." c="X"/>
-
-    :param pageno: number of page to extract, or all pages if None
-    :return: XML-ish text representation in bytes
-    """
-
-    if pageno is not None:
-        pages = ['-dFirstPage=%i' % pageno, '-dLastPage=%i' % pageno]
-    else:
-        pages = []
-
-    # Note due to bug https://bugs.ghostscript.com/show_bug.cgi?id=701971
-    # Ghostscript <= 9.50 will truncate output unless we write to stdout, so
-    # don't write to a file.
-    args_gs = (
-        [
-            GS,
-            '-dQUIET',
-            '-dSAFER',
-            '-dBATCH',
-            '-dNOPAUSE',
-            '-sDEVICE=txtwrite',
-            '-dTextFormat=0',
-        ]
-        + pages
-        + ['-o', '-', fspath(input_file), "-sstdout=%stderr"]
-    )
-
-    try:
-        p = run(args_gs, stdout=PIPE, stderr=PIPE, check=True)
-    except CalledProcessError as e:
-        raise SubprocessOutputError(
-            'Ghostscript text extraction failed\n%s\n%s'
-            % (input_file, e.stderr.decode(errors='replace'))
-        )
-
-    return p.stdout
-
-
-def rasterize_pdf(
-    input_file,
-    output_file,
-    xres,
-    yres,
-    raster_device,
-    log,
-    pageno=1,
-    page_dpi=None,
-    rotation=None,
-    filter_vector=False,
-):
-    """Rasterize one page of a PDF at resolution (xres, yres) in canvas units.
-
-    The image is sized to match the integer pixels dimensions implied by
-    (xres, yres) even if those numbers are noninteger. The image's DPI will
-     be overridden with the values in page_dpi.
-
-    :param input_file: pathlike
-    :param output_file: pathlike
-    :param xres: resolution at which to rasterize page
-    :param yres:
-    :param raster_device:
-    :param log:
-    :param pageno: page number to rasterize (beginning at page 1)
-    :param page_dpi: resolution tuple (x, y) overriding output image DPI
-    :param rotation: 0, 90, 180, 270: clockwise angle to rotate page
-    :param filter_vector: if True, remove vector graphics objects
-    :return:
-    """
-    res = round(xres, 6), round(yres, 6)
-    if not page_dpi:
-        page_dpi = res
-    if not log:
-        log = gslog
-
-    args_gs = (
-        [
-            GS,
-            '-dQUIET',
-            '-dSAFER',
-            '-dBATCH',
-            '-dNOPAUSE',
-            f'-sDEVICE={raster_device}',
-            f'-dFirstPage={pageno}',
-            f'-dLastPage={pageno}',
-            f'-r{res[0]:f}x{res[1]:f}',
-        ]
-        + (['-dFILTERVECTOR'] if filter_vector else [])
-        + [
-            '-o',
-            '-',
-            '-sstdout=%stderr',
-            '-dAutoRotatePages=/None',  # Probably has no effect on raster
-            '-f',
-            fspath(input_file),
-        ]
-    )
-
-    log.debug(args_gs)
-    try:
-        p = run(args_gs, stdout=PIPE, stderr=PIPE, check=True)
-    except CalledProcessError as e:
-        log.error(e.stderr.decode(errors='replace'))
-        raise SubprocessOutputError('Ghostscript rasterizing failed')
-    else:
-        stderr = p.stderr.decode(errors='replace')
-        if _gs_error_reported(stderr):
-            log.error(stderr)
-        elif stderr:
-            log.debug(stderr)
-
-    with Image.open(BytesIO(p.stdout)) as im:
-        if rotation is not None:
-            log.debug("Rotating output by %i", rotation)
-            # rotation is a clockwise angle and Image.ROTATE_* is
-            # counterclockwise so this cancels out the rotation
-            if rotation == 90:
-                im = im.transpose(Image.ROTATE_90)
-            elif rotation == 180:
-                im = im.transpose(Image.ROTATE_180)
-            elif rotation == 270:
-                im = im.transpose(Image.ROTATE_270)
-            if rotation % 180 == 90:
-                page_dpi = page_dpi[1], page_dpi[0]
-        im.save(fspath(output_file), dpi=page_dpi)
-
-
-def generate_pdfa(
-    pdf_pages,
-    output_file,
-    compression,
-    log,
-    threads=None,  # deprecated parameter
-    pdf_version='1.5',
-    pdfa_part='2',
-):
-    """Generate a PDF/A.
-
-    The pdf_pages, a list files, will be merged into output_file. One or more
-    PDF files may be merged. One of the files in this list must be a pdfmark
-    file that provides Ghostscript with details on how to perform the PDF/A
-    conversion. By default with we pick PDF/A-2b, but this works for 1 or 3.
-
-    compression can be 'jpeg', 'lossless', or an empty string. In 'jpeg',
-    Ghostscript is instructed to convert color and grayscale images to DCT
-    (JPEG encoding). In 'lossless' Ghostscript is told to convert images to
-    Flate (lossless/PNG). If the parameter is omitted Ghostscript is left to
-    make its own decisions about how to encode images; it appears to use a
-    heuristic to decide how to encode images. As of Ghostscript 9.25, we
-    support passthrough JPEG which allows Ghostscript to avoid transcoding
-    images entirely. (The feature was added in 9.23 but broken, and the 9.24
-    release of Ghostscript had regressions, so we don't support it until 9.25.)
-    """
-    if not log:
-        log = gslog
-    if threads is not None:
-        warnings.warn(
-            "use of deprecated parameter 'threads'", category=DeprecationWarning
-        )
-
-    compression_args = []
-    if compression == 'jpeg':
-        compression_args = [
-            "-dAutoFilterColorImages=false",
-            "-dColorImageFilter=/DCTEncode",
-            "-dAutoFilterGrayImages=false",
-            "-dGrayImageFilter=/DCTEncode",
-        ]
-    elif compression == 'lossless':
-        compression_args = [
-            "-dAutoFilterColorImages=false",
-            "-dColorImageFilter=/FlateEncode",
-            "-dAutoFilterGrayImages=false",
-            "-dGrayImageFilter=/FlateEncode",
-        ]
-    else:
-        compression_args = [
-            "-dAutoFilterColorImages=true",
-            "-dAutoFilterGrayImages=true",
-        ]
-
-    # Older versions of Ghostscript expect a leading slash in
-    # sColorConversionStrategy, newer ones should not have it. See Ghostscript
-    # git commit fe1c025d.
-    strategy = 'RGB' if version() >= '9.19' else '/RGB'
-
-    if version() == '9.23':
-        # 9.23: new feature JPEG passthrough is broken in some cases, best to
-        # disable it always
-        # https://bugs.ghostscript.com/show_bug.cgi?id=699216
-        compression_args.append('-dPassThroughJPEGImages=false')
-
-    # nb no need to specify ProcessColorModel when ColorConversionStrategy
-    # is set; see:
-    # https://bugs.ghostscript.com/show_bug.cgi?id=699392
-    args_gs = (
-        [
-            GS,
-            "-dQUIET",
-            "-dBATCH",
-            "-dNOPAUSE",
-            "-dSAFER",
-            "-dCompatibilityLevel=" + str(pdf_version),
-            "-sDEVICE=pdfwrite",
-            "-dAutoRotatePages=/None",
-            "-sColorConversionStrategy=" + strategy,
-        ]
-        + compression_args
-        + [
-            "-dJPEGQ=95",
-            "-dPDFA=" + pdfa_part,
-            "-dPDFACompatibilityPolicy=1",
-            "-o",
-            "-",
-            "-sstdout=%stderr",
-        ]
-    )
-    args_gs.extend(fspath(s) for s in pdf_pages)  # Stringify Path objs
-    try:
-        with Path(output_file).open('wb') as output:
-            p = run(args_gs, stdout=output, stderr=PIPE, check=True)
-    except CalledProcessError as e:
-        # Ghostscript does not change return code when it fails to create
-        # PDF/A - check PDF/A status elsewhere
-        log.error(e.stderr.decode(errors='replace'))
-        raise SubprocessOutputError('Ghostscript PDF/A rendering failed')
-    else:
-        stderr = p.stderr.decode('utf-8', errors='replace')
-        if _gs_error_reported(stderr):
-            last_part = None
-            repcount = 0
-            for part in stderr.split('****'):
-                if part != last_part:
-                    if repcount > 1:
-                        log.error(f"(previous error message repeated {repcount} times)")
-                        repcount = 0
-                    log.error(part)
-                else:
-                    repcount += 1
-                last_part = part
-        elif 'overprint mode not set' in stderr:
-            # Unless someone is going to print PDF/A documents on a
-            # magical sRGB printer I can't see the removal of overprinting
-            # being a problem....
-            log.debug(
-                "Ghostscript had to remove PDF 'overprinting' from the "
-                "input file to complete PDF/A conversion. "
-            )

src/ocrmypdf/exec/pngquant.py

@@ -1,71 +0,0 @@
-# © 2018 James R. Barlow: github.com/jbarlow83
-#
-# This file is part of OCRmyPDF.
-#
-# OCRmyPDF is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# OCRmyPDF is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with OCRmyPDF.  If not, see <http://www.gnu.org/licenses/>.
-
-"""Interface to pngquant executable"""
-
-from functools import lru_cache
-from subprocess import run
-from tempfile import NamedTemporaryFile
-
-from PIL import Image
-
-from ..exceptions import MissingDependencyError
-from . import get_version
-
-
-@lru_cache(maxsize=1)
-def version():
-    return get_version('pngquant', regex=r'(\d+(\.\d+)*).*')
-
-
-def available():
-    try:
-        version()
-    except MissingDependencyError:
-        return False
-    return True
-
-
-def quantize(input_file, output_file, quality_min, quality_max):
-    if input_file.endswith('.jpg'):
-        with Image.open(input_file) as im, NamedTemporaryFile(suffix='.png') as tmp:
-            im.save(tmp)
-            args = [
-                'pngquant',
-                '--force',
-                '--skip-if-larger',
-                '--output',
-                output_file,
-                '--quality',
-                f'{quality_min}-{quality_max}',
-                '--',
-                tmp.name,
-            ]
-            run(args)
-    else:
-        args = [
-            'pngquant',
-            '--force',
-            '--skip-if-larger',
-            '--output',
-            output_file,
-            '--quality',
-            f'{quality_min}-{quality_max}',
-            '--',
-            input_file,
-        ]
-        run(args)

src/ocrmypdf/exec/qpdf.py

@@ -1,61 +0,0 @@
-# © 2017 James R. Barlow: github.com/jbarlow83
-#
-# This file is part of OCRmyPDF.
-#
-# OCRmyPDF is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# OCRmyPDF is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with OCRmyPDF.  If not, see <http://www.gnu.org/licenses/>.
-
-"""Interface to qpdf executable"""
-
-from io import StringIO
-
-import pikepdf
-
-
-def version():
-    return pikepdf.__libqpdf_version__
-
-
-def check(input_file, log=None):
-    pdf = None
-    try:
-        pdf = pikepdf.open(input_file)
-    except pikepdf.PdfError as e:
-        if log:
-            log.error(e)
-        return False
-    else:
-        messages = pdf.check()
-        for msg in messages:
-            if 'error' in msg.lower():
-                log.error(msg)
-            else:
-                log.warning(msg)
-
-        sio = StringIO()
-        linearize = None
-        try:
-            pdf.check_linearization(sio)
-        except RuntimeError:
-            pass
-        else:
-            linearize = sio.getvalue()
-            if linearize:
-                log.warning(linearize)
-
-        if not messages and not linearize:
-            return True
-        return False
-    finally:
-        if pdf:
-            pdf.close()

src/ocrmypdf/exec/unpaper.py

@@ -1,127 +0,0 @@
-# © 2015 James R. Barlow: github.com/jbarlow83
-#
-# This file is part of OCRmyPDF.
-#
-# OCRmyPDF is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# OCRmyPDF is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with OCRmyPDF.  If not, see <http://www.gnu.org/licenses/>.
-
-# unpaper documentation:
-# https://github.com/Flameeyes/unpaper/blob/master/doc/basic-concepts.md
-
-"""Interface to unpaper executable"""
-
-import os
-import shlex
-from functools import lru_cache
-from subprocess import PIPE, STDOUT, CalledProcessError
-from tempfile import TemporaryDirectory
-
-from PIL import Image
-
-from ..exceptions import MissingDependencyError, SubprocessOutputError
-from . import get_version
-from . import run as external_run
-
-
-@lru_cache(maxsize=1)
-def version():
-    return get_version('unpaper')
-
-
-def run(input_file, output_file, dpi, log, mode_args):
-    args_unpaper = ['unpaper', '-v', '--dpi', str(dpi)] + mode_args
-
-    SUFFIXES = {'1': '.pbm', 'L': '.pgm', 'RGB': '.ppm'}
-
-    with TemporaryDirectory() as tmpdir, Image.open(input_file) as im:
-        if im.mode not in SUFFIXES.keys():
-            log.info("Converting image to other colorspace")
-            try:
-                if im.mode == 'P' and len(im.getcolors()) == 2:
-                    im = im.convert(mode='1')
-                else:
-                    im = im.convert(mode='RGB')
-            except IOError as e:
-                im.close()
-                raise MissingDependencyError(
-                    "Could not convert image with type " + im.mode
-                ) from e
-
-        try:
-            suffix = SUFFIXES[im.mode]
-        except KeyError:
-            raise MissingDependencyError(
-                "Failed to convert image to a supported format."
-            ) from e
-
-        input_pnm = os.path.join(tmpdir, f'input{suffix}')
-        output_pnm = os.path.join(tmpdir, f'output{suffix}')
-        im.save(input_pnm, format='PPM')
-
-        # To prevent any shenanigans from accepting arbitrary parameters in
-        # --unpaper-args, we:
-        # 1) run with cwd set to a tmpdir with only unpaper's files
-        # 2) forbid the use of '/' in arguments, to prevent changing paths
-        # 3) append absolute paths for the input and output file
-        # This should ensure that a user cannot clobber some other file with
-        # their unpaper arguments (whether intentionally or otherwise)
-        args_unpaper.extend([input_pnm, output_pnm])
-        try:
-            proc = external_run(
-                args_unpaper,
-                check=True,
-                close_fds=True,
-                universal_newlines=True,
-                stderr=STDOUT,
-                cwd=tmpdir,
-                stdout=PIPE,
-            )
-        except CalledProcessError as e:
-            log.debug(e.output)
-            raise e from e
-        else:
-            log.debug(proc.stdout)
-            # unpaper sets dpi to 72; fix this
-            try:
-                with Image.open(output_pnm) as imout:
-                    imout.save(output_file, dpi=(dpi, dpi))
-            except (FileNotFoundError, OSError):
-                raise SubprocessOutputError(
-                    "unpaper: failed to produce the expected output file. "
-                    + " Called with: "
-                    + str(args_unpaper)
-                ) from None
-
-
-def validate_custom_args(args: str):
-    unpaper_args = shlex.split(args)
-    if any('/' in arg for arg in unpaper_args):
-        raise ValueError('No filenames allowed in --unpaper-args')
-    return unpaper_args
-
-
-def clean(input_file, output_file, dpi, log, unpaper_args=None):
-    default_args = [
-        '--layout',
-        'none',
-        '--mask-scan-size',
-        '100',  # don't blank out narrow columns
-        '--no-border-align',  # don't align visible content to borders
-        '--no-mask-center',  # don't center visible content within page
-        '--no-grayfilter',  # don't remove light gray areas
-        '--no-blackfilter',  # don't remove solid black areas
-        '--no-deskew',  # don't deskew
-    ]
-    if not unpaper_args:
-        unpaper_args = default_args
-    run(input_file, output_file, dpi, log, unpaper_args)

src/ocrmypdf/extra_plugins/awslambda.py

@@ -0,0 +1,193 @@
+# © 2021 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+"""Alternate executor to support OCRmyPDF in AWS Lambda.
+
+AWS Lambda does not support the standard multiprocessing module because it
+environment.
+
+This alternate executor avoids that. However, it has drawbacks. Most notably,
+it divvies up work among worker processes at the beginning, to avoid coordinating
+effort in ways that require shared queues and semaphores. In this implementation,
+there is no shared queue, so no possible lock contention between workers. The
+main process has a shared pipe with each worker.
+
+If some tasks are larger than others, some workers will may fall far behind
+while others have deep queues. The last worker may end up with fewer tasks.
+"""
+
+
+import logging
+import logging.handlers
+import signal
+from contextlib import suppress
+from enum import Enum, auto
+from itertools import islice, repeat, takewhile, zip_longest
+from multiprocessing import Pipe, Process
+from multiprocessing.connection import Connection, wait
+from typing import Callable, Iterable, Iterator
+from unittest.mock import Mock
+
+from ocrmypdf import Executor, hookimpl
+from ocrmypdf._concurrent import NullProgressBar
+from ocrmypdf.exceptions import InputFileError
+from ocrmypdf.helpers import remove_all_log_handlers
+
+
+class MessageType(Enum):
+    exception = auto()
+    result = auto()
+    complete = auto()
+
+
+def split_every(n: int, iterable: Iterable) -> Iterator:
+    """Split iterable into groups of n.
+
+    >>> list(split_every(4, range(10)))
+    [[0, 1, 2], [3, 4, 5], [6, 7, 8], [9]]
+
+    https://stackoverflow.com/a/22919323
+    """
+    iterator = iter(iterable)
+    return takewhile(bool, (list(islice(iterator, n)) for _ in repeat(None)))
+
+
+def process_sigbus(*args):
+    raise InputFileError("A worker process lost access to an input file")
+
+
+class ConnectionLogHandler(logging.handlers.QueueHandler):
+    def __init__(self, conn: Connection) -> None:
+        super().__init__(None)
+        self.conn = conn
+
+    def enqueue(self, record):
+        self.conn.send(('log', record))
+
+
+def process_loop(
+    conn: Connection, user_init: Callable[[], None], loglevel, task, task_args
+):
+    """Initialize a process pool worker"""
+
+    # Install SIGBUS handler (so our parent process can abort somewhat gracefully)
+    with suppress(AttributeError):  # Windows and Cygwin do not have SIGBUS
+        # Windows and Cygwin do not have pthread_sigmask or SIGBUS
+        signal.signal(signal.SIGBUS, process_sigbus)
+
+    # Reconfigure the root logger for this process to send all messages to a queue
+    h = ConnectionLogHandler(conn)
+    root = logging.getLogger()
+    remove_all_log_handlers(root)
+    root.setLevel(loglevel)
+    root.addHandler(h)
+
+    user_init()
+
+    for args in task_args:
+        try:
+            result = task(args)
+        except Exception as e:
+            conn.send((MessageType.exception, e))
+            break
+        else:
+            conn.send((MessageType.result, result))
+
+    conn.send((MessageType.complete, None))
+    conn.close()
+    return
+
+
+class LambdaExecutor(Executor):
+    def _execute(
+        self,
+        *,
+        use_threads: bool,
+        max_workers: int,
+        tqdm_kwargs: dict,
+        worker_initializer: Callable,
+        task: Callable,
+        task_arguments: Iterable,
+        task_finished: Callable,
+    ):
+        if use_threads and max_workers == 1:
+            with self.pbar_class(**tqdm_kwargs) as pbar:
+                for args in task_arguments:
+                    result = task(args)
+                    task_finished(result, pbar)
+            return
+
+        task_arguments = list(task_arguments)
+        grouped_args = list(
+            zip_longest(*list(split_every(max_workers, task_arguments)))
+        )
+        if not grouped_args:
+            return
+
+        processes = []
+        connections = []
+        for chunk in grouped_args:
+            parent_conn, child_conn = Pipe()
+
+            worker_args = [args for args in chunk if args is not None]
+            process = Process(
+                target=process_loop,
+                args=(
+                    child_conn,
+                    worker_initializer,
+                    logging.getLogger("").level,
+                    task,
+                    worker_args,
+                ),
+            )
+            process.daemon = True
+            processes.append(process)
+            connections.append(parent_conn)
+
+        for process in processes:
+            process.start()
+
+        with self.pbar_class(**tqdm_kwargs) as pbar:
+            while connections:
+                for r in wait(connections):
+                    try:
+                        msg_type, msg = r.recv()
+                    except EOFError:
+                        connections.remove(r)
+                        continue
+
+                    if msg_type == MessageType.result:
+                        if task_finished:
+                            task_finished(msg, pbar)
+                    elif msg_type == 'log':
+                        record = msg
+                        logger = logging.getLogger(record.name)
+                        logger.handle(record)
+                    elif msg_type == MessageType.complete:
+                        connections.remove(r)
+                    elif msg_type == MessageType.exception:
+                        for process in processes:
+                            process.terminate()
+                        raise msg
+
+        for process in processes:
+            process.join()
+
+
+@hookimpl
+def get_executor(progressbar_class):
+    return LambdaExecutor(pbar_class=progressbar_class)
+
+
+@hookimpl
+def get_logging_console():
+    return logging.StreamHandler()
+
+
+@hookimpl
+def get_progressbar_class():
+    return NullProgressBar

src/ocrmypdf/helpers.py

@@ -1,50 +1,84 @@
 # © 2016 James R. Barlow: github.com/jbarlow83
 #
-# This file is part of OCRmyPDF.
-#
-# OCRmyPDF is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# OCRmyPDF is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with OCRmyPDF.  If not, see <http://www.gnu.org/licenses/>.
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
 
 import logging
 import multiprocessing
 import os
 import shutil
 import warnings
+from collections import namedtuple
 from collections.abc import Iterable
 from contextlib import suppress
 from functools import wraps
+from io import StringIO
+from math import isclose
 from pathlib import Path
+from typing import Any, Sequence
+
+import pikepdf
 
 log = logging.getLogger(__name__)
 
 
-def safe_symlink(input_file, soft_link_name, *args, **kwargs):
-    """
-    Helper function: relinks soft symbolic link if necessary
-    """
-    if len(args) == 1 and isinstance(args[0], logging.Logger):
-        log.warning("Deprecated: safe_symlink(,log)")
-    if 'log' in kwargs:
-        log.warning('Deprecated: safe_symlink(...log=)')
+class Resolution(namedtuple('Resolution', ('x', 'y'))):
+    """The number of pixels per inch in each 2D direction."""
 
