Bug 49857 – Keep overlap testing logic until real 3d transforms are being used

• Status: RESOLVED
• Resolution: FIXED
• Component: Layout and Rendering

[Simon Fraser (smfr)]

When content uses translateZ(0) to force compositing layers, it throws us out of the overlap testing mode. We should stay in this mode until actual 3d is used.

[Simon Fraser (smfr)]

Created attachment 74483 [details]
Patch

Comment on attachment 74483 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=74483&action=review

> WebCore/rendering/RenderLayerCompositor.cpp:1290
> +    RenderStyle* style = renderer->style();

Useless variable!

> WebCore/rendering/RenderLayerCompositor.cpp:1294
> +    TransformationMatrix* transform = toRenderBoxModelObject(renderer)->layer()->transform();

I think this one is unnecessary too.

[Simon Fraser (smfr)]

Hmm, this patch has some unwanted side-effects that break some tests.

[Simon Fraser (smfr)]

Ah, looks like overlap testing is creating layers in cases where we should be able to flatten them.

[Simon Fraser (smfr)]

I filed bug 50192 on overlap testing badness, which I'll fix before this one.

[Eric Seidel (no email)]

Looks like this hasn't been landed.

[Simon Fraser (smfr)]

(In reply to comment #6)
> Looks like this hasn't been landed.

See previous comment.

[Simon Fraser (smfr)]

This might help http://mir.aculo.us/2011/03/16/how-to-play-a-sound-in-a-web-browser-it-aint-easy/

[Simon Fraser (smfr)]

See also bug 56917.

[Adrienne Walker]

(In reply to comment #9)
> See also bug 56917.

I kind of wonder why we disable the overlap test at all for 3d transformed layers.

There's really no reason we couldn't calculate a bounding box for those layers.  The bounding box may not fit perfectly, but we'd still end up potentially generating a lot fewer composited layers.

[Simon Fraser (smfr)]

(In reply to comment #10)
> (In reply to comment #9)
> > See also bug 56917.
> 
> I kind of wonder why we disable the overlap test at all for 3d transformed layers.
> 
> There's really no reason we couldn't calculate a bounding box for those layers.  The bounding box may not fit perfectly, but we'd still end up potentially generating a lot fewer composited layers.

I think a simpler solution is to use overlap at overflow:hidden boundaries.

[Simon Fraser (smfr)]

I filed bug 62487.

[Simon Fraser (smfr)]

This change will cause extra layers to be created in the following tests:
compositing/tiling/huge-layer-add-remove-child.html
compositing/tiling/huge-layer-resize.html
compositing/tiling/huge-layer.html

[Simon Fraser (smfr)]

http://trac.webkit.org/changeset/88580

[Alexey Proskuryakov]

This change has caused bug 62797.