Bug 240858

Summary:

Apple Emoji render slightly differently with GPU Process DOM Rendering enabled

Product:

WebKit

Reporter:

Cameron McCormack (:heycam) <heycam>

Component:

Layout and Rendering

Assignee:

Nobody <webkit-unassigned>

Status:

NEW

Severity:

Normal

CC:

bfulgham, mmaxfield, simon.fraser, webkit-bug-importer, zalan

Priority:

Keywords:

InRadar

Version:

WebKit Nightly Build

Hardware:

Unspecified

OS:

Unspecified

See Also:

https://bugs.webkit.org/show_bug.cgi?id=240497

Attachments:

Description	Flags
screen shot with GPUP DOM rendering enabled	none
screen shot with GPUP DOM rendering disabled	none
screen shot with GPUP DOM rendering enabled	none
screen shot with GPUP DOM rendering disabled	none

Cameron McCormack (:heycam)

Reported 2022-05-23 22:33:30 PDT

Created attachment 459697 [details] screen shot with GPUP DOM rendering enabled Attaching screen shots on iPad with GPUP DOM Rendering enabled and disabled. Notice that the emoji rendering is slightly different. This makes me wonder if CoreText is not selecting an emoji of an appropriate size. Maybe it's unaware of the scale factor when it's drawing to the RemoteDisplayListRecorderProxy?

Attachments
screen shot with GPUP DOM rendering enabled (420.81 KB, image/png) 2022-05-23 22:33 PDT, Cameron McCormack (:heycam)	no flags	Details
screen shot with GPUP DOM rendering disabled (420.14 KB, image/png) 2022-05-23 22:33 PDT, Cameron McCormack (:heycam)	no flags	Details
screen shot with GPUP DOM rendering enabled (445.89 KB, image/png) 2022-05-23 22:46 PDT, Cameron McCormack (:heycam)	no flags	Details
screen shot with GPUP DOM rendering disabled (447.98 KB, image/png) 2022-05-23 22:46 PDT, Cameron McCormack (:heycam)	no flags	Details
Show Obsolete (2) View All Add attachment proposed patch, testcase, etc.

Cameron McCormack (:heycam)

Comment 1 2022-05-23 22:33:48 PDT

Created attachment 459698 [details] screen shot with GPUP DOM rendering disabled

Radar WebKit Bug Importer

Comment 2 2022-05-23 22:34:10 PDT

<rdar://problem/93807748>

Cameron McCormack (:heycam)

Comment 3 2022-05-23 22:46:38 PDT

Created attachment 459699 [details] screen shot with GPUP DOM rendering enabled

Cameron McCormack (:heycam)

Comment 4 2022-05-23 22:46:53 PDT

Created attachment 459700 [details] screen shot with GPUP DOM rendering disabled

Myles C. Maxfield

Comment 5 2022-05-24 12:35:02 PDT

The blacks look grey I guess. Perhaps there's an issue with transparency?

Cameron McCormack (:heycam)

Comment 6 2022-05-24 22:02:23 PDT

Looks like it's because the CGContext we create in the glyph recorder is created with type kCGContextTypeUnknown, and CoreText assumes that it's not going to get a sensible scale value out of the CTM, and instead assumes some large value, resulting in the largest bitmap strike being chosen.

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