+    __slots__ = ()
+
+    def round(self, ndigits: int):
+        return Resolution(round(self.x, ndigits), round(self.y, ndigits))
+
+    def to_int(self):
+        return Resolution(int(round(self.x)), int(round(self.y)))
+
+    @property
+    def is_square(self) -> bool:
+        return isclose(self.x, self.y, rel_tol=1e-3)
+
+    def take_max(self, vals, yvals=None):
+        if yvals is not None:
+            return Resolution(max(self.x, *vals), max(self.y, *yvals))
+        max_x, max_y = self.x, self.y
+        for x, y in vals:
+            max_x = max(x, max_x)
+            max_y = max(y, max_y)
+        return Resolution(max_x, max_y)
+
+    def flip_axis(self):
+        return Resolution(self.y, self.x)
+
+    def __str__(self):
+        return f"{self.x:f}x{self.y:f}"
+
+    def __repr__(self):  # pragma: no cover
+        return f"Resolution({self.x}x{self.y} dpi)"
+
+
+class NeverRaise(Exception):
+    """An exception that is never raised"""
+
+
+def safe_symlink(input_file: os.PathLike, soft_link_name: os.PathLike):
+    """Create a symbolic link at ``soft_link_name``, which references ``input_file``.
+
+    Think of this as copying ``input_file`` to ``soft_link_name`` with less overhead.
+
+    Use symlinks safely. Self-linking loops are prevented. On Windows, file copy is
+    used since symlinks may require administrator privileges. An existing link at the
+    destination is removed.
+    """
     input_file = os.fspath(input_file)
     soft_link_name = os.fspath(soft_link_name)
 
     # Guard against soft linking to oneself
     if input_file == soft_link_name:
         log.warning(
-            "No symbolic link made. You are using "
-            "the original data directory as the working directory."
+            "No symbolic link created. You are using  the original data directory "
+            "as the working directory."
         )
         return
 
@@ -53,10 +87,7 @@ def safe_symlink(input_file, soft_link_name, *args, **kwargs):
         # do not delete or overwrite real (non-soft link) file
         if not os.path.islink(soft_link_name):
             raise FileExistsError(f"{soft_link_name} exists and is not a link")
-        try:
-            os.unlink(soft_link_name)
-        except OSError:
-            log.debug("Can't unlink %s", soft_link_name)
+        os.unlink(soft_link_name)
 
     if not os.path.exists(input_file):
         raise FileNotFoundError(f"trying to create a broken symlink to {input_file}")
@@ -72,21 +103,30 @@ def safe_symlink(input_file, soft_link_name, *args, **kwargs):
     os.symlink(os.path.abspath(input_file), soft_link_name)
 
 
-def is_iterable_notstr(thing):
+def samefile(f1: os.PathLike, f2: os.PathLike):
+    if os.name == 'nt':
+        return f1 == f2
+    else:
+        return os.path.samefile(f1, f2)
+
+
+def is_iterable_notstr(thing: Any) -> bool:
+    """Is this is an iterable type, other than a string?"""
     return isinstance(thing, Iterable) and not isinstance(thing, str)
 
 
-def monotonic(L):
-    """Does list increase monotonically?"""
+def monotonic(L: Sequence) -> bool:
+    """Does this sequence increase monotonically?"""
     return all(b > a for a, b in zip(L, L[1:]))
 
 
-def page_number(input_file):
+def page_number(input_file: os.PathLike) -> int:
     """Get one-based page number implied by filename (000002.pdf -> 2)"""
     return int(os.path.basename(os.fspath(input_file))[0:6])
 
 
-def available_cpu_count():
+def available_cpu_count() -> int:
+    """Returns number of CPUs in the system."""
     try:
         return multiprocessing.cpu_count()
     except NotImplementedError:
@@ -97,7 +137,7 @@ def available_cpu_count():
     return 1
 
 
-def is_file_writable(test_file):
+def is_file_writable(test_file: os.PathLike) -> bool:
     """Intentionally racy test if target is writable.
 
     We intend to write to the output file if and only if we succeed and
@@ -105,11 +145,7 @@ def is_file_writable(test_file):
     the location is writable.
     """
     try:
-        if not isinstance(test_file, Path):
-            p = Path(test_file)
-        else:
-            p = test_file
-
+        p = Path(test_file)
         if p.is_symlink():
             p = p.resolve(strict=False)
 
@@ -136,8 +172,79 @@ def is_file_writable(test_file):
         return False
 
 
+def check_pdf(input_file: Path) -> bool:
+    """Check if a PDF complies with the PDF specification.
+
+    Checks for proper formatting and proper linearization. Uses pikepdf (which in
+    turn, uses QPDF) to perform the checks.
+    """
+    try:
+        pdf = pikepdf.open(input_file)
+    except pikepdf.PdfError as e:
+        log.error(e)
+        return False
+    else:
+        with pdf:
+            messages = pdf.check()
+            for msg in messages:
+                if 'error' in msg.lower():
+                    log.error(msg)
+                else:
+                    log.warning(msg)
+
+            sio = StringIO()
+            linearize_msgs = ''
+            try:
+                # If linearization is missing entirely, we do not complain. We do
+                # complain if linearization is present but incorrect.
+                pdf.check_linearization(sio)
+            except RuntimeError:
+                pass
+            except (
+                # Workaround for a problematic pikepdf version
+                # pragma: no cover
+                getattr(pikepdf, 'ForeignObjectError')
+                if pikepdf.__version__ == '2.1.0'
+                else NeverRaise
+            ):
+                pass
+            else:
+                linearize_msgs = sio.getvalue()
+                if linearize_msgs:
+                    log.warning(linearize_msgs)
+
+            if not messages and not linearize_msgs:
+                return True
+            return False
+
+
+def clamp(n, smallest, largest):  # mypy doesn't understand types for this
+    """Clamps the value of ``n`` to between ``smallest`` and ``largest``."""
+    return max(smallest, min(n, largest))
+
+
+def remove_all_log_handlers(logger):
+    "Remove all log handlers, usually used in a child process."
+    for handler in logger.handlers[:]:
+        logger.removeHandler(handler)
+        handler.close()  # To ensure handlers with opened resources are released
+
+
+def pikepdf_enable_mmap():
+    # try:
+    #     if pikepdf._qpdf.set_access_default_mmap(True):
+    #         log.debug("pikepdf mmap enabled")
+    # except AttributeError:
+    #     log.debug("pikepdf mmap not available")
+    # We found a race condition probably related to pybind issue #2252 that can
+    # cause a crash. For now, disable pikepdf mmap to be on the safe side.
+    # Fix is not in pybind11 2.6.0
+    # log.debug("pikepdf mmap disabled")
+    return
+
+
 def deprecated(func):
-    """Warn that function is deprecated"""
+    """Warn that function is deprecated."""
 
     @wraps(func)
     def new_func(*args, **kwargs):

src/ocrmypdf/hocrtransform.py

@@ -29,15 +29,28 @@
 # SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 
 import argparse
+import os
 import re
-from collections import namedtuple
+from itertools import chain
 from math import atan, cos, sin
+from pathlib import Path
+from typing import Any, NamedTuple, Optional, Tuple, Union
 from xml.etree import ElementTree
 
+from reportlab.lib.colors import black, cyan, magenta, red
 from reportlab.lib.units import inch
 from reportlab.pdfgen.canvas import Canvas
 
-Rect = namedtuple('Rect', ['x1', 'y1', 'x2', 'y2'])
+Element = ElementTree.Element
+
+
+class Rect(NamedTuple):  # pylint: disable=inherit-non-class
+    """A rectangle for managing PDF coordinates."""
+
+    x1: Any
+    y1: Any
+    x2: Any
+    y2: Any
 
 
 class HocrTransformError(Exception):
@@ -64,9 +77,9 @@ class HocrTransform:
         {'ff': 'ff', 'ffi': 'f‌f‌i', 'ffl': 'f‌f‌l', 'fi': 'fi', 'fl': 'fl'}
     )
 
-    def __init__(self, hocrFileName, dpi):
+    def __init__(self, *, hocr_filename: Union[str, Path], dpi: float):
         self.dpi = dpi
-        self.hocr = ElementTree.parse(hocrFileName)
+        self.hocr = ElementTree.parse(os.fspath(hocr_filename))
 
         # if the hOCR file has a namespace, ElementTree requires its use to
         # find elements
@@ -77,7 +90,7 @@ class HocrTransform:
 
         # get dimension in pt (not pixel!!!!) of the OCRed image
         self.width, self.height = None, None
-        for div in self.hocr.findall(".//%sdiv[@class='ocr_page']" % (self.xmlns)):
+        for div in self.hocr.findall(self._child_xpath('div', 'ocr_page')):
             coords = self.element_coordinates(div)
             pt_coords = self.pt_from_pixel(coords)
             self.width = pt_coords.x2 - pt_coords.x1
@@ -94,32 +107,32 @@ class HocrTransform:
         """
         if self.hocr is None:
             return ''
-        body = self.hocr.find(".//%sbody" % (self.xmlns))
+        body = self.hocr.find(self._child_xpath('body'))
         if body:
             return self._get_element_text(body)
         else:
             return ''
 
-    def _get_element_text(self, element):
+    def _get_element_text(self, element: Element):
         """
         Return the textual content of the element and its children
         """
         text = ''
         if element.text is not None:
             text += element.text
-        for child in element.getchildren():
+        for child in element:
             text += self._get_element_text(child)
         if element.tail is not None:
             text += element.tail
         return text
 
     @classmethod
-    def element_coordinates(cls, element):
+    def element_coordinates(cls, element: Element) -> Rect:
         """
         Returns a tuple containing the coordinates of the bounding box around
         an element
         """
-        out = (0, 0, 0, 0)
+        out = Rect._make(0 for _ in range(4))
         if 'title' in element.attrib:
             matches = cls.box_pattern.search(element.attrib['title'])
             if matches:
@@ -128,7 +141,7 @@ class HocrTransform:
         return out
 
     @classmethod
-    def baseline(cls, element):
+    def baseline(cls, element: Element) -> Tuple[float, float]:
         """
         Returns a tuple containing the baseline slope and intercept.
         """
@@ -136,32 +149,47 @@ class HocrTransform:
             matches = cls.baseline_pattern.search(element.attrib['title'])
             if matches:
                 return float(matches.group(1)), int(matches.group(2))
-        return (0, 0)
+        return (0.0, 0.0)
 
-    def pt_from_pixel(self, pxl):
+    def pt_from_pixel(self, pxl) -> Rect:
         """
         Returns the quantity in PDF units (pt) given quantity in pixels
         """
         return Rect._make((c / self.dpi * inch) for c in pxl)
 
+    def _child_xpath(self, html_tag: str, html_class: Optional[str] = None) -> str:
+        xpath = f".//{self.xmlns}{html_tag}"
+        if html_class:
+            xpath += f"[@class='{html_class}']"
+        return xpath
+
     @classmethod
-    def replace_unsupported_chars(cls, s):
+    def replace_unsupported_chars(cls, s: str) -> str:
         """
         Given an input string, returns the corresponding string that:
-        - is available in the helvetica facetype
-        - does not contain any ligature (to allow easy search in the PDF file)
+        * is available in the Helvetica facetype
+        * does not contain any ligature (to allow easy search in the PDF file)
         """
         return s.translate(cls.ligatures)
 
+    def topdown_position(self, element):
+        pxl_line_coords = self.element_coordinates(element)
+        line_box = self.pt_from_pixel(pxl_line_coords)
+        # Coordinates here are still in the hocr coordinate system, so 0 on the y axis
+        # is the top of the page and increasing values of y will move towards the
+        # bottom of the page.
+        return line_box.y2
+
     def to_pdf(
         self,
-        outFileName,
-        imageFileName=None,
-        showBoundingboxes=False,
-        fontname="Helvetica",
-        invisibleText=False,
-        interwordSpaces=False,
-    ):
+        *,
+        out_filename: Path,
+        image_filename: Optional[Path] = None,
+        show_bounding_boxes: bool = False,
+        fontname: str = "Helvetica",
+        invisible_text: bool = False,
+        interword_spaces: bool = False,
+    ) -> None:
         """
         Creates a PDF file with an image superimposed on top of the text.
         Text is positioned according to the bounding box of the lines in
@@ -169,19 +197,36 @@ class HocrTransform:
         The image need not be identical to the image used to create the hOCR
         file.
         It can have a lower resolution, different color mode, etc.
+
+        Arguments:
+            out_filename: Path of PDF to write.
+            image_filename: Image to use for this file. If omitted, the OCR text
+                is shown.
+            show_bounding_boxes: Show bounding boxes around various text regions,
+                for debugging.
+            fontname: Name of font to use.
+            invisible_text: If True, text is rendered invisible so that is
+                selectable but never drawn. If False, text is visible and may
+                be seen if the image is skipped or deleted in Acrobat.
+            interword_spaces: If True, insert spaces between words rather than
+                drawing each word without spaces. Generally this improves text
+                extraction.
         """
         # create the PDF file
         # page size in points (1/72 in.)
-        pdf = Canvas(outFileName, pagesize=(self.width, self.height), pageCompression=1)
+        pdf = Canvas(
+            os.fspath(out_filename),
+            pagesize=(self.width, self.height),
+            pageCompression=1,
+        )
 
         # draw bounding box for each paragraph
         # light blue for bounding box of paragraph
-        pdf.setStrokeColorRGB(0, 1, 1)
+        pdf.setStrokeColor(cyan)
         # light blue for bounding box of paragraph
-        pdf.setFillColorRGB(0, 1, 1)
+        pdf.setFillColor(cyan)
         pdf.setLineWidth(0)  # no line for bounding box
-        for elem in self.hocr.findall(".//%sp[@class='%s']" % (self.xmlns, "ocr_par")):
-
+        for elem in self.hocr.iterfind(self._child_xpath('p', 'ocr_par')):
             elemtxt = self._get_element_text(elem).rstrip()
             if len(elemtxt) == 0:
                 continue
@@ -190,14 +235,19 @@ class HocrTransform:
             pt = self.pt_from_pixel(pxl_coords)
 
             # draw the bbox border
-            if showBoundingboxes:  # pragma: no cover
+            if show_bounding_boxes:  # pragma: no cover
                 pdf.rect(
                     pt.x1, self.height - pt.y2, pt.x2 - pt.x1, pt.y2 - pt.y1, fill=1
                 )
 
         found_lines = False
-        for line in self.hocr.findall(
-            ".//%sspan[@class='%s']" % (self.xmlns, "ocr_line")
+        for line in sorted(
+            chain(
+                self.hocr.iterfind(self._child_xpath('span', 'ocr_header')),
+                self.hocr.iterfind(self._child_xpath('span', 'ocr_line')),
+                self.hocr.iterfind(self._child_xpath('span', 'ocr_textfloat')),
+            ),
+            key=self.topdown_position,
         ):
             found_lines = True
             self._do_line(
@@ -205,26 +255,28 @@ class HocrTransform:
                 line,
                 "ocrx_word",
                 fontname,
-                invisibleText,
-                interwordSpaces,
-                showBoundingboxes,
+                invisible_text,
+                interword_spaces,
+                show_bounding_boxes,
             )
 
         if not found_lines:
             # Tesseract did not report any lines (just words)
-            root = self.hocr.find(".//%sdiv[@class='%s']" % (self.xmlns, "ocr_page"))
+            root = self.hocr.find(self._child_xpath('div', 'ocr_page'))
             self._do_line(
                 pdf,
                 root,
                 "ocrx_word",
                 fontname,
-                invisibleText,
-                interwordSpaces,
-                showBoundingboxes,
+                invisible_text,
+                interword_spaces,
+                show_bounding_boxes,
             )
         # put the image on the page, scaled to fill the page
-        if imageFileName is not None:
-            pdf.drawImage(imageFileName, 0, 0, width=self.width, height=self.height)
+        if image_filename is not None:
+            pdf.drawImage(
+                os.fspath(image_filename), 0, 0, width=self.width, height=self.height
+            )
 
         # finish up the page and save it
         pdf.showPage()
@@ -236,14 +288,16 @@ class HocrTransform:
 
     def _do_line(
         self,
-        pdf,
-        line,
-        elemclass,
-        fontname,
-        invisibleText,
-        interwordSpaces,
-        showBoundingboxes,
+        pdf: Canvas,
+        line: Optional[Element],
+        elemclass: str,
+        fontname: str,
+        invisible_text: bool,
+        interword_spaces: bool,
+        show_bounding_boxes: bool,
     ):
+        if not line:
+            return
         pxl_line_coords = self.element_coordinates(line)
         line_box = self.pt_from_pixel(pxl_line_coords)
         line_height = line_box.y2 - line_box.y1
@@ -262,17 +316,17 @@ class HocrTransform:
         # on a sloped baseline and the edge of the bounding box.
         fontsize = (line_height - abs(intercept)) / cos_a
         text.setFont(fontname, fontsize)
-        if invisibleText:
+        if invisible_text:
             text.setTextRenderMode(3)  # Invisible (indicates OCR text)
 
         # Intercept is normally negative, so this places it above the bottom
         # of the line box
         baseline_y2 = self.height - (line_box.y2 + intercept)
 
-        if showBoundingboxes:  # pragma: no cover
+        if show_bounding_boxes:  # pragma: no cover
             # draw the baseline in magenta, dashed
             pdf.setDash()
-            pdf.setStrokeColorRGB(0.95, 0.65, 0.95)
+            pdf.setStrokeColor(magenta)
             pdf.setLineWidth(0.5)
             # negate slope because it is defined as a rise/run in pixel
             # coordinates and page coordinates have the y axis flipped
@@ -284,12 +338,12 @@ class HocrTransform:
             )
             # light green for bounding box of word/line
             pdf.setDash(6, 3)
-            pdf.setStrokeColorRGB(1, 0, 0)
+            pdf.setStrokeColor(red)
 
         text.setTextTransform(cos_a, -sin_a, sin_a, cos_a, line_box.x1, baseline_y2)
-        pdf.setFillColorRGB(0, 0, 0)  # text in black
+        pdf.setFillColor(black)  # text in black
 
