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Test Info:
- This WPT test may be referenced by the following Test IDs:
- /web-animations/timing-model/animations/reversing-an-animation.html - WPT Dashboard Interop Dashboard
<!DOCTYPE html>
<meta charset=utf-8>
<title>Reversing an animation</title>
<link rel="help"
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="../../testcommon.js"></script>
<body>
<div id="log"></div>
<script>
'use strict';
promise_test(async t => {
const div = createDiv(t);
const animation = div.animate({}, { duration: 100 * MS_PER_SEC,
iterations: Infinity });
await animation.ready;
// Wait a frame because if currentTime is still 0 when we call
// reverse(), it will throw (per spec).
await waitForAnimationFrames(1);
assert_greater_than_equal(animation.currentTime, 0,
'currentTime expected to be greater than 0, one frame after starting');
animation.currentTime = 50 * MS_PER_SEC;
const previousPlaybackRate = animation.playbackRate;
animation.reverse();
assert_equals(animation.playbackRate, previousPlaybackRate,
'Playback rate should not have changed');
await animation.ready;
assert_equals(animation.playbackRate, -previousPlaybackRate,
'Playback rate should be inverted');
}, 'Reversing an animation inverts the playback rate');
promise_test(async t => {
const div = createDiv(t);
const animation = div.animate({}, { duration: 100 * MS_PER_SEC,
iterations: Infinity });
animation.currentTime = 50 * MS_PER_SEC;
animation.pause();
await animation.ready;
animation.reverse();
await animation.ready;
assert_equals(animation.playState, 'running',
'Animation.playState should be "running" after reverse()');
}, 'Reversing an animation plays a pausing animation');
test(t => {
const div = createDiv(t);
const animation = div.animate({}, 100 * MS_PER_SEC);
animation.currentTime = 50 * MS_PER_SEC;
animation.reverse();
assert_equals(animation.currentTime, 50 * MS_PER_SEC,
'The current time should not change it is in the middle of ' +
'the animation duration');
}, 'Reversing an animation maintains the same current time');
test(t => {
const div = createDiv(t);
const animation = div.animate({}, { duration: 200 * MS_PER_SEC,
delay: -100 * MS_PER_SEC });
assert_true(animation.pending,
'The animation is pending before we call reverse');
animation.reverse();
assert_true(animation.pending,
'The animation is still pending after calling reverse');
}, 'Reversing an animation does not cause it to leave the pending state');
promise_test(async t => {
const div = createDiv(t);
const animation = div.animate({}, { duration: 200 * MS_PER_SEC,
delay: -100 * MS_PER_SEC });
let readyResolved = false;
animation.ready.then(() => { readyResolved = true; });
animation.reverse();
await Promise.resolve();
assert_false(readyResolved,
'ready promise should not have been resolved yet');
}, 'Reversing an animation does not cause it to resolve the ready promise');
test(t => {
const div = createDiv(t);
const animation = div.animate({}, 100 * MS_PER_SEC);
animation.currentTime = 200 * MS_PER_SEC;
animation.reverse();
assert_equals(animation.currentTime, 100 * MS_PER_SEC,
'reverse() should start playing from the animation effect end ' +
'if the playbackRate > 0 and the currentTime > effect end');
}, 'Reversing an animation when playbackRate > 0 and currentTime > ' +
'effect end should make it play from the end');
test(t => {
const div = createDiv(t);
const animation = div.animate({}, 100 * MS_PER_SEC);
animation.currentTime = -200 * MS_PER_SEC;
animation.reverse();
assert_equals(animation.currentTime, 100 * MS_PER_SEC,
'reverse() should start playing from the animation effect end ' +
'if the playbackRate > 0 and the currentTime < 0');
}, 'Reversing an animation when playbackRate > 0 and currentTime < 0 ' +
'should make it play from the end');
test(t => {
const div = createDiv(t);
const animation = div.animate({}, 100 * MS_PER_SEC);
animation.playbackRate = -1;
animation.currentTime = -200 * MS_PER_SEC;
animation.reverse();
assert_equals(animation.currentTime, 0,
'reverse() should start playing from the start of animation time ' +
'if the playbackRate < 0 and the currentTime < 0');
}, 'Reversing an animation when playbackRate < 0 and currentTime < 0 ' +
'should make it play from the start');
test(t => {
const div = createDiv(t);
const animation = div.animate({}, 100 * MS_PER_SEC);
animation.playbackRate = -1;
animation.currentTime = 200 * MS_PER_SEC;
