Bug 254202

Summary:	[GPU Process] REGRESSION (261700@main): Various "css-backgrounds/background-size-" tests fail with pixel differences
Product:	WebKit	Reporter:	Said Abou-Hallawa <sabouhallawa>
Component:	Layout and Rendering	Assignee:	Said Abou-Hallawa <sabouhallawa>
Status:	RESOLVED FIXED
Severity:	Normal	CC:	bfulgham, simon.fraser, webkit-bug-importer, zalan
Priority:	P2	Keywords:	InRadar
Version:	WebKit Nightly Build
Hardware:	Unspecified
OS:	Unspecified

Description Said Abou-Hallawa 2023-03-21 01:19:28 PDT

There is a slight difference between a frame decoded using CGImageSourceCreateImageAtIndex() and a frame decode using CGImageSourceCreateThumbnailAtIndex(). A thumbnail frame has to be decoded for a certain size which is called sizeForDrawing.

The test page draws a tiled background-image by calling BitmapImage::drawPattern() which ends up calling CGImageSourceCreateImageAtIndex().
The expected page draws an HTMLImageElements by calling BitmapImage::draw() which ends up calling CGImageSourceCreateThumbnailAtIndex().

The fix is to switch back to use CGImageSourceCreateImageAtIndex() for small images. This way we can ensure the image is decoded the same way for both the test and the expected pages.

Comment 1 Said Abou-Hallawa 2023-03-21 01:19:54 PDT

rdar://106952740

Comment 2 Said Abou-Hallawa 2023-03-21 01:25:17 PDT

Pull request: https://github.com/WebKit/WebKit/pull/11750

Comment 3 EWS 2023-03-21 12:33:59 PDT

Committed 261932@main (ff57fe9af291): <https://commits.webkit.org/261932@main>

Reviewed commits have been landed. Closing PR #11750 and removing active labels.