Bug 1180125 part 3 - Extract DelayedEventDispatcher; r=dbaron

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.

layout/style/AnimationCommon.h

@@ -13,6 +13,7 @@
 #include "nsChangeHint.h"
 #include "nsCSSProperty.h"
 #include "nsDisplayList.h" // For nsDisplayItem::Type
+#include "mozilla/EventDispatcher.h"
 #include "mozilla/MemoryReporting.h"
 #include "mozilla/StyleAnimationValue.h"
 #include "mozilla/dom/Animation.h"
@@ -511,6 +512,72 @@ private:
   nsCSSPseudoElements::Type        mPseudoType;
 };
 
+template <class EventInfo>
+class DelayedEventDispatcher
+{
+public:
+  void QueueEvent(EventInfo&& aEventInfo)
+  {
+    mPendingEvents.AppendElement(mozilla::Forward<EventInfo>(aEventInfo));
+  }
+
+  // Takes a reference to the owning manager's pres context so it can
+  // detect if the pres context is destroyed while dispatching one of
+  // the events.
+  void DispatchEvents(nsPresContext* const & aPresContext)
+  {
+    if (!aPresContext || mPendingEvents.IsEmpty()) {
+      return;
+    }
+
+    EventArray events;
+    mPendingEvents.SwapElements(events);
+    // FIXME: Sort events here in timeline order, then document order
+    for (EventInfo& info : events) {
+      EventDispatcher::Dispatch(info.mElement, aPresContext, &info.mEvent);
+
+      if (!aPresContext) {
+        break;
+      }
+    }
+  }
+
+  void ClearEventQueue() { mPendingEvents.Clear(); }
+  bool HasQueuedEvents() const { return !mPendingEvents.IsEmpty(); }
+
+  // Methods for supporting cycle-collection
+  void Traverse(nsCycleCollectionTraversalCallback* aCallback,
+                const char* aName)
+  {
+    for (EventInfo& info : mPendingEvents) {
+      ImplCycleCollectionTraverse(*aCallback, info.mElement, aName);
+    }
+  }
+  void Unlink() { mPendingEvents.Clear(); }
+
+protected:
+  typedef nsTArray<EventInfo> EventArray;
+
+  EventArray mPendingEvents;
+};
+
+template <class EventInfo>
+inline void
+ImplCycleCollectionUnlink(DelayedEventDispatcher<EventInfo>& aField)
+{
+  aField.Unlink();
+}
+
+template <class EventInfo>
+inline void
+ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
+                            DelayedEventDispatcher<EventInfo>& aField,
+                            const char* aName,
+                            uint32_t aFlags = 0)
+{
+  aField.Traverse(&aCallback, aName);
+}
+
 } // namespace mozilla
 
 #endif /* !defined(mozilla_css_AnimationCommon_h) */

layout/style/nsAnimationManager.cpp

@@ -7,7 +7,6 @@
 #include "nsTransitionManager.h"
 #include "mozilla/dom/CSSAnimationBinding.h"
 
-#include "mozilla/EventDispatcher.h"
 #include "mozilla/MemoryReporting.h"
 #include "mozilla/StyleAnimationValue.h"
 #include "mozilla/dom/DocumentTimeline.h"
@@ -251,10 +250,9 @@ CSSAnimation::QueueEvents()
     StickyTimeDuration elapsedTime =
       std::min(StickyTimeDuration(mEffect->InitialAdvance()),
                computedTiming.mActiveDuration);
-    AnimationEventInfo ei(owningElement, mAnimationName, NS_ANIMATION_START,
-                          elapsedTime,
-                          PseudoTypeAsString(owningPseudoType));
-    manager->QueueEvent(ei);
+    manager->QueueEvent(
+      AnimationEventInfo(owningElement, mAnimationName, NS_ANIMATION_START,
+                         elapsedTime, PseudoTypeAsString(owningPseudoType)));
     // Then have the shared code below append an 'animationend':
     message = NS_ANIMATION_END;
   } else {
@@ -274,9 +272,9 @@ CSSAnimation::QueueEvents()
     elapsedTime = computedTiming.mActiveDuration;
   }
 
-  AnimationEventInfo ei(owningElement, mAnimationName, message, elapsedTime,
-                        PseudoTypeAsString(owningPseudoType));
-  manager->QueueEvent(ei);
+  manager->QueueEvent(
+    AnimationEventInfo(owningElement, mAnimationName, message, elapsedTime,
+                       PseudoTypeAsString(owningPseudoType)));
 }
 
 CommonAnimationManager*
@@ -305,15 +303,7 @@ CSSAnimation::PseudoTypeAsString(nsCSSPseudoElements::Type aPseudoType)
 
