Bug 130664 – [CSS Blending] Compositing requirements for blending are not computed correctly

• Status: RESOLVED
• Resolution: FIXED
• Component: CSS

[Ion Rosca]

Here is the requirement regarding layer acceleration for blend modes:
    If a layer having blending is accelerated for any reason then its stacking context layer needs to be accelerated too.

What happens now:
1) If a blending layer is accelerated, all its RenderLayer ascendants get accelerated.  
2) If a non-accelerated layer has an accelerated sibling, then all its ascendants are accelerated.

[Ion Rosca]

Created attachment 227636 [details]
use cases

[Ion Rosca]

Created attachment 227676 [details]
patch v1

[Ion Rosca]

Created attachment 228178 [details]
add ifdef to blending code, nits

[Mihnea Ovidenie]

Comment on attachment 228178 [details]
add ifdef to blending code, nits

View in context: https://bugs.webkit.org/attachment.cgi?id=228178&action=review

> Source/WebCore/ChangeLog:13
> +        being the closest stacking context should be accelerated as well.

Probably this can be rewritten: "if a layer having blend mode is composited, its closest stacking context ancestor should be composited as well"

> Source/WebCore/ChangeLog:23
> +        * rendering/RenderLayerCompositor.cpp:

You should mention something about the renaming of m_subtreeHasBlending => m_hasUnisolatedCompositedBlendingDescendants in CompositingState.

> Source/WebCore/rendering/RenderLayer.h:789
> +    bool isolatesCompositedBlending() const

In general, i would like to see as much as possible code related to this feature guarded by ENABLE(CSS_COMPOSITING)

> Source/WebCore/rendering/RenderLayerCompositor.cpp:-208
> -        , m_subtreeHasBlending(other.m_subtreeHasBlending)

Maybe you can make these bool bit fields in a follow up patch.

[Ion Rosca]

Created attachment 228203 [details]
more comments and ifdefs

[WebKit Commit Bot]

Comment on attachment 228203 [details]
more comments and ifdefs

Clearing flags on attachment: 228203

Committed r166634: <http://trac.webkit.org/changeset/166634>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.