52 lines
1.5 KiB
HTML
52 lines
1.5 KiB
HTML
<!DOCTYPE html>
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<link rel="help" src="https://drafts.csswg.org/scroll-animations-1/#avoiding-cycles">
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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="/web-animations/testcommon.js"></script>
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<style>
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#scroller {
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overflow: hidden;
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width: 100px;
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height: 100px;
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scroll-timeline: --timeline;
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}
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#contents {
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height: 200px;
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}
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@keyframes expand {
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from { width: 100px; }
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to { width: 200px; }
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}
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#element {
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width: 0px;
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}
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#element.animate {
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animation: expand 10s linear;
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animation-timeline: --timeline;
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}
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/* Ensure stable expectations if feature is not supported */
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@supports not (animation-timeline:--foo) {
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#element { animation-play-state: paused; }
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}
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</style>
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<div id=scroller>
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<div id=contents></div>
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<div id=element></div>
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</div>
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<script>
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promise_test(async (t) => {
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assert_equals(getComputedStyle(element).width, '0px');
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await runAndWaitForFrameUpdate(() => {
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element.classList.add('animate');
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});
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assert_equals(getComputedStyle(element).width, '100px');
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scroller.scrollTop = 50;
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// Scrolling position should not yet be reflected in the animation,
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// since the new scroll position has not yet been sampled.
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assert_equals(getComputedStyle(element).width, '100px');
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await waitForNextFrame();
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assert_equals(getComputedStyle(element).width, '150px');
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}, 'Scroll position is sampled once per frame');
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</script>
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