This changes the behavior of the CanPerformOnCompositorThread methods of
both ElementAnimations and ElementTransitions to check that the
respective animations or transitions are actually running. This is ok
because:
- The main caller is nsLayoutUtils::HasAnimationsForCompositor, and all
of its callers pretty clearly want the more restricted behavior (they're
concerned with layer activity)
- The only other callers of these functions are
nsAnimationManager::FlushAnimations and
nsTransitionManager::FlushTransitions (determining when to do
throttling), nsAnimationManager::GetAnimationsForCompositor (whose
only caller,
nsDisplayListBuilder::AddAnimationsAndTransitionsToLayer, also checks
IsRunningAt). I think these also all want or are fine with having
the IsRunningAt check.
As to the actual changes:
- In the animation manager, I think it's a mistake that
ElementAnimation::IsRunningAt didn't already check
mIterationDuration, since we throw out animations with a bad
iteration-duration in ElementAnimations::EnsureStyleRuleFor. So this
makes that change as well.
- In the transition manager, IsRunningAt already checks
!IsRemovedSentinel().
I've confirmed in gdb on a device that this fixes the repeated
nsIFrame::SchedulePaint calls that were the symptom of this bug.
I believe this patch also makes it so that a short animation of a
property that can't be animated on the compositor doesn't prevent the
entire duration of the animation of a property that can from being
throttled (having the main thread style updates suppressed).
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38a6cfb99b