Bug 1454550 - Call AnimationHelper::SampleAnimationForEachNode only for layers that have animations. r=kats

This is slightly efficient since we don't need to call
GetBaseAnimationStyle() or we do skip allocating animation data for such case.

MozReview-Commit-ID: BYFNwZsZ1oE

--HG--
extra : rebase_source : 441d7431bd444f1513a32d4da3c206c7df34ed94

gfx/layers/AnimationHelper.cpp

@@ -134,7 +134,7 @@ CompositorAnimationStorage::SetAnimations(uint64_t aId, const AnimationArray& aV
 }
 
 
-bool
+void
 AnimationHelper::SampleAnimationForEachNode(
   TimeStamp aTime,
   AnimationArray& aAnimations,
@@ -142,19 +142,13 @@ AnimationHelper::SampleAnimationForEachNode(
   AnimationValue& aAnimationValue,
   bool& aHasInEffectAnimations)
 {
-  bool activeAnimations = false;
-
-  if (aAnimations.IsEmpty()) {
-    return activeAnimations;
-  }
+  MOZ_ASSERT(!aAnimations.IsEmpty(), "Should be called with animations");
 
   // Process in order, since later aAnimations override earlier ones.
   for (size_t i = 0, iEnd = aAnimations.Length(); i < iEnd; ++i) {
     Animation& animation = aAnimations[i];
     AnimData& animData = aAnimationData[i];
 
-    activeAnimations = true;
-
     MOZ_ASSERT((!animation.originTime().IsNull() &&
                 animation.startTime().type() ==
                   MaybeTimeDuration::TTimeDuration) ||
@@ -258,7 +252,6 @@ AnimationHelper::SampleAnimationForEachNode(
                "All of members of TransformData should be the same");
   }
 #endif
-  return activeAnimations;
 }
 
 struct BogusAnimation {};
@@ -514,6 +507,10 @@ AnimationHelper::SampleAnimations(CompositorAnimationStorage* aStorage,
        !iter.Done(); iter.Next()) {
     bool hasInEffectAnimations = false;
     AnimationArray* animations = iter.UserData();
+    if (animations->IsEmpty()) {
+      continue;
+    }
+
     AnimationValue animationValue;
     InfallibleTArray<AnimData> animationData;
     AnimationHelper::SetAnimations(*animations,

gfx/layers/AnimationHelper.h

@@ -196,10 +196,8 @@ public:
   /**
    * Sample animations based on a given time stamp for a element(layer) with
    * its animation data.
-   * Returns true if there exists compositor animation, and stores corresponding
-   * animated value in |aAnimationValue|.
    */
-  static bool
+  static void
   SampleAnimationForEachNode(TimeStamp aTime,
                              AnimationArray& aAnimations,
                              InfallibleTArray<AnimData>& aAnimationData,

gfx/layers/composite/AsyncCompositionManager.cpp

@@ -649,17 +649,20 @@ SampleAnimations(Layer* aLayer,
       aLayer,
       [&] (Layer* layer)
       {
+        AnimationArray& animations = layer->GetAnimations();
+        if (animations.IsEmpty()) {
+          return;
+        }
+        isAnimating = true;
         bool hasInEffectAnimations = false;
         AnimationValue animationValue = layer->GetBaseAnimationStyle();
-        if (AnimationHelper::SampleAnimationForEachNode(aTime,
-                                                        layer->GetAnimations(),
-                                                        layer->GetAnimationData(),
-                                                        animationValue,
-                                                        hasInEffectAnimations)) {
-          isAnimating = true;
-        }
+        AnimationHelper::SampleAnimationForEachNode(aTime,
+                                                    animations,
+                                                    layer->GetAnimationData(),
+                                                    animationValue,
+                                                    hasInEffectAnimations);
         if (hasInEffectAnimations) {
-          Animation& animation = layer->GetAnimations().LastElement();
+          Animation& animation = animations.LastElement();
           ApplyAnimatedValue(layer,
                              aStorage,
                              animation.property(),