Branch: refs/heads/webkitglib/2.50
Home: https://github.com/WebKit/WebKit
Commit: 2d70a37a490c8a8ca6131d758470fec702c4c6c1
https://github.com/WebKit/WebKit/commit/2d70a37a490c8a8ca6131d758470fec702c4c6c1
Author: Nathan Solomon <[email protected]>
Date: 2026-01-18 (Sun, 18 Jan 2026)
Changed paths:
A
LayoutTests/compositing/iframes/transparent-background-layer-promotion-expected.txt
A
LayoutTests/compositing/iframes/transparent-background-layer-promotion.html
M Source/WebCore/rendering/RenderLayerCompositor.cpp
Log Message:
-----------
Cherry-pick 305492@main (366280b0f896).
https://bugs.webkit.org/show_bug.cgi?id=301462
REGRESSION (Safari 26, 292627@main): Translate on semi transparent
background sometimes makes background darker
https://bugs.webkit.org/show_bug.cgi?id=301462
rdar://163509267
Reviewed by Simon Fraser.
When an element inside an iframe gains its own compositing layer (via
will-change, transforms, animations, etc.), the iframe's compositing
structure
changes. The iframe's background gets painted into the updated
layers, but the old background painting in the outer document's layers is
never
invalidated. These stale and new layers composite together.
If the iframe's background is transparent, this causes the
transparent background to appear darker than intended.
Add renderer()->repaint() when the iframe's internal compositing changes.
This forces the iframe element in the outer document to repaint and clear
its old content, ensuring the background only exists in the correct layer.
Test: transparent-background-layer-promotion.html
*
LayoutTests/compositing/iframes/transparent-background-layer-promotion-expected.txt:
Added.
*
LayoutTests/compositing/iframes/transparent-background-layer-promotion.html:
Added.
* Source/WebCore/rendering/RenderLayerCompositor.cpp:
(WebCore::RenderLayerCompositor::attachRootLayer):
Canonical link: https://commits.webkit.org/305492@main
Canonical link: https://commits.webkit.org/298234.394@webkitglib/2.50
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