NEW284300
[scroll-animations] WPT test scroll-animations/view-timelines/view-timeline-root-source.html is a flaky failure on iOS 
https://bugs.webkit.org/show_bug.cgi?id=284300
Summary [scroll-animations] WPT test scroll-animations/view-timelines/view-timeline-r...
Antoine Quint
Reported 2024-12-09 08:51:10 PST
The test imported/w3c/web-platform-tests/scroll-animations/view-timelines/view-timeline-root-source.html is a flaky failure on iOS following the fix for bug 284298.
Attachments
Add attachment proposed patch, testcase, etc.
Radar WebKit Bug Importer
Comment 1 2024-12-09 11:44:52 PST
<rdar://problem/141168977>
Antoine Quint
Comment 2 2025-04-28 05:01:42 PDT
The timeline current time is sometimes computed as -85.714287% due to the subject having a reported top position of 1200px instead of 250px (observed in the test by using `getBoundingClientRect()`). So this appears to be an issue in our layout code.
Antoine Quint
Comment 3 2025-04-28 05:05:12 PDT
Interestingly, waiting for an additional two frames after setting `scrollTop` makes the test pass reliably.
Antoine Quint
Comment 4 2025-04-28 05:10:26 PDT
Oh, I see the target has `margin: 200vh`. Switching to using `margin: 250px` makes the test pass reliably as well.
Antoine Quint
Comment 5 2025-04-28 12:45:17 PDT
Moving to the CSS component as a result. Might end up being Layout & Rendering, but it feels like a better start.
Note You need to log in before you can comment on or make changes to this bug.