44 lines
1.6 KiB
HTML
44 lines
1.6 KiB
HTML
<!DOCTYPE HTML>
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<meta charset=utf-8>
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<title>Element Timing: observe elements with elementtiming attribute</title>
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<body>
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<style>
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body {
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margin: 0;
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}
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</style>
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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/element-timing-helpers.js"></script>
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<script>
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let beforeRender;
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let img;
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async_test(function (t) {
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assert_implements(window.PerformanceElementTiming, "PerformanceElementTiming is not implemented");
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const observer = new PerformanceObserver(
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t.step_func_done(function(entryList) {
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assert_equals(entryList.getEntries().length, 1);
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const entry = entryList.getEntries()[0];
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const pathname = window.location.origin + '/element-timing/resources/square100.png';
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checkElement(entry, pathname, 'my_image', 'my_id', beforeRender, img);
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// Assume viewport has size at least 100, so the element is fully visible.
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checkRect(entry, [0, 100, 0, 100]);
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checkNaturalSize(entry, 100, 100);
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})
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);
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observer.observe({entryTypes: ['element']});
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// We add the image during onload to be sure that the observer is registered
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// in time for it to observe the element timing.
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window.onload = () => {
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// Add image of width equal to 100 and height equal to 100.
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img = document.createElement('img');
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img.src = 'resources/square100.png';
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img.setAttribute('elementtiming', 'my_image');
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img.setAttribute('id', 'my_id');
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document.body.appendChild(img);
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beforeRender = performance.now();
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};
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}, 'Element with elementtiming attribute is observable.');
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</script>
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</body>
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