loaf-duration-clamping.html

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This WPT test may be referenced by the following Test IDs:
- /long-animation-frame/loaf-duration-clamping.html - WPT Dashboard Interop Dashboard

<!DOCTYPE HTML>

<meta charset=utf-8>

<title>Long Animation Frame Timing: duration clamping</title>

<script src="/resources/testharness.js"></script>

<script src="/resources/testharnessreport.js"></script>

<script src="resources/utils.js"></script>

<body>

<h1>Test</h1>

<script>

promise_test(async t => {

  const loaf_promise = new Promise(resolve => new PerformanceObserver(entries => {

      resolve(entries.getEntries()[0]);

  }).observe({type: "long-animation-frame"}));

  // Block the main thread for 60ms without triggering a render

  t.step_timeout(() => {

    busy_wait(60);

  }, 0);

  const entry = await loaf_promise;

  const COARSE_RESOLUTION = 0.005;

  const FLOATING_POINT_ERROR_EPSILON = 0.01;

  const coarse_duration = Math.round(entry.duration / COARSE_RESOLUTION) * COARSE_RESOLUTION;

  assert_approx_equals(entry.duration, coarse_duration, FLOATING_POINT_ERROR_EPSILON,

      "duration should be coarsened");

}, "LoAF duration should be clamped even when there is no render");

</script>

</body>