PDF accessibility - untagged text with scale transform

#447444703 Filed 2025-09-26 New

Summary

What this page reproduces

This reproducer isolates a PDF accessibility tagging issue where transform: scale(...) text may become untagged in generated PDFs.

In affected builds, screen reader output and PDF structure can miss lines using pure scale transforms, while rotate-only or rotate+scale lines are tagged.

Downloads

Generated comparison PDFs

These were generated from the same repro page, with and without the patch.

Reproducer Content

Rotate

Scale

Rotate and Scale

Matrix scale only

Steps

1. Open this page in Chromium.
2. Press "Open Print Dialog" (or Ctrl+P).
3. Destination: "Save as PDF".
4. Save the PDF.
5. Validate with Acrobat Read Out Loud and/or PAC 2024.

Expected on fixed build:
- All four lines are tagged and appear in logical structure.

Typical broken behavior:
- "Scale" and "Matrix scale only" can be missing or untagged.

Reference

Chromium fix direction

Skip creating the 2D-scale effect node while printing in FragmentPaintPropertyTreeBuilder::NeedsEffectFor2DScaleTransform().

This matches orphaned CL 7352262 and can be verified with a red/green unit test in paint_property_tree_builder_test.cc.