Bug 95235 – [chromium] Do not clip root layer's subtree to viewport

• Component: Layout and Rendering
• Status: RESOLVED FIXED

[Shawn Singh]

The root layer's renderSurface should be clipped to the viewport's bounds (like it is now), but the root layer should not propagate that clipRect further down the subtree.

Advantages of making this change:
 - root layer becomes less special, and in a separate patch it should be possible to simplify calcDrawTransforms nicely because of this
 - renderSurfaces can remain more cacheable because they will not change size because of getting clipped.
 - makes visibleContentRect and drawableContentRect behavior more consistent across all layers, regardless of whether they contribute to root surface or other surface.

This patch will slightly change expected results of visibleContentRect and drawableContentRect in 94542 (in a clean positive way).

[Shawn Singh]

Created attachment 161081 [details]
Patch

It seemed to me that fixing the unit tests by adding parent->setMasksToBounds(true) was reasonable, since it still retains the real underlying purpose and intent behind the tests.  Tested on OSX, manual, layout, and unit tests, no obvious regressions

[Dana Jansens]

Comment on attachment 161081 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=161081&action=review

> Source/WebKit/chromium/tests/CCOcclusionTrackerTest.cpp:956
> +        parent->setMasksToBounds(true);

I think this could just go in createRoot() and then you don't have to edit every test.

[Shawn Singh]

(In reply to comment #2)
> (From update of attachment 161081 [details])
> View in context: https://bugs.webkit.org/attachment.cgi?id=161081&action=review
> 
> > Source/WebKit/chromium/tests/CCOcclusionTrackerTest.cpp:956
> > +        parent->setMasksToBounds(true);
> 
> I think this could just go in createRoot() and then you don't have to edit every test.

I can do that, sure.   I felt like it would have been better to only affect the tests that really needed it, though.

[Dana Jansens]

Comment on attachment 161081 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=161081&action=review

>>> Source/WebKit/chromium/tests/CCOcclusionTrackerTest.cpp:956
>>> +        parent->setMasksToBounds(true);
>> 
>> I think this could just go in createRoot() and then you don't have to edit every test.
> 
> I can do that, sure.   I felt like it would have been better to only affect the tests that really needed it, though.

oh I see. that's fine too then :)

[Adrienne Walker]

Comment on attachment 161081 [details]
Patch

R=me.

[Shawn Singh]

Committed r127017: <http://trac.webkit.org/changeset/127017>