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<!DOCTYPE HTML>
<meta charset=utf-8>
<title>Element Timing: src change triggers new entry</title>
<body>
<style>
body {
margin: 0;
}
</style>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="resources/element-timing-helpers.js"></script>
<img elementtiming='my_image' id='my_id' />
<script>
setup({"hide_test_state": true});
const performanceEntryPromise = (pathname) => {
return new Promise(resolve => {
new PerformanceObserver((entryList, observer) => {
assert_equals(entryList.getEntries().length, 1);
if (entryList.getEntries()[0].url == pathname) {
observer.disconnect();
resolve(entryList.getEntries()[0]);
}
}).observe({ type: 'element' });
});
}
promise_test(async (t) => {
assert_implements(window.PerformanceElementTiming, "PerformanceElementTiming is not implemented");
// Take beforeRender timestamp.
const beforeRender1 = performance.now();
const img = document.getElementById('my_id');
const url1 = 'resources/square100.png';
const pathname1 = (new URL(url1, document.location)).href
// Register performance observer.
const promise1 = performanceEntryPromise(pathname1);
//Load image
await new Promise(resolve => {
img.addEventListener('load', resolve);
img.src = url1;
});
// Get element entry.
const entry1 = await promise1;
// Check entry.
checkElement(entry1, pathname1, 'my_image', 'my_id', beforeRender1, img);
checkRect(entry1, [0, 100, 0, 100]);
checkNaturalSize(entry1, 100, 100);
// Take beforeRender timestamp before changing image src.
const beforeRender2 = performance.now();
// Set the src to trigger another entry.
const url2 = '/images/black-rectangle.png';
const pathname2 = (new URL(url2, document.location)).href;
const promise2 = performanceEntryPromise(pathname2);
//Load image with changed src.
await new Promise(resolve => {
img.addEventListener('load', resolve);
img.src = url2;
});
// Get the corresponding element entry.
const entry2 = await promise2;
// Check entry.
checkElement(entry2, pathname2, 'my_image', 'my_id', beforeRender2, img);
checkRect(entry2, [0, 100, 0, 50]);
checkNaturalSize(entry2, 100, 50);
}, 'Element Timing: changing src causes a new entry to be dispatched.')
</script>
</body>
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