-        elements = line.findall(".//%sspan[@class='%s']" % (self.xmlns, elemclass))
+        elements = line.findall(self._child_xpath('span', elemclass))
         for elem in elements:
             elemtxt = self._get_element_text(elem).strip()
             elemtxt = self.replace_unsupported_chars(elemtxt)
@@ -298,7 +352,7 @@ class HocrTransform:
 
             pxl_coords = self.element_coordinates(elem)
             box = self.pt_from_pixel(pxl_coords)
-            if interwordSpaces:
+            if interword_spaces:
                 # if  `--interword-spaces` is true, append a space
                 # to the end of each text element to allow simpler PDF viewers
                 # such as PDF.js to better recognize words in search and copy
@@ -318,7 +372,7 @@ class HocrTransform:
             font_width = pdf.stringWidth(elemtxt, fontname, fontsize)
 
             # draw the bbox border
-            if showBoundingboxes:  # pragma: no cover
+            if show_bounding_boxes:  # pragma: no cover
                 pdf.rect(
                     box.x1, self.height - line_box.y2, box_width, line_height, fill=0
                 )
@@ -380,10 +434,10 @@ if __name__ == "__main__":
     parser.add_argument('outputfile', help='Path to the PDF file to be generated')
     args = parser.parse_args()
 
-    hocr = HocrTransform(args.hocrfile, args.resolution)
+    hocr = HocrTransform(hocr_filename=args.hocrfile, dpi=args.resolution)
     hocr.to_pdf(
-        args.outputfile,
-        args.image,
-        args.boundingboxes,
-        interwordSpaces=args.interword_spaces,
+        out_filename=args.outputfile,
+        image_filename=args.image,
+        show_bounding_boxes=args.boundingboxes,
+        interword_spaces=args.interword_spaces,
     )

src/ocrmypdf/leptonica.py

@@ -3,20 +3,10 @@
 #
 # © 2013-16: jbarlow83 from Github (https://github.com/jbarlow83)
 #
-# This file is part of OCRmyPDF.
-#
-# OCRmyPDF is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# OCRmyPDF is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with OCRmyPDF.  If not, see <http://www.gnu.org/licenses/>.
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
 #
 # Python FFI wrapper for Leptonica library
 
@@ -24,26 +14,29 @@ import argparse
 import logging
 import os
 import sys
-import warnings
+import threading
+from collections import deque
 from collections.abc import Sequence
 from contextlib import suppress
 from ctypes.util import find_library
 from functools import lru_cache
-from io import BytesIO
+from io import BytesIO, UnsupportedOperation
 from os import fspath
 from tempfile import TemporaryFile
+from warnings import warn
 
-from .exceptions import MissingDependencyError
-from .exec import shim_paths_with_program_files
-from .lib._leptonica import ffi
+from ocrmypdf.exceptions import MissingDependencyError
+from ocrmypdf.lib._leptonica import ffi
 
 # pylint: disable=protected-access
 
 logger = logging.getLogger(__name__)
 
 if os.name == 'nt':
+    from ocrmypdf.subprocess._windows import shim_env_path
+
     libname = 'liblept-5'
-    os.environ['PATH'] = shim_paths_with_program_files()
+    os.environ['PATH'] = shim_env_path()
 else:
     libname = 'lept'
 _libpath = find_library(libname)
@@ -66,6 +59,24 @@ if not _libpath:
         ---------------------------------------------------------------------
         """
     )
+if os.name == 'nt':
+    # On Windows, recent versions of libpng require zlib. We have to make sure
+    # the zlib version being loaded is the same one that libpng was built with.
+    # This tries to import zlib from Tesseract's installation folder, falling back
+    # to find_library() if liblept is being loaded from somewhere else.
+    # Loading zlib from other places could cause a version mismatch
+    _zlib_path = os.path.join(os.path.dirname(_libpath), 'zlib1.dll')
+    if not os.path.exists(_zlib_path):
+        _zlib_path = find_library('zlib')
+    try:
+        zlib = ffi.dlopen(_zlib_path)
+    except ffi.error as e:
+        raise MissingDependencyError(
+            """
+            Could not load the zlib library. It could be that Tesseract is not installed properly,
+            we can't find the installation on your system PATH environment variable.
+            """
+        ) from e
 try:
     lept = ffi.dlopen(_libpath)
     lept.setMsgSeverity(lept.L_SEVERITY_WARNING)
@@ -75,11 +86,11 @@ except ffi.error as e:
     ) from e
 
 
-class _LeptonicaErrorTrap:
+class _LeptonicaErrorTrap_Redirect:
     """
-    Context manager to trap errors reported by Leptonica.
+    Context manager to trap errors reported by Leptonica < 1.79 or on Apple Silicon.
 
-    Leptonica's error return codes don't provide much informatino about what
+    Leptonica's error return codes don't provide much information about what
     went wrong. Leptonica does, however, write more detailed errors to stderr
     (provided this is not disabled at compile time). The Leptonica source
     code is very consistent in its use of macros to generate errors.
@@ -90,20 +101,23 @@ class _LeptonicaErrorTrap:
 
     """
 
+    leptonica_lock = threading.Lock()
+
     def __init__(self):
         self.tmpfile = None
         self.copy_of_stderr = -1
         self.no_stderr = False
 
     def __enter__(self):
-        from io import UnsupportedOperation
-
         self.tmpfile = TemporaryFile()
 
         # Save the old stderr, and redirect stderr to temporary file
-        with suppress(AttributeError):
-            sys.stderr.flush()
+        self.leptonica_lock.acquire()
         try:
+            # It would make sense to do sys.stderr.flush() here, but that can deadlock
+            # due to https://bugs.python.org/issue6721. So don't flush. Pretend
+            # there's nothing important sys.stderr. If the user cared they would
+            # be use Leptonica 1.79 or later anyway and avoid this mess.
             self.copy_of_stderr = os.dup(sys.stderr.fileno())
             os.dup2(self.tmpfile.fileno(), sys.stderr.fileno(), inheritable=False)
         except AttributeError:
@@ -115,7 +129,10 @@ class _LeptonicaErrorTrap:
             os.dup2(self.tmpfile.fileno(), 2, inheritable=False)
         except UnsupportedOperation:
             self.copy_of_stderr = None
-        return
+        except Exception:
+            self.leptonica_lock.release()
+            raise
+        return self
 
     def __exit__(self, exc_type, exc_value, traceback):
         # Restore old stderr
@@ -132,6 +149,8 @@ class _LeptonicaErrorTrap:
         self.tmpfile.seek(0)  # Cursor will be at end, so move back to beginning
         leptonica_output = self.tmpfile.read().decode(errors='replace')
         self.tmpfile.close()
+        self.leptonica_lock.release()
+
         # If there are Python errors, record them
         if exc_type:
             logger.warning(leptonica_output)
@@ -149,6 +168,64 @@ class _LeptonicaErrorTrap:
         return False
 
 
+tls = threading.local()
+tls.trap = None
+
+
+class _LeptonicaErrorTrap_Queue:
+    def __init__(self):
+        self.queue = deque()
+
+    def __enter__(self):
+        self.queue.clear()
+        tls.trap = self.queue
+
+    def __exit__(self, exc_type, exc_value, traceback):
+        tls.trap = None
+        output = ''.join(self.queue)
+        self.queue.clear()
+
+        # If there are Python errors, record them
+        if exc_type:
+            logger.warning(output)
+
+        if 'Error' in output:
+            if 'image file not found' in output:
+                raise FileNotFoundError()
+            if 'pixWrite: stream not opened' in output:
+                raise LeptonicaIOError()
+            if 'index not valid' in output:
+                raise IndexError()
+            raise LeptonicaError(output)
+        return False
+
+
+try:
+
+    @ffi.callback("void(char *)")
+    def _stderr_handler(cstr):
+        msg = ffi.string(cstr).decode(errors='replace')
+        if msg.startswith("Error"):
+            logger.error(msg)
+        elif msg.startswith("Warning"):
+            logger.warning(msg)
+        else:
+            logger.debug(msg)
+        if tls.trap is not None:
+            tls.trap.append(msg)
+        return
+
+    lept.leptSetStderrHandler(_stderr_handler)
+except (ffi.error, MemoryError):
+    # Pre-1.79 Leptonica does not have leptSetStderrHandler
+    # And some platforms, notably Apple ARM 64, do not allow the write+execute
+    # memory needed to set up the callback function.
+    _LeptonicaErrorTrap = _LeptonicaErrorTrap_Redirect
+else:
+    # 1.79 have this new symbol
+    _LeptonicaErrorTrap = _LeptonicaErrorTrap_Queue
+
+
 class LeptonicaError(Exception):
     pass
 
@@ -314,7 +391,7 @@ class Pix(LeptonicaObject):
 
     @classmethod
     def read(cls, path):
-        warnings.warn('Use Pix.open() instead', DeprecationWarning)
+        warn('Use Pix.open() instead', DeprecationWarning)
         return cls.open(path)
 
     @classmethod
@@ -351,7 +428,7 @@ class Pix(LeptonicaObject):
             py_file.write(buffer)
 
     @classmethod
-    def frompil(self, pillow_image):
+    def frompil(cls, pillow_image):
         """Create a copy of a PIL.Image from this Pix"""
         bio = BytesIO()
         pillow_image.save(bio, format='png', compress_level=1)
@@ -363,7 +440,7 @@ class Pix(LeptonicaObject):
 
     def topil(self):
         """Returns a PIL.Image version of this Pix"""
-        from PIL import Image
+        from PIL import Image  # pylint: disable=import-outside-toplevel
 
         # Leptonica manages data in words, so it implicitly does an endian
         # swap.  Tell Pillow about this when it reads the data.
@@ -534,16 +611,7 @@ class Pix(LeptonicaObject):
             )
             return Pix(thresh_pix)
 
-    def crop_to_foreground(
-        self,
-        threshold=128,
-        mindist=70,
-        erasedist=30,
-        pagenum=0,
-        showmorph=0,
-        display=0,
-        pdfdir=ffi.NULL,
-    ):
+    def crop_to_foreground(self, threshold=128, mindist=70, erasedist=30, showmorph=0):
         if get_leptonica_version() < 'leptonica-1.76':
             # Leptonica 1.76 changed the API for pixFindPageForeground; we don't
             # support the old version
@@ -866,6 +934,8 @@ def get_leptonica_version():
     Caveat: Leptonica expects the caller to free this memory.  We don't,
     since that would involve binding to libc to access libc.free(),
     a pointless effort to reclaim 100 bytes of memory.
+
+    Reminder that this returns "leptonica-1.xx" or "leptonica-1.yy.0".
     """
     return ffi.string(lept.getLeptonicaVersion()).decode()
 

src/ocrmypdf/lib/__init__.py

@@ -1,18 +1,8 @@
 # © 2017 James R. Barlow: github.com/jbarlow83
 #
-# This file is part of OCRmyPDF.
-#
-# OCRmyPDF is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# OCRmyPDF is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with OCRmyPDF.  If not, see <http://www.gnu.org/licenses/>.
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
 
 """Bindings to external libraries"""

src/ocrmypdf/lib/compile_leptonica.py

@@ -1,20 +1,10 @@
 #!/usr/bin/env python3
 # © 2017 James R. Barlow: github.com/jbarlow83
 #
-# This file is part of OCRmyPDF.
-#
-# OCRmyPDF is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# OCRmyPDF is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with OCRmyPDF.  If not, see <http://www.gnu.org/licenses/>.
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
 
 from pathlib import Path
 
@@ -509,6 +499,8 @@ void selDestroy ( SEL **psel );
 l_int32
 setMsgSeverity(l_int32 newsev);
 
+void
+leptSetStderrHandler(void (*handler)(const char *));
 """
 )
 

src/ocrmypdf/optimize.py

@@ -1,108 +1,153 @@
 # © 2018 James R. Barlow: github.com/jbarlow83
 #
-# This file is part of OCRmyPDF.
-#
-# OCRmyPDF is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# OCRmyPDF is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with OCRmyPDF.  If not, see <http://www.gnu.org/licenses/>.
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
-import concurrent.futures
+
+import logging
 import sys
 import tempfile
 from collections import defaultdict
 from os import fspath
 from pathlib import Path
+from typing import (
+    Callable,
+    Dict,
+    Iterator,
+    List,
+    MutableSet,
+    NamedTuple,
+    NewType,
+    Optional,
+    Sequence,
+    Tuple,
+)
 
+import img2pdf
 import pikepdf
-from pikepdf import Dictionary, Name
+from pikepdf import Dictionary, Name, Object, Pdf, PdfImage
 from PIL import Image
-from tqdm import tqdm
 
-from . import leptonica
-from ._jobcontext import PDFContext
-from .exceptions import OutputFileAccessError
-from .exec import jbig2enc, pngquant
-from .helpers import safe_symlink
+from ocrmypdf import leptonica
+from ocrmypdf._concurrent import Executor, SerialExecutor
+from ocrmypdf._exec import jbig2enc, pngquant
+from ocrmypdf._jobcontext import PdfContext
+from ocrmypdf.exceptions import OutputFileAccessError
+from ocrmypdf.helpers import safe_symlink
+
+log = logging.getLogger(__name__)
 
 DEFAULT_JPEG_QUALITY = 75
 DEFAULT_PNG_QUALITY = 70
 
 
-def img_name(root, xref, ext):
-    return fspath(root / f'{xref:08d}{ext}')
+Xref = NewType('Xref', int)
 
 
-def png_name(root, xref):
+class XrefExt(NamedTuple):  # pylint: disable=inherit-non-class
+    xref: Xref
+    ext: str
+
+
+def img_name(root: Path, xref: Xref, ext: str) -> Path:
+    return root / f'{xref:08d}{ext}'
+
+
+def png_name(root: Path, xref: Xref) -> Path:
     return img_name(root, xref, '.png')
 
 
-def jpg_name(root, xref):
+def jpg_name(root: Path, xref: Xref) -> Path:
     return img_name(root, xref, '.jpg')
 
 
-def tif_name(root, xref):
-    return img_name(root, xref, '.tif')
+def extract_image_filter(
+    pike: Pdf, root: Path, image: Object, xref: Xref
+) -> Optional[Tuple[PdfImage, Tuple[Name, Object]]]:
+    del pike  # unused args
+    del root
 
-
-def extract_image_filter(pike, root, log, image, xref):
     if image.Subtype != Name.Image:
         return None
     if image.Length < 100:
-        log.debug("Skipping small image, xref %s", xref)
+        log.debug(f"Skipping small image, xref {xref}")
+        return None
+    if image.Width < 8 or image.Height < 8:  # Issue 732
+        log.debug(f"Skipping oddly sized image, xref {xref}")
         return None
 
-    pim = pikepdf.PdfImage(image)
+    pim = PdfImage(image)
 
     if len(pim.filter_decodeparms) > 1:
-        log.debug("Skipping multiply filtered, xref %s", xref)
+        log.debug(f"Skipping multiply filtered image, xref {xref}")
         return None
     filtdp = pim.filter_decodeparms[0]
 
     if pim.bits_per_component > 8:
+        log.debug(f"Skipping wide gamut image, xref {xref}")
         return None  # Don't mess with wide gamut images
 
     if filtdp[0] == Name.JPXDecode:
+        log.debug(f"Skipping JPEG2000 iamge, xref {xref}")
         return None  # Don't do JPEG2000
 
+    if filtdp[0] == Name.CCITTFaxDecode and filtdp[1].get('/K', 0) >= 0:
+        log.debug(f"Skipping CCITT Group 3 image, xref {xref}")
+        return None  # pikepdf doesn't support Group 3 yet
+
     if Name.Decode in image:
+        log.debug(f"Skipping image with Decode table, xref {xref}")
         return None  # Don't mess with custom Decode tables
 
     return pim, filtdp
 
 
-def extract_image_jbig2(*, pike, root, log, image, xref, options):
-    result = extract_image_filter(pike, root, log, image, xref)
+def extract_image_jbig2(
+    *, pike: pikepdf.Pdf, root: Path, image: Object, xref: Xref, options
+) -> Optional[XrefExt]:
+    del options  # unused arg
+
+    result = extract_image_filter(pike, root, image, xref)
     if result is None:
         return None
     pim, filtdp = result
 
     if (
         pim.bits_per_component == 1
-        and filtdp != Name.JBIG2Decode
+        and filtdp[0] != Name.JBIG2Decode
         and jbig2enc.available()
     ):
-        try:
-            imgname = Path(root / f'{xref:08d}')
-            with imgname.open('wb') as f:
-                ext = pim.extract_to(stream=f)
-            imgname.rename(imgname.with_suffix(ext))
-        except pikepdf.UnsupportedImageTypeError:
-            return None
-        return xref, ext
+        # Save any colorspace associated with the image, so that we
+        # will export a pure 1-bit PNG with no palette or ICC profile.
+        # Showing the palette or ICC to jbig2enc will cause it to perform
+        # colorspace transform to 1bpp, which will conflict the palette or
+        # ICC if it exists.
+        colorspace = pim.obj.get(pikepdf.Name.ColorSpace, None)
+        if colorspace is not None or pim.image_mask:
+            try:
+                # Set to DeviceGray temporarily; we already in 1 bpc.
+                pim.obj.ColorSpace = pikepdf.Name.DeviceGray
+                imgname = root / f'{xref:08d}'
+                with imgname.open('wb') as f:
+                    ext = pim.extract_to(stream=f)
+                imgname.rename(imgname.with_suffix(ext))
+            except pikepdf.UnsupportedImageTypeError:
+                return None
+            finally:
+                # Restore image colorspace after temporarily setting it to DeviceGray
+                if colorspace is not None:
+                    pim.obj.ColorSpace = colorspace
+                else:
+                    del pim.obj.ColorSpace
+            return XrefExt(xref, ext)
     return None
 
 
-def extract_image_generic(*, pike, root, log, image, xref, options):
-    result = extract_image_filter(pike, root, log, image, xref)
+def extract_image_generic(
+    *, pike: Pdf, root: Path, image: PdfImage, xref: Xref, options
+) -> Optional[XrefExt]:
+    result = extract_image_filter(pike, root, image, xref)
     if result is None:
         return None
     pim, filtdp = result
@@ -111,11 +156,6 @@ def extract_image_generic(*, pike, root, log, image, xref, options):
     if pim.bits_per_component == 1:
         return None
 
-    try:
-        pim.indexed  # pikepdf 1.6.3 can't handle [/Indexed [/Array...]]
-    except NotImplementedError:
-        return None
-
     if filtdp[0] == Name.DCTDecode and options.optimize >= 2:
         # This is a simple heuristic derived from some training data, that has
         # about a 70% chance of guessing whether the JPEG is high quality,
@@ -134,13 +174,13 @@ def extract_image_generic(*, pike, root, log, image, xref, options):
         #     with Image.open(stream) as im:
         #         im.save(jpg_name(root, xref), icc_profile=iccbytes)
         try:
-            imgname = Path(root / f'{xref:08d}')
+            imgname = root / f'{xref:08d}'
             with imgname.open('wb') as f:
                 ext = pim.extract_to(stream=f)
             imgname.rename(imgname.with_suffix(ext))
         except pikepdf.UnsupportedImageTypeError:
             return None
-        return xref, ext
+        return XrefExt(xref, ext)
     elif (
         pim.indexed
         and pim.colorspace in pim.SIMPLE_COLORSPACES
@@ -149,12 +189,12 @@ def extract_image_generic(*, pike, root, log, image, xref, options):
         # Try to improve on indexed images - these are far from low hanging
         # fruit in most cases
         pim.as_pil_image().save(png_name(root, xref))
-        return xref, '.png'
+        return XrefExt(xref, '.png')
     elif not pim.indexed and pim.colorspace in pim.SIMPLE_COLORSPACES:
         # An optimization opportunity here, not currently taken, is directly
         # generating a PNG from compressed data
         pim.as_pil_image().save(png_name(root, xref))
-        return xref, '.png'
+        return XrefExt(xref, '.png')
     elif (
         not pim.indexed
         and pim.colorspace == Name.ICCBased
@@ -165,12 +205,17 @@ def extract_image_generic(*, pike, root, log, image, xref, options):
         # paying any attention to the ICC profile, provided we're not doing
         # lossy JBIG2
         pim.as_pil_image().save(png_name(root, xref))
-        return xref, '.png'
+        return XrefExt(xref, '.png')
 
     return None
 
 
-def extract_images(pike, root, log, options, extract_fn):
+def extract_images(
+    pike: Pdf,
+    root: Path,
+    options,
+    extract_fn: Callable[..., Optional[XrefExt]],
+) -> Iterator[Tuple[int, XrefExt]]:
     """Extract image using extract_fn
 
