This patch removes a lot of code involved with observing the refresh driver from
nsAnimationManager and nsTransitionManager now that we no longer need to do
this.
The one piece it does not remove, however, is
AnimationCollection::mNeedsRefreshes since this flag actually serves a secondary
purpose in telling us when the animation style has not changed and so does
not need to be updated. A subsequent patch in this series will rename this
and update the code that makes use of it.
This patch also reworks the dispatch of events in nsRefreshDriver. Previously
the refresh driver would dispatch the transition events for all subdocuments
then the animation events. This arrangement is complicated and not obviously
necessary. This patch simplifies this arrangement by dispatching transition
events and animation events for each document before proceeding to
subdocuments.
In order to sort between events that have the same timestamp we use the
sort order of the corresponding animations so we need to store a pointer
to the animation along with the event.
The elapsedTime member reported on AnimationEvents measures the time from
the *end* of the delay phase (i.e. the beginning of the active interval) to
when the event occurred. However, the AnimationTimeToTimeStamp method
introduced in the previous patch expects a time relative to the animation's
start time (i.e. the *start* of the delay phase). This patch adds a method
that performs the necessary conversion from an elapsedTime to an animation
time before calling AnimationTimeToTimeStamp. It also provides extra handling
for cases such as when the animation's start time has not yet been resolved or
when animation effect has disappeared.
This patch lines up the parameters of AnimationEventInfo and
TransitionEventInfo constructors so that they are more logical and consistent.
Specifically, it groups the element and pseudo type together since they
form a logical pair denoting the event target. For AnimationEventInfo this
patch also places the type of event before the common event parameters since
the event type seems to be more significant.
This patch also performs some miscelleaneous housekeeping: removing some
unnecessary namespace prefixes, whitespace fixes, and making
TransitionEventInfo use the same concrete type to store the target element
as AnimationEventInfo (dom::Element instead of nsIContent).
Currently we define a helper method, InitialAdvance, on KeyframeEffectReadOnly.
However, this method is only used for filling out the elapsedTime member of
AnimationEvents (which are generated by CSS animations). This patch moves this
method to CSSAnimation since it is unneeded for other types of Animations.
In the new composite order arrangement CSSAnimations and CSSTransition have the
following life-cycle:
1. Animation created by markup
=> composite order determined by markup
(e.g. CSS animations use tree order and animation-name order;
CSS transitions use transition trigger order)
2. Animation cancelled by changing markup
=> composite order is undefined
3. Animation is played again using the API
=> composite order is defined by when the animation is first played.
Another way of saying this is that, at the point when the animation is
played, it is appended to the "global animation list".
4. Animation is subsequently cancelled / played => no change
We need a way to know when we are going from 2 to 3. It would seem like we
could do that by setting mAnimationIndex to some sentinel value while it is
in 2. However, even when in 2, although the spec doesn't define the composite
order animations at this point (from an API point of view you can't access these
objects and they don't contribute to style so it doesn't need to be defined), we
sometimes will need to establish an order.
This can happen, for example, when an animation queues events and then is later
cancelled before the events are dispatched. Because we sort events based on
their associated animation at the time of dispatch (for performance reasons) we
need a deterministic order for these idle animations.
We do that (in a subsequent patch in this series) by setting mAnimationIndex
when we transition from 1 to 2. That is, these idle animations are effectively
ordered by when they became idle (which always happens in a deterministic
fashion).
The Web Animations specification has replaced the term "sequence number" with
references to a global animation list. This patch applies similar naming
to our animation structures.
We currently determine if we need refresh driver ticks when composing style
but sometimes we might not need ticks for composing style but we might need
one more tick in order to queue a final end event. Currently, this doesn't
seem to be a problem because FlushAnimations calls Animation::Tick where we
queue up events. When we remove the call to Animation::Tick from
FlushAnimations in order to make FlushAnimations purely responsible for
posting restyles, however, we will create a situation where we might mark an
animation collection as no longer needing refreshes and not simultaneously
queueing the corresponding event. If another animation collection is deleted in
the meantime we may trigger the code that causes us to disassociate from the
refresh driver and the corresponding event will never be dispatched.
