Remove cumulative paint layer limit - #790
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Dense scenes could silently stop emitting requested clip and effect layers after crossing the global limit, corrupting later content. Always preserve the layer stack and cover the previous cutoff with a recording-scene regression test. Assisted-by: Codex/GPT-5
nicoburns
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Aug 25, 2026
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This seems reasonable, but can we ditch the test please.
Vello Classic and Vello Hybrid both still have issues with resource allocation, but this isn't really guarding against it effectively.
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Sorry about the useless test. Dropped it. |
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…arley - stylo BreakSpaces now maps to parley::WhiteSpaceCollapse::BreakSpaces instead of Preserve. With the upstream Parley bump (#790) preserved trailing spaces no longer hang unconditionally, so the old mapping regressed the css-text/white-space/break-spaces-* tests. - CSS ch/ic advances are scaled linearly from font units (as Parley's shaper does) instead of via GlyphMetrics' fixed-point scaling, so e.g. width: 4ch at 20px Ahem is 80px rather than 79.99px and no longer wraps content that exactly fits. - Repin Parley to 346f8c5: quantized line-height: normal now rounds ascent/descent/leading before summing, matching browsers' whole-pixel normal line heights.
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Motivation
Dense scenes silently stop emitting requested clip and effect layers once cumulative painting crosses the nominal 1,024-layer limit, so later content is painted with the wrong layer stack and becomes visibly corrupted even when frame rate is healthy. The cap is enforced in backend-independent paint code, so it affects CPU and GPU renderers alike.
Why the cap can be removed
The cap was introduced at 28 in 596d419 as a workaround for Vello #644, then raised to 1,024 in c74b019. Vello fixed the underlying empty-clip encoding bug in Vello #651, merged in August 2024; Blitz now uses Vello 0.10.0, so retaining the old global workaround causes silent data loss without protecting current renderers from that historical bug.
Changes
Validation
cargo test -p blitz-paint --libcargo clippy -p blitz-paint --no-deps -- -D warningscargo fmt --all -- --checkgit diff --checkThe workspace Clippy command currently stops on an unrelated existing
needless_returnwarning atpackages/blitz-dom/src/mutator.rs:1218with Rust 1.96.1; the affected crate passes Clippy with dependency linting disabled.Note
AI-assistance disclosure: this change and PR description were prepared with assistance from Codex/GPT-5 and reviewed by the submitter.
WPT results
No changes in test results compared to
main.Generated by the WPT workflow.