Bug 868082. Allow SetIsFixedPosition to be used on layers with transforms. In CompositorParent, use the animated transform value as the base transform in CompositorParent::TransformFixedLayers when it has been set by the animation sampler. r=cwiis

--HG--
extra : rebase_source : 3b809428bf8740753a98defc30ad7b7d96339442

gfx/layers/Layers.h

@@ -910,6 +910,12 @@ public:
   uint64_t GetAnimationGeneration() { return mAnimationGeneration; }
   void SetAnimationGeneration(uint64_t aCount) { mAnimationGeneration = aCount; }
 
+  /**
+   * Returns the local transform for this layer: either mTransform or,
+   * for shadow layers, GetShadowTransform()
+   */
+  const gfx3DMatrix GetLocalTransform();
+
   /**
    * DRAWING PHASE ONLY
    *
@@ -1164,12 +1170,6 @@ protected:
   // appends additional info to aTo.
   virtual nsACString& PrintInfo(nsACString& aTo, const char* aPrefix);
 
-  /**
-   * Returns the local transform for this layer: either mTransform or,
-   * for shadow layers, GetShadowTransform()
-   */
-  const gfx3DMatrix GetLocalTransform();
-
   /**
    * Returns the local opacity for this layer: either mOpacity or,
    * for shadow layers, GetShadowOpacity()

gfx/layers/composite/AsyncCompositionManager.cpp

@@ -169,7 +169,14 @@ AsyncCompositionManager::TransformFixedLayers(Layer* aLayer,
     // The transform already takes the resolution scale into account.  Since we
     // will apply the resolution scale again when computing the effective
     // transform, we must apply the inverse resolution scale here.
-    gfx3DMatrix layerTransform = aLayer->GetTransform();
+    LayerComposite* layerComposite = aLayer->AsLayerComposite();
+    gfx3DMatrix layerTransform;
+    if (layerComposite->GetShadowTransformSetByAnimation()) {
+      // Start with the animated transform
+      layerTransform = aLayer->GetLocalTransform();
+    } else {
+      layerTransform = aLayer->GetTransform();
+    }
     Translate2D(layerTransform, translation);
     if (ContainerLayer* c = aLayer->AsContainerLayer()) {
       layerTransform.Scale(1.0f/c->GetPreXScale(),
@@ -179,8 +186,8 @@ AsyncCompositionManager::TransformFixedLayers(Layer* aLayer,
     layerTransform.ScalePost(1.0f/aLayer->GetPostXScale(),
                              1.0f/aLayer->GetPostYScale(),
                              1);
-    LayerComposite* layerComposite = aLayer->AsLayerComposite();
     layerComposite->SetShadowTransform(layerTransform);
+    layerComposite->SetShadowTransformSetByAnimation(false);
 
     const nsIntRect* clipRect = aLayer->GetClipRect();
     if (clipRect) {
@@ -308,6 +315,7 @@ SampleAnimations(Layer* aLayer, TimeStamp aPoint)
       }
       NS_ASSERTION(!aLayer->GetIsFixedPosition(), "Can't animate transforms on fixed-position layers");
       layerComposite->SetShadowTransform(matrix);
+      layerComposite->SetShadowTransformSetByAnimation(true);
       break;
     }
     default:
@@ -378,6 +386,8 @@ AsyncCompositionManager::ApplyAsyncContentTransformToTree(TimeStamp aCurrentFram
                         1.0f/aLayer->GetPostYScale(),
                         1);
     layerComposite->SetShadowTransform(transform);
+    NS_ASSERTION(!layerComposite->GetShadowTransformSetByAnimation(),
+                 "overwriting animated transform!");
 
     TransformFixedLayers(
       aLayer,
@@ -512,6 +522,8 @@ AsyncCompositionManager::TransformScrollableLayer(Layer* aLayer, const gfx3DMatr
                               1.0f/container->GetPostYScale(),
                               1);
   layerComposite->SetShadowTransform(computedTransform);
+  NS_ASSERTION(!layerComposite->GetShadowTransformSetByAnimation(),
+               "overwriting animated transform!");
   TransformFixedLayers(aLayer, fixedOffset, scaleDiff, fixedLayerMargins);
 }
 

gfx/layers/composite/LayerManagerComposite.cpp

@@ -658,6 +658,7 @@ LayerComposite::LayerComposite(LayerManagerComposite *aManager)
   , mCompositor(aManager->GetCompositor())
   , mShadowOpacity(1.0)
   , mUseShadowClipRect(false)
+  , mShadowTransformSetByAnimation(false)
   , mDestroyed(false)
 { }
 

gfx/layers/composite/LayerManagerComposite.h

@@ -331,12 +331,17 @@ public:
   {
     mShadowTransform = aMatrix;
   }
+  void SetShadowTransformSetByAnimation(bool aSetByAnimation)
+  {
+    mShadowTransformSetByAnimation = aSetByAnimation;
+  }
 
   // These getters can be used anytime.
   float GetShadowOpacity() { return mShadowOpacity; }
   const nsIntRect* GetShadowClipRect() { return mUseShadowClipRect ? &mShadowClipRect : nullptr; }
   const nsIntRegion& GetShadowVisibleRegion() { return mShadowVisibleRegion; }
   const gfx3DMatrix& GetShadowTransform() { return mShadowTransform; }
+  bool GetShadowTransformSetByAnimation() { return mShadowTransformSetByAnimation; }
 
 protected:
   gfx3DMatrix mShadowTransform;
@@ -346,6 +351,7 @@ protected:
   RefPtr<Compositor> mCompositor;
   float mShadowOpacity;
   bool mUseShadowClipRect;
+  bool mShadowTransformSetByAnimation;
   bool mDestroyed;
 };
 

gfx/layers/ipc/CompositorParent.cpp

@@ -507,6 +507,7 @@ SetShadowProperties(Layer* aLayer)
   LayerComposite* layerComposite = aLayer->AsLayerComposite();
   // Set the layerComposite's base transform to the layer's base transform.
   layerComposite->SetShadowTransform(aLayer->GetBaseTransform());
+  layerComposite->SetShadowTransformSetByAnimation(false);
   layerComposite->SetShadowVisibleRegion(aLayer->GetVisibleRegion());
   layerComposite->SetShadowClipRect(aLayer->GetClipRect());
   layerComposite->SetShadowOpacity(aLayer->GetOpacity());

layout/base/FrameLayerBuilder.cpp

@@ -2147,12 +2147,7 @@ ContainerState::ProcessDisplayItems(const nsDisplayList& aList,
                                mParameters.mYScale);
       }
 
-      // If a transform layer is marked as fixed then the shadow transform gets
-      // overwritten by CompositorParent when doing scroll compensation on
-      // fixed layers. This means we need to make sure transform layers are not
-      // marked as fixed.
-      ownLayer->SetIsFixedPosition(
-        isFixed && item->GetType() != nsDisplayItem::TYPE_TRANSFORM);
+      ownLayer->SetIsFixedPosition(isFixed);
 
       // Update that layer's clip and visible rects.
       NS_ASSERTION(ownLayer->Manager() == mManager, "Wrong manager");