Bug 1171966 - Update SMIL animation styles only when there are pendin…

…g change

dom/smil/nsSMILAnimationController.cpp

@@ -32,6 +32,7 @@ nsSMILAnimationController::nsSMILAnimationController(nsIDocument* aDoc)
     mDeferredStartSampling(false),
     mRunningSample(false),
     mRegisteredWithRefreshDriver(false),
+	mMightHavePendingStyleUpdates(false),
     mDocument(aDoc)
 {
   MOZ_ASSERT(aDoc, "need a non-null document");
@@ -459,6 +460,7 @@ nsSMILAnimationController::DoSample(bool aSkipUnchangedContainers)
   // when the inherited value is *also* being animated, we really should be
   // traversing our animated nodes in an ancestors-first order (bug 501183)
   currentCompositorTable->EnumerateEntries(DoComposeAttribute, nullptr);
+  mMightHavePendingStyleUpdates = true;
 
   // Update last compositor table
   mLastCompositorTable = currentCompositorTable.forget();
@@ -843,7 +845,12 @@ nsSMILAnimationController::AddStyleUpdate(AnimationElementPtrKey* aKey,
 void
 nsSMILAnimationController::AddStyleUpdatesTo(RestyleTracker& aTracker)
 {
+  MOZ_ASSERT(mMightHavePendingStyleUpdates,
+             "Should only add style updates when we think we might have some");
+
   mAnimationElementTable.EnumerateEntries(AddStyleUpdate, &aTracker);
+
+  mMightHavePendingStyleUpdates = false;
 }
 
 //----------------------------------------------------------------------

dom/smil/nsSMILAnimationController.h

@@ -74,10 +74,8 @@ class nsSMILAnimationController final : public nsSMILTimeContainer,
 
   void SetResampleNeeded()
   {
-    if (!mRunningSample) {
-      if (!mResampleNeeded) {
-        FlagDocumentNeedsFlush();
-      }
+    if (!mRunningSample && !mResampleNeeded) {
+      FlagDocumentNeedsFlush();
       mResampleNeeded = true;
     }
   }
@@ -104,11 +102,17 @@ class nsSMILAnimationController final : public nsSMILTimeContainer,
   void NotifyRefreshDriverDestroying(nsRefreshDriver* aRefreshDriver);
 
   // Helper to check if we have any animation elements at all
-  bool HasRegisteredAnimations()
-  { return mAnimationElementTable.Count() != 0; }
+  bool HasRegisteredAnimations() const
+  {
+    return mAnimationElementTable.Count() != 0;
+  }
 
   void AddStyleUpdatesTo(mozilla::RestyleTracker& aTracker);
-
+  bool MightHavePendingStyleUpdates() const
+  {
+    return mMightHavePendingStyleUpdates;
+  }
+
 protected:
   ~nsSMILAnimationController();
 
@@ -224,6 +228,9 @@ class nsSMILAnimationController final : public nsSMILTimeContainer,
 
   // Are we registered with our document's refresh driver?
   bool                       mRegisteredWithRefreshDriver;
+
+  // Have we updated animated values without adding them to the restyle tracker?
+  bool                       mMightHavePendingStyleUpdates;
 
   // Store raw ptr to mDocument.  It owns the controller, so controller
   // shouldn't outlive it

layout/base/RestyleManager.cpp

@@ -1737,18 +1737,14 @@ RestyleManager::UpdateOnlyAnimationStyles()
   bool doCSS = mLastUpdateForThrottledAnimations != now;
   mLastUpdateForThrottledAnimations = now;
 
-  bool doSMIL = false;
+
   nsIDocument* document = mPresContext->Document();
-  nsSMILAnimationController* animationController = nullptr;
-  if (document->HasAnimationController()) {
-    animationController = document->GetAnimationController();
-    // FIXME:  Ideally, we only want to do this if animation timelines
-    // have advanced.  However, different SMIL animations could be
-    // getting their time from different outermost SVG elements, so
-    // finding all of them might be a pain.  So this could be optimized
-    // to set doSMIL to true in fewer cases.
-    doSMIL = true;
-  }
+  nsSMILAnimationController* animationController =
+    document->HasAnimationController() ?
+    document->GetAnimationController() :
+    nullptr;
+  bool doSMIL = animationController &&
+                animationController->MightHavePendingStyleUpdates();
 
   if (!doCSS && !doSMIL) {
     return;