Bug 24436 – With ACCELERATED_COMPOSITING turned on ASSERT in RenderLayer::updateClipRects()

• Component: Layout and Rendering
• Status: RESOLVED FIXED

[Chris Marrin]

Turn on ACCELERATED_COMPOSITING, build debug and run the attached test case. You should see an assert at:

    RenderLayer.cpp:2432

[Chris Marrin]

Created attachment 28374 [details]
Test case showing bug

[Simon Fraser (smfr)]

The problem here is that we use different clip rect roots for painting, and for hit testing. For painting, every composited layer is a clipping root. For hit testing (which happens in software), only elements with transforms are clipping roots.

For now, I think the best solution is to compute temporary clip rects any time we're hit testing in a page with composited content.

[Simon Fraser (smfr)]

Created attachment 28879 [details]
Patch

[Darin Adler]

Comment on attachment 28879 [details]
Patch

Is this going to increase the stack size used by hitTestLayer? How big is ClipRects?

I don't think it's good to name a boolean "temporaryClipRects". That sounds like the name of a variable that stores somre rects in it.

[Simon Fraser (smfr)]

(In reply to comment #4)
> (From update of attachment 28879 [details] [review])
> Is this going to increase the stack size used by hitTestLayer? How big is
> ClipRects?

ClipRects is 3 * sizeof(IntRect) + 4 bytes.

I think it's OK to use more stack space for hit testing transformed elements, since they are uncommon and having deeply nested ones will be very rare.

> I don't think it's good to name a boolean "temporaryClipRects". That sounds
> like the name of a variable that stores somre rects in it.

Agreed, I can fix.

[Dave Hyatt]

Comment on attachment 28879 [details]
Patch

r=me

[Simon Fraser (smfr)]

http://trac.webkit.org/changeset/41951