Bug 214660

Summary:	markContextChangedAndNotifyCanvasObserver and markContextChanged over-notify
Product:	WebKit	Reporter:	Kenneth Russell <kbr>
Component:	WebGL	Assignee:	Nobody <webkit-unassigned>
Status:	NEW ---
Severity:	Normal	CC:	dino, jdarpinian, webkit-bug-importer
Priority:	P2	Keywords:	InRadar
Version:	WebKit Nightly Build
Hardware:	Unspecified
OS:	Unspecified
Bug Depends on:	126447, 126448, 212461
Bug Blocks:

Description Kenneth Russell 2020-07-22 15:07:52 PDT

WebGLRenderingContextBase::markContextChanged and WebGLRenderingContextBase::markContextChangedAndNotifyCanvasObserver dispatch too many notifications:

- markContextChangedAndNotifyCanvasObserver doesn't take into account whether a user-level framebuffer is bound. If one is, then it shouldn't notify.
- markContextChanged calls "htmlCanvas()->clearCopiedImage()" and "renderBox->contentChanged(CanvasPixelsChanged)" for every draw call - this seems expensive.

dino@ indicated in discussion on Slack that with the addition of WebGLRenderingContextBase::prepareForDisplay in Bug 212461, at least some of these notifications can be done once per frame, at the end of the frame, rather than on each operation that might touch the WebGL back buffer.

Comment 1 Kenneth Russell 2020-07-22 15:08:57 PDT

Noticed this while fixing Bug 126447 and Bug 126448.

Comment 2 Radar WebKit Bug Importer 2020-07-29 15:08:37 PDT

<rdar://problem/66294753>