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<!doctype HTML>
<html>
<meta charset="utf8">
<title>Content Visibility: resize observer interactions</title>
<link rel="author" title="Chris Harrelson" href="mailto:chrishtr@chromium.org">
<link rel="help" href="https://drafts.csswg.org/css-contain/#content-visibility">
<meta name="assert" content="content-visibility hidden subtrees do not trigger resize observer">
<style>
.hidden {
content-visibility: hidden;
}
</style>
<div id="container">
<div id="resize" style="width: 50px; height: 50px">
</div>
</div>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script>
async_test((t) => {
let didCallback = false;
async function runTest() {
let resizeCallback = function (entries) {
didCallback = true;
}
let resizeObserver = new ResizeObserver(resizeCallback);
resizeObserver.observe(resize);
requestAnimationFrame(step2);
}
async function step2() {
assert_equals(true, didCallback, 'Resize observation should happen in first frame after registering');
didCallback = false;
const container = document.getElementById("container");
container.classList.add("hidden");
// Change the size of #resize. This should cause a resize observation, but
// only when the element becomes unhidden.
resize.style.width = '100px';
requestAnimationFrame(step3);
}
async function step3() {
assert_equals(false, didCallback,
'ResizeObsever should not run during while unrendered');
requestAnimationFrame(step4);
}
async function step4() {
assert_equals(false, didCallback,
'ResizeObsever should not run while unrendered');
const container = document.getElementById("container");
container.classList.remove("hidden");
requestAnimationFrame(step5);
}
async function step5() {
assert_equals(true, didCallback,
'ResizeObsevers should now run once becoming visible');
t.done();
}
window.onload = function() {
requestAnimationFrame(() => requestAnimationFrame(runTest));
};
}, "ResizeObserver skipped while hidden");
</script>
</html>
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