Bug 130934 - Subpixel rendering: Simple line layout should not round to integral position while painting.
Summary: Subpixel rendering: Simple line layout should not round to integral position ...
Status: RESOLVED FIXED
Alias: None
Product: WebKit
Classification: Unclassified
Component: Layout and Rendering (show other bugs)
Version: 528+ (Nightly build)
Hardware: Unspecified Unspecified
: P2 Normal
Assignee: zalan
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2014-03-29 13:52 PDT by zalan
Modified: 2014-03-29 15:37 PDT (History)
5 users (show)

See Also:

Attachments
Patch (5.43 KB, patch)
2014-03-29 14:03 PDT, zalan 		simon.fraser: review+
Details | Formatted Diff | Diff
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Description zalan 2014-03-29 13:52:55 PDT 
It could push content off by a device pixel compared to when RenderLayer is injected and hides the subpixel position.
Comment 1 zalan 2014-03-29 14:03:39 PDT 
Created attachment 228117 [details]
Patch
Comment 2 Simon Fraser (smfr) 2014-03-29 14:05:12 PDT 
Comment on attachment 228117 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=228117&action=review

> Source/WebCore/ChangeLog:17
> +        Without RenderLayer:
> +        Renderer's layout position (10.5px, 10.5px) -> rounded and painted at (11px, 11px)
> +
> +        With RenderLayer:
> +        Rendere's layout position (10.5px, 10.5px) -> RenderLayer position (10.5px, 10.5px) ->
> +        renderer's relative pos (0px, 0px) -> rounded and painted at (0px, 0p) which
> +        translates to (10.5px, 10.5px) (vs. (11px, 11px)

I don't think it's necessary to include the math in the changelog. If you want to preserve this info for the future, put it in the bugzilla bug.
Comment 3 zalan 2014-03-29 15:22:06 PDT 
Without RenderLayer:
Renderer's layout position (10.5px, 10.5px) -> rounded and painted at (11px, 11px)

With RenderLayer:
Rendere's layout position (10.5px, 10.5px) -> RenderLayer position (10.5px, 10.5px) -> renderer's relative pos (0px, 0px) -> rounded and painted at (0px, 0p) which translates to (10.5px, 10.5px) (vs. (11px, 11px)
Comment 4 zalan 2014-03-29 15:37:10 PDT 
Committed r166456: <http://trac.webkit.org/changeset/166456>