     Enumerate images on each page, lookup their xref/ID number in the PDF.
@@ -186,8 +231,8 @@ def extract_images(pike, root, log, options, extract_fn):
     extension. extract_fn must also extract the file it finds interesting.
     """
 
-    include_xrefs = set()
-    exclude_xrefs = set()
+    include_xrefs: MutableSet[Xref] = set()
+    exclude_xrefs: MutableSet[Xref] = set()
     pageno_for_xref = {}
     errors = 0
     for pageno, page in enumerate(pike.pages):
@@ -198,12 +243,14 @@ def extract_images(pike, root, log, options, extract_fn):
         for _imname, image in dict(xobjs).items():
             if image.objgen[1] != 0:
                 continue  # Ignore images in an incremental PDF
-            xref = image.objgen[0]
+            xref = Xref(image.objgen[0])
             if hasattr(image, 'SMask'):
                 # Ignore soft masks
-                smask_xref = image.SMask.objgen[0]
+                smask_xref = Xref(image.SMask.objgen[0])
                 exclude_xrefs.add(smask_xref)
+                log.debug(f"Skipping image {smask_xref} because it is an SMask")
             include_xrefs.add(xref)
+            log.debug(f"Treating {xref} as an optimization candidate")
             if xref not in pageno_for_xref:
                 pageno_for_xref[xref] = pageno
 
@@ -212,99 +259,100 @@ def extract_images(pike, root, log, options, extract_fn):
         image = pike.get_object((xref, 0))
         try:
             result = extract_fn(
-                pike=pike, root=root, log=log, image=image, xref=xref, options=options
+                pike=pike, root=root, image=image, xref=xref, options=options
             )
-        except Exception as e:
-            log.debug("Image xref %s, error %s", xref, repr(e))
+        except Exception:  # pylint: disable=broad-except
+            log.exception(f"While extracting image xref {xref}, an error occurred")
             errors += 1
         else:
             if result:
                 _, ext = result
-                yield pageno_for_xref[xref], xref, ext
+                yield pageno_for_xref[xref], XrefExt(xref, ext)
 
 
-def extract_images_generic(pike, root, log, options):
+def extract_images_generic(
+    pike: Pdf, root: Path, options
+) -> Tuple[List[Xref], List[Xref]]:
     """Extract any >=2bpp image we think we can improve"""
 
     jpegs = []
     pngs = []
-    for _, xref, ext in extract_images(pike, root, log, options, extract_image_generic):
-        log.debug('xref = %s ext = %s', xref, ext)
-        if ext == '.png':
-            pngs.append(xref)
-        elif ext == '.jpg':
-            jpegs.append(xref)
+    for _, xref_ext in extract_images(pike, root, options, extract_image_generic):
+        log.debug('%s', xref_ext)
+        if xref_ext.ext == '.png':
+            pngs.append(xref_ext.xref)
+        elif xref_ext.ext == '.jpg':
+            jpegs.append(xref_ext.xref)
     log.debug("Optimizable images: JPEGs: %s PNGs: %s", len(jpegs), len(pngs))
     return jpegs, pngs
 
 
-def extract_images_jbig2(pike, root, log, options):
+def extract_images_jbig2(pike: Pdf, root: Path, options) -> Dict[int, List[XrefExt]]:
     """Extract any bitonal image that we think we can improve as JBIG2"""
 
     jbig2_groups = defaultdict(list)
-    for pageno, xref, ext in extract_images(
-        pike, root, log, options, extract_image_jbig2
-    ):
+    for pageno, xref_ext in extract_images(pike, root, options, extract_image_jbig2):
         group = pageno // options.jbig2_page_group_size
-        jbig2_groups[group].append((xref, ext))
+        jbig2_groups[group].append(xref_ext)
 
-    # Elide empty groups
-    jbig2_groups = {
-        group: xrefs for group, xrefs in jbig2_groups.items() if len(xrefs) > 0
-    }
     log.debug("Optimizable images: JBIG2 groups: %s", (len(jbig2_groups),))
     return jbig2_groups
 
 
-def _produce_jbig2_images(jbig2_groups, root, log, options):
+def _produce_jbig2_images(
+    jbig2_groups: Dict[int, List[XrefExt]], root: Path, options, executor: Executor
+) -> None:
     """Produce JBIG2 images from their groups"""
 
-    def jbig2_group_futures(executor, root, groups):
+    def jbig2_group_args(root: Path, groups: Dict[int, List[XrefExt]]):
         for group, xref_exts in groups.items():
             prefix = f'group{group:08d}'
-            future = executor.submit(
-                jbig2enc.convert_group,
-                cwd=fspath(root),
-                infiles=(img_name(root, xref, ext) for xref, ext in xref_exts),
-                out_prefix=prefix,
+            yield (
+                fspath(root),  # =cwd
+                (img_name(root, xref, ext) for xref, ext in xref_exts),  # =infiles
+                prefix,  # =out_prefix
             )
-            yield future
 
-    def jbig2_single_futures(executor, root, groups):
+    def jbig2_single_args(root, groups: Dict[int, List[XrefExt]]):
         for group, xref_exts in groups.items():
             prefix = f'group{group:08d}'
             # Second loop is to ensure multiple images per page are unpacked
             for n, xref_ext in enumerate(xref_exts):
                 xref, ext = xref_ext
-                future = executor.submit(
-                    jbig2enc.convert_single,
-                    cwd=fspath(root),
-                    infile=img_name(root, xref, ext),
-                    outfile=root / f'{prefix}.{n:04d}',
+                yield (
+                    fspath(root),
+                    img_name(root, xref, ext),
+                    root / f'{prefix}.{n:04d}',
                 )
-                yield future
 
     if options.jbig2_page_group_size > 1:
-        jbig2_futures = jbig2_group_futures
+        jbig2_args = jbig2_group_args
+        jbig2_convert = jbig2enc.convert_group_mp
     else:
-        jbig2_futures = jbig2_single_futures
+        jbig2_args = jbig2_single_args
+        jbig2_convert = jbig2enc.convert_single_mp
 
-    with concurrent.futures.ThreadPoolExecutor(max_workers=options.jobs) as executor:
-        futures = jbig2_futures(executor, root, jbig2_groups)
-        with tqdm(
+    executor(
+        use_threads=True,
+        max_workers=options.jobs,
+        tqdm_kwargs=dict(
             total=len(jbig2_groups),
             desc="JBIG2",
             unit='item',
             disable=not options.progress_bar,
-        ) as pbar:
-            for future in concurrent.futures.as_completed(futures):
-                proc = future.result()
-                if proc.stderr:
-                    log.debug(proc.stderr.decode())
-                pbar.update()
+        ),
+        task=jbig2_convert,
+        task_arguments=jbig2_args(root, jbig2_groups),
+    )
 
 
-def convert_to_jbig2(pike, jbig2_groups, root, log, options):
+def convert_to_jbig2(
+    pike: Pdf,
+    jbig2_groups: Dict[int, List[XrefExt]],
+    root: Path,
+    options,
+    executor: Executor,
+) -> None:
     """Convert images to JBIG2 and insert into PDF.
 
     When the JBIG2 page group size is > 1 we do several JBIG2 images at once
@@ -318,7 +366,7 @@ def convert_to_jbig2(pike, jbig2_groups, root, log, options):
     and needs no dictionary. Currently this must be lossless JBIG2.
     """
 
-    _produce_jbig2_images(jbig2_groups, root, log, options)
+    _produce_jbig2_images(jbig2_groups, root, options, executor)
 
     for group, xref_exts in jbig2_groups.items():
         prefix = f'group{group:08d}'
@@ -342,165 +390,147 @@ def convert_to_jbig2(pike, jbig2_groups, root, log, options):
             )
 
 
-def transcode_jpegs(pike, jpegs, root, log, options):
-    for xref in tqdm(
-        jpegs, desc="JPEGs", unit='image', disable=not options.progress_bar
-    ):
-        in_jpg = Path(jpg_name(root, xref))
-        opt_jpg = in_jpg.with_suffix('.opt.jpg')
+def _optimize_jpeg(args):
+    xref, in_jpg, opt_jpg, jpeg_quality = args
 
-        # This produces a debug warning from PIL
-        # DEBUG:PIL.Image:Error closing: 'NoneType' object has no attribute
-        # 'close'.  Seems to be mostly harmless
-        # https://github.com/python-pillow/Pillow/issues/1144
-        with Image.open(fspath(in_jpg)) as im:
-            im.save(fspath(opt_jpg), optimize=True, quality=options.jpeg_quality)
+    # This may produce a debug warning from PIL
+    # DEBUG:PIL.Image:Error closing: 'NoneType' object has no attribute
+    # 'close'.  Seems to be mostly harmless
+    # https://github.com/python-pillow/Pillow/issues/1144
+    with Image.open(in_jpg) as im:
+        im.save(opt_jpg, optimize=True, quality=jpeg_quality)
 
-        if opt_jpg.stat().st_size > in_jpg.stat().st_size:
-            log.debug("xref %s, jpeg, made larger - skip", xref)
-            continue
+    if opt_jpg.stat().st_size > in_jpg.stat().st_size:
+        log.debug("xref %s, jpeg, made larger - skip", xref)
+        opt_jpg.unlink()
+        opt_jpg = None
+    return xref, opt_jpg
+
+
+def transcode_jpegs(
+    pike: Pdf, jpegs: Sequence[Xref], root: Path, options, executor
+) -> None:
+    def jpeg_args():
+        for xref in jpegs:
+            in_jpg = jpg_name(root, xref)
+            opt_jpg = in_jpg.with_suffix('.opt.jpg')
+            yield xref, in_jpg, opt_jpg, options.jpeg_quality
+
+    def finish_jpeg(result, pbar):
+        xref, opt_jpg = result
+        if opt_jpg:
+            compdata = leptonica.CompressedData.open(opt_jpg)
+            im_obj = pike.get_object(xref, 0)
+            im_obj.write(compdata.read(), filter=Name.DCTDecode)
+        pbar.update()
+
+    executor(
+        use_threads=True,  # Processes are significantly slower at this task
+        max_workers=options.jobs,
+        tqdm_kwargs=dict(
+            desc="JPEGs",
+            total=len(jpegs),
+            unit='image',
+            disable=not options.progress_bar,
+        ),
+        task=_optimize_jpeg,
+        task_arguments=jpeg_args(),
+        task_finished=finish_jpeg,
+    )
+
+
+def _transcode_png(pike: Pdf, filename: Path, xref: Xref) -> bool:
+    output = filename.with_suffix('.png.pdf')
+    with output.open('wb') as f:
+        img2pdf.convert(fspath(filename), outputstream=f)
+
+    with pikepdf.open(output) as pdf_image:
+        foreign_image = next(pdf_image.pages[0].images.values())
+        local_image = pike.copy_foreign(foreign_image)
 
-        compdata = leptonica.CompressedData.open(opt_jpg)
         im_obj = pike.get_object(xref, 0)
-        im_obj.write(compdata.read(), filter=Name.DCTDecode)
+        im_obj.write(
+            local_image.read_raw_bytes(),
+            filter=local_image.Filter,
+            decode_parms=local_image.DecodeParms,
+        )
+
+        # Don't copy keys from the new image...
+        del_keys = set(im_obj.keys()) - set(local_image.keys())
+        # ...except for the keep_fields, which are essential to displaying
+        # the image correctly and preserving its metadata. (/Decode arrays
+        # and /SMaskInData are implicitly discarded prior to this point.)
+        keep_fields = {
+            '/ID',
+            '/Intent',
+            '/Interpolate',
+            '/Mask',
+            '/Metadata',
+            '/OC',
+            '/OPI',
+            '/SMask',
+            '/StructParent',
+        }
+        del_keys -= keep_fields
+        for key in local_image.keys():
+            if key != Name.Length and str(key) not in keep_fields:
+                im_obj[key] = local_image[key]
+        for key in del_keys:
+            del im_obj[key]
+    return True
 
 
-def transcode_pngs(pike, images, image_name_fn, root, log, options):
-    modified = set()
+def transcode_pngs(
+    pike: Pdf,
+    images: Sequence[Xref],
+    image_name_fn: Callable[[Path, Xref], Path],
+    root: Path,
+    options,
+    executor,
+) -> None:
+    modified: MutableSet[Xref] = set()
     if options.optimize >= 2:
         png_quality = (
             max(10, options.png_quality - 10),
             min(100, options.png_quality + 10),
         )
-        with concurrent.futures.ThreadPoolExecutor(
-            max_workers=options.jobs
-        ) as executor:
-            futures = []
+
+        def pngquant_args():
             for xref in images:
                 log.debug(image_name_fn(root, xref))
-                futures.append(
-                    executor.submit(
-                        pngquant.quantize,
-                        image_name_fn(root, xref),
-                        png_name(root, xref),
-                        png_quality[0],
-                        png_quality[1],
-                    )
+                yield (
+                    image_name_fn(root, xref),
+                    png_name(root, xref),
+                    png_quality[0],
+                    png_quality[1],
                 )
                 modified.add(xref)
-            with tqdm(
+
+        executor(
+            use_threads=True,
+            max_workers=options.jobs,
+            tqdm_kwargs=dict(
                 desc="PNGs",
-                total=len(futures),
+                total=len(images),
                 unit='image',
                 disable=not options.progress_bar,
-            ) as pbar:
-                for _future in concurrent.futures.as_completed(futures):
-                    pbar.update()
+            ),
+            task=pngquant.quantize_mp,
+            task_arguments=pngquant_args(),
+        )
 
     for xref in modified:
-        im_obj = pike.get_object(xref, 0)
-        try:
-            pix = leptonica.Pix.open(png_name(root, xref))
-            if pix.mode == '1':
-                compdata = pix.generate_pdf_ci_data(leptonica.lept.L_G4_ENCODE, 0)
-            else:
-                compdata = leptonica.CompressedData.open(png_name(root, xref))
-        except leptonica.LeptonicaError as e:
-            # Most likely this means file not found, i.e. quantize did not
-            # produce an improved version
-            log.error(e)
-            continue
-
-        # If re-coded image is larger don't use it - we test here because
-        # pngquant knows the size of the temporary output file but not the actual
-        # object in the PDF
-        if len(compdata) > int(im_obj.stream_dict.Length):
-            log.debug(
-                f"pngquant: pngquant did not improve over original image "
-                f"{len(compdata)} > {int(im_obj.stream_dict.Length)}"
-            )
-            continue
-        if compdata.type == leptonica.lept.L_FLATE_ENCODE:
-            return rewrite_png(pike, im_obj, compdata, log)
-        elif compdata.type == leptonica.lept.L_G4_ENCODE:
-            return rewrite_png_as_g4(pike, im_obj, compdata, log)
+        filename = png_name(root, xref)
+        _transcode_png(pike, filename, xref)
 
 
-def rewrite_png_as_g4(pike, im_obj, compdata, log):
-    im_obj.BitsPerComponent = 1
-    im_obj.Width = compdata.w
-    im_obj.Height = compdata.h
-
-    im_obj.write(compdata.read())
-
-    log.debug(f"PNG to G4 {im_obj.objgen}")
-    if Name.Predictor in im_obj:
-        del im_obj.Predictor
-    if Name.DecodeParms in im_obj:
-        del im_obj.DecodeParms
-    im_obj.DecodeParms = Dictionary(
-        K=-1, BlackIs1=bool(compdata.minisblack), Columns=compdata.w
-    )
-
-    im_obj.Filter = Name.CCITTFaxDecode
-    return
-
-
-def rewrite_png(pike, im_obj, compdata, log):
-    # When a PNG is inserted into a PDF, we more or less copy the IDAT section from
-    # the PDF and transfer the rest of the PNG headers to PDF image metadata.
-    # One thing we have to do is tell the PDF reader whether a predictor was used
-    # on the image before Flate encoding. (Typically one is.)
-    # According to Leptonica source, PDF readers don't actually need us
-    # to specify the correct predictor, they just need a value of either:
-    #   1 - no predictor
-    #   10-14 - there is a predictor
-    # Leptonica's compdata->predictor only tells TRUE or FALSE
-    # 10-14 means the actual predictor is specified in the data, so for any
-    # number >= 10 the PDF reader will use whatever the PNG data specifies.
-    # In practice Leptonica should use Paeth, 14, but 15 seems to be the
-    # designated value for "optimal". So we will use 15.
-    # See:
-    #   - PDF RM 7.4.4.4 Table 10
-    #   - https://github.com/DanBloomberg/leptonica/blob/master/src/pdfio2.c#L757
-    predictor = 15 if compdata.predictor > 0 else 1
-    dparms = Dictionary(Predictor=predictor)
-    if predictor > 1:
-        dparms.BitsPerComponent = compdata.bps  # Yes, this is redundant
-        dparms.Colors = compdata.spp
-        dparms.Columns = compdata.w
-
-    im_obj.BitsPerComponent = compdata.bps
-    im_obj.Width = compdata.w
-    im_obj.Height = compdata.h
-
-    log.debug(
-        f"PNG {im_obj.objgen}: palette={compdata.ncolors} spp={compdata.spp} bps={compdata.bps}"
-    )
-    if compdata.ncolors > 0:
-        # .ncolors is the number of colors in the palette, not the number of
-        # colors used in a true color image. The palette string is always
-        # given as RGB tuples even when the image is grayscale; see
-        # https://github.com/DanBloomberg/leptonica/blob/master/src/colormap.c#L2067
-        palette_pdf_string = compdata.get_palette_pdf_string()
-        palette_data = pikepdf.Object.parse(palette_pdf_string)
-        palette_stream = pikepdf.Stream(pike, bytes(palette_data))
-        palette = [Name.Indexed, Name.DeviceRGB, compdata.ncolors - 1, palette_stream]
-        cs = palette
-    else:
-        # ncolors == 0 means we are using a colorspace without a palette
-        if compdata.spp == 1:
-            cs = Name.DeviceGray
-        elif compdata.spp == 3:
-            cs = Name.DeviceRGB
-        elif compdata.spp == 4:
-            cs = Name.DeviceCMYK
-    im_obj.ColorSpace = cs
-    im_obj.write(compdata.read(), filter=Name.FlateDecode, decode_parms=dparms)
-
-
-def optimize(input_file, output_file, context, save_settings):
-    log = context.log
+def optimize(
+    input_file: Path,
+    output_file: Path,
+    context,
+    save_settings,
+    executor: Executor = SerialExecutor(),
+) -> None:
     options = context.options
     if options.optimize == 0:
         safe_symlink(input_file, output_file)
@@ -514,25 +544,25 @@ def optimize(input_file, output_file, context, save_settings):
         options.jbig2_page_group_size = 10 if options.jbig2_lossy else 1
 
     with pikepdf.Pdf.open(input_file) as pike:
-        root = Path(output_file).parent / 'images'
+        root = output_file.parent / 'images'
         root.mkdir(exist_ok=True)
 
