<!DOCTYPE html>
<meta charset=utf-8>
<title>Element Timing: observe images in carousel</title>
<style>
body {
margin: 0;
}
/* Do not display images by default */
.carousel-image {
display: none;
}
</style>
<body>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="resources/element-timing-helpers.js"></script>
<div class="slideshow-container">
<div class='carousel-image'>
<img src="resources/circle.svg" elementtiming='image0' id='image0'>
</div>
<div class='carousel-image'>
<img src="resources/square100.png" elementtiming='image1' id='image1'>
</div>
</div>
<script>
async_test(function (t) {
assert_implements(window.PerformanceElementTiming, "PerformanceElementTiming is not implemented");
const beforeRenderTimes = [];
let entry_count = 0;
const entry_count_per_element = [0, 0];
const pathname0 = window.location.origin + '/element-timing/resources/circle.svg';
const pathname1 = window.location.origin + '/element-timing/resources/square100.png';
const observer = new PerformanceObserver(t.step_func(list => {
list.getEntries().forEach(entry => {
if (entry_count % 2 == 0) {
checkElement(entry, pathname0, 'image0', 'image0', beforeRenderTimes[entry_count],
document.getElementById('image0'));
checkRect(entry, [0, 200, 0, 200]);
checkNaturalSize(entry, 200, 200);
entry_count_per_element[0]++;
}
else {
checkElement(entry, pathname1, 'image1', 'image1', beforeRenderTimes[entry_count],
document.getElementById('image1'));
checkRect(entry, [0, 100, 0, 100]);
checkNaturalSize(entry, 100, 100);
entry_count_per_element[1]++;
}
entry_count++;
// Check each image twice before ending the test.
if (entry_count == 4) {
assert_equals(entry_count_per_element[0], 2);
assert_equals(entry_count_per_element[1], 2);
t.done();
}
})
}));
observer.observe({entryTypes: ['element']});
let slideIndex = 0;
showCarousel();
function showCarousel() {
beforeRenderTimes.push(performance.now());
const slides = document.getElementsByClassName("carousel-image");
slides[slideIndex].style.display = "block";
slides[1 - slideIndex].style.display = "none";
slideIndex = 1 - slideIndex;
t.step_timeout(showCarousel, 50); // Change image every 50 ms.
}
}, 'Entries for elements within an image carousel are dispatched when the elements are redrawn.');
</script>
</body>
</html>
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