animation.reverse();
assert_equals(animation.currentTime, 0,
'reverse() should start playing from the start of animation time ' +
'if the playbackRate < 0 and the currentTime > effect end');
}, 'Reversing an animation when playbackRate < 0 and currentTime > effect ' +
'end should make it play from the start');
test(t => {
const div = createDiv(t);
const animation = div.animate({}, { duration: 100 * MS_PER_SEC,
iterations: Infinity });
animation.currentTime = -200 * MS_PER_SEC;
assert_throws_dom('InvalidStateError',
() => { animation.reverse(); },
'reverse() should throw InvalidStateError ' +
'if the playbackRate > 0 and the currentTime < 0 ' +
'and the target effect is positive infinity');
}, 'Reversing an animation when playbackRate > 0 and currentTime < 0 ' +
'and the target effect end is positive infinity should throw an exception');
promise_test(async t => {
const animation = createDiv(t).animate({}, { duration: 100 * MS_PER_SEC,
iterations: Infinity });
animation.currentTime = -200 * MS_PER_SEC;
try { animation.reverse(); } catch(e) { }
assert_equals(animation.playbackRate, 1, 'playbackRate is unchanged');
await animation.ready;
assert_equals(animation.playbackRate, 1, 'playbackRate remains unchanged');
}, 'When reversing throws an exception, the playback rate remains unchanged');
test(t => {
const div = createDiv(t);
const animation = div.animate({}, { duration: 100 * MS_PER_SEC,
iterations: Infinity });
animation.currentTime = -200 * MS_PER_SEC;
animation.playbackRate = 0;
try {
animation.reverse();
} catch (e) {
assert_unreached(`Unexpected exception when calling reverse(): ${e}`);
}
}, 'Reversing animation when playbackRate = 0 and currentTime < 0 ' +
'and the target effect end is positive infinity should NOT throw an ' +
'exception');
test(t => {
const div = createDiv(t);
const animation = div.animate({}, { duration: 100 * MS_PER_SEC,
iterations: Infinity });
animation.playbackRate = -1;
animation.currentTime = -200 * MS_PER_SEC;
animation.reverse();
assert_equals(animation.currentTime, 0,
'reverse() should start playing from the start of animation time ' +
'if the playbackRate < 0 and the currentTime < 0 ' +
'and the target effect is positive infinity');
}, 'Reversing an animation when playbackRate < 0 and currentTime < 0 ' +
'and the target effect end is positive infinity should make it play ' +
'from the start');
promise_test(async t => {
const div = createDiv(t);
const animation = div.animate({}, 100 * MS_PER_SEC);
animation.playbackRate = 0;
animation.currentTime = 50 * MS_PER_SEC;
animation.reverse();
await animation.ready;
assert_equals(animation.playbackRate, 0,
'reverse() should preserve playbackRate if the playbackRate == 0');
assert_equals(animation.currentTime, 50 * MS_PER_SEC,
'reverse() should not affect the currentTime if the playbackRate == 0');
}, 'Reversing when when playbackRate == 0 should preserve the current ' +
'time and playback rate');
test(t => {
const div = createDiv(t);
const animation =
new Animation(new KeyframeEffect(div, null, 100 * MS_PER_SEC));
assert_equals(animation.currentTime, null);
animation.reverse();
assert_equals(animation.currentTime, 100 * MS_PER_SEC,
'animation.currentTime should be at its effect end');
}, 'Reversing an idle animation from starts playing the animation');
test(t => {
const div = createDiv(t);
const animation =
new Animation(new KeyframeEffect(div, null, 100 * MS_PER_SEC), null);
assert_throws_dom('InvalidStateError', () => { animation.reverse(); });
}, 'Reversing an animation without an active timeline throws an ' +
'InvalidStateError');
promise_test(async t => {
const animation = createDiv(t).animate(null, 100 * MS_PER_SEC);
await animation.ready;
animation.updatePlaybackRate(2);
animation.reverse();
await animation.ready;
assert_equals(animation.playbackRate, -2);
}, 'Reversing should use the negative pending playback rate');
promise_test(async t => {
const animation = createDiv(t).animate(null, {
duration: 100 * MS_PER_SEC,
iterations: Infinity,
});
animation.currentTime = -200 * MS_PER_SEC;
await animation.ready;
animation.updatePlaybackRate(2);
assert_throws_dom('InvalidStateError', () => { animation.reverse(); });
assert_equals(animation.playbackRate, 1);
await animation.ready;
assert_equals(animation.playbackRate, 2);
}, 'When reversing fails, it should restore any previous pending playback'
+ ' rate');
</script>
</body>