Declare certain APIs public

docs/release_notes.rst

@@ -1,9 +1,13 @@
 Release notes
 =============
 
-OCRmyPDF uses `semantic versioning <http://semver.org/>`_ for its command line interface.
+OCRmyPDF uses `semantic versioning <http://semver.org/>`_ for its command line interface and its public API.
 
-The OCRmyPDF package itself does not contain a public API, although it is fairly stable and breaking changes are usually timed with a major release. A future release will clearly define the stable 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.
+
+Unfortunately, the public API does **not** expose the ability to actually OCR a PDF. This is due to a limitation in an underlying library (ruffus) that makes OCRmyPDF non-reentrant.
+
+Note that it is licensed under GPLv3, so scripts that ``import ocrmypdf`` and are released publicly should probably also be licensed under GPLv3.
 
 .. Issue regex
    find:    [^`]\#([0-9]{1,3})[^0-9]

src/ocrmypdf/__init__.py

@@ -23,3 +23,16 @@ PROGRAM_NAME = 'ocrmypdf'
 __version__ = pkg_resources.get_distribution('ocrmypdf').version
 
 VERSION = __version__
+
+from .exceptions import (
+    ExitCode, BadArgsError, PdfMergeFailedError, MissingDependencyError,
+    UnsupportedImageFormatError, DpiError, OutputFileAccessError,
+    PriorOcrFoundError, InputFileError, SubprocessOutputError,
+    EncryptedPdfError, TesseractConfigError
+)
+
+from . import helpers
+from . import hocrtransform
+from . import leptonica
+from . import pdfa
+from . import pdfinfo

src/ocrmypdf/__main__.py

@@ -34,7 +34,7 @@ import ruffus.cmdline as cmdline
 import ruffus.proxy_logger as proxy_logger
 
 from ._jobcontext import JobContext, JobContextManager, cleanup_working_files
-from .pipeline import build_pipeline
+from ._pipeline import build_pipeline
 from .pdfa import file_claims_pdfa
 from .helpers import is_iterable_notstr, re_symlink, is_file_writable, \
     available_cpu_count