raf-coarsened-time.https.html

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This test has a WPT meta file that expects 1 subtest issues.
This WPT test may be referenced by the following Test IDs:
- /hr-time/raf-coarsened-time.https.html - WPT Dashboard Interop Dashboard

<!doctype html>

<html>

<head>

  <link rel="help" href="https://html.spec.whatwg.org/multipage/webappapis.html#update-the-rendering">

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

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

</head>

<body>

<script>

    /* Coarsen to 5 microseconds or coarser */

    const COARSE_RESOLUTION = 0.005;

    const CUSTOM_TIMELINE_DELTA = 0.002;

    const FLOATING_POINT_ERROR_EPSILON = 0.01;

    // Note that this test would fail if the platform introduces a jitter.

    // It is recommended that platforms that implement jitter run this test

    // with a flag that turns jitter off, if possible.

    const customTimeline = new DocumentTimeline({originTime: CUSTOM_TIMELINE_DELTA});

    promise_test(async t => {

        for (let i = 0; i < 32; ++i) {

            const timestamp = await new Promise(resolve => requestAnimationFrame(ts => resolve(ts)));

            const coarse_timestamp = Math.round(timestamp / COARSE_RESOLUTION) * COARSE_RESOLUTION;

            assert_approx_equals(timestamp, coarse_timestamp, FLOATING_POINT_ERROR_EPSILON,

              "timestamp should be coarsened");

            assert_approx_equals(timestamp, document.timeline.currentTime, FLOATING_POINT_ERROR_EPSILON,

              "document.timeline.currentTimeline should be the same as the rAF callback");

            assert_approx_equals(customTimeline.currentTime + CUSTOM_TIMELINE_DELTA,

              timestamp, FLOATING_POINT_ERROR_EPSILON,

              "originTime for custom timeline should not be coarsened");

});

</script>

</body>

</html>