Bug 234997

Summary: Basic color with alpha doesn't match other browsers on non-sRGB monitors
Product: WebKit Reporter: Sam Weinig <sam>
Component: CSSAssignee: Nobody <webkit-unassigned>
Status: NEW ---    
Severity: Normal CC: simon.fraser, webkit-bug-importer
Priority: P2 Keywords: InRadar
Version: Other   
Hardware: Unspecified   
OS: Unspecified   
Attachments:
Description Flags
Test using boxes
none
Test using boxes
none
Test using boxes
none
Test using rgb() instead none

Description Sam Weinig 2022-01-07 17:59:26 PST 
The test css/css-color/t425-hsla-basic-a.xht is failing due to some issue with how we handle hsla() colors. With a simpler test that doesn't use text, it is easier to see that we don't match other browsers.
Comment 1 Sam Weinig 2022-01-07 18:00:02 PST Comment hidden (obsolete)
Comment 2 Sam Weinig 2022-01-07 18:00:57 PST Comment hidden (obsolete)
Comment 3 Sam Weinig 2022-01-07 18:02:42 PST 
Created attachment 448655 [details]
Test using boxes
Comment 4 Sam Weinig 2022-01-07 18:10:21 PST 
Created attachment 448656 [details]
Test using rgb() instead
Comment 5 Sam Weinig 2022-01-07 18:10:54 PST 
Don't think this is hsla() related. But rather something about how we draw.
Comment 6 Sam Weinig 2022-01-07 18:39:58 PST 
Looks like this is likely due to using the display colorspace as our working color space for our CGContextRefs. As such, this is not a problem on sRGB displays.

We should try to see if we can use extended-srgb as we do on iOS, but it will likely be a bit costly due to the lack of a dedicated scaler. But it is an experiment worth doing.
Comment 7 Radar WebKit Bug Importer 2022-01-14 18:00:18 PST 
<rdar://problem/87627670>