-        jpegs, pngs = extract_images_generic(pike, root, log, options)
-        transcode_jpegs(pike, jpegs, root, log, options)
+        jpegs, pngs = extract_images_generic(pike, root, options)
+        transcode_jpegs(pike, jpegs, root, options, executor)
         # if options.optimize >= 2:
         # Try pngifying the jpegs
-        #    transcode_pngs(pike, jpegs, jpg_name, root, log, options)
-        transcode_pngs(pike, pngs, png_name, root, log, options)
+        #    transcode_pngs(pike, jpegs, jpg_name, root, options)
+        transcode_pngs(pike, pngs, png_name, root, options, executor)
 
-        jbig2_groups = extract_images_jbig2(pike, root, log, options)
-        convert_to_jbig2(pike, jbig2_groups, root, log, options)
+        jbig2_groups = extract_images_jbig2(pike, root, options)
+        convert_to_jbig2(pike, jbig2_groups, root, options, executor)
 
-        target_file = Path(output_file).with_suffix('.opt.pdf')
+        target_file = output_file.with_suffix('.opt.pdf')
         pike.remove_unreferenced_resources()
         pike.save(target_file, **save_settings)
 
-    input_size = Path(input_file).stat().st_size
-    output_size = Path(target_file).stat().st_size
+    input_size = input_file.stat().st_size
+    output_size = target_file.stat().st_size
     if output_size == 0:
         raise OutputFileAccessError(
             f"Output file not created after optimizing. We probably ran "
@@ -540,7 +570,7 @@ def optimize(input_file, output_file, context, save_settings):
         )
     ratio = input_size / output_size
     savings = 1 - output_size / input_size
-    log.info(f"Optimize ratio: {ratio:.2f} savings: {(100 * savings):.1f}%")
+    log.info(f"Optimize ratio: {ratio:.2f} savings: {(savings):.1%}")
 
     if savings < 0:
         log.info("Image optimization did not improve the file - discarded")
@@ -553,8 +583,8 @@ def optimize(input_file, output_file, context, save_settings):
 
 
 def main(infile, outfile, level, jobs=1):
-    from tempfile import TemporaryDirectory
-    from shutil import copy
+    from shutil import copy  # pylint: disable=import-outside-toplevel
+    from tempfile import TemporaryDirectory  # pylint: disable=import-outside-toplevel
 
     class OptimizeOptions:
         """Emulate ocrmypdf's options"""
@@ -572,6 +602,7 @@ def main(infile, outfile, level, jobs=1):
             self.quiet = True
             self.progress_bar = False
 
+    infile = Path(infile)
     options = OptimizeOptions(
         input_file=infile,
         jobs=jobs,
@@ -582,7 +613,7 @@ def main(infile, outfile, level, jobs=1):
     )
 
     with TemporaryDirectory() as td:
-        context = PDFContext(options, td, infile, None)
+        context = PdfContext(options, td, infile, None, None)
         tmpout = Path(td) / 'out.pdf'
         optimize(
             infile,

src/ocrmypdf/pdfa.py

@@ -1,39 +1,17 @@
-# © 2015 James R. Barlow: github.com/jbarlow83
+# © 2020 James R. Barlow: github.com/jbarlow83
 #
-# This file is part of OCRmyPDF.
-#
-# OCRmyPDF is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# OCRmyPDF is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with OCRmyPDF.  If not, see <http://www.gnu.org/licenses/>.
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
 
 """
-Generate a PDFMARK file for Ghostscript >= 9.14, for PDF/A conversion
-
-pdfmark is an extension to the Postscript language that describes some PDF
-features like bookmarks and annotations. It was originally specified Adobe
-Distiller, for Postscript to PDF conversion:
-https://www.adobe.com/content/dam/acom/en/devnet/acrobat/pdfs/pdfmark_reference.pdf
-
-Ghostscript uses pdfmark for PDF to PDF/A conversion as well. To use Ghostscript
-to create a PDF/A, we need to create a pdfmark file with the necessary metadata.
-
-This takes care of the many version-specific bugs and pecularities in
-Ghostscript's handling of pdfmark.
-
+Utilities for PDF/A production and confirmation with Ghostspcript.
 """
 
 import base64
 from pathlib import Path
-from string import Template
+from typing import Dict, Iterator, Union
 
 import pikepdf
 import pkg_resources
@@ -43,58 +21,89 @@ ICC_PROFILE_RELPATH = 'data/sRGB.icc'
 SRGB_ICC_PROFILE = pkg_resources.resource_filename('ocrmypdf', ICC_PROFILE_RELPATH)
 
 
-# This is a template written in PostScript which is needed to create PDF/A
-# files, from the Ghostscript documentation. Lines beginning with % are
-# comments. Python substitution variables have a '$' prefix.
-pdfa_def_template = u"""%!
-% Define an ICC profile :
-/ICCProfile $icc_profile
-def
+def _postscript_objdef(
+    alias: str,
+    dictionary: Dict[str, str],
+    *,
+    stream_name: str = None,
+    stream_data: bytes = None,
+) -> Iterator[str]:
+    assert (stream_name is None) == (stream_data is None)
 
-[/_objdef {icc_PDFA} /type /stream /OBJ pdfmark
-[{icc_PDFA} << /N 3 >> /PUT pdfmark
-[{icc_PDFA} ICCProfile /PUT pdfmark
+    objtype = '/stream' if stream_name else '/dict'
 
-% Define the output intent dictionary :
+    if stream_name:
+        assert stream_data is not None
+        a85_data = base64.a85encode(stream_data, adobe=True).decode('ascii')
+        yield f'{stream_name} ' + a85_data
+        yield 'def'
 
-[/_objdef {OutputIntent_PDFA} /type /dict /OBJ pdfmark
-[{OutputIntent_PDFA} <<
-  /Type /OutputIntent             % Must be so (the standard requires).
-  /S /GTS_PDFA1                   % Must be so (the standard requires).
-  /DestOutputProfile {icc_PDFA}            % Must be so (see above).
-  /OutputConditionIdentifier ($icc_identifier)
->> /PUT pdfmark
-[{Catalog} <</OutputIntents [ {OutputIntent_PDFA} ]>> /PUT pdfmark
-"""
+    if alias != '{Catalog}':  # Catalog needs no definition
+        yield f'[/_objdef {alias} /type {objtype} /OBJ pdfmark'
+
+    yield f'[{alias} <<'
+    for key, val in dictionary.items():
+        yield f'  {key} {val}'
+    yield '>> /PUT pdfmark'
+
+    if stream_name:
+        yield f'[{alias} {stream_name[1:]} /PUT pdfmark'
 
 
-def generate_pdfa_ps(target_filename, icc='sRGB'):
-    """Create a Postscript pdfmark file for Ghostscript PDF/A conversion
+def _make_postscript(icc_name: str, icc_data: bytes, colors: int) -> Iterator[str]:
+    yield '%!'
+    yield from _postscript_objdef(
+        '{icc_PDFA}',  # Not an f-string
+        {'/N': str(colors)},
+        stream_name='/ICCProfile',
+        stream_data=icc_data,
+    )
+    yield ''
+    yield from _postscript_objdef(
+        '{OutputIntent_PDFA}',
+        {
+            '/Type': '/OutputIntent',
+            '/S': '/GTS_PDFA1',
+            '/DestOutputProfile': '{icc_PDFA}',
+            '/OutputConditionIdentifier': f'({icc_name})',  # Only f-string
+        },
+    )
+    yield ''
+    yield from _postscript_objdef(
+        '{Catalog}', {'/OutputIntents': '[ {OutputIntent_PDFA} ]'}
+    )
 
-    A pdfmark file is a small Postscript program that provides some information
-    Ghostscript needs to perform PDF/A conversion. The only information we put
-    in specifies that we want the file to be a PDF/A, and we want to Ghostscript
-    to convert objects to the sRGB colorspace if it runs into any object that
-    it decides must be converted.
 
-    See the Adobe pdfmark Reference for details:
-    https://www.adobe.com/content/dam/acom/en/devnet/acrobat/pdfs/pdfmark_reference.pdf
+def generate_pdfa_ps(target_filename: Path, icc: str = 'sRGB'):
+    """Create a Postscript PDFMARK file for Ghostscript PDF/A conversion
 
-    :param target_filename: filename to save
-    :param icc: ICC identifier such as 'sRGB'
+    pdfmark is an extension to the Postscript language that describes some PDF
+    features like bookmarks and annotations. It was originally specified Adobe
+    Distiller, for Postscript to PDF conversion.
+
+    Ghostscript uses pdfmark for PDF to PDF/A conversion as well. To use Ghostscript
+    to create a PDF/A, we need to create a pdfmark file with the necessary metadata.
+
+    This function takes care of the many version-specific bugs and pecularities in
+    Ghostscript's handling of pdfmark.
+
+    The only information we put in specifies that we want the file to be a
+    PDF/A, and we want to Ghostscript to convert objects to the sRGB colorspace
+    if it runs into any object that it decides must be converted.
+
+    Arguments:
+        target_filename: filename to save
+        icc: ICC identifier such as 'sRGB'
+    References:
+        Adobe PDFMARK Reference: https://www.adobe.com/content/dam/acom/en/devnet/acrobat/pdfs/pdfmark_reference.pdf
     """
     if icc == 'sRGB':
         icc_profile = SRGB_ICC_PROFILE
     else:
         raise NotImplementedError("Only supporting sRGB")
 
-    # Read the ICC profile, encode as ASCII85 and convert to a string which we
-    # will insert in the .ps file
     bytes_icc_profile = Path(icc_profile).read_bytes()
-    icc_profile = base64.a85encode(bytes_icc_profile, adobe=True).decode('ascii')
-
-    t = Template(pdfa_def_template)
-    ps = t.substitute(icc_profile=icc_profile, icc_identifier=icc)
+    ps = '\n'.join(_make_postscript(icc, bytes_icc_profile, 3))
 
     # We should have encoded everything to pure ASCII by this point, and
     # to be safe, only allow ASCII in PostScript
@@ -102,8 +111,8 @@ def generate_pdfa_ps(target_filename, icc='sRGB'):
     return target_filename
 
 
-def file_claims_pdfa(filename):
-    """Determines if the file claims to be PDF/A compliant
+def file_claims_pdfa(filename: Path):
+    """Determines if the file claims to be PDF/A compliant.
 
     This only checks if the XMP metadata contains a PDF/A marker. It does not
     do full PDF/A validation.
@@ -119,7 +128,7 @@ def file_claims_pdfa(filename):
             }
         valid_part_conforms = {'1A', '1B', '2A', '2B', '2U', '3A', '3B', '3U'}
         conformance = f'PDF/A-{pdfmeta.pdfa_status}'
-        pdfa_dict = {}
+        pdfa_dict: Dict[str, Union[str, bool]] = {}
         if pdfmeta.pdfa_status in valid_part_conforms:
             pdfa_dict['pass'] = True
             pdfa_dict['output'] = 'pdfa'

src/ocrmypdf/pdfinfo/__init__.py

@@ -1,19 +1,9 @@
 #!/usr/bin/env python3
 # © 2015 James R. Barlow: github.com/jbarlow83
 #
-# This file is part of OCRmyPDF.
-#
-# OCRmyPDF is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# OCRmyPDF is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with OCRmyPDF.  If not, see <http://www.gnu.org/licenses/>.
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
-from .info import Colorspace, Encoding, PdfInfo
+
+from ocrmypdf.pdfinfo.info import Colorspace, Encoding, PdfInfo

src/ocrmypdf/pdfinfo/ghosttext.py

@@ -1,102 +0,0 @@
-# © 2018 James R. Barlow: github.com/jbarlow83
-#
-# This file is part of OCRmyPDF.
-#
-# OCRmyPDF is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# OCRmyPDF is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with OCRmyPDF.  If not, see <http://www.gnu.org/licenses/>.
-
-import logging
-import re
-import xml.etree.ElementTree as ET
-
-from ..exec import ghostscript
-
-gslog = logging.getLogger()
-
-# Forgive me for I have sinned
-# I am using regular expressions to parse XML. However the XML in this case,
-# generated by Ghostscript, is self-consistent enough to be parseable.
-regex_remove_char_tags = re.compile(
-    br"""
-    <char\b
-    (?:   [^>]   # anything single character but >
-        | \">\"  # special case: trap ">"
-    )*
-    />           # terminate with '/>'
-""",
-    re.VERBOSE,
-)
-
-
-def page_get_textblocks(infile, pageno, xmltext, height):
-    """Get text boxes out of Ghostscript txtwrite xml"""
-
-    root = xmltext
-    if not hasattr(xmltext, 'findall'):
-        return []
-
-    def blocks():
-        for span in root.findall('.//span'):
-            bbox_str = span.attrib['bbox']
-            font_size = span.attrib['size']
-            pts = [int(pt) for pt in bbox_str.split()]
-            pts[1] = pts[1] - int(float(font_size) + 0.5)
-            bbox_topdown = tuple(pts)
-            bb = bbox_topdown
-            bbox_bottomup = (bb[0], height - bb[3], bb[2], height - bb[1])
-            yield bbox_bottomup
-
-    def joined_blocks():
-        prev = None
-        for bbox in blocks():
-            if prev is None:
-                prev = bbox
-            if bbox[1] == prev[1] and bbox[3] == prev[3]:
-                gap = prev[2] - bbox[0]
-                height = abs(bbox[3] - bbox[1])
-                if gap < height:
-                    # Join boxes
-                    prev = (prev[0], prev[1], bbox[2], bbox[3])
-                    continue
-            # yield previously joined bboxes and start anew
-            yield prev
-            prev = bbox
-        if prev is not None:
-            yield prev
-
-    return [block for block in joined_blocks()]
-
-
-def extract_text_xml(infile, pdf, pageno=None, log=gslog):
-    existing_text = ghostscript.extract_text(infile, pageno=None)
-    existing_text = regex_remove_char_tags.sub(b' ', existing_text)
-
-    try:
-        root = ET.fromstringlist([b'<document>\n', existing_text, b'</document>\n'])
-        page_xml = root.findall('page')
-    except ET.ParseError as e:
-        log.error(
-            "An error occurred while attempting to retrieve existing text in "
-            "the input file. Will attempt to continue assuming that there is "
-            "no existing text in the file. The error was:"
-        )
-        log.error(e)
-        page_xml = [None] * len(pdf.pages)
-
-    page_count_difference = len(pdf.pages) - len(page_xml)
-    if page_count_difference != 0:
-        log.error("The number of pages in the input file is inconsistent.")
-        log.error(f"Expected {len(pdf.pages)}, txtwrite says {len(page_xml)}")
-        if page_count_difference > 0:
-            page_xml.extend([None] * page_count_difference)
-    return page_xml

src/ocrmypdf/pdfinfo/info.py

@@ -1,38 +1,31 @@
 #!/usr/bin/env python3
 # © 2015 James R. Barlow: github.com/jbarlow83
 #
-# This file is part of OCRmyPDF.
-#
-# OCRmyPDF is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# OCRmyPDF is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with OCRmyPDF.  If not, see <http://www.gnu.org/licenses/>.
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
+
+import atexit
 import logging
 import re
 from collections import defaultdict, namedtuple
+from contextlib import ExitStack
 from decimal import Decimal
 from enum import Enum
+from functools import partial
 from math import hypot, isclose
-from os import fspath
+from os import PathLike
 from pathlib import Path
+from typing import Container, Iterator, Optional, Tuple, Union
 from warnings import warn
 
 import pikepdf
-from pikepdf import PdfMatrix
-from tqdm import tqdm
+from pikepdf import Object, Pdf, PdfMatrix
 
-from ocrmypdf.exceptions import EncryptedPdfError
-from ocrmypdf.exec import ghostscript
-from ocrmypdf.pdfinfo import ghosttext
+from ocrmypdf._concurrent import Executor, SerialExecutor
+from ocrmypdf.exceptions import EncryptedPdfError, InputFileError
+from ocrmypdf.helpers import Resolution, available_cpu_count, pikepdf_enable_mmap
 from ocrmypdf.pdfinfo.layout import get_page_analysis, get_text_boxes
 
 logger = logging.getLogger()
@@ -40,7 +33,7 @@ logger = logging.getLogger()
 Colorspace = Enum('Colorspace', 'gray rgb cmyk lab icc index sep devn pattern jpeg2000')
 
 Encoding = Enum(
-    'Encoding', 'ccitt jpeg jpeg2000 jbig2 asciihex ascii85 lzw flate ' + 'runlength'
+    'Encoding', 'ccitt jpeg jpeg2000 jbig2 asciihex ascii85 lzw flate runlength'
 )
 
 FRIENDLY_COLORSPACE = {
@@ -90,7 +83,7 @@ UNIT_SQUARE = (1.0, 0.0, 0.0, 1.0, 0.0, 0.0)
 def _is_unit_square(shorthand):
     values = map(float, shorthand)
     pairwise = zip(values, UNIT_SQUARE)
-    return all([isclose(a, b, rel_tol=1e-3) for a, b in pairwise])
+    return all(isclose(a, b, rel_tol=1e-3) for a, b in pairwise)
 
 
 XobjectSettings = namedtuple('XobjectSettings', ['name', 'shorthand', 'stack_depth'])
@@ -98,15 +91,19 @@ XobjectSettings = namedtuple('XobjectSettings', ['name', 'shorthand', 'stack_dep
 InlineSettings = namedtuple('InlineSettings', ['iimage', 'shorthand', 'stack_depth'])
 
 ContentsInfo = namedtuple(
-    'ContentsInfo', ['xobject_settings', 'inline_images', 'found_vector', 'name_index']
+    'ContentsInfo',
+    ['xobject_settings', 'inline_images', 'found_vector', 'found_text', 'name_index'],
 )
 
 TextboxInfo = namedtuple('TextboxInfo', ['bbox', 'is_visible', 'is_corrupt'])
 
 
-class VectorInfo:
-    def __init__(self):
-        pass
+class VectorMarker:
+    pass
+
+
+class TextMarker:
+    pass
 
 
 def _normalize_stack(graphobjs):
@@ -120,7 +117,7 @@ def _normalize_stack(graphobjs):
             yield (operands, operator)
 
 
-def _interpret_contents(contentstream, initial_shorthand=UNIT_SQUARE):
+def _interpret_contents(contentstream: Object, initial_shorthand=UNIT_SQUARE):
     """Interpret the PDF content stream.
 
     The stack represents the state of the PDF graphics stack.  We are only
@@ -153,9 +150,11 @@ def _interpret_contents(contentstream, initial_shorthand=UNIT_SQUARE):
     inline_images = []
     name_index = defaultdict(lambda: [])
     found_vector = False
+    found_text = False
     vector_ops = set('S s f F f* B B* b b*'.split())
+    text_showing_ops = set("""TJ Tj " '""".split())
     image_ops = set('BI ID EI q Q Do cm'.split())
-    operator_whitelist = ' '.join(vector_ops | image_ops)
+    operator_whitelist = ' '.join(vector_ops | text_showing_ops | image_ops)
 
     for n, graphobj in enumerate(
         _normalize_stack(
@@ -195,16 +194,19 @@ def _interpret_contents(contentstream, initial_shorthand=UNIT_SQUARE):
             inline_images.append(inline)
         elif operator in vector_ops:
             found_vector = True
+        elif operator in text_showing_ops:
+            found_text = True
 
     return ContentsInfo(
         xobject_settings=xobject_settings,
         inline_images=inline_images,
         found_vector=found_vector,
+        found_text=found_text,
         name_index=name_index,
     )
 
 
-def _get_dpi(ctm_shorthand, image_size):
+def _get_dpi(ctm_shorthand, image_size) -> Resolution:
     """Given the transformation matrix and image size, find the image DPI.
 
     PDFs do not include image resolution information within image data.
@@ -227,7 +229,7 @@ def _get_dpi(ctm_shorthand, image_size):
     width-axis vector v0 (1, 0), height-axis vector vh (0, 1) with the matrix,
     which gives the dimensions of the image in PDF units. From there we can
     compare to actual image dimensions. PDF uses
-    row vector * matrix_tranposed unlike the traditional
+    row vector * matrix_transposed unlike the traditional
     matrix * column vector.
 