Long-term (bug 1195180) we will check if it we can stop observing the refresh
driver and queue events in the same step. Until then, this patch adds a method
to detect this particular situation and uses it to avoid unregistering from
the refresh driver while we still have end events to queue.
We want to move the newly-introduced RequestRestyle call from FlushAnimations
to Animation::Tick. However, nsAnimationManager::CheckAnimationRule calls
Animation::Tick so this would cause us to start posting animation restyles
within a restyle.
Typically, Animations have an effect (currently there is only one type of
effect: KeyframeEffectReadOnly) and when there is any change in timing they
pass it down to their effect. However, the Animation is dependent on the
duration of the effect for determining if it is "finished" or not. As a result,
when an effect's timing changes, the owning Animation needs to know.
(The way this *should* work is that effects should tell their animation or
trigger some chain of events that causes animation's to update themselves.
However, the current implementation of effects is fairly primitive and does
not do this or even have a reference to the owning Animation. When we
implement the script API for updating the timing properties of effects we will
have to fix this but for now it is up to code in layout/style to update the
Animation when it touches the corresponding effect's timing.)
nsAnimationManager::CheckAnimationRule currently does this by calling
Animation::Tick() which ensures the Animation's finished state is updated
accordingly.
Ultimately we want to ensure that Animation::Tick is called exactly once per
frame (and at the appropriate point in that frame) so we'd like to remove this
call from CheckAnimationRule.
This patch achieves that by:
* Making Animation::SetEffect update the animation's timing - this is necessary
for animations that are created by CheckAnimationRule and will be
necessary when once we make Animation.effect writeable from script anyway.
* Calling Animation::SetEffect even for the case when we are updating the
existing effect.
Another side-effect of calling Animation::Tick within
nsAnimationManager::CheckAnimationRule is that CSSAnimation::Tick queues
events. There are some tests (e.g. layout/style/test/test_animations.html) that
assume that animationstart events are dispatched immediately when new
animations are created. That will change with bug 1134163 but for now we
should maintain this existing behavior since changing this might introduce
compatibility issues that are best dealt with as a separate bug rather than
blocking this refactoring. To that end, this patch also explicitly queues
animationstart events for newly-created animations.
nsTransitionManager::WillRefresh and nsAnimationManager::WillRefresh are now
identical and all methods they call exist on CommonAnimationManager so we
can unify them there.
The implementations of FlushAnimations and FlushTransitions should now be all
but equivalent so this patch combines them into a single implementation on
CommonAnimationManager.
Regarding some of the minor differences between the two methods:
* The combined implementation drops the check for an empty list of collections
found only in FlushTransitions. This seems like a very minor optimization
that could possibly cause us to fail to unregister from the refresh driver
if we forgot to do so when removing the last collection.
* The combined implementation uses the loop implementation from FlushAnimations
since it is more compact.
This patch also removes the extra nested scope since it doesn't seem necessary.
Prior to this patch, CSSAnimation defined a method for converting an
nsCSSPseudoElements::Type to a nsString (but only for the set of
pseudo-elements that can have animations). We would like to re-use this
when setting up transition events so this patch moves it to
AnimationCollection. Re-using this method more widely means we can make
a few further simplifications to the code.
This patch extracts a utility class for queueing up a series of EventInfo
objects (of templated type) and then dispatching them. This covers the event
queuing behavior in nsAnimationManager so that we can reuse it in
nsTransitionManager.
The long-term plan is to drop the mozilla::css namespace altogether. Before we
go to much further with refactoring code in AnimationCommon, we should drop
usage of the mozilla::css namespace. Specifically, this patch moves the
CommonAnimationManager and AnimValuesStyleRule classes to the mozilla namespace.
This patch prepares the way for script-generated events by making
event dispatch a separate process that happens after sampling animations.
This will allow us to sample animations from their associated timeline
(removing the need for a further manager to tracker script-generated
animations).
Furthermore, once we sample animations from timelines the order in which they
are sampled is likely to be more or less random so by making event dispatch at
separate step, we have an opportunity to sort the events and dispatch in
a consistent and sensible order. It also ensures that event callbacks will
not be run until all animations (including transitions) have been updated
ensuring they see a consistent view of timing properties.
This patch only affects event handling for CSS animations. Transitions will
be dealt with in a subsequent patch.
