C++ PendingAnimationTracker类代码示例

bool
Animation::IsPossiblyOrphanedPendingAnimation() const
{
  // Check if we are pending but might never start because we are not being
  // tracked.
  //
  // This covers the following cases:
  //
  // * We started playing but our effect's target element was orphaned
  //   or bound to a different document.
  //   (note that for the case of our effect changing we should handle
  //   that in SetEffect)
  // * We started playing but our timeline became inactive.
  //   In this case the pending animation tracker will drop us from its hashmap
  //   when we have been painted.
  // * When we started playing we couldn't find a PendingAnimationTracker to
  //   register with (perhaps the effect had no document) so we simply
  //   set mPendingState in DoPlay and relied on this method to catch us on the
  //   next tick.

  // If we're not pending we're ok.
  if (mPendingState == PendingState::NotPending) {
    return false;
  }

  // If we have a pending ready time then we will be started on the next
  // tick.
  if (!mPendingReadyTime.IsNull()) {
    return false;
  }

  // If we don't have an active timeline then we shouldn't start until
  // we do.
  if (!mTimeline || mTimeline->GetCurrentTime().IsNull()) {
    return false;
  }

  // If we have no rendered document, or we're not in our rendered document's
  // PendingAnimationTracker then there's a good chance no one is tracking us.
  //
  // If we're wrong and another document is tracking us then, at worst, we'll
  // simply start/pause the animation one tick too soon. That's better than
  // never starting/pausing the animation and is unlikely.
  nsIDocument* doc = GetRenderedDocument();
  if (!doc) {
    return false;
  }

  PendingAnimationTracker* tracker = doc->GetPendingAnimationTracker();
  return !tracker ||
         (!tracker->IsWaitingToPlay(*this) &&
          !tracker->IsWaitingToPause(*this));
}

// https://w3c.github.io/web-animations/#pause-an-animation
void
Animation::DoPause(ErrorResult& aRv)
{
  if (IsPausedOrPausing()) {
    return;
  }

  AutoMutationBatchForAnimation mb(*this);

  // If we are transitioning from idle, fill in the current time
  if (GetCurrentTime().IsNull()) {
    if (mPlaybackRate >= 0.0) {
      mHoldTime.SetValue(TimeDuration(0));
    } else {
      if (EffectEnd() == TimeDuration::Forever()) {
        aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
        return;
      }
      mHoldTime.SetValue(TimeDuration(EffectEnd()));
    }
  }

  bool reuseReadyPromise = false;
  if (mPendingState == PendingState::PlayPending) {
    CancelPendingTasks();
    reuseReadyPromise = true;
  }

  if (!reuseReadyPromise) {
    // Clear ready promise. We'll create a new one lazily.
    mReady = nullptr;
  }

  mPendingState = PendingState::PausePending;

  nsIDocument* doc = GetRenderedDocument();
  if (doc) {
    PendingAnimationTracker* tracker =
      doc->GetOrCreatePendingAnimationTracker();
    tracker->AddPausePending(*this);
  } else {
    TriggerOnNextTick(Nullable<TimeDuration>());
  }

  UpdateTiming(SeekFlag::NoSeek, SyncNotifyFlag::Async);
  if (IsRelevant()) {
    nsNodeUtils::AnimationChanged(this);
  }
}

// http://w3c.github.io/web-animations/#pause-an-animation
void
Animation::DoPause(ErrorResult& aRv)
{
  if (IsPausedOrPausing()) {
    return;
  }

  // If we are transitioning from idle, fill in the current time
  if (GetCurrentTime().IsNull()) {
    if (mPlaybackRate >= 0.0) {
      mHoldTime.SetValue(TimeDuration(0));
    } else {
      if (EffectEnd() == TimeDuration::Forever()) {
        aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
        return;
      }
      mHoldTime.SetValue(TimeDuration(EffectEnd()));
    }
  }

  bool reuseReadyPromise = false;
  if (mPendingState == PendingState::PlayPending) {
    CancelPendingTasks();
    reuseReadyPromise = true;
  }

