Parse WebVTT REGION blocks into Layout objects#380
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Implement region parsing in the WebVTT reader so that cues referencing a region get proper origin/extent geometry (using W3C TTML-WebVTT mapping formulas), enabling correct cross-format conversion to DFXP and other positioned formats. Also includes: - Fix .x/.y typo in geometry.py fit_to_screen() safety guard - Fix _remove_noon_off_on_italics typo in SCC specialized_collections - Add empty-collection guard in _remove_spaces_at_end_of_the_line - Replace magic numbers with _InstructionNode constants - Remove dead _remove_styles() method from WebVTT reader - Remove redundant if-guard and unused class attributes in WebVTT writer
🟡 PR Compliance ReviewRisk Level: MEDIUM
REVIEW REQUIRED - Address issues before merging Full report available in workflow artifacts |
🟡 PR Compliance ReviewRisk Level: MEDIUM
REVIEW REQUIRED - Address issues before merging Full report available in workflow artifacts |
lorandvarga
previously approved these changes
Jul 2, 2026
🟡 PR Compliance ReviewRisk Level: MEDIUM
REVIEW REQUIRED - Address issues before merging Full report available in workflow artifacts |
lorandvarga
approved these changes
Jul 2, 2026
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Implement region parsing in the WebVTT reader so that cues referencing
a region get proper origin/extent geometry (using W3C TTML-WebVTT
mapping formulas), enabling correct cross-format conversion to DFXP
and other positioned formats.
Also includes:
What changes for production
WebVTT files with REGION blocks: Previously region references were stored as raw passthrough only (no geometry). Now they produce Layout objects with computed origin/extent.
This is additive — cues without regions are unaffected.
VTT→VTT round-trip**: Preserved via
webvtt_positioningpassthrough (writer still outputs the raw cue settings string).SCC→all formats: No behavior change. The SCC fixes are pure renames/guards with identical runtime behavior.
geometry.py fix: Affects a safety guard for absolute-unit clamping. Currently unexploitable (all callers pass percent values), but now correctly checks both axes.