Prior to this patch, CSSAnimation defined a method for converting an
nsCSSPseudoElements::Type to a nsString (but only for the set of
pseudo-elements that can have animations). We would like to re-use this
when setting up transition events so this patch moves it to
AnimationCollection. Re-using this method more widely means we can make
a few further simplifications to the code.
This patch extracts a utility class for queueing up a series of EventInfo
objects (of templated type) and then dispatching them. This covers the event
queuing behavior in nsAnimationManager so that we can reuse it in
nsTransitionManager.
The long-term plan is to drop the mozilla::css namespace altogether. Before we
go to much further with refactoring code in AnimationCommon, we should drop
usage of the mozilla::css namespace. Specifically, this patch moves the
CommonAnimationManager and AnimValuesStyleRule classes to the mozilla namespace.
This patch prepares the way for script-generated events by making
event dispatch a separate process that happens after sampling animations.
This will allow us to sample animations from their associated timeline
(removing the need for a further manager to tracker script-generated
animations).
Furthermore, once we sample animations from timelines the order in which they
are sampled is likely to be more or less random so by making event dispatch at
separate step, we have an opportunity to sort the events and dispatch in
a consistent and sensible order. It also ensures that event callbacks will
not be run until all animations (including transitions) have been updated
ensuring they see a consistent view of timing properties.
This patch only affects event handling for CSS animations. Transitions will
be dealt with in a subsequent patch.
The connection between an Animation and an AnimationTimeline is optional. That
is, it is possible to have an Animation without an AnimationTimeline. Until now
we have often just assumed the timeline will be set but eventually we need to
support the possibility of the timeline being null. Indeed, later in this patch
series we will set the timeline out-of-band (i.e. not in the constructor) using
SetTimeline which opens up the possibility that timeline will be null for
a period of time.
This patch paves the way for having an optional timeline by storing the global
used for, e.g. creating promises, on the Animation object itself.
This patch also extends the tests for Element.getAnimations(). It doesn't
actually exercise the code added (it's not actually called yet since it doesn't
need to be for Element.getAnimations) but simply provides a useful regression
and interop test.
This patch re-uses Animation::mSequenceNum to store the index of CSS animations
within their corresponding animation-name property. When the animation is
removed from an animation-name property it reverts to using the default
animation composite order.
This patch also updates Animation::DoCancel to call UpdateTiming instead of
UpdateEffect. This is because UpdateTiming is responsible for updating the
sequence number (when custom composite order is not in effect). When we remove
an animation from animation-name it will be cancelled and at that point we
expect its sequence number to be cleared which will only happen if
UpdateTiming gets called.
In order to sort CSS animation objects correctly, we need to know which
element's animation-name property they appear in, if any. Normally that's
simply the target element of the animation's keyframe effect but it can differ
in the following cases:
1) When script modifies a CSSAnimation's effect to target a different element
(or simply removes the effect altogether). In this case we use the
*owning* element to determine the priority of the animation, not the target
element.
This scenario does not yet occur (bug 1049975).
2) When script creates a CSSAnimation object using the CSSAnimation constructor.
In this case, the owning element should be empty (null) and we should
determine the priority of the animation in the same way as any other
Animation object.
Again, this is not yet supported (or even specced) but will be eventually.
3) When script holds a reference to a CSSAnimation object but then updates the
animation-name property such that the animation object is cancelled. In this
case the owning element should be cleared (null) so we know to not to try and
sort this with regard to any animation-name property.
This is possible using code such as the following:
elem.style.animation = 'a 5s';
var a = elem.getAnimations()[0];
elem.style.animation = 'b 5s';
a.play(); // Bring a back to life
document.timeline.getAnimations();
// ^ At this point we need to know how to sort 'a' and 'b' which depends
// on recognizing that a is no longer part of an animation-name list.
Until we implement bug 1049975, we could support sorting animations without
adding the reference to the owning element by setting a flag on the CSSAnimation
object but (having tried this) it turns out to be cleaner to just introduce this
reference now, particularly since we know we will need it later.
Note that we will also need this information in future to dispatch events to the
correct element in circumstances such as (1) once we separate updating timing
information (including events) from applying animation values.