  // Mark this as no longer running on the compositor so that next time
  // we update animations we won't throttle them and will have a chance
  // to remove the animation from any layer it might be on.
  mIsRunningOnCompositor = false;

  if (!reuseReadyPromise) {
    // Clear ready promise. We'll create a new one lazily.
    mReady = nullptr;
  }

  mPendingState = PendingState::PausePending;

  nsIDocument* doc = GetRenderedDocument();
  if (doc) {
    PendingAnimationTracker* tracker =
      doc->GetOrCreatePendingAnimationTracker();
    tracker->AddPausePending(*this);
  } else {
    TriggerOnNextTick(Nullable<TimeDuration>());
  }

  UpdateTiming(SeekFlag::NoSeek, SyncNotifyFlag::Async);
}

VectorImage::RequestRefresh(const TimeStamp& aTime)
{
  if (HadRecentRefresh(aTime)) {
    return;
  }

  PendingAnimationTracker* tracker =
    mSVGDocumentWrapper->GetDocument()->GetPendingAnimationTracker();
  if (tracker && ShouldAnimate()) {
    tracker->TriggerPendingAnimationsOnNextTick(aTime);
  }

  EvaluateAnimation();

  mSVGDocumentWrapper->TickRefreshDriver();

  if (mHasPendingInvalidation) {
    mHasPendingInvalidation = false;
    SendInvalidationNotifications();
  }
}

// http://w3c.github.io/web-animations/#pause-an-animation
void
Animation::DoPause()
{
  if (IsPausedOrPausing()) {
    return;
  }

  bool reuseReadyPromise = false;
  if (mPendingState == PendingState::PlayPending) {
    CancelPendingTasks();
    reuseReadyPromise = true;
  }

  // Mark this as no longer running on the compositor so that next time
  // we update animations we won't throttle them and will have a chance
  // to remove the animation from any layer it might be on.
  mIsRunningOnCompositor = false;

  if (!reuseReadyPromise) {
    // Clear ready promise. We'll create a new one lazily.
    mReady = nullptr;
  }

  mPendingState = PendingState::PausePending;

  nsIDocument* doc = GetRenderedDocument();
  if (!doc) {
    TriggerOnNextTick(Nullable<TimeDuration>());
    return;
  }

  PendingAnimationTracker* tracker = doc->GetOrCreatePendingAnimationTracker();
  tracker->AddPausePending(*this);

  UpdateFinishedState();
}

// https://w3c.github.io/web-animations/#play-an-animation
void
Animation::PlayNoUpdate(ErrorResult& aRv, LimitBehavior aLimitBehavior)
{
  AutoMutationBatchForAnimation mb(*this);

  bool abortedPause = mPendingState == PendingState::PausePending;

  Nullable<TimeDuration> currentTime = GetCurrentTime();
  if (mPlaybackRate > 0.0 &&
      (currentTime.IsNull() ||
       (aLimitBehavior == LimitBehavior::AutoRewind &&
        (currentTime.Value() < TimeDuration() ||
         currentTime.Value() >= EffectEnd())))) {
    mHoldTime.SetValue(TimeDuration(0));
  } else if (mPlaybackRate < 0.0 &&
             (currentTime.IsNull() ||
              (aLimitBehavior == LimitBehavior::AutoRewind &&
               (currentTime.Value() <= TimeDuration() ||
                currentTime.Value() > EffectEnd())))) {
    if (EffectEnd() == TimeDuration::Forever()) {
      aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
      return;
    }
    mHoldTime.SetValue(TimeDuration(EffectEnd()));
  } else if (mPlaybackRate == 0.0 && currentTime.IsNull()) {
    mHoldTime.SetValue(TimeDuration(0));
  }

  bool reuseReadyPromise = false;
  if (mPendingState != PendingState::NotPending) {
    CancelPendingTasks();
    reuseReadyPromise = true;
  }

  // If the hold time is null then we're either already playing normally (and
  // we can ignore this call) or we aborted a pending pause operation (in which
  // case, for consistency, we need to go through the motions of doing an
  // asynchronous start even though we already have a resolved start time).
  if (mHoldTime.IsNull() && !abortedPause) {
    return;
  }

