Bug 185673 - Letter spacing in canvas text renders differently based on sub pixel placement
Summary: Letter spacing in canvas text renders differently based on sub pixel placement
Status: NEW
Alias: None
Product: WebKit
Classification: Unclassified
Component: Canvas (show other bugs)
Version: WebKit Nightly Build
Hardware: Unspecified Unspecified
: P2 Normal
Assignee: Nobody
URL:
Keywords: InRadar
Depends on:
Blocks:
 
Reported: 2018-05-15 23:00 PDT by Jon Lee
Modified: 2018-05-15 23:46 PDT (History)
6 users (show)

See Also:

Attachments
Test (1.48 KB, text/html)
2018-05-15 23:00 PDT, Jon Lee 		no flags Details
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Description Jon Lee 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.
Comment 1 Radar WebKit Bug Importer 2018-05-15 23:01:40 PDT 
<rdar://problem/40285072>
Comment 2 Myles C. Maxfield 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.