fix(pptx): scale right legend row pitch

[developer0hye]

Summary

• scale PowerPoint column-chart right-legend rows from the legend text size instead of the generic fixed 14pt stack pitch
• keep the separately calibrated horizontal-bar and non-PowerPoint legend paths unchanged
• add a focused renderer regression using the page 8 font metrics from fix(docx): honor in-cell picture row floors #1407
• store reproducible 300 DPI GT/before/after evidence and a machine-readable layout audit for PPTX multi-entry right legends use a fixed 14pt row pitch #1434

Related issue

Fixes #1434

Testing

• Red first: cargo test -p office2pdf a_powerpoint_column_right_legend_uses_the_native_text_scaled_row_pitch -- --nocapture failed before the implementation with [14.0, 14.0] row pitches instead of the native 19.2pt pitch.
• cargo test -p office2pdf a_powerpoint_column_right_legend_uses_the_native_text_scaled_row_pitch -- --nocapture — passed; the PowerPoint column/right path is within 0.1pt of 19.2pt and the PowerPoint bar control remains 14pt.
• cargo test -p office2pdf --lib diagram_visual_tests -- --nocapture — 202 passed.
• python3 -m unittest discover -s scripts/tests -p 'test_compare_render.py' — 26 passed.
• python3 -m unittest discover -s scripts/tests -p 'test_compare_layout.py' — 26 passed.
• python3 -m unittest discover -s scripts/tests -p 'test_check_visual_pr.py' — 42 passed.
• CARGO_INCREMENTAL=0 cargo clippy --workspace --all-targets -- -D warnings — passed.
• CARGO_INCREMENTAL=0 cargo test --workspace — core 2,756; DOCX 188; PDF validation 7; PPTX 130; XLSX 206; CLI 17; package/model roundtrip and doctests all passed with zero failures.
• Rebuilt and converted the fix(docx): honor in-cell picture row floors #1407 PPTX; page 8 legend baselines are 19.152pt apart versus native PowerPoint's 19.2pt.
• python3 scripts/compare_render.py native-powerpoint.pdf office2pdf.pdf --page 8 --dpi 300 --audit --artifacts-dir ... — all six GT text lines matched; the remaining three >5pt shifts are the shared legend block offsets tracked by PPTX column-chart right legends center 9.2pt too low #1435 and PPTX column-chart right legends are right-fitted 11pt too far left #1436.
• magick compare -metric AE -fuzz 5% before.png after.png diff.png — 16,447 changed pixels (0.183%), confined to the three legend rows.

Visual impact

• No rendered PDF change
• Rendered PDF change or visual evidence added

Visual audit

• Issue: PPTX multi-entry right legends use a fixed 14pt row pitch #1434
• Fixture: the PowerPoint fixture from PR fix(docx): honor in-cell picture row floors #1407
• Page(s): 8
• Renderer and DPI: pdftoppm, 300 DPI
• Evidence mode: fix
• Layout audit report: assets/bugfixes/issue-1434/layout-audit.json
• Layout audit page count: Pass
• Layout audit text flow: compare_layout misclassifies equivalent split and joined text lines as extra #1446
• Layout audit large shifts: PPTX column-chart right legends center 9.2pt too low #1435, PPTX column-chart right legends are right-fitted 11pt too far left #1436
• New follow-up issues found in this audit: compare_layout misclassifies equivalent split and joined text lines as extra #1446, PPTX open custom-geometry lines render rounded instead of flat caps #1447
• Model vision findings: At 300 DPI Codex inspected the full GT, before, and after pages; the 5% pixel diff; matched title, table, chart, footer, and each legend-row crop; and the three machine-generated large-shift crops. The legend row pitch is fixed and the before/after change is confined to those three entries. Remaining visible clusters are the chart-title style (PPTX chart titles drop rich-text weight and color #1424), legend vertical and horizontal block offsets (PPTX column-chart right legends center 9.2pt too low #1435 and PPTX column-chart right legends are right-fitted 11pt too far left #1436), automatic plot geometry (PPTX column charts use an uncalibrated automatic vertical plot rectangle #1437), legend-key size (PPTX column-chart right legend keys are 0.56pt too large #1439), and the title rule's rounded line caps (PPTX open custom-geometry lines render rounded instead of flat caps #1447). The table text is visibly equivalent, while its split/joined PDF line topology is falsely reported as extra text by compare_layout misclassifies equivalent split and joined text lines as extra #1446.
• GT: assets/bugfixes/issue-1434/gt.jpg
• Before: assets/bugfixes/issue-1434/before.jpg
• After: assets/bugfixes/issue-1434/after.jpg

Visual comparison

GT	Before	After

Required inspection

• Rendered all evidence at 150 DPI or higher
• Stored progressive JPEG quality 86 assets with metadata stripped
• Used Codex/Claude vision to inspect the full GT/output pages, diff, and matched crops
• Inspected matched region crops at full resolution
• Ran compare_layout.py --audit and dispositioned every large text-instance shift and painted-visibility mismatch
• Ran the 5% fuzz pixel-difference sweep
• Inventoried hairlines and border dash styles
• Inventoried font weight, italic, and underline emphasis

Deviation audit

Check	Result
Page count/order	Matches GT — page 8 is compared against page 8 in both one-page audit extracts
Element presence	Matches GT — title, rule, table, chart, axes, legend, footer, and slide number are all present
Position/size	Remaining: #1435 and #1436 track the legend block offsets, #1437 tracks the automatic plot rectangle, and #1439 tracks legend-key size
Rotation/flip	Matches GT — no rotated or flipped page-8 element differs
Fill	Matches GT — table, series, legend-key, footer, and slide-number fills are present with matching colors
Stroke/border	Remaining: #1447 tracks the rounded title-rule caps; chart axes, gridlines, and table rules are present
Shape outline geometry	Remaining: #1439 tracks the oversized legend-key square outlines
Text content	Remaining: #1446 tracks the machine audit's split/joined-line false positives; visible text content matches GT
Font family/weight/style	Remaining: #1424 tracks the chart title's missing rich-text weight and style; slide, table, axis, and legend emphasis otherwise matches
Text color	Remaining: #1424 tracks the chart title's missing teal text color
Alignment	Remaining: #1435 and #1436 track the legend block's vertical and horizontal alignment
Line/paragraph spacing	Fixed — the three right-legend baselines now advance by 19.152pt versus native 19.2pt instead of the former 14pt
Clipping/overflow	No deviation observed — full-resolution crops show no clipped legend labels, table text, title, or footer

Checklist

• Commits include a Signed-off-by line
• PR scope contains one root cause
• Remaining visual deviations each reference an open issue