  // Clear the start time until we resolve a new one. We do this except
  // for the case where we are aborting a pause and don't have a hold time.
  //
  // If we're aborting a pause and *do* have a hold time (e.g. because
  // the animation is finished or we just applied the auto-rewind behavior
  // above) we should respect it by clearing the start time. If we *don't*
  // have a hold time we should keep the current start time so that the
  // the animation continues moving uninterrupted by the aborted pause.
  //
  // (If we're not aborting a pause, mHoldTime must be resolved by now
  //  or else we would have returned above.)
  if (!mHoldTime.IsNull()) {
    mStartTime.SetNull();
  }

  if (!reuseReadyPromise) {
    // Clear ready promise. We'll create a new one lazily.
    mReady = nullptr;
  }

  mPendingState = PendingState::PlayPending;

  nsIDocument* doc = GetRenderedDocument();
  if (doc) {
    PendingAnimationTracker* tracker =
      doc->GetOrCreatePendingAnimationTracker();
    tracker->AddPlayPending(*this);
  } else {
    TriggerOnNextTick(Nullable<TimeDuration>());
  }

  UpdateTiming(SeekFlag::NoSeek, SyncNotifyFlag::Async);
  if (IsRelevant()) {
    nsNodeUtils::AnimationChanged(this);
  }
}

// https://w3c.github.io/web-animations/#setting-the-target-effect
void
Animation::SetEffectNoUpdate(AnimationEffectReadOnly* aEffect)
{
  RefPtr<Animation> kungFuDeathGrip(this);

  if (mEffect == aEffect) {
    return;
  }

  AutoMutationBatchForAnimation mb(*this);
  bool wasRelevant = mIsRelevant;

  if (mEffect) {
    if (!aEffect) {
      // If the new effect is null, call ResetPendingTasks before clearing
      // mEffect since ResetPendingTasks needs it to get the appropriate
      // PendingAnimationTracker.
      ResetPendingTasks();
    }

    // We need to notify observers now because once we set mEffect to null
    // we won't be able to find the target element to notify.
    if (mIsRelevant) {
      nsNodeUtils::AnimationRemoved(this);
    }

    // Break links with the old effect and then drop it.
    RefPtr<AnimationEffectReadOnly> oldEffect = mEffect;
    mEffect = nullptr;
    oldEffect->SetAnimation(nullptr);

    // The following will not do any notification because mEffect is null.
    UpdateRelevance();
  }

  if (aEffect) {
    // Break links from the new effect to its previous animation, if any.
    RefPtr<AnimationEffectReadOnly> newEffect = aEffect;
    Animation* prevAnim = aEffect->GetAnimation();
    if (prevAnim) {
      prevAnim->SetEffect(nullptr);
    }

    // Create links with the new effect. SetAnimation(this) will also update
    // mIsRelevant of this animation, and then notify mutation observer if
    // needed by calling Animation::UpdateRelevance(), so we don't need to
    // call it again.
    mEffect = newEffect;
    mEffect->SetAnimation(this);

    // Notify possible add or change.
    // If the target is different, the change notification will be ignored by
    // AutoMutationBatchForAnimation.
    if (wasRelevant && mIsRelevant) {
      nsNodeUtils::AnimationChanged(this);
    }

    // Reschedule pending pause or pending play tasks.
    // If we have a pending animation, it will either be registered
    // in the pending animation tracker and have a null pending ready time,
    // or, after it has been painted, it will be removed from the tracker
    // and assigned a pending ready time.
    // After updating the effect we'll typically need to repaint so if we've
    // already been assigned a pending ready time, we should clear it and put
    // the animation back in the tracker.
    if (!mPendingReadyTime.IsNull()) {
      mPendingReadyTime.SetNull();

      nsIDocument* doc = GetRenderedDocument();
      if (doc) {
        PendingAnimationTracker* tracker =
          doc->GetOrCreatePendingAnimationTracker();
        if (mPendingState == PendingState::PlayPending) {
          tracker->AddPlayPending(*this);
        } else {
          tracker->AddPausePending(*this);
        }
      }
    }
  }

  UpdateTiming(SeekFlag::NoSeek, SyncNotifyFlag::Async);
}