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In some circumstances when composing style, we tweak the time of the animation
before telling the effect to compose style. This is to avoid visual flicker in
certain situations where the main thread progress is being synchronized with an
animation running on the compositor.
In the past, effects would store their latest sample time locally so when
tweaking the animation time, we would need to call UpdateEffect() after tweaking
the time, and then again after restoring it as otherwise the style composed by
the effect would not reflect the adjusted time.
Now, however, effect's always query their animation for the time so this is no
longer necessary. Furthermore, the actions triggered by UpdateEffect are not
desirable in this case because they can, amongst other things, cause the
associated EffectSet to be destroyed and recreated.
Specifically, Animation::UpdateEffect() calls
KeyframeEffectReadOnly::NotifyAnimationTimingUpdated() which:
* Calls UpdateTargetRegistration which can trigger EffectSet
destruction/creation which is undesirable in this case because we intend to
restore whatever changes we make to the Animation's state and deleting and
recreating the EffectSet will cause any pointers to it to dangle.
* Cause us to possibly reset the "is running on compositor" status.
This too is undesirable since we intend to restore the state of the
Animation immediately after tweaking the hold time so we don't want to
act as if any state has changed.
* Similarly for marking the cascade as possibly needing an update or
requesting a restyle.
In summary, all the actions performed by NotifyAnimationTimingUpdated are
unnecessary and undesirable in this situation where we are temporarily tweaking
an Animation's current time only to restore it immediately afterwards since the
actions are all involved with recognizing actual changes in state.
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|---|---|---|
| .. | ||
| test | ||
| Animation.cpp | ||
| Animation.h | ||
| AnimationComparator.h | ||
| AnimationEffectReadOnly.cpp | ||
| AnimationEffectReadOnly.h | ||
| AnimationEffectTimingReadOnly.cpp | ||
| AnimationEffectTimingReadOnly.h | ||
| AnimationTimeline.cpp | ||
| AnimationTimeline.h | ||
| AnimationUtils.cpp | ||
| AnimationUtils.h | ||
| AnimValuesStyleRule.cpp | ||
| AnimValuesStyleRule.h | ||
| ComputedTimingFunction.cpp | ||
| ComputedTimingFunction.h | ||
| DocumentTimeline.cpp | ||
| DocumentTimeline.h | ||
| EffectCompositor.cpp | ||
| EffectCompositor.h | ||
| EffectSet.cpp | ||
| EffectSet.h | ||
| KeyframeEffect.cpp | ||
| KeyframeEffect.h | ||
| moz.build | ||
| PendingAnimationTracker.cpp | ||
| PendingAnimationTracker.h | ||
| PseudoElementHashEntry.h | ||