2046973 - Update animation.reverse() and the setter of playbackRate to match the spec

Status: RESOLVED FIXED

(Core :: DOM: Animation, enhancement)

Description

[Boris Chiou [:boris]]

This bug is for these tests:

1. scroll-timelines/setting-playback-rate.html
2. scroll-timelines/finish-animation.html
3. scroll-timelines/reverse-animation.html

The above tests manipulate the playback rate and check the current time (and start time). If the active duration is incorrect, we may have incorrect end time so the timing normalization or any calculation may be wrong. We may have other issues to make these tests pass but at least we can start to check the calculation of active duration with the playback rate.

Comment 1

[Boris Chiou [:boris]]

Note that reverse-animation.html will be passed once we follow the spec change: https://github.com/w3c/csswg-drafts/issues/14173

Comment 2

[Boris Chiou [:boris]]

Attachment: Bug 2046973 - Update SetPlaybackRate() to match the spec.

We missed the implementation for finite timelines. The spec udpate was added
into web-animations-1 [1] directly, instead of web-animations-2.

[1] https://drafts.csswg.org/web-animations-1/#set-the-playback-rate

Comment 3

[Boris Chiou [:boris]]

Attachment: Bug 2046973 - Fix Reverse() to make sure we call Play() to update the animation for zero playback rate.

Otherwise, calling reverse() is no-op and our behavior may mismatch
other browers because the start time and current time is not correct
after calling reverse() with zero playback rate. This also matches the spec.

Also, we intentionally preserve zero playback rate (instead of setting to
-0); otherwise, we may get new failures in
web-animations/timing-model/animations/reversing-an-animation.html and
scroll-animations/scroll-timelines/reverse-animation.html.

In addition, need to update the test of animation mutation observers
because we update the animaiton after we call reverse() for zero
playback rate.

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/bad01910529d
https://hg.mozilla.org/integration/autoland/rev/04b05b83e804
Update SetPlaybackRate() to match the spec. r=layout-scroll-driven-animation-reviewers,dshin
https://github.com/mozilla-firefox/firefox/commit/6ba4be10618f
https://hg.mozilla.org/integration/autoland/rev/4fbf969ba677
Fix Reverse() to make sure we call Play() to update the animation for zero playback rate. r=layout-scroll-driven-animation-reviewers,dshin

Comment 5

[Serban Stanca [:SerbanS]]

https://hg.mozilla.org/mozilla-central/rev/04b05b83e804
https://hg.mozilla.org/mozilla-central/rev/4fbf969ba677

Comment 6

[Vadim Makeev]

Release notes: https://github.com/mdn/content/pull/45884