Bug 298725

Summary: [CG] radius of CGGaussianBlurStyle is not in the BaseCTM coordinates
Product: WebKit Reporter: Said Abou-Hallawa <sabouhallawa>
Component: Layout and RenderingAssignee: 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   
Attachments:
Description Flags
test case none

Said Abou-Hallawa
Reported 2025-09-11 09:39:40 PDT
Created attachment 476698 [details] test case 1. Lunch ToT WebKit on a Retina display 2. Enable the internal feature "GraphicsContext Blur Filter Rendering" 3. Open the attached test case. 4. "Disable Full Page Accelerated Drawing" From Debug/Drawing Compositing Flags 5. Compare the display of the accelerated drawing versus the unaccelerated drawing Results: The unaccelerated drawing is incorrect. The blur radius is doubled for unaccelerated drawing. In /299740@main, the radius of the CGGaussianBlurStyle was scaled by the device scale factor as a work around for a CG bug on accelerated drawing. The radius should not be scaled by the device scale factor. In other words it should be in the BaseCTM coordinates. This is the behavior of the unaccelerated drawing. So the workaround should stay for the accelerated drawing only till the CG bug is fixed.
Attachments
test case (865 bytes, text/html)
2025-09-11 09:39 PDT, Said Abou-Hallawa 		no flags
Details
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Radar WebKit Bug Importer
Comment 1 2025-09-11 09:40:15 PDT
<rdar://problem/160383014>
Said Abou-Hallawa
Comment 2 2025-09-11 09:49:57 PDT
Pull request: https://github.com/WebKit/WebKit/pull/50609
EWS
Comment 3 2025-09-12 11:14:29 PDT
Committed 299903@main (763d74646247): <https://commits.webkit.org/299903@main> Reviewed commits have been landed. Closing PR #50609 and removing active labels.
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