Bug 185673

Summary:

Letter spacing in canvas text renders differently based on sub pixel placement

Product:

WebKit

Reporter:

Jon Lee <jonlee>

Component:

Canvas

Assignee:

Nobody <webkit-unassigned>

Status:

NEW

Severity:

Normal

CC:

dino, mmaxfield, sabouhallawa, simon.fraser, webkit-bug-importer, zalan

Priority:

Keywords:

InRadar

Version:

WebKit Nightly Build

Hardware:

Unspecified

OS:

Unspecified

Attachments:

Description	Flags
Test	none

Jon Lee

Reported 2018-05-15 23:00:27 PDT

Created attachment 340470 [details] Test See test page. I'm rendering text at various sub-pixel locations. The text appears to jiggle. It's worse 1x than 2x. Compare to Chrome and Firefox, which do not suffer from this.

Attachments
Test (1.48 KB, text/html) 2018-05-15 23:00 PDT, Jon Lee	no flags	Details
View All Add attachment proposed patch, testcase, etc.

Radar WebKit Bug Importer

Comment 1 2018-05-15 23:01:40 PDT

<rdar://problem/40285072>

Myles C. Maxfield

Comment 2 2018-05-15 23:46:03 PDT

Yeah, we have a dupe of this. Every time we disable sub pixel quantization, we get a huge regression because our CoreGraphics glyph cache hit rate plummets.

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