Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: 6a6822efc75ae88b07a8290a19b27eea03cdba8b
https://github.com/WebKit/WebKit/commit/6a6822efc75ae88b07a8290a19b27eea03cdba8b
Author: Simon Fraser <[email protected]>
Date: 2024-10-07 (Mon, 07 Oct 2024)
Changed paths:
M LayoutTests/TestExpectations
A LayoutTests/compositing/repaint/sticky-repaint-on-scroll-expected.txt
A LayoutTests/compositing/repaint/sticky-repaint-on-scroll.html
M LayoutTests/platform/mac-wk2/TestExpectations
M Source/WebCore/rendering/RenderLayer.cpp
M Source/WebCore/rendering/RenderLayer.h
Log Message:
-----------
Excessive repainting when scrolling position:sticky in some configurations
https://bugs.webkit.org/show_bug.cgi?id=280316
rdar://120280327
Reviewed by Alan Baradlay.
https://www.stripe.press/poor-charlies-almanack/talk-one has a tiled
`position:sticky` element
which repaints on every scroll. This happens when
`RenderLayer::recursiveUpdateLayerPositionsAfterScroll()`
and `RenderLayer::recursiveUpdateLayerPositions()` have different criteria for
the `clearRepaintRects()`
condition; the former was testing `!isVisuallyNonEmpty()` and the latter just
`m_hasVisibleContent`.
The fix is to have both code paths use a new
`isVisibilityHiddenOrOpacityZero()` which just does the
simple check for the visibility and opacity properties. This shouldn't cause
much new repainting, because
`recursiveUpdateLayerPositionsAfterScroll()` was doing the stricter check, and
we'll almost always do layout
after scroll.
The test requires async scrolling (programmatic scrolling triggers layouts on
every scroll as the layout viewport changes).
* LayoutTests/TestExpectations:
* LayoutTests/compositing/repaint/sticky-repaint-on-scroll-expected.txt: Added.
* LayoutTests/compositing/repaint/sticky-repaint-on-scroll.html: Added.
* LayoutTests/platform/mac-wk2/TestExpectations:
* Source/WebCore/rendering/RenderLayer.cpp:
(WebCore::RenderLayer::calculateClipRects const):
Canonical link: https://commits.webkit.org/284802@main
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