     The offset, width and height vectors can be combined in a matrix and
@@ -265,14 +267,20 @@ def _get_dpi(ctm_shorthand, image_size):
     dpi_w = scale_w * 72.0
     dpi_h = scale_h * 72.0
 
-    return dpi_w, dpi_h
+    return Resolution(dpi_w, dpi_h)
 
 
 class ImageInfo:
     DPI_PREC = Decimal('1.000')
 
-    def __init__(self, *, name='', pdfimage=None, inline=None, shorthand=None):
-
+    def __init__(
+        self,
+        *,
+        name='',
+        pdfimage: Optional[Object] = None,
+        inline: Optional[Object] = None,
+        shorthand=None,
+    ):
         self._name = str(name)
         self._shorthand = shorthand
 
@@ -282,6 +290,8 @@ class ImageInfo:
         elif pdfimage is not None:
             self._origin = 'xobject'
             pim = pikepdf.PdfImage(pdfimage)
+        else:
+            raise ValueError("Either pdfimage or inline must be set")
         self._width = pim.width
         self._height = pim.height
 
@@ -356,12 +366,8 @@ class ImageInfo:
         return self._enc
 
     @property
-    def xres(self):
-        return _get_dpi(self._shorthand, (self._width, self._height))[0]
-
-    @property
-    def yres(self):
-        return _get_dpi(self._shorthand, (self._width, self._height))[1]
+    def dpi(self):
+        return _get_dpi(self._shorthand, (self._width, self._height))
 
     def __repr__(self):
         class_locals = {
@@ -371,11 +377,11 @@ class ImageInfo:
         }
         return (
             "<ImageInfo '{name}' {type_} {width}x{height} {color} "
-            "{comp} {bpc} {enc} {xres}x{yres}>"
+            "{comp} {bpc} {enc} {dpi}>"
         ).format(**class_locals)
 
 
-def _find_inline_images(contentsinfo):
+def _find_inline_images(contentsinfo: ContentsInfo) -> Iterator[ImageInfo]:
     "Find inline images in the contentstream"
 
     for n, inline in enumerate(contentsinfo.inline_images):
@@ -384,7 +390,7 @@ def _find_inline_images(contentsinfo):
         )
 
 
-def _image_xobjects(container):
+def _image_xobjects(container) -> Iterator[Tuple[Object, str]]:
     """Search for all XObject-based images in the container
 
     Usually the container is a page, but it could also be a Form XObject
@@ -404,7 +410,7 @@ def _image_xobjects(container):
         return
     xobjs = resources['/XObject'].as_dict()
     for xobj in xobjs:
-        candidate = xobjs[xobj]
+        candidate: Object = xobjs[xobj]
         if not '/Subtype' in candidate:
             continue
         if candidate['/Subtype'] == '/Image':
@@ -412,7 +418,9 @@ def _image_xobjects(container):
             yield (pdfimage, xobj)
 
 
-def _find_regular_images(container, contentsinfo):
+def _find_regular_images(
+    container: Object, contentsinfo: ContentsInfo
+) -> Iterator[ImageInfo]:
     """Find images stored in the container's /Resources /XObject
 
     Usually the container is a page, but it could also be a Form XObject
@@ -436,7 +444,7 @@ def _find_regular_images(container, contentsinfo):
             yield ImageInfo(name=draw.name, pdfimage=pdfimage, shorthand=draw.shorthand)
 
 
-def _find_form_xobject_images(pdf, container, contentsinfo):
+def _find_form_xobject_images(pdf: Pdf, container: Object, contentsinfo: ContentsInfo):
     """Find any images that are in Form XObjects in the container
 
     The container may be a page, or a parent Form XObject.
@@ -468,7 +476,9 @@ def _find_form_xobject_images(pdf, container, contentsinfo):
             )
 
 
-def _process_content_streams(*, pdf, container, shorthand=None):
+def _process_content_streams(
+    *, pdf: Pdf, container: Object, shorthand=None
+) -> Iterator[Union[VectorMarker, TextMarker, ImageInfo]]:
     """Find all individual instances of images drawn in the container
 
     Usually the container is a page, but it may also be a Form XObject.
@@ -509,13 +519,15 @@ def _process_content_streams(*, pdf, container, shorthand=None):
     contentsinfo = _interpret_contents(container, initial_shorthand)
 
     if contentsinfo.found_vector:
-        yield VectorInfo()
+        yield VectorMarker()
+    if contentsinfo.found_text:
+        yield TextMarker()
     yield from _find_inline_images(contentsinfo)
     yield from _find_regular_images(container, contentsinfo)
     yield from _find_form_xobject_images(pdf, container, contentsinfo)
 
 
-def _page_has_text(text_blocks, page_width, page_height):
+def _page_has_text(text_blocks, page_width, page_height) -> bool:
     """Smarter text detection that ignores text in margins"""
 
     pw, ph = float(page_width), float(page_height)
@@ -528,7 +540,7 @@ def _page_has_text(text_blocks, page_width, page_height):
         margin_ratio * ph,  # bottom  (first quadrant: bottom < top)
     )
 
-    def rects_intersect(a, b):
+    def rects_intersect(a, b) -> bool:
         """
         Where (a,b) are 4-tuple rects (left-0, top-1, right-2, bottom-3)
         https://stackoverflow.com/questions/306316/determine-if-two-rectangles-overlap-each-other
@@ -544,7 +556,7 @@ def _page_has_text(text_blocks, page_width, page_height):
     return has_text
 
 
-def simplify_textboxes(miner, textbox_getter):
+def simplify_textboxes(miner, textbox_getter) -> Iterator[TextboxInfo]:
     """Extract only limited content from text boxes
 
     We do this to save memory and ensure that our objects are pickleable.
@@ -558,149 +570,227 @@ def simplify_textboxes(miner, textbox_getter):
         yield TextboxInfo(box.bbox, visible, corrupt)
 
 
-def _pdf_get_pageinfo(pdf, pageno: int, infile, xmltext):
-    pageinfo = {}
-    pageinfo['pageno'] = pageno
-    pageinfo['images'] = []
-
-    page = pdf.pages[pageno]
-    mediabox = [Decimal(d) for d in page.MediaBox.as_list()]
-    width_pt = mediabox[2] - mediabox[0]
-    height_pt = mediabox[3] - mediabox[1]
-
-    if xmltext is not None:
-        bboxes = ghosttext.page_get_textblocks(
-            fspath(infile), pageno, xmltext=xmltext, height=height_pt
-        )
-        pageinfo['bboxes'] = bboxes
-    else:
-        pscript5_mode = str(pdf.docinfo.get('/Creator')).startswith('PScript5')
-        miner = get_page_analysis(infile, pageno, pscript5_mode)
-        pageinfo['textboxes'] = list(simplify_textboxes(miner, get_text_boxes))
-        bboxes = (box.bbox for box in pageinfo['textboxes'])
-
-    pageinfo['has_text'] = _page_has_text(bboxes, width_pt, height_pt)
-
-    userunit = page.get('/UserUnit', Decimal(1.0))
-    if not isinstance(userunit, Decimal):
-        userunit = Decimal(userunit)
-    pageinfo['userunit'] = userunit
-    pageinfo['width_inches'] = width_pt * userunit / Decimal(72.0)
-    pageinfo['height_inches'] = height_pt * userunit / Decimal(72.0)
-
-    try:
-        pageinfo['rotate'] = int(page['/Rotate'])
-    except KeyError:
-        pageinfo['rotate'] = 0
-
-    userunit_shorthand = (userunit, 0, 0, userunit, 0, 0)
-    contentsinfo = [
-        ci
-        for ci in _process_content_streams(
-            pdf=pdf, container=page, shorthand=userunit_shorthand
-        )
-    ]
-
-    pageinfo['has_vector'] = False
-    if any(isinstance(ci, VectorInfo) for ci in contentsinfo):
-        pageinfo['has_vector'] = True
-
-    pageinfo['images'] = [im for im in contentsinfo if isinstance(im, ImageInfo)]
-    if pageinfo['images']:
-        xres = Decimal(max(image.xres for image in pageinfo['images']))
-        yres = Decimal(max(image.yres for image in pageinfo['images']))
-        pageinfo['xres'], pageinfo['yres'] = xres, yres
-        pageinfo['width_pixels'] = int(round(xres * pageinfo['width_inches']))
-        pageinfo['height_pixels'] = int(round(yres * pageinfo['height_inches']))
-
-    return pageinfo
+worker_pdf = None
 
 
-def _pdf_get_all_pageinfo(infile, detailed_analysis=False, log=None, progbar=False):
-    pdf = pikepdf.open(infile)  # Do not close in this function
-    try:
-        if pdf.is_encrypted:
-            raise EncryptedPdfError()  # Triggered by encryption with empty passwd
-        if detailed_analysis:
-            pages_xml = None
-        else:
-            pages_xml = ghosttext.extract_text_xml(infile, pdf, pageno=None, log=log)
+def _pdf_pageinfo_sync_init(pdf: Pdf, infile: Path, pdfminer_loglevel):
+    global worker_pdf  # pylint: disable=global-statement
+    pikepdf_enable_mmap()
 
-        pages = []
-        for n, _ in tqdm(
-            enumerate(pdf.pages),
-            total=len(pdf.pages),
-            desc="Scan",
-            unit='page',
-            disable=not progbar,
-        ):
-            page_xml = pages_xml[n] if pages_xml else None
-            page = PageInfo(pdf, n, infile, page_xml, detailed_analysis)
-            pages.append(page)
-    except Exception:
-        pdf.close()
-        raise
+    logging.getLogger('pdfminer').setLevel(pdfminer_loglevel)
 
-    return pages, pdf
+    # If the pdf is not opened, open a copy for our worker process to use
+    if pdf is None:
+        worker_pdf = pikepdf.open(infile)
+
+        def on_process_close():
+            worker_pdf.close()
+
+        # Close when this process exits
+        atexit.register(on_process_close)
+
+
+def _pdf_pageinfo_sync(args):
+    pageno, thread_pdf, infile, check_pages, detailed_analysis = args
+    pdf = thread_pdf if thread_pdf is not None else worker_pdf
+    with ExitStack() as stack:
+        if not pdf:  # When called with SerialExecutor
+            pdf = stack.enter_context(pikepdf.open(infile))
+        page = PageInfo(pdf, pageno, infile, check_pages, detailed_analysis)
+        return page
+
+
+def _pdf_pageinfo_concurrent(
+    pdf,
+    executor: Executor,
+    infile,
+    progbar,
+    max_workers,
+    check_pages,
+    detailed_analysis=False,
+):
+    pages = [None] * len(pdf.pages)
+
+    def update_pageinfo(result, pbar):
+        page = result
+        if not page:
+            raise InputFileError("Could read a page in the PDF")
+        pages[page.pageno] = page
+        pbar.update()
+
+    if max_workers is None:
+        max_workers = available_cpu_count()
+
+    total = len(pdf.pages)
+
+    use_threads = False  # No performance gain if threaded due to GIL
+    n_workers = min(1 + len(pages) // 4, max_workers)
+    if n_workers == 1:
+        # But if we decided on only one worker, there is no point in using
+        # a separate process.
+        use_threads = True
+
+    # If we use a thread, we can pass the already-open Pdf for them to use
+    # If we use processes, we pass a None which tells the init function to open its
+    # own
+    initial_pdf = pdf if use_threads else None
+
+    contexts = (
+        (n, initial_pdf, infile, check_pages, detailed_analysis) for n in range(total)
+    )
+    assert n_workers == 1 if use_threads else n_workers >= 1, "Not multithreadable"
+    executor(
+        use_threads=use_threads,
+        max_workers=n_workers,
+        tqdm_kwargs=dict(
+            total=total, desc="Scanning contents", unit='page', disable=not progbar
+        ),
+        worker_initializer=partial(
+            _pdf_pageinfo_sync_init,
+            initial_pdf,
+            infile,
+            logging.getLogger('pdfminer').level,
+        ),
+        task=_pdf_pageinfo_sync,
+        task_arguments=contexts,
+        task_finished=update_pageinfo,
+    )
+    return pages
 
 
 class PageInfo:
-    def __init__(self, pdf, pageno, infile, xmltext, detailed_analysis=False):
+    def __init__(
+        self,
+        pdf: Pdf,
+        pageno: int,
+        infile: PathLike,
+        check_pages: Container[int],
+        detailed_analysis: bool = False,
+    ):
         self._pageno = pageno
         self._infile = infile
-        self._pageinfo = _pdf_get_pageinfo(pdf, pageno, infile, xmltext)
         self._detailed_analysis = detailed_analysis
+        self._gather_pageinfo(pdf, pageno, infile, check_pages, detailed_analysis)
+
+    def _gather_pageinfo(
+        self,
+        pdf: Pdf,
+        pageno: int,
+        infile: PathLike,
+        check_pages: Container[int],
+        detailed_analysis: bool,
+    ):
+        page = pdf.pages[pageno]
+        mediabox = [Decimal(d) for d in page.MediaBox.as_list()]
+        width_pt = mediabox[2] - mediabox[0]
+        height_pt = mediabox[3] - mediabox[1]
+
+        check_this_page = pageno in check_pages
+
+        if check_this_page and detailed_analysis:
+            pscript5_mode = str(pdf.docinfo.get('/Creator')).startswith('PScript5')
+            miner = get_page_analysis(infile, pageno, pscript5_mode)
+            self._textboxes = list(simplify_textboxes(miner, get_text_boxes))
+            bboxes = (box.bbox for box in self._textboxes)
+
+            self._has_text = _page_has_text(bboxes, width_pt, height_pt)
+        else:
+            self._textboxes = []
+            self._has_text = None  # i.e. "no information"
+
+        userunit = page.get('/UserUnit', Decimal(1.0))
+        if not isinstance(userunit, Decimal):
+            userunit = Decimal(userunit)
+        self._userunit = userunit
+        self._width_inches = width_pt * userunit / Decimal(72.0)
+        self._height_inches = height_pt * userunit / Decimal(72.0)
+
+        try:
+            self._rotate = int(page['/Rotate'])
+        except KeyError:
+            self._rotate = 0
+
+        userunit_shorthand = (userunit, 0, 0, userunit, 0, 0)
+
+        if check_this_page:
+            self._has_vector = False
+            self._has_text = False
+            self._images = []
+            for ci in _process_content_streams(
+                pdf=pdf, container=page, shorthand=userunit_shorthand
+            ):
+                if isinstance(ci, VectorMarker):
+                    self._has_vector = True
+                elif isinstance(ci, TextMarker):
+                    self._has_text = True
+                elif isinstance(ci, ImageInfo):
+                    self._images.append(ci)
+                else:
+                    raise NotImplementedError()
+        else:
+            self._has_vector = None  # i.e. "no information"
+            self._has_text = None
+            self._images = None
+
+        self._dpi = None
+        if self._images:
+            dpi = Resolution(0.0, 0.0).take_max(image.dpi for image in self._images)
+            self._dpi = dpi
+            self._width_pixels = int(round(dpi.x * float(self._width_inches)))
+            self._height_pixels = int(round(dpi.y * float(self._height_inches)))
 
     @property
-    def pageno(self):
+    def pageno(self) -> int:
         return self._pageno
 
     @property
-    def has_text(self):
-        return self._pageinfo['has_text']
+    def has_text(self) -> bool:
+        return self._has_text
 
     @property
-    def has_corrupt_text(self):
+    def has_corrupt_text(self) -> bool:
         if not self._detailed_analysis:
             raise NotImplementedError('Did not do detailed analysis')
-        return any(tbox.is_corrupt for tbox in self._pageinfo['textboxes'])
+        return any(tbox.is_corrupt for tbox in self._textboxes)
 
     @property
-    def has_vector(self):
-        return self._pageinfo['has_vector']
+    def has_vector(self) -> bool:
+        return self._has_vector
 
     @property
-    def width_inches(self):
-        return self._pageinfo['width_inches']
+    def width_inches(self) -> Decimal:
+        return self._width_inches
 
     @property
-    def height_inches(self):
-        return self._pageinfo['height_inches']
+    def height_inches(self) -> Decimal:
+        return self._height_inches
 
     @property
-    def width_pixels(self):
-        return int(round(self.width_inches * self.xres))
+    def width_pixels(self) -> int:
+        return int(round(float(self.width_inches) * self.dpi.x))
 
     @property
-    def height_pixels(self):
-        return int(round(self.height_inches * self.yres))
+    def height_pixels(self) -> int:
+        return int(round(float(self.height_inches) * self.dpi.y))
 
     @property
-    def rotation(self):
-        return self._pageinfo.get('rotate', None)
+    def rotation(self) -> int:
+        return self._rotate
 
     @rotation.setter
     def rotation(self, value):
         if value in (0, 90, 180, 270, 360, -90, -180, -270):
-            self._pageinfo['rotate'] = value
+            self._rotate = value
         else:
             raise ValueError("rotation must be a cardinal angle")
 
     @property
     def images(self):
-        return self._pageinfo['images']
+        return self._images
 
-    def get_textareas(self, visible=None, corrupt=None):
+    def get_textareas(
+        self, visible: Optional[bool] = None, corrupt: Optional[bool] = None
+    ):
         def predicate(obj, want_visible, want_corrupt):
             result = True
             if want_visible is not None:
@@ -711,31 +801,25 @@ class PageInfo:
                     result = False
             return result
 
-        if 'textboxes' not in self._pageinfo:
+        if not self._textboxes:
             if visible is not None and corrupt is not None:
-                raise NotImplementedError('Ghostscript textboxes cannot be classified')
-            return self._pageinfo['bboxes']
+                raise NotImplementedError('Incomplete information on textboxes')
+            return self._textboxes
 
-        return (
-            obj.bbox
-            for obj in self._pageinfo['textboxes']
-            if predicate(obj, visible, corrupt)
-        )
+        return (obj.bbox for obj in self._textboxes if predicate(obj, visible, corrupt))
 
     @property
-    def xres(self):
-        return self._pageinfo.get('xres', None)
+    def dpi(self) -> Resolution:
+        if self._dpi is None:
+            return Resolution(0.0, 0.0)
+        return self._dpi
 
     @property
-    def yres(self):
-        return self._pageinfo.get('yres', None)
+    def userunit(self) -> Decimal:
+        return self._userunit
 
     @property
-    def userunit(self):
-        return self._pageinfo.get('userunit', None)
-
-    @property
-    def min_version(self):
+    def min_version(self) -> str:
         if self.userunit is not None:
             return '1.6'
         else:
@@ -743,65 +827,77 @@ class PageInfo:
 
     def __repr__(self):
         return (
-            '<PageInfo ' 'pageno={} {}"x{}" rotation={} res={}x{} has_text={}>'
-        ).format(
-            self.pageno,
-            self.width_inches,
-            self.height_inches,
-            self.rotation,
-            self.xres,
-            self.yres,
-            self.has_text,
+            f'<PageInfo '
+            f'pageno={self.pageno} {self.width_inches}"x{self.height_inches}" '
+            f'rotation={self.rotation} dpi={self.dpi} has_text={self.has_text}>'
         )
 
 
 class PdfInfo:
     """Get summary information about a PDF"""
 
-    def __init__(self, infile, detailed_page_analysis=False, log=logger, progbar=False):
+    def __init__(
+        self,
+        infile,
+        *,
+        detailed_analysis: bool = False,
+        progbar: bool = False,
+        max_workers: int = None,
+        check_pages=None,
+        executor: Executor = SerialExecutor(),
+    ):
         self._infile = infile
-        if ghostscript.version() in ('9.52',):
-            detailed_page_analysis = True  # txtwrite doesn't work in these versions
-        self._pages, pdf = _pdf_get_all_pageinfo(
-            infile, detailed_page_analysis, log=log, progbar=progbar
-        )
-        self._needs_rendering = pdf.root.get('/NeedsRendering', False)
-        self._has_acroform = False
-        if '/AcroForm' in pdf.root:
-            if len(pdf.root.AcroForm.get('/Fields', [])) > 0:
-                self._has_acroform = True
-            elif '/XFA' in pdf.root.AcroForm:
-                self._has_acroform = True
-        pdf.close()
+        if check_pages is None:
+            check_pages = range(0, 1_000_000_000)
+
+        with pikepdf.open(infile) as pdf:
+            if pdf.is_encrypted:
+                raise EncryptedPdfError()  # Triggered by encryption with empty passwd
+            self._pages = _pdf_pageinfo_concurrent(
+                pdf,
+                executor,
+                infile,
+                progbar,
+                max_workers,
+                check_pages=check_pages,
+                detailed_analysis=detailed_analysis,
+            )
+            self._needs_rendering = pdf.Root.get('/NeedsRendering', False)
+            self._has_acroform = False
+            if '/AcroForm' in pdf.Root:
+                if len(pdf.Root.AcroForm.get('/Fields', [])) > 0:
+                    self._has_acroform = True
+                elif '/XFA' in pdf.Root.AcroForm:
+                    self._has_acroform = True
 