 ////////////////////////// nsAnimationManager ////////////////////////////
 
-NS_IMPL_CYCLE_COLLECTION_CLASS(nsAnimationManager)
-NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(nsAnimationManager)
-  tmp->mPendingEvents.Clear();
-NS_IMPL_CYCLE_COLLECTION_UNLINK_END
-NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(nsAnimationManager)
-  for (AnimationEventInfo& info : tmp->mPendingEvents) {
-    ImplCycleCollectionTraverse(cb, info.mElement, "mPendingEvents.mElement");
-  }
-NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+NS_IMPL_CYCLE_COLLECTION(nsAnimationManager, mEventDispatcher)
 
 NS_IMPL_CYCLE_COLLECTING_ADDREF(nsAnimationManager)
 NS_IMPL_CYCLE_COLLECTING_RELEASE(nsAnimationManager)
@@ -366,7 +356,7 @@ nsAnimationManager::SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const
 
   // Measurement of the following members may be added later if DMD finds it is
   // worthwhile:
-  // - mPendingEvents
+  // - mEventDispatcher
 }
 
 /* virtual */ size_t
@@ -537,23 +527,17 @@ nsAnimationManager::CheckAnimationRule(nsStyleContext* aStyleContext,
 
   TimeStamp refreshTime = mPresContext->RefreshDriver()->MostRecentRefresh();
   collection->EnsureStyleRuleFor(refreshTime, EnsureStyleRule_IsNotThrottled);
-  // We don't actually dispatch the mPendingEvents now.  We'll either
+  // We don't actually dispatch the pending events now.  We'll either
   // dispatch them the next time we get a refresh driver notification
   // or the next time somebody calls
   // nsPresShell::FlushPendingNotifications.
-  if (!mPendingEvents.IsEmpty()) {
+  if (mEventDispatcher.HasQueuedEvents()) {
     mPresContext->Document()->SetNeedStyleFlush();
   }
 
   return GetAnimationRule(aElement, aStyleContext->GetPseudoType());
 }
 
-void
-nsAnimationManager::QueueEvent(AnimationEventInfo& aEventInfo)
-{
-  mPendingEvents.AppendElement(aEventInfo);
-}
-
 struct KeyframeData {
   float mKey;
   uint32_t mIndex; // store original order since sort algorithm is not stable
@@ -1022,19 +1006,3 @@ nsAnimationManager::FlushAnimations(FlushFlags aFlags)
 
   MaybeStartOrStopObservingRefreshDriver();
 }
-
-void
-nsAnimationManager::DoDispatchEvents()
-{
-  EventArray events;
-  mPendingEvents.SwapElements(events);
-  // FIXME: Sort events here in timeline order, then document order
-  for (uint32_t i = 0, i_end = events.Length(); i < i_end; ++i) {
-    AnimationEventInfo &info = events[i];
-    EventDispatcher::Dispatch(info.mElement, mPresContext, &info.mEvent);
-
-    if (!mPresContext) {
-      break;
-    }
-  }
-}

layout/style/nsAnimationManager.h

@@ -50,8 +50,6 @@ struct AnimationEventInfo {
   }
 };
 
-typedef InfallibleTArray<AnimationEventInfo> EventArray;
-
 namespace dom {
 
 class CSSAnimation final : public Animation
@@ -281,7 +279,11 @@ public:
   /**
    * Add a pending event.
    */
-  void QueueEvent(mozilla::AnimationEventInfo& aEventInfo);
+  void QueueEvent(mozilla::AnimationEventInfo&& aEventInfo)
+  {
+    mEventDispatcher.QueueEvent(
+      mozilla::Forward<mozilla::AnimationEventInfo>(aEventInfo));
+  }
 
   /**
    * Dispatch any pending events.  We accumulate animationend and
@@ -290,14 +292,8 @@ public:
    * accumulate animationstart events at other points when style
    * contexts are created.
    */
-  void DispatchEvents() {
-    // Fast-path the common case: no events
-    if (!mPendingEvents.IsEmpty()) {
-      DoDispatchEvents();
-    }
-  }
-
-  void ClearEventQueue() { mPendingEvents.Clear(); }
+  void DispatchEvents()  { mEventDispatcher.DispatchEvents(mPresContext); }
+  void ClearEventQueue() { mEventDispatcher.ClearEventQueue(); }
 
 protected:
   virtual ~nsAnimationManager() {}
@@ -315,6 +311,8 @@ protected:
     return true;
   }
 
+  mozilla::DelayedEventDispatcher<mozilla::AnimationEventInfo> mEventDispatcher;
+
 private:
   void BuildAnimations(nsStyleContext* aStyleContext,
                        mozilla::dom::Element* aTarget,
@@ -331,11 +329,6 @@ private:
   static void UpdateCascadeResults(nsStyleContext* aStyleContext,
                                    mozilla::AnimationCollection*
                                      aElementAnimations);
-
-  // The guts of DispatchEvents
-  void DoDispatchEvents();
-
-  mozilla::EventArray mPendingEvents;
 };
 
 #endif /* !defined(nsAnimationManager_h_) */