Bug 238067

Summary: REGRESSION (iOS 15.4 / r285529): Flicker on CSS transition of opacity and transform
Product: WebKit Reporter: em_te
Component: AnimationsAssignee: Nobody <webkit-unassigned>
Status: RESOLVED DUPLICATE    
Severity: Normal CC: dino, graouts, graouts, kbr, webkit-bug-importer
Priority: P2 Keywords: InRadar
Version: Safari 15   
Hardware: Unspecified   
OS: Unspecified   
See Also: https://bugs.webkit.org/show_bug.cgi?id=231358
https://bugs.webkit.org/show_bug.cgi?id=237918
Attachments:
Description Flags
test case showing flicker none

em_te
Reported 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.
Attachments
test case showing flicker (532 bytes, text/html)
2022-03-17 23:53 PDT, em_te 		no flags
Details
View All Add attachment proposed patch, testcase, etc.
Radar WebKit Bug Importer
Comment 1 2022-03-18 01:09:07 PDT
<rdar://problem/90476139>
Antoine Quint
Comment 2 2022-03-18 06:26:07 PDT
This regressed with r285529, the fix for bug 231358.
Antoine Quint
Comment 3 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.
Antoine Quint
Comment 4 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 ***
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