Closed Bug 1526728 Opened 2 years ago Closed 2 years ago

[wpt-sync] Sync PR 15279 - [animation-worklet] Basic pause implementation (reland)


(Testing :: web-platform-tests, enhancement, P4)



(firefox67 fixed)

Tracking Status
firefox67 --- fixed


(Reporter:, Unassigned)




(Whiteboard: [wptsync downstream])

Sync web-platform-tests PR 15279 into mozilla-central (this bug is closed when the sync is complete).

Details from upstream follow.

Majid Valipour <> wrote:

[animation-worklet] Basic pause implementation (reland)

Pausing worklet animation now holds the time. This works as expected for
main thread animations. Implementing this for composited worklet
animations will be done in a follow up patch.

Major changes:

  • Add and expose pause() method pausing the animation.
  • Introduce hold_time that is used when animation is paused.
  • Rework how current time is computed, it is now closer to
    regular animations i.e., we either compute it based on
    "start time and timeline.currentTime" or use "hold time".
  • Instead of setting start time we now set the current time
    which then works backward to compute either the start time
    or the hold time based on the animation state.
  • When transitioning animation play state, we now always set
    the current time. Previously this was adhoc and inconsistent.
  • Introduce has_started_ to differentiate when playing an
    animation for the first time vs playing it from pause.
  • Update playback_rate related calculation to use new logic.


  • wpt/animation-worklet/worklet-animation-pause.https.html: js test for basic current time calculations
  • wpt/animation-worklet/worklet-animation-pause-immediately.https.html: reftest for basic pause
  • wpt/animation-worklet/worklet-animation-pause-result.https.html: reftest for pause/resume.
  • WorkletAnimationTest.PausePlay: unit test for basic state transition and time calc

Relanding: Original CL was reverted here

  • Address flakiness in unit test by using more accurate error value matching other tests.
  • Speculative fix for layout test fail by waiting for an async animation frame. Locally
    running the test for 100 repeats does not show any flakes.

Bug: 821910
Change-Id: I11fd2960443081be81055904d6d56a2abc3282f5

WPT-Export-Revision: 251d535541b775379bb33d422596c8d67b2c7f7f

Whiteboard: [wptsync downstream] → [wptsync downstream error]
Whiteboard: [wptsync downstream error] → [wptsync downstream]
Ran 8 tests and 10 subtests
OK     : 3
FAIL   : 9
ERROR  : 1

New tests that have failures or other problems:
/animation-worklet/worklet-animation-pause-immediately.https.html: TIMEOUT
/animation-worklet/worklet-animation-pause-resume.https.html: TIMEOUT
/animation-worklet/worklet-animation-pause.https.html: TIMEOUT
Pushed by
[wpt PR 15279] - [animation-worklet] Basic pause implementation (reland), a=testonly
[wpt PR 15279] - Update wpt metadata, a=testonly
Pushed by
[wpt PR 15279] - [animation-worklet] Basic pause implementation (reland), a=testonly
[wpt PR 15279] - Update wpt metadata, a=testonly
Closed: 2 years ago
Resolution: --- → FIXED
Target Milestone: --- → mozilla67
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