Bug 256624

Summary: [UI-side compositing] Eliminate unnecessary invalidate of scrollbar layers when scrolling
Product: WebKit Reporter: Simon Fraser (smfr) <simon.fraser>
Component: CompositingAssignee: Nikos Mouchtaris <nmouchtaris>
Status: RESOLVED FIXED    
Severity: Normal CC: nmouchtaris, simon.fraser, webkit-bug-importer
Priority: P2 Keywords: InRadar
Version: WebKit Nightly Build   
Hardware: Unspecified   
OS: Unspecified   

Description Simon Fraser (smfr) 2023-05-10 19:18:39 PDT 
Traces show that that we mark the scrollbar layers as needing repaint, and hit GraphicsLayerCA::platformCALayerPaintContents() for them, on every scroll.

If these are layers for native scrollbars, we don't paint them in the web process at all (the NSScrollerImps only live in the UI Process), so we shouldn't need to dirty the scrollbar layers.
Comment 1 Radar WebKit Bug Importer 2023-05-10 19:19:07 PDT 
<rdar://problem/109184266>
Comment 2 Nikos Mouchtaris 2023-05-12 17:39:11 PDT 
Pull request: https://github.com/WebKit/WebKit/pull/13840
Comment 3 EWS 2023-05-15 17:46:15 PDT 
Committed 264094@main (d19192443a84): <https://commits.webkit.org/264094@main>

Reviewed commits have been landed. Closing PR #13840 and removing active labels.