     @property
     def pages(self):
         return self._pages
 
     @property
-    def min_version(self):
+    def min_version(self) -> str:
         # The minimum PDF is the maximum version that any particular page needs
         return max(page.min_version for page in self.pages)
 
     @property
-    def has_userunit(self):
+    def has_userunit(self) -> bool:
         return any(page.userunit != 1.0 for page in self.pages)
 
     @property
-    def has_acroform(self):
+    def has_acroform(self) -> bool:
         return self._has_acroform
 
     @property
-    def filename(self):
+    def filename(self) -> Union[str, Path]:
         if not isinstance(self._infile, (str, Path)):
             raise NotImplementedError("can't get filename from stream")
         return self._infile
 
     @property
-    def needs_rendering(self):
+    def needs_rendering(self) -> bool:
         return self._needs_rendering
 
-    def __getitem__(self, item):
+    def __getitem__(self, item) -> PageInfo:
         return self._pages[item]
 
     def __len__(self):
@@ -812,16 +908,16 @@ class PdfInfo:
 
 
 def main():
-    import argparse
+    import argparse  # pylint: disable=import-outside-toplevel
+    from pprint import pprint  # pylint: disable=import-outside-toplevel
 
     parser = argparse.ArgumentParser()
     parser.add_argument('infile')
     args = parser.parse_args()
-    pagesinfo, pdfinfo = _pdf_get_all_pageinfo(args.infile)
-    from pprint import pprint
+    pdfinfo = PdfInfo(args.infile)
 
     pprint(pdfinfo)
-    for page in pagesinfo:
+    for page in pdfinfo.pages:
         pprint(page)
         for im in page.images:
             pprint(im)

src/ocrmypdf/pdfinfo/layout.py

@@ -1,19 +1,9 @@
 # © 2018 James R. Barlow: github.com/jbarlow83
 #
-# This file is part of OCRmyPDF.
-#
-# OCRmyPDF is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# OCRmyPDF is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with OCRmyPDF.  If not, see <http://www.gnu.org/licenses/>.
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
 
 import re
 from math import copysign
@@ -25,65 +15,16 @@ import pdfminer.encodingdb
 import pdfminer.pdfdevice
 import pdfminer.pdfinterp
 from pdfminer.converter import PDFLayoutAnalyzer
-from pdfminer.glyphlist import glyphname2unicode
 from pdfminer.layout import LAParams, LTChar, LTPage, LTTextBox
 from pdfminer.pdfdocument import PDFTextExtractionNotAllowed
-from pdfminer.pdffont import PDFFont, PDFSimpleFont, PDFUnicodeNotDefined
+from pdfminer.pdffont import PDFSimpleFont, PDFUnicodeNotDefined
 from pdfminer.pdfpage import PDFPage
 from pdfminer.utils import bbox2str, matrix2str
 
-from ..exceptions import EncryptedPdfError
+from ocrmypdf.exceptions import EncryptedPdfError, InputFileError
 
 STRIP_NAME = re.compile(r'[0-9]+')
 
-#
-#  pdfminer 20181108 patches
-#
-
-if pdfminer.__version__ == '20181108':
-
-    def name2unicode(name):
-        """Fix pdfminer's name2unicode function
-
-        Font cids that are mapped to names of the form /g123 seem to be, by convention
-        characters with no corresponding Unicode entry. These can be subsetted fonts
-        or symbolic fonts. There seems to be no way to map /g123 fonts to Unicode,
-        barring a ToUnicode data structure.
-        """
-        if name in glyphname2unicode:
-            return glyphname2unicode[name]
-        if name.startswith('g') or name.startswith('a'):
-            raise KeyError(name)
-        if name.startswith('uni'):
-            try:
-                return chr(int(name[3:], 16))
-            except ValueError:  # Not hexadecimal
-                raise KeyError(name)
-        m = STRIP_NAME.search(name)
-        if not m:
-            raise KeyError(name)
-        return chr(int(m.group(0)))
-
-    pdfminer.encodingdb.name2unicode = name2unicode
-
-    original_PDFFont_init = PDFFont.__init__
-
-    def PDFFont__init__(self, descriptor, widths, default_width=None):
-        original_PDFFont_init(self, descriptor, widths, default_width)
-        # PDF spec says descent should be negative
-        # A font with a positive descent implies it floats entirely above the
-        # baseline, i.e. it's not really a baseline anymore. I have fonts that
-        # claim a positive descent, but treating descent as positive always seems
-        # to misposition text.
-        if self.descent > 0:
-            self.descent = -self.descent
-
-    PDFFont.__init__ = PDFFont__init__
-
-#
-# end of pdfminer 20181108 patches
-#
-
 
 original_PDFSimpleFont_init = PDFSimpleFont.__init__
 
@@ -269,9 +210,20 @@ class TextPositionTracker(PDFLayoutAnalyzer):
 
 def get_page_analysis(infile, pageno, pscript5_mode):
     rman = pdfminer.pdfinterp.PDFResourceManager(caching=True)
-    dev = TextPositionTracker(rman, laparams=LAParams())
+    if pdfminer.__version__ < '20200402':
+        # Workaround for https://github.com/pdfminer/pdfminer.six/issues/395
+        disable_boxes_flow = 2
+    else:
+        disable_boxes_flow = None
+    dev = TextPositionTracker(
+        rman,
+        laparams=LAParams(
+            all_texts=True, detect_vertical=True, boxes_flow=disable_boxes_flow
+        ),
+    )
     interp = pdfminer.pdfinterp.PDFPageInterpreter(rman, dev)
 
+    patcher = None
     if pscript5_mode:
         patcher = patch.multiple(
             'pdfminer.pdffont.PDFType3Font',
@@ -284,12 +236,17 @@ def get_page_analysis(infile, pageno, pscript5_mode):
 
     try:
         with Path(infile).open('rb') as f:
-            page = PDFPage.get_pages(f, pagenos=[pageno], maxpages=0)
-            interp.process_page(next(page))
-    except PDFTextExtractionNotAllowed:
-        raise EncryptedPdfError()
+            page_iter = PDFPage.get_pages(f, pagenos=[pageno], maxpages=0)
+            page = next(page_iter, None)
+            if page is None:
+                raise InputFileError(
+                    f"pdfminer could not process page {pageno} (counting from 0)."
+                )
+            interp.process_page(page)
+    except PDFTextExtractionNotAllowed as e:
+        raise EncryptedPdfError() from e
     finally:
-        if pscript5_mode:
+        if patcher is not None:
             patcher.stop()
 
     return dev.get_result()

src/ocrmypdf/pluginspec.py

@@ -0,0 +1,445 @@
+# © 2020 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+from abc import ABC, abstractmethod, abstractstaticmethod
+from argparse import ArgumentParser, Namespace
+from collections import namedtuple
+from logging import Handler
+from pathlib import Path
+from typing import TYPE_CHECKING, AbstractSet, List, Optional
+
+import pluggy
+
+from ocrmypdf._concurrent import Executor
+from ocrmypdf.helpers import Resolution
+
+if TYPE_CHECKING:
+    from PIL import Image
+
+    # pylint: disable=ungrouped-imports
+    from ocrmypdf._jobcontext import PageContext
+    from ocrmypdf.pdfinfo import PdfInfo
+
+    # pylint: enable=ungrouped-imports
+
+hookspec = pluggy.HookspecMarker('ocrmypdf')
+
+# pylint: disable=unused-argument
+
+
+@hookspec(firstresult=True)
+def get_logging_console() -> Handler:
+    """Returns a custom logging handler.
+
+    Generally this is necessary when both logging output and a progress bar are both
+    outputting to ``sys.stderr``.
+
+    Note:
+        This is a :ref:`firstresult hook<firstresult>`.
+    """
+
+
+@hookspec
+def add_options(parser: ArgumentParser) -> None:
+    """Allows the plugin to add its own command line and API arguments.
+
+    OCRmyPDF converts command line arguments to API arguments, so adding
+    arguments here will cause new arguments to be processed for API calls
+    to ``ocrmypdf.ocr``, or when invoked on the command line.
+
+    Note:
+        This hook will be called from the main process, and may modify global state
+        before child worker processes are forked.
+    """
+
+
+@hookspec
+def check_options(options: Namespace) -> None:
+    """Called to ask the plugin to check all of the options.
+
+    The plugin may check if options that it added are valid.
+
+    Warnings or other messages may be passed to the user by creating a logger
+    object using ``log = logging.getLogger(__name__)`` and logging to this.
+
+    The plugin may also modify the *options*. All objects that are in options
+    must be picklable so they can be marshalled to child worker processes.
+
+    Raises:
+        ocrmypdf.exceptions.ExitCodeException: If options are not acceptable
+            and the application should terminate gracefully with an informative
+            message and error code.
+    Note:
+        This hook will be called from the main process, and may modify global state
+        before child worker processes are forked.
+    """
+
+
+@hookspec(firstresult=True)
+def get_executor(progressbar_class) -> Executor:
+    """Called to obtain an object that manages parallel execution.
+
+    This may be used to replace OCRmyPDF's default parallel execution system
+    with a third party alternative. For example, you could make OCRmyPDF run in a
+    distributed environment.
+
+    OCRmyPDF's executors are analogous to the standard Python executors in
+    ``conconcurrent.futures``, but they do not work the same way. Executors may
+    be reused for different, unrelated batch operations, since all of the context
+    for a given job are passed to :meth:`Executor.__call__`.
+
+    Should be of type :class:`Executor` or otherwise conforming to the protocol
+    of that call.
+
+    Arguments:
+        progressbar_class: A progress bar class, which will be created when
+
+    Note:
+        This hook will be called from the main process, and may modify global state
+        before child worker processes are forked.
+    Note:
+        This is a :ref:`firstresult hook<firstresult>`.
+    """
+
+
+@hookspec(firstresult=True)
+def get_progressbar_class():
+    """Called to obtain a class that can be used to monitor progress.
+
+    A progress bar is assumed, but this could be used for any type of monitoring.
+
+    The class should follow a tqdm-like protocol. Calling the class should return
+    a new progress bar object, which is activated with ``__enter__`` and terminated
+    ``__exit__``. An update method is called whenever the progress bar is updated.
+    Progress bar objects will not be reused; a new one will be created for each
+    group of tasks.
+
+    The progress bar is held in the main process/thread and not updated by child
+    process/threads. When a child notifies the parent of completed work, the
+    parent updates the progress bar.
+
+    The arguments are the same as `tqdm <https://github.com/tqdm/tqdm>`_ accepts.
+
+    Progress bars should never write to ``sys.stdout``, or they will corrupt the
+    output if OCRmyPDF writes a PDF to standard output.
+
+    The type of events that OCRmyPDF reports to a progress bar may change in
+    minor releases.
+
+    Here is how OCRmyPDF will use the progress bar:
+
+    Example:
+        pbar_class = pm.hook.get_progressbar_class()
+        with pbar_class(**tqdm_kwargs) as pbar:
+            ...
+            pbar.update(1)
+    """
+
+
+@hookspec
+def validate(pdfinfo: 'PdfInfo', options: Namespace) -> None:
+    """Called to give a plugin an opportunity to review *options* and *pdfinfo*.
+
+    *options* contains the "work order" to process a particular file. *pdfinfo*
+    contains information about the input file obtained after loading and
+    parsing. The plugin may modify the *options*. For example, you could decide
+    that a certain type of file should be treated with ``options.force_ocr = True``
+    based on information in its *pdfinfo*.
+
+    Raises:
+        ocrmypdf.exceptions.ExitCodeException: If options or pdfinfo are not acceptable
+            and the application should terminate gracefully with an informative
+            message and error code.
+    Note:
+        This hook will be called from the main process, and may modify global state
+        before child worker processes are forked.
+    """
+
+
+@hookspec(firstresult=True)
+def rasterize_pdf_page(
+    input_file: Path,
+    output_file: Path,
+    raster_device: str,
+    raster_dpi: Resolution,
+    pageno: int,
+    page_dpi: Optional[Resolution],
+    rotation: Optional[int],
+    filter_vector: bool,
+) -> Path:
+    """Rasterize one page of a PDF at resolution raster_dpi in canvas units.
+
+    The image is sized to match the integer pixels dimensions implied by
+    raster_dpi even if those numbers are noninteger. The image's DPI will
+    be overridden with the values in page_dpi.
+
+    Args:
+        input_file: The PDF to rasterize.
+        output_file: The desired name of the rasterized image.
+        raster_device: Type of image to produce at output_file
+        raster_dpi: Resolution at which to rasterize page
+        pageno: Page number to rasterize (beginning at page 1)
+        page_dpi: Resolution, overriding output image DPI
+        rotation: Cardinal angle, clockwise, to rotate page
+        filter_vector: If True, remove vector graphics objects
+    Returns:
+        Path: output_file if successful
+    Note:
+        This hook will be called from child processes. Modifying global state
+        will not affect the main process or other child processes.
+    Note:
+        This is a :ref:`firstresult hook<firstresult>`.
+    """
+
+
+@hookspec(firstresult=True)
+def filter_ocr_image(page: 'PageContext', image: 'Image') -> 'Image':
+    """Called to filter the image before it is sent to OCR.
+
+    This is the image that OCR sees, not what the user sees when they view the
+    PDF. If ``redo_ocr`` is enabled, portions of the image will be masked so
+    they are not shown to OCR. The main use of this hook is expected to be hiding
+    content from OCR.
+
+    The input image may be color, grayscale, or monochrome, and the
+    output image may differ. The pixel width and height of the
+    output image must be identical to the input image, or misalignment between
+    the OCR text layer and visual position of the text will occur. Likewise,
+    the output must be a faithful representation of the input, or alignment
+    errors may occurs.
+
+    Tesseract OCR only deals with monochrome images, and internally converts
+    non-monochrome images to OCR.
+
+    Note:
+        This hook will be called from child processes. Modifying global state
+        will not affect the main process or other child processes.
+    Note:
+        This is a :ref:`firstresult hook<firstresult>`.
+    """
+
+
+@hookspec(firstresult=True)
+def filter_page_image(page: 'PageContext', image_filename: Path) -> Path:
+    """Called to filter the whole page before it is inserted into the PDF.
+
+    A whole page image is only produced when preprocessing command line arguments
+    are issued or when ``--force-ocr`` is issued. If no whole page is image is
+    produced for a given page, this function will not be called. This is not
+    the image that will be shown to OCR.
+
+    If the function does not want to modify the image, it should return
+    ``image_filename``. The hook may overwrite ``image_filename`` with a new file.
+
+    The output image should preserve the same physical unit dimensions, that is
+    (width * dpi_x, height * dpi_y). That is, if the image is resized, the DPI
+    must be adjusted by the reciprocal. If this is not preserved, the PDF page
+    will be resized and the OCR layer misaligned. OCRmyPDF does not nothing
+    to enforce these constraints; it is up to the plugin to do sensible things.
+
+    OCRmyPDF will create the PDF page based on the image format used (unless the
+    hook is overriden). If you convert the image to a JPEG, the output page will
+    be created as a JPEG, etc. If you change the colorspace, that change will be
+    kept. Note that the OCRmyPDF image optimization stage, if enabled, may
+    ultimately chose a different format.
+
+    If the return value is a file that does not exist, ``FileNotFoundError``
+    will occur. The return value should be a path to a file in the same folder
+    as ``image_filename``.
+
+    Implementation detail: If the value returned is falsy, OCRmyPDF will ignore
+    the return value and assume the input file was unmodified. This is deprecated.
+    To leave the image unmodified, ``image_filename`` should be returned.
+
+    Note:
+        This hook will be called from child processes. Modifying global state
+        will not affect the main process or other child processes.
+    Note:
+        This is a :ref:`firstresult hook<firstresult>`.
+    """
+
+
+@hookspec(firstresult=True)
+def filter_pdf_page(
+    page: 'PageContext', image_filename: Path, output_pdf: Path
+) -> Path:
+    """Called to convert a filtered whole page image into a PDF.
+
+    A whole page image is only produced when preprocessing command line arguments
+    are issued or when ``--force-ocr`` is issued. If no whole page is image is
+    produced for a given page, this function will not be called. This is not
+    the image that will be shown to OCR. The whole page image is filtered in
+    the hook above, ``filter_page_image``, then this function is called for
+    PDF conversion.
+
+    This function will only be called when OCRmyPDF runs in a mode such as
+    "force OCR" mode where rasterizing of all content is performed.
+
+    Clever things could be done at this stage such as segmenting the page image into
+    color regions or vector equivalents.
+
+    The provider of the hook implementation is responsible for ensuring that the
+    OCR text layer is aligned with the PDF produced here, or text misalignment
+    will result.
+
+    Currently this function must produce a single page PDF or the pipeline will
+    fail.  If the intent is to remove the PDF, then create a single page empty
+    PDF.
+
+    Args:
+        page: Context for this page.
+        image_filename: Filename of the input image used to create output_pdf,
+            for "reference" if recreating the output_pdf entirely.
+        output_pdf: The previous created output_pdf.
+
+    Returns:
+        output_pdf
+
+    Note:
+        This hook will be called from child processes. Modifying global state
+        will not affect the main process or other child processes.
+    Note:
+        This is a :ref:`firstresult hook<firstresult>`.
+    """
+
+
+OrientationConfidence = namedtuple('OrientationConfidence', ('angle', 'confidence'))
+"""Expresses an OCR engine's confidence in page rotation.
+
+Attributes:
+    angle (int): The clockwise angle (0, 90, 180, 270) that the page should be
+        rotated. 0 means no rotation.
+    confidence (float): How confident the OCR engine is that this the correct
+        rotation. 0 is not confident, 15 is very confident. Arbitrary units.
+"""
+
+
+class OcrEngine(ABC):
+    """A class representing an OCR engine with capabilities similar to Tesseract OCR.
+
+    This could be used to create a plugin for another OCR engine instead of
+    Tesseract OCR.
+    """
+
+    @abstractstaticmethod
+    def version() -> str:
+        """Returns the version of the OCR engine."""
+
+    @abstractstaticmethod
+    def creator_tag(options: Namespace) -> str:
+        """Returns the creator tag to identify this software's role in creating the PDF.
+
+        This tag will be inserted in the XMP metadata and DocumentInfo dictionary
+        as appropriate. Ideally you should include the name of the OCR engine and its
+        version. The text should not contain line breaks. This is to help developers
+        like yourself identify the software that produced this file.
+
+        OCRmyPDF will always prepend its name to this value.
+        """
+
+    @abstractmethod
+    def __str__(self):
+        """Returns name of OCR engine and version.
+
+        This is used when OCRmyPDF wants to mention the name of the OCR engine
+        to the user, usually in an error message.
+        """
+
+    @abstractstaticmethod
+    def languages(options: Namespace) -> AbstractSet[str]:
+        """Returns the set of all languages that are supported by the engine.
+
+        Languages are typically given in 3-letter ISO 3166-1 codes, but actually
+        can be any value understood by the OCR engine."""
+
+    @abstractstaticmethod
+    def get_orientation(input_file: Path, options: Namespace) -> OrientationConfidence:
+        """Returns the orientation of the image."""
+
+    @abstractstaticmethod
+    def generate_hocr(
+        input_file: Path, output_hocr: Path, output_text: Path, options: Namespace
+    ) -> None:
+        """Called to produce a hOCR file and sidecar text file."""
+
+    @abstractstaticmethod
+    def generate_pdf(
+        input_file: Path, output_pdf: Path, output_text: Path, options: Namespace
+    ) -> None:
+        """Called to produce a text only PDF.
+
+        Args:
+            input_file: A page image on which to perform OCR.
+            output_pdf: The expected name of the output PDF, which must be
+                a single page PDF with no visible content of any kind, sized
+                to the dimensions implied by the input_file's width, height
+                and DPI. The image will be grafted onto the input PDF page.
+        """
+
+
+@hookspec(firstresult=True)
+def get_ocr_engine() -> OcrEngine:
+    """Returns an OcrEngine to use for processing this file.
+
+    The OcrEngine may be instantiated multiple times, by both the main process
+    and child process. As such, it must be obtain store any state in ``options``
+    or some common location.
+
+    Note:
+        This is a :ref:`firstresult hook<firstresult>`.
+    """
+
+
+@hookspec(firstresult=True)
+def generate_pdfa(
+    pdf_pages: List[Path],
+    pdfmark: Path,
+    output_file: Path,
+    compression: str,
+    pdf_version: str,
+    pdfa_part: str,
+    progressbar_class,
+) -> Path:
+    """Generate a PDF/A.
+
+    This API strongly assumes a PDF/A generator with Ghostscript's semantics.
+
+    OCRmyPDF will modify the metadata and possibly linearize the PDF/A after it
+    is generated.
+
+    Arguments:
+        pdf_pages: A list of one or more filenames, will be merged into output_file.
+        pdfmark: A PostScript file intended for Ghostscript with details on
+            how to perform the PDF/A conversion.
+        output_file: The name of the desired output file.
+        compression: One of ``'jpeg'``, ``'lossless'``, ``''``. For ``'jpeg'``,
+            the PDF/A generator should convert all images to JPEG encoding where
+            possible. For lossless, all images should be converted to FlateEncode
+            (lossless PNG). If an empty string, the PDF generator should make its
+            own decisions about how to encode images.
+        pdf_version: The minimum PDF version that the output file should be.
+            At its own discretion, the PDF/A generator may raise the version,
+            but should not lower it.
+        pdfa_part: The desired PDF/A compliance level, such as ``'2B'``.
+        progressbar_class: The class of a progress bar with a tqdm-like API. An
+            instance of this class will be initialized when PDF/A conversion
+            begins, using
+            ``instance = progressbar_class(total: int, desc: str, unit:str)``,
+            defining the number of work units, a user-visible description,
+            and the name of the work units ("page"). Then ``instance.update()``
+            will be called when a work unit is completed. If ``None``, no
+            progress information is reported.
+
+    Returns:
+        Path: If successful, the hook should return ``output_file``.
+
+    Note:
+        This is a :ref:`firstresult hook<firstresult>`.
+
+    See also:
+        https://github.com/tqdm/tqdm
+    """

