<!DOCTYPE html>
<meta charset="utf-8">
<title>ScrollTimeline current time algorithm - root scroller</title>
<link rel="help" href="https://wicg.github.io/scroll-animations/#current-time-algorithm">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/web-animations/testcommon.js"></script>
<script src="./testcommon.js"></script>

<style>
html {
  /* Ensure the document is scrollable. */
  min-height: 100%;
  min-width: 100%;
  padding-bottom: 100px;
  padding-right: 100px;
}
</style>

<script>
promise_test(async t => {
  const scroller = document.scrollingElement;
  // Allow layout to finish, otherwise the scroller isn't set up by the time
  // we check the currentTime of the scroll timeline.
  await waitForNextFrame();

  const blockScrollTimeline = new ScrollTimeline(
      { source: scroller, axis: 'block' });
  const inlineScrollTimeline = new ScrollTimeline(
      { source: scroller, axis: 'inline' });

  // Wait for new animation frame which allows the timeline to fully initialize
  await waitForNextFrame();

  // Unscrolled, both timelines should read a currentTime of 0.
  assert_percents_equal(blockScrollTimeline.currentTime, 0);
  assert_percents_equal(inlineScrollTimeline.currentTime, 0);

  // Now do some scrolling and make sure that the ScrollTimelines update.
  scroller.scrollTop = 50;
  scroller.scrollLeft = 75;
  // Wait for new animation frame  which allows the timeline to compute new
  // current time.
  await waitForNextFrame();

  assert_percents_equal(blockScrollTimeline.currentTime, 50);
  assert_percents_equal(inlineScrollTimeline.currentTime, 75);
}, 'currentTime calculates the correct time for a document.scrollingElement source');
</script>
