[ManojDevarajulu]

Fixes #5185.
Supersedes #5186 (adds automated regression test, avoids repeated object allocation in the character loop).

Problem

When quad corrections are unset (e.g. in the table layout path or when importing pymupdf4llm, which calls TOOLS.unset_quad_corrections(True)), expanded ligatures (fi, fl, ff, tt) and combining marks receive a zero-width bounding box for subsequent characters.

In extract_cells, character inclusion is evaluated using:

abs(bbox & cell) > 0.5 * abs(bbox)

For zero-area bounding boxes (abs(bbox) == 0.0), 0.0 > 0.0 evaluates to False. As a result, the second character of ligatures is silently dropped from table cells (fine-tuning -> fne-tuning, figures -> fgures, different -> diferent).

Note: Upstream main now triggers this even without pymupdf4llm because the latest source unsets quad corrections in the table layout path.

Solution

1. Empty-bbox fallback: When bbox.is_empty (width or height <= 0), test whether the character's origin point lies inside the cell.
2. Performance: Pre-allocate cell_rect = pymupdf.Rect(cell) once per extract_cells call instead of re-instantiating pymupdf.Rect(cell) repeatedly inside the character loop.
3. Automated test: Added tests/test_5185.py verifying that zero-width ligature characters inside the cell are preserved ("fine") and zero-width characters outside the cell are excluded.

Verification

• Tested with tests/test_5185.py: passed.
• Tested against the arXiv paper from pymupdf4llm: table cells drop the second letter of a ligature when quad corrections are unset #5185 (2203.07436v4.pdf, p.44): restored 5x fine-tuning (previously extracted as fne-tuning).
• Existing test suite (tests/test_tables.py): 46 passed.

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[ManojDevarajulu]

I have read the CLA Document and I hereby sign the CLA

[ManojDevarajulu]

recheck

[ManojDevarajulu]

Hey @ToukoUrsin @JorjMcKie, just checking in on this one whenever you get some time to take a look. Let me know if anything needs changing!