James R. Barlow
6ff6c8614f
This currently distorts the output size because Tesseract assumes it knows the DPI better than we do. Does not work for Ghostscript, because it emerges that Ghostscript honors /UserUnit for rasterizing but not in pdfwrite (resolve/wontfix). https://bugs.ghostscript.com/show_bug.cgi?id=690781 Ghostscript’s output would need to be patched in a PDF/A safe way for this to work. Temporary route may be to block Ghostscript if /UserUnit.
134 lines
4.0 KiB
Python
134 lines
4.0 KiB
Python
#!/usr/bin/env python3
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# © 2015 James R. Barlow: github.com/jbarlow83
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from subprocess import CalledProcessError, STDOUT, PIPE, run, check_output
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from functools import lru_cache
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import sys
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import os
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import re
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from ..exceptions import InputFileError, SubprocessOutputError, \
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MissingDependencyError, EncryptedPdfError
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from . import get_program
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@lru_cache(maxsize=1)
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def version():
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args_qpdf = [
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get_program('qpdf'),
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'--version'
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]
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try:
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p = run(args_qpdf, universal_newlines=True, stderr=STDOUT,
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stdout=PIPE)
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except CalledProcessError as e:
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print("Could not find qpdf executable on system PATH.",
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file=sys.stderr)
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raise MissingDependencyError() from e
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qpdf_version = re.match(r'qpdf version (.+)', p.stdout).group(1)
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return qpdf_version
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def check(input_file, log=None):
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args_qpdf = [
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get_program('qpdf'),
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'--check',
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input_file
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]
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if log is None:
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import logging as log
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try:
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check_output(args_qpdf, stderr=STDOUT, universal_newlines=True)
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except CalledProcessError as e:
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if e.returncode == 2:
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log.error("{0}: not a valid PDF, and could not repair it.".format(
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input_file))
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log.error("Details:")
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log.error(e.output)
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elif e.returncode == 3:
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log.info("qpdf --check returned warnings:")
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log.info(e.output)
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else:
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log.warning(e.output)
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return False
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return True
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def _probably_encrypted(e):
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"""qpdf can report a false positive "file is encrypted" message for damaged
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files - suppress this"""
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return e.returncode == 2 and \
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'invalid password' in e.output and \
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'file is damaged' not in e.output
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def repair(input_file, output_file, log):
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args_qpdf = [
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get_program('qpdf'), input_file, output_file
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]
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try:
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check_output(args_qpdf, stderr=STDOUT, universal_newlines=True)
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except CalledProcessError as e:
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if e.returncode == 3 and e.output.find("operation succeeded"):
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log.debug('qpdf found and fixed errors: ' + e.output)
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log.debug(e.output)
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return
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if _probably_encrypted(e):
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log.error("{0}: this PDF is password-protected - password must "
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"be removed for OCR".format(input_file))
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raise EncryptedPdfError() from e
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elif e.returncode == 2:
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log.error("{0}: not a valid PDF, and could not repair it.".format(
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input_file))
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log.error("Details: " + e.output)
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raise InputFileError() from e
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else:
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log.error("{0}: unknown error".format(
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input_file))
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log.error(e.output)
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raise SubprocessOutputError() from e
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def get_npages(input_file, log):
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try:
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pages = check_output(
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[get_program('qpdf'), '--show-npages', input_file],
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universal_newlines=True, close_fds=True)
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except CalledProcessError as e:
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if e.returncode == 2 and e.output.find('No such file'):
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log.error(e.output)
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raise InputFileError() from e
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return int(pages)
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def split_pages(input_file, work_folder, npages):
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"""Split multipage PDF into individual pages.
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Incredibly enough, this multiple process approach is about 70 times
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faster than using Ghostscript.
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"""
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for n in range(int(npages)):
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args_qpdf = [
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get_program('qpdf'), input_file,
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'--pages', input_file, '{0}'.format(n + 1), '--',
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os.path.join(work_folder, '{0:06d}.page.pdf'.format(n + 1))
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]
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run(args_qpdf, check=True)
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def merge(*, min_version, input_files, output_file):
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"""Merge the list of input files (all filenames) into the output file.
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The input files may contain one or more pages.
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"""
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args_qpdf = [
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get_program('qpdf'), '--min-version={}'.format(min_version),
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input_files[0], '--pages'
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] + input_files + ['--', output_file]
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run(args_qpdf, check=True)
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