50 lines
1.8 KiB
HTML
50 lines
1.8 KiB
HTML
<!doctype html>
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<title>Layout Instability IDL tests</title>
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<meta name="timeout" content="long">
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<link rel="help" href="https://wicg.github.io/layout-instability/">
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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="/resources/WebIDLParser.js"></script>
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<script src="/resources/idlharness.js"></script>
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<script src="resources/util.js"></script>
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<script>
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'use strict';
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idl_test(
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['layout-instability'],
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['performance-timeline', 'geometry', 'dom', 'hr-time'],
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async (idl_array, t) => {
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idl_array.add_objects({
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LayoutShift: ['layoutShift'],
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LayoutShiftAttribution: ['layoutShiftAttribution'],
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});
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// If LayoutShift isn't supported, avoid the timeout below and just let the
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// objects declared above be null. The tests will still fail, but we will
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// consistently generate the same set of subtests on all platforms.
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if (!PerformanceObserver ||
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!PerformanceObserver.supportedEntryTypes ||
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!PerformanceObserver.supportedEntryTypes.includes('layout-shift')) {
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return;
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}
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// Make sure that the image has initially been laid out, so that the movement
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// later is counted as a layout shift.
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await waitForAnimationFrames(2);
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self.layoutShift = await new Promise((resolve, reject) => {
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const observer = new PerformanceObserver(entryList => {
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resolve(entryList.getEntries()[0]);
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});
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observer.observe({type: 'layout-shift', buffered: true});
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t.step_timeout(() => reject('Timed out waiting for LayoutShift entry'), 3000);
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// Move the image, to cause layout shift.
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image.style.marginTop = '100px';
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});
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self.layoutShiftAttribution = layoutShift.sources[0];
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}
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);
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</script>
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<img id="image" src="/images/green-100x50.png">
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