Bug 130934 – Subpixel rendering: Simple line layout should not round to integral position while painting.

• Component: Layout and Rendering
• Status: RESOLVED FIXED

[zalan]

It could push content off by a device pixel compared to when RenderLayer is injected and hides the subpixel position.

[zalan]

Created attachment 228117 [details]
Patch

[Simon Fraser (smfr)]

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.

[zalan]

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)

[zalan]

Committed r166456: <http://trac.webkit.org/changeset/166456>