pdftract/notes/pdftract-14w0w.md
jedarden e238f40605 docs(pdftract-14w0w): verify gap detection implementation complete
The detect_column_gaps function was already implemented in columns.rs with full test coverage. All acceptance criteria verified:
- 8 zeros < threshold: no gap
- 20 zeros middle: 1 gap detected
- Leading zeros >= threshold: gap emitted
- All-zero histogram: 0 gaps

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
2026-05-27 22:54:08 -04:00

1.8 KiB

pdftract-14w0w: Gap detection verification

Summary

The detect_column_gaps function was already implemented in crates/pdftract-core/src/layout/columns.rs (lines 156-201). All acceptance criteria tests pass.

Implementation details

The function:

  • Takes histogram slice and page_width
  • Calculates threshold: (page_width * 0.03).ceil() as usize
  • Returns Vec<ColumnGap { lo, hi }>

Key behaviors:

  • Handles leading zeros (left margin) - emits gap if >= threshold
  • Handles trailing zeros (right margin) - emits gap if >= threshold
  • Handles all-zero histogram (empty page) - returns no gaps
  • Handles empty histogram - returns no gaps

Acceptance criteria verification

Criterion Test Status
8 zeros, page_width=600: NO gap test_detect_column_gaps_short_zeros_no_gap PASS
20 zeros middle, page_width=600: 1 gap test_detect_column_gaps_middle_gap PASS
Leading zeros >= threshold: 1 gap test_detect_column_gaps_leading_gap PASS
All-zero histogram: 0 gaps test_detect_column_gaps_all_zeros_no_gaps PASS

Additional tests:

  • test_detect_column_gaps_trailing_gap - trailing margin gap
  • test_detect_column_gaps_multiple_gaps - multiple separated gaps
  • test_detect_column_gaps_threshold_exact - gap at exact threshold
  • test_detect_column_gaps_threshold_minus_one - gap just below threshold
  • test_detect_column_gaps_empty_histogram - empty input
  • test_detect_column_gaps_no_zeros - no gaps in histogram
  • test_detect_column_gaps_small_page - small page width
  • test_detect_column_gaps_leading_and_trailing - both margins

All 36 column tests PASS (including 13 detect_column_gaps tests).

Files verified

  • crates/pdftract-core/src/layout/columns.rs - implementation (lines 89-201)
  • crates/pdftract-core/src/layout/mod.rs - exports ColumnGap, detect_column_gaps