James R. Barlow
b5a6a9f9f1
A tagged/structured PDF carries a logical structure tree (/Root/StructTreeRoot, /MarkInfo) that maps marked page content to semantic elements via MCIDs. When --force-ocr rasterizes pages or --redo-ocr rewrites the text layer, those MCIDs are destroyed or renumbered and the tree is left dangling. We cannot rebuild it to match the new text, so discard it for force/redo modes, following the same pattern as the thumbnail and search-index discards. --skip-text leaves text pages untouched, so their structure is preserved. Also broaden the default-mode "looks born-digital" stop signal to fire on /StructTreeRoot, not just /MarkInfo/Marked, so structure-tree-only PDFs are no longer silently OCR'd. The existing --tagged-pdf-mode ignore escape hatch is unchanged.
94 lines
3.0 KiB
Python
94 lines
3.0 KiB
Python
# SPDX-FileCopyrightText: 2023 James R. Barlow
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# SPDX-License-Identifier: MPL-2.0
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from __future__ import annotations
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import pikepdf
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import pytest
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from pikepdf import Name
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import ocrmypdf
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from ocrmypdf.pdfinfo import PdfInfo
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def test_block_tagged(resources):
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with pytest.raises(ocrmypdf.exceptions.TaggedPDFError):
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ocrmypdf.ocr(resources / 'tagged.pdf', '_.pdf')
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def test_detect_structure_tree(resources):
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assert PdfInfo(resources / 'tagged.pdf').has_structure_tree is True
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def test_structure_tree_without_markinfo_blocks(resources, tmp_path):
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"""A PDF with a structure tree but no /MarkInfo flag is still blocked."""
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untagged = tmp_path / 'struct_only.pdf'
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with pikepdf.open(resources / 'tagged.pdf') as pdf:
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del pdf.Root.MarkInfo
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pdf.save(untagged)
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info = PdfInfo(untagged)
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assert info.is_tagged is False
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assert info.has_structure_tree is True
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with pytest.raises(ocrmypdf.exceptions.TaggedPDFError):
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ocrmypdf.ocr(untagged, '_.pdf')
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def test_force_tagged_warns(resources, outpdf, caplog):
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caplog.set_level('WARNING')
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ocrmypdf.ocr(
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resources / 'tagged.pdf',
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outpdf,
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force_ocr=True,
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plugins=['tests/plugins/tesseract_noop.py'],
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)
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assert 'structural markup' in caplog.text
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def test_tagged_pdf_mode_ignore_with_skip_text(resources, outpdf, caplog):
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"""Ignore tagged_pdf_mode should warn but not error, and keep structure."""
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caplog.set_level('WARNING')
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ocrmypdf.ocr(
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resources / 'tagged.pdf',
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outpdf,
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tagged_pdf_mode='ignore',
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skip_text=True, # Tagged PDF has text, so skip pages with text
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plugins=['tests/plugins/tesseract_noop.py'],
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)
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assert 'structural markup' in caplog.text
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# skip-text leaves the text pages untouched, so the structure tree remains valid
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with pikepdf.open(outpdf) as pdf:
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assert Name.StructTreeRoot in pdf.Root
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def test_tagged_pdf_mode_ignore_with_force(resources, outpdf, caplog):
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"""Ignore tagged_pdf_mode with force mode should warn and discard structure."""
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caplog.set_level('WARNING')
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ocrmypdf.ocr(
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resources / 'tagged.pdf',
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outpdf,
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tagged_pdf_mode='ignore',
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force_ocr=True,
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plugins=['tests/plugins/tesseract_noop.py'],
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)
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assert 'structural markup' in caplog.text
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# force-ocr rasterizes every page, destroying the MCIDs the tree relies on
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with pikepdf.open(outpdf) as pdf:
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assert Name.StructTreeRoot not in pdf.Root
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assert Name.MarkInfo not in pdf.Root
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def test_tagged_pdf_mode_ignore_with_redo(resources, outpdf):
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"""Redo mode rewrites the text layer, so structure is discarded."""
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ocrmypdf.ocr(
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resources / 'tagged.pdf',
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outpdf,
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tagged_pdf_mode='ignore',
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redo_ocr=True,
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plugins=['tests/plugins/tesseract_noop.py'],
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)
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with pikepdf.open(outpdf) as pdf:
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assert Name.StructTreeRoot not in pdf.Root
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assert Name.MarkInfo not in pdf.Root
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