Hiroyuki Ikezoe
063af963dd
On a paint-skip transaction, FrameMetrics::UpdatePendingScrollInfo mutates the ScrollMetadata retained from an earlier paint but left mVisualScrollUpdateType / mVisualDestination in place. AsyncPanZoomController::NotifyMainThreadTransaction then re-applied that already-consumed main-thread visual scroll update, clobbering the scroll offset the paint-skip had just applied (e.g. a scrollIntoView() followed by a deferred scrollBy() correction landing back at the anchor instead of below it). Clear the visual scroll update when applying the paint-skip scroll offset update, so the reused metadata no longer carries a stale destination. Differential Revision: https://phabricator.services.mozilla.com/D310979
36 lines
1.3 KiB
HTML
36 lines
1.3 KiB
HTML
<!DOCTYPE html>
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<meta charset="utf-8">
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<meta name="viewport" content="width=device-width, initial-scale=1, minimum-scale=1">
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<title>CSSOM View - scrollIntoView() then a deferred scrollBy() correction</title>
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<link rel="help" href="https://drafts.csswg.org/cssom-view/#dom-element-scrollintoview">
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<link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=2053004">
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<script src="/resources/testharness.js"></script>
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<script src="/resources/testharnessreport.js"></script>
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<script src="/dom/events/scrolling/scroll_support.js"></script>
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<div style="height: 200px;"></div>
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<h1 id="a">A</h1>
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<div style="height: 200vh;"></div>
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<script>
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const OFFSET = 80;
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promise_test(async t => {
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const target = document.getElementById("a");
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await waitForCompositorReady();
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await waitForCompositorCommit();
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window.addEventListener("scroll", () => {
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step_timeout(() => window.scrollBy(0, -OFFSET), 1);
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}, { once: true });
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target.scrollIntoView();
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await waitForDelayWithoutScrollEvent(window);
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await waitForCompositorCommit();
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assert_equals(target.getBoundingClientRect().top, OFFSET,
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"#a should rest OFFSET below the top after the deferred scrollBy()");
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}, "scrollIntoView() followed by a deferred scrollBy() preserves the scroll correction");
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</script>
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