Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: ef00a2bc79a56bdd9cb2ac27ab3d42662f82deea
https://github.com/WebKit/WebKit/commit/ef00a2bc79a56bdd9cb2ac27ab3d42662f82deea
Author: Ahmad Saleem <[email protected]>
Date: 2026-05-08 (Fri, 08 May 2026)
Changed paths:
M
LayoutTests/imported/w3c/web-platform-tests/css/css-values/tree-counting/sibling-index-keyframe-font-style-dynamic-expected.txt
M
LayoutTests/imported/w3c/web-platform-tests/css/css-values/tree-counting/sibling-index-keyframe-font-variation-settings-dynamic-expected.txt
M
LayoutTests/imported/w3c/web-platform-tests/css/css-values/tree-counting/sibling-index-keyframe-font-weight-dynamic-expected.txt
M
LayoutTests/imported/w3c/web-platform-tests/css/css-values/tree-counting/sibling-index-keyframe-length-value-dynamic-expected.txt
M
LayoutTests/imported/w3c/web-platform-tests/css/css-values/tree-counting/sibling-index-keyframe-registered-properties-dynamic-expected.txt
M
LayoutTests/imported/w3c/web-platform-tests/css/css-values/tree-counting/sibling-index-keyframe-rotate-dynamic-expected.txt
M
LayoutTests/imported/w3c/web-platform-tests/css/css-values/tree-counting/sibling-index-keyframe-scale-dynamic-expected.txt
M
LayoutTests/imported/w3c/web-platform-tests/css/css-values/tree-counting/sibling-index-keyframe-transform-dynamic-expected.txt
M
LayoutTests/imported/w3c/web-platform-tests/css/css-values/tree-counting/sibling-index-keyframe-value-dynamic-expected.txt
M Source/WebCore/animation/BlendingKeyframes.cpp
M Source/WebCore/animation/BlendingKeyframes.h
M Source/WebCore/animation/KeyframeEffect.cpp
Log Message:
-----------
sibling-index() in @keyframes doesn't re-resolve when siblings change
https://bugs.webkit.org/show_bug.cgi?id=314376
rdar://176531901
Reviewed by Antoine Quint.
When a keyframe value uses sibling-index() or sibling-count(), the
resolved keyframe style is frozen at the value computed at animation
start. Adding or removing a preceding sibling correctly invalidates
the target's style (via ChildrenAffectedBy{Forward,Backward}PositionalRules),
but KeyframeEffect::recomputeKeyframesIfNecessary() had no signal to
re-run styleForKeyframe, so the blended keyframe kept the stale index.
Track tree-counting usage on the keyframe style and recompute keyframes
when it is set, mirroring the existing handling of usesAnchorFunctions.
* Source/WebCore/animation/BlendingKeyframes.cpp:
(WebCore::BlendingKeyframes::usesTreeCountingFunctions const):
* Source/WebCore/animation/BlendingKeyframes.h:
* Source/WebCore/animation/KeyframeEffect.cpp:
(WebCore::KeyframeEffect::recomputeKeyframesIfNecessary): Recompute
blending keyframes when they reference tree-counting functions, so the
target's style invalidation on sibling change propagates through to the
animated value.
> Progressions:
*
LayoutTests/imported/w3c/web-platform-tests/css/css-values/tree-counting/sibling-index-keyframe-font-style-dynamic-expected.txt:
*
LayoutTests/imported/w3c/web-platform-tests/css/css-values/tree-counting/sibling-index-keyframe-font-variation-settings-dynamic-expected.txt:
*
LayoutTests/imported/w3c/web-platform-tests/css/css-values/tree-counting/sibling-index-keyframe-font-weight-dynamic-expected.txt:
*
LayoutTests/imported/w3c/web-platform-tests/css/css-values/tree-counting/sibling-index-keyframe-length-value-dynamic-expected.txt:
*
LayoutTests/imported/w3c/web-platform-tests/css/css-values/tree-counting/sibling-index-keyframe-registered-properties-dynamic-expected.txt:
*
LayoutTests/imported/w3c/web-platform-tests/css/css-values/tree-counting/sibling-index-keyframe-rotate-dynamic-expected.txt:
*
LayoutTests/imported/w3c/web-platform-tests/css/css-values/tree-counting/sibling-index-keyframe-scale-dynamic-expected.txt:
*
LayoutTests/imported/w3c/web-platform-tests/css/css-values/tree-counting/sibling-index-keyframe-transform-dynamic-expected.txt:
*
LayoutTests/imported/w3c/web-platform-tests/css/css-values/tree-counting/sibling-index-keyframe-value-dynamic-expected.txt:
Canonical link: https://commits.webkit.org/312895@main
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