Bug 238067 - REGRESSION (iOS 15.4 / r285529): Flicker on CSS transition of opacity and transform
Summary: REGRESSION (iOS 15.4 / r285529): Flicker on CSS transition of opacity and tra...
Status: RESOLVED DUPLICATE of bug 237972
Alias: None
Product: WebKit
Classification: Unclassified
Component: Animations (show other bugs)
Version: Safari 15
Hardware: Unspecified Unspecified
: P2 Normal
Assignee: Nobody
URL:
Keywords: InRadar
Depends on:
Blocks:
 
Reported: 2022-03-17 23:53 PDT by em_te
Modified: 2022-03-18 12:11 PDT (History)
5 users (show)

See Also:

Attachments
test case showing flicker (532 bytes, text/html)
2022-03-17 23:53 PDT, em_te 		no flags Details
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Description em_te 2022-03-17 23:53:21 PDT 
Created attachment 455068 [details]
test case showing flicker

Doing a simple CSS transition shows a flicker on the latest Safari after the iOS 15.4 update.
See test case attached.

The transition is just:

  #box {
    transform: scale(0.3);
    opacity: 0.3;
    transition: transform 0.5s, opacity 1.5s;
  }
  #box:hover {
    opacity: 1;
    transform: scale(1);
  }

Normally the transitions are smooth but now the transitions seem to repeat themselves causing a mismatched flicker.
Comment 1 Radar WebKit Bug Importer 2022-03-18 01:09:07 PDT 
<rdar://problem/90476139>
Comment 2 Antoine Quint 2022-03-18 06:26:07 PDT 
This regressed with r285529, the fix for bug 231358.
Comment 3 Antoine Quint 2022-03-18 07:48:24 PDT 
r285529 did something very stupid in addLeafAnimation(): we would add the animationGroupBeginTime each time this function was called which meant that any time we committed animation on a layer. This was fine as long as there was only one commit per animation. But this also meant that if you had two or more animations running with different durations, such as in the test case, further commits would add an extra 1s to the leaf animation begin time.
Comment 4 Antoine Quint 2022-03-18 08:46:39 PDT 
Going to fix this in bug 237972 since it was filed earlier and is the same issue. Thanks a lot for filing this bug with a reduction, this really helped!

*** This bug has been marked as a duplicate of bug 237972 ***