Reduce the side-effects of animations turning off overlap testing

[Simon Fraser (smfr)]

Some pages have elements that go into and out of compositing layers when animations/transitions on unrelated elements run, because we turn off overlap testing if we see an accelerated transform animation. This unwanted switching into/out of compositing layers can cause flashing in some cases. We should try to avoid it.

One site that shows this is http://t.aol.com with an iPad user agent.

[Radar WebKit Bug Importer]

<rdar://problem/12000100>

[Simon Fraser (smfr)]

Created attachment 248680 [details]
Patch

[Dean Jackson]

Comment on attachment 248680 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=248680&action=review

> Source/WebCore/page/animation/AnimationBase.cpp:742
> +                TransformationMatrix::Decomposed2Type toDecomp;
> +                transform.decompose2(toDecomp);
> +                // Any rotation prevents us from using a simple start/end rect union.
> +                if (toDecomp.angle)
> +                    return false;

Is this the only case? I wonder if a matrix animation to/from a skew would show up with a rotation component.

[WebKit Commit Bot]

Comment on attachment 248680 [details]
Patch

Rejecting attachment 248680 [details] from commit-queue.

Failed to run "['/Volumes/Data/EWS/WebKit/Tools/Scripts/webkit-patch', '--status-host=webkit-queues.appspot.com', '--bot-id=webkit-cq-02', 'apply-attachment', '--no-update', '--non-interactive', 248680, '--port=mac']" exit_code: 2 cwd: /Volumes/Data/EWS/WebKit

Last 500 characters of output:
iting/layer-creation/translate-scale-transition-overlap-expected.txt
patching file LayoutTests/compositing/layer-creation/translate-scale-transition-overlap.html
patching file LayoutTests/compositing/layer-creation/translate-transition-overlap-expected.txt
patching file LayoutTests/compositing/layer-creation/translate-transition-overlap.html

Failed to run "[u'/Volumes/Data/EWS/WebKit/Tools/Scripts/svn-apply', '--force', '--reviewer', u'Dean Jackson']" exit_code: 1 cwd: /Volumes/Data/EWS/WebKit

Full output: http://webkit-queues.appspot.com/results/6138387316604928

[Simon Fraser (smfr)]

https://trac.webkit.org/r181515

[Alexey Proskuryakov]

This made animations/animation-on-inline-crash.html assert on all debug bots:

Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0   com.apple.JavaScriptCore      	0x0000000106efb56a WTFCrashWithSecurityImplication + 42 (Assertions.cpp:335)
1   com.apple.WebCore             	0x000000010b19b5a1 WTF::match_constness<WebCore::RenderElement, WebCore::RenderBox>::type& WTF::downcast<WebCore::RenderBox, WebCore::RenderElement>(WebCore::RenderElement&) + 65 (TypeCasts.h:80)
2   com.apple.WebCore             	0x000000010c0f9065 WebCore::KeyframeAnimation::computeExtentOfTransformAnimation(WebCore::LayoutRect&) const + 117 (KeyframeAnimation.cpp:206)
3   com.apple.WebCore             	0x000000010afc5b78 WebCore::CompositeAnimation::computeExtentOfTransformAnimation(WebCore::LayoutRect&) const + 264 (CompositeAnimation.cpp:417)
4   com.apple.WebCore             	0x000000010ad9797b WebCore::AnimationControllerPrivate::computeExtentOfAnimation(WebCore::RenderElement&, WebCore::LayoutRect&) const + 235 (AnimationController.cpp:429)
5   com.apple.WebCore             	0x000000010ad98372 WebCore::AnimationController::computeExtentOfAnimation(WebCore::RenderElement&, WebCore::LayoutRect&) const + 98 (AnimationController.cpp:597)

[Simon Fraser (smfr)]

Assertion fixed in https://trac.webkit.org/r181521