src/ocrmypdf/py.typed

@@ -0,0 +1 @@
+# ocrmypdf is typed

src/ocrmypdf/quality.py

@@ -1,37 +1,27 @@
 # © 2020 James R. Barlow: github.com/jbarlow83
 #
-# This file is part of OCRmyPDF.
-#
-# OCRmyPDF is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# OCRmyPDF is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with OCRmyPDF.  If not, see <http://www.gnu.org/licenses/>.
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+"""Utilities to measure OCR quality"""
+
 
 import re
 from typing import Iterable
 
-"""Utilities to measure OCR quality"""
-
 
 class OcrQualityDictionary:
     """Manages a dictionary for simple OCR quality checks."""
 
-    def __init__(self, *, wordlist: Iterable[str] = []):
+    def __init__(self, *, wordlist: Iterable[str]):
         """Construct a dictionary from a list of words.
 
         Words for which capitalization is important should be capitalized in the
         dictionary. Words that contain spaces or other punctuation will never match.
         """
-        self.dictionary = set()
-        self.dictionary.update(w for w in wordlist)
+        self.dictionary = set(wordlist)
 
     def measure_words_matched(self, ocr_text: str) -> float:
         """Check how many unique words in the OCR text match a dictionary.

src/ocrmypdf/subprocess/__init__.py

@@ -0,0 +1,318 @@
+# © 2020 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+"""Wrappers to manage subprocess calls"""
+
+import logging
+import os
+import re
+import sys
+from collections.abc import Mapping
+from contextlib import suppress
+from distutils.version import LooseVersion, Version
+from functools import lru_cache
+from pathlib import Path
+from subprocess import PIPE, STDOUT, CalledProcessError, CompletedProcess, Popen
+from subprocess import run as subprocess_run
+from typing import Callable, Optional, Type, Union
+
+from ocrmypdf.exceptions import MissingDependencyError
+
+# pylint: disable=logging-format-interpolation
+
+log = logging.getLogger(__name__)
+
+
+def run(args, *, env=None, logs_errors_to_stdout=False, **kwargs):
+    """Wrapper around :py:func:`subprocess.run`
+
+    The main purpose of this wrapper is to log subprocess output in an orderly
+    fashion that indentifies the responsible subprocess. An additional
+    task is that this function goes to greater lengths to find possible Windows
+    locations of our dependencies when they are not on the system PATH.
+
+    Arguments should be identical to ``subprocess.run``, except for following:
+
+    Arguments:
+        logs_errors_to_stdout: If True, indicates that the process writes its error
+            messages to stdout rather than stderr, so stdout should be logged
+            if there is an error. If False, stderr is logged. Could be used with
+            stderr=STDOUT, stdout=PIPE for example.
+    """
+    args, env, process_log, _text = _fix_process_args(args, env, kwargs)
+
+    stderr = None
+    stderr_name = 'stderr' if not logs_errors_to_stdout else 'stdout'
+    try:
+        proc = subprocess_run(args, env=env, **kwargs)
+    except CalledProcessError as e:
+        stderr = getattr(e, stderr_name, None)
+        raise
+    else:
+        stderr = getattr(proc, stderr_name, None)
+    finally:
+        if process_log.isEnabledFor(logging.DEBUG) and stderr:
+            with suppress(AttributeError, UnicodeDecodeError):
+                stderr = stderr.decode('utf-8', 'replace')
+            if logs_errors_to_stdout:
+                process_log.debug("stdout/stderr = %s", stderr)
+            else:
+                process_log.debug("stderr = %s", stderr)
+    return proc
+
+
+def run_polling_stderr(args, *, callback, check=False, env=None, **kwargs):
+    """Run a process like ``ocrmypdf.subprocess.run``, and poll stderr.
+
+    Every line of produced by stderr will be forwarded to the callback function.
+    The intended use is monitoring progress of subprocesses that output their
+    own progress indicators. In addition, each line will be logged if debug
+    logging is enabled.
+
+    Requires stderr to be opened in text mode for ease of handling errors. In
+    addition the expected encoding= and errors= arguments should be set. Note
+    that if stdout is already set up, it need not be binary.
+    """
+    args, env, process_log, text = _fix_process_args(args, env, kwargs)
+    assert text, "Must use text=True"
+
+    with Popen(args, env=env, **kwargs) as proc:
+        lines = []
+        while proc.poll() is None:
+            for msg in iter(proc.stderr.readline, ''):
+                if process_log.isEnabledFor(logging.DEBUG):
+                    process_log.debug(msg.strip())
+                callback(msg)
+                lines.append(msg)
+        stderr = ''.join(lines)
+
+        if check and proc.returncode != 0:
+            raise CalledProcessError(proc.returncode, args, output=None, stderr=stderr)
+        return CompletedProcess(args, proc.returncode, None, stderr=stderr)
+
+
+def _fix_process_args(args, env, kwargs):
+    assert 'universal_newlines' not in kwargs, "Use text= instead of universal_newlines"
+
+    if not env:
+        env = os.environ
+
+    # Search in spoof path if necessary
+    program = args[0]
+
+    if os.name == 'nt':
+        from ocrmypdf.subprocess._windows import fix_windows_args
+
+        args = fix_windows_args(program, args, env)
+
+    log.debug("Running: %s", args)
+    process_log = log.getChild(os.path.basename(program))
+    text = kwargs.get('text', False)
+    if sys.version_info < (3, 7):
+        if os.name == 'nt':
+            # Can't use close_fds=True on Windows with Python 3.6 or older
+            # https://bugs.python.org/issue19575, etc.
+            kwargs['close_fds'] = False
+        if 'text' in kwargs:
+            # Convert run(...text=) to run(...universal_newlines=) for Python 3.6
+            kwargs['universal_newlines'] = kwargs['text']
+            del kwargs['text']
+    return args, env, process_log, text
+
+
+@lru_cache(maxsize=None)
+def get_version(
+    program: str, *, version_arg: str = '--version', regex=r'(\d+(\.\d+)*)', env=None
+):
+    """Get the version of the specified program
+
+    Arguments:
+        program: The program to version check.
+        version_arg: The argument needed to ask for its version, e.g. ``--version``.
+        regex: A regular expression to parse the program's output and obtain the
+            version.
+        env: Custom ``os.environ`` in which to run program.
+    """
+    args_prog = [program, version_arg]
+    try:
+        proc = run(
+            args_prog,
+            close_fds=True,
+            text=True,
+            stdout=PIPE,
+            stderr=STDOUT,
+            check=True,
+            env=env,
+        )
+        output = proc.stdout
+    except FileNotFoundError as e:
+        raise MissingDependencyError(
+            f"Could not find program '{program}' on the PATH"
+        ) from e
+    except CalledProcessError as e:
+        if e.returncode != 0:
+            raise MissingDependencyError(
+                f"Ran program '{program}' but it exited with an error:\n{e.output}"
+            ) from e
+        raise MissingDependencyError(
+            f"Could not find program '{program}' on the PATH"
+        ) from e
+
+    match = re.match(regex, output.strip())
+    if not match:
+        raise MissingDependencyError(
+            f"The program '{program}' did not report its version. "
+            f"Message was:\n{output}"
+        )
+    version = match.group(1)
+
+    return version
+
+
+missing_program = '''
+The program '{program}' could not be executed or was not found on your
+system PATH.
+'''
+
+missing_optional_program = '''
+The program '{program}' could not be executed or was not found on your
+system PATH.  This program is required when you use the
+{required_for} arguments.  You could try omitting these arguments, or install
+the package.
+'''
+
+missing_recommend_program = '''
+The program '{program}' could not be executed or was not found on your
+system PATH.  This program is recommended when using the {required_for} arguments,
+but not required, so we will proceed.  For best results, install the program.
+'''
+
+old_version = '''
+OCRmyPDF requires '{program}' {need_version} or higher.  Your system appears
+to have {found_version}.  Please update this program.
+'''
+
+old_version_required_for = '''
+OCRmyPDF requires '{program}' {need_version} or higher when run with the
+{required_for} arguments.  If you omit these arguments, OCRmyPDF may be able to
+proceed.  For best results, install the program.
+'''
+
+osx_install_advice = '''
+If you have homebrew installed, try these command to install the missing
+package:
+    brew install {package}
+'''
+
+linux_install_advice = '''
+On systems with the aptitude package manager (Debian, Ubuntu), try these
+commands:
+    sudo apt-get update
+    sudo apt-get install {package}
+
+On RPM-based systems (Red Hat, Fedora), search for instructions on
+installing the RPM for {program}.
+'''
+
+windows_install_advice = '''
+If not already installed, install the Chocolatey package manager. Then use
+a command prompt to install the missing package:
+    choco install {package}
+'''
+
+
+def _get_platform():
+    if sys.platform.startswith('freebsd'):
+        return 'freebsd'
+    elif sys.platform.startswith('linux'):
+        return 'linux'
+    elif sys.platform.startswith('win'):
+        return 'windows'
+    return sys.platform
+
+
+def _error_trailer(program, package, **kwargs):
+    if isinstance(package, Mapping):
+        package = package.get(_get_platform(), program)
+
+    if _get_platform() == 'darwin':
+        log.info(osx_install_advice.format(**locals()))
+    elif _get_platform() == 'linux':
+        log.info(linux_install_advice.format(**locals()))
+    elif _get_platform() == 'windows':
+        log.info(windows_install_advice.format(**locals()))
+
+
+def _error_missing_program(program, package, required_for, recommended):
+    if recommended:
+        log.warning(missing_recommend_program.format(**locals()))
+    elif required_for:
+        log.error(missing_optional_program.format(**locals()))
+    else:
+        log.error(missing_program.format(**locals()))
+    _error_trailer(**locals())
+
+
+def _error_old_version(program, package, need_version, found_version, required_for):
+    if required_for:
+        log.error(old_version_required_for.format(**locals()))
+    else:
+        log.error(old_version.format(**locals()))
+    _error_trailer(**locals())
+
+
+def check_external_program(
+    *,
+    program: str,
+    package: str,
+    version_checker: Union[str, Callable],
+    need_version: str,
+    required_for: Optional[str] = None,
+    recommended=False,
+    version_parser: Type[Version] = LooseVersion,
+):
+    """Check for required version of external program and raise exception if not.
+
+    Args:
+        program: The name of the program to test.
+        package: The name of a software package that typically supplies this program.
+            Usually the same as program.
+        version_check: A callable without arguments that retrieves the installed
+            version of program.
+        need_version: The minimum required version.
+        required_for: The name of an argument of feature that requires this program.
+        recommended: If this external program is recommended, instead of raising
+            an exception, log a warning and allow execution to continue.
+        version_parser: A class that should be used to parse and compare version
+            numbers. Used when version numbers do not follow standard conventions.
+    """
+
+    try:
+        if callable(version_checker):
+            found_version = version_checker()
+        else:
+            found_version = version_checker
+    except (CalledProcessError, FileNotFoundError, MissingDependencyError):
+        _error_missing_program(program, package, required_for, recommended)
+        if not recommended:
+            raise MissingDependencyError(program)
+        return
+
+    def remove_leading_v(s):
+        if s.startswith('v'):
+            return s[1:]
+        return s
+
+    found_version = remove_leading_v(found_version)
+    need_version = remove_leading_v(need_version)
+
+    if found_version and version_parser(found_version) < version_parser(need_version):
+        _error_old_version(program, package, need_version, found_version, required_for)
+        if not recommended:
+            raise MissingDependencyError(program)
+
+    log.debug('Found %s %s', program, found_version)

src/ocrmypdf/subprocess/_windows.py

@@ -0,0 +1,162 @@
+# © 2020 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import logging
+import os
+import shutil
+import sys
+from distutils.version import LooseVersion
+from itertools import chain, filterfalse
+from pathlib import Path
+from typing import Any, Callable, Iterator, Optional, Tuple, TypeVar, cast
+
+try:
+    import winreg
+except ModuleNotFoundError as e:
+    raise ModuleNotFoundError("This module is for Windows only") from e
+
+log = logging.getLogger(__name__)
+
+T = TypeVar('T')
+
+
+def registry_enum(
+    key: winreg.HKEYType, enum_fn: Callable[[winreg.HKEYType, int], T]
+) -> Iterator[T]:
+    LIMIT = 999
+    n = 0
+    while n < LIMIT:
+        try:
+            yield enum_fn(key, n)
+            n += 1
+        except OSError:
+            break
+    if n == LIMIT:
+        raise ValueError(f"Too many registry keys under {key}")
+
+
+def registry_subkeys(key: winreg.HKEYType) -> Iterator[str]:
+    return registry_enum(key, winreg.EnumKey)
+
+
+def registry_values(key: winreg.HKEYType) -> Iterator[Tuple[str, Any, int]]:
+    return registry_enum(key, winreg.EnumValue)
+
+
+def registry_path_ghostscript(env=None) -> Iterator[Path]:
+    try:
+        with winreg.OpenKey(
+            winreg.HKEY_LOCAL_MACHINE, r"SOFTWARE\Artifex\GPL Ghostscript"
+        ) as k:
+            latest_gs = max(registry_subkeys(k), key=LooseVersion)
+        with winreg.OpenKey(
+            winreg.HKEY_LOCAL_MACHINE, fr"SOFTWARE\Artifex\GPL Ghostscript\{latest_gs}"
+        ) as k:
+            _, gs_path, _ = next(registry_values(k))
+            yield Path(gs_path) / 'bin'
+    except OSError as e:
+        log.warning(e)
+
+
+def registry_path_tesseract(env=None) -> Iterator[Path]:
+    try:
+        with winreg.OpenKey(winreg.HKEY_LOCAL_MACHINE, r"SOFTWARE\Tesseract-OCR") as k:
+            for subkey, val, _valtype in registry_values(k):
+                if subkey == 'InstallDir':
+                    tesseract_path = Path(val)
+                    yield tesseract_path
+    except OSError as e:
+        log.warning(e)
+
+
+def program_files_paths(env=None) -> Iterator[Path]:
+    if not env:
+        env = os.environ
+    program_files = env.get('PROGRAMFILES', '')
+
+    def path_walker() -> Iterator[Path]:
+        for path in Path(program_files).iterdir():
+            if not path.is_dir():
+                continue
+            if path.name.lower() == 'tesseract-ocr':
+                yield path
+            elif path.name.lower() == 'gs':
+                yield from (p for p in path.glob('**/bin') if p.is_dir())
+
+    return iter(
+        sorted(
+            (p for p in path_walker()),
+            key=lambda p: (p.name, p.parent.name),
+            reverse=True,
+        )
+    )
+
+
+def paths_from_env(env=None) -> Iterator[Path]:
+    return (Path(p) for p in os.get_exec_path(env) if p)
+
+
+def shim_path(new_paths: Callable[[Any], Iterator[Path]], env=None) -> str:
+    if not env:
+        env = os.environ
+    return os.pathsep.join(str(p) for p in new_paths(env) if p)
+
+
+SHIMS = [
+    paths_from_env,
+    registry_path_ghostscript,
+    registry_path_tesseract,
+    program_files_paths,
+]
+
+
+def fix_windows_args(program, args, env):
+    """Adjust our desired program and command line arguments for use on Windows"""
+
+    if sys.version_info < (3, 8):
+        # bpo-33617 - Windows needs manual Path -> str conversion
+        args = [os.fspath(arg) for arg in args]
+        program = os.fspath(program)
+
+    # If we are running a .py on Windows, ensure we call it with this Python
+    # (to support test suite shims)
+    if program.lower().endswith('.py'):
+        args = [sys.executable] + args
+
+    # If the program we want is not on the PATH, check elsewhere
+    for shim in SHIMS:
+        shimmed_path = shim_path(shim, env)
+        new_args0 = shutil.which(args[0], path=shimmed_path)
+        if new_args0:
+            args[0] = new_args0
+            break
+
+    return args
+
+
+def unique_everseen(iterable, key=None):
+    "List unique elements, preserving order. Remember all elements ever seen."
+    # unique_everseen('AAAABBBCCDAABBB') --> A B C D
+    # unique_everseen('ABBCcAD', str.lower) --> A B C D
+    seen = set()
+    seen_add = seen.add
+    if key is None:
+        key = lambda x: x
+    for element in iterable:
+        k = key(element)
+        if k not in seen:
+            seen_add(k)
+            yield element
+
+
+def shim_env_path(env=None):
+    if env is None:
+        env = os.environ
+
+    shim_paths = chain.from_iterable(shim(env) for shim in SHIMS)
+    return os.pathsep.join(
+        str(p) for p in unique_everseen(shim_paths, key=lambda p: str.casefold(str(p)))
+    )

tests/__init__.py

@@ -0,0 +1,7 @@
+# © 2021 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# Empty __init__.py file

tests/cache/2400dpi/__-l__eng__000001_ocr.png__000001_ocr_tess__pdf__txt/stderr.bin

@@ -1 +1 @@
-Tesseract Open Source OCR Engine v4.0.0 with Leptonica
+Tesseract Open Source OCR Engine v4.1.1 with Leptonica

tests/cache/3small/__-l__eng__000001_ocr.png__000001_ocr_tess__pdf__txt/stderr.bin

@@ -1 +1 @@
-Tesseract Open Source OCR Engine v4.1.0 with Leptonica
+Tesseract Open Source OCR Engine v4.1.1 with Leptonica