Bug 287422

Summary: [view-transitions] Old snapshot disappears or degrades with large absolutely positioned elements inside `overflow: hidden` containers
Product: WebKit Reporter: Maksym <undrfined>
Component: Layout and RenderingAssignee: Nobody <webkit-unassigned>
Status: NEW    
Severity: Normal CC: alec, bfulgham, mattwoodrow, nicole, ntim, simon.fraser, webkit-bug-importer, zalan
Priority: P2 Keywords: InRadar
Version: Safari 18   
Hardware: Mac (Apple Silicon)   
OS: macOS 15   
Attachments:
Description Flags
Screen recording of Chromium and Safari behaviour comparison none

Maksym
Reported 2025-02-10 12:08:14 PST
Created attachment 474180 [details] Screen recording of Chromium and Safari behaviour comparison If an element that has `overflow: hidden` and a decently sized (approx. 383800px of height on my M1 Pro) div inside of it with `position: absolute`, running `document.startViewTransition` makes the old snapshot of the element not visible (or rendered with significantly reduced image quality). This makes animating transitions of, for example, virtualized lists/tables much more difficult. Attached is a video of comparing the behaviour of Chromium and Safari, where the old snapshot does not disappear on Chromium. Here's an example: https://codepen.io/Maksym-Yakubych/pen/azboPwa
Attachments
Screen recording of Chromium and Safari behaviour comparison (6.36 MB, video/quicktime)
2025-02-10 12:08 PST, Maksym 		no flags
Details
View All Add attachment proposed patch, testcase, etc.
Radar WebKit Bug Importer
Comment 1 2025-02-17 12:09:17 PST
<rdar://problem/145000705>
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