Bug 1157066. When reading back the OMTA transfrom of a layer don't include transforms from async panning or zooming. r=kats,birtles

Containerless scrolling means that the pan zoom controller applies it's transforms (to compensate for differences between the state of layout the last time we painted and the current state as composited to the screen) to the layers that are scrolled instead of the container layer that contains the layers that scroll.

When running test_animations_omta.html there is a zoom of 1.306122 applied, and the page is scrolled down to 67 screen pixels (before the test starts, not sure why exactly). Gecko scrolls as close to 67 screen pixels as it can: 67/1.306122 = 51.29689 css pixels, which is 3077.813 appunits. Gecko scrolls to 3078 app units. When AsyncCompositionManager::TransformScrollableLayer runs we calculate the scroll position of gecko and the current scroll position that the pan zoom controller is using. Since there are no async pan or zoom operations taking place these should match. However when the gecko scroll position is calculated we get 3078/60*1.306122 = 67.0040586. So it applies a transform of 0.0040586 to the container layer for the transform that test_animations_omta.html is animating off main thread. When test_animations_omta.html reads the transform of this layer it fails because it's expecting 0 and 0.0040586 is outside of it's epsilon for considering it to be close enough.

gfx/layers/composite/AsyncCompositionManager.cpp

@@ -1030,7 +1030,8 @@ AsyncCompositionManager::TransformScrollableLayer(Layer* aLayer)
 }
 
 bool
-AsyncCompositionManager::TransformShadowTree(TimeStamp aCurrentFrame)
+AsyncCompositionManager::TransformShadowTree(TimeStamp aCurrentFrame,
+                                             TransformsToSkip aSkip)
 {
   PROFILER_LABEL("AsyncCompositionManager", "TransformShadowTree",
     js::ProfileEntry::Category::GRAPHICS);
@@ -1045,6 +1046,7 @@ AsyncCompositionManager::TransformShadowTree(TimeStamp aCurrentFrame)
   // transforms.
   bool wantNextFrame = SampleAnimations(root, aCurrentFrame);
 
+  if (!(aSkip & TransformsToSkip::APZ)) {
     // FIXME/bug 775437: unify this interface with the ~native-fennec
     // derived code
     //
@@ -1071,6 +1073,7 @@ AsyncCompositionManager::TransformShadowTree(TimeStamp aCurrentFrame)
         }
       }
     }
+  }
 
   LayerComposite* rootComposite = root->AsLayerComposite();
 

gfx/layers/composite/AsyncCompositionManager.h

@@ -95,7 +95,9 @@ public:
 
   // Sample transforms for layer trees.  Return true to request
   // another animation frame.
-  bool TransformShadowTree(TimeStamp aCurrentFrame);
+  enum class TransformsToSkip : uint8_t { NoneOfThem = 0, APZ = 1 };
+  bool TransformShadowTree(TimeStamp aCurrentFrame,
+    TransformsToSkip aSkip = TransformsToSkip::NoneOfThem);
 
   // Calculates the correct rotation and applies the transform to
   // our layer manager
@@ -208,6 +210,8 @@ private:
   gfx::Matrix mWorldTransform;
 };
 
+MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS(AsyncCompositionManager::TransformsToSkip)
+
 class MOZ_STACK_CLASS AutoResolveRefLayers {
 public:
   explicit AutoResolveRefLayers(AsyncCompositionManager* aManager) : mManager(aManager)

gfx/layers/ipc/CompositorParent.cpp

@@ -1152,12 +1152,6 @@ CompositorParent::ShadowLayersUpdated(LayerTransactionParent* aLayerTree,
     if (mPaused) {
       DidComposite();
     }
-    // When testing we synchronously update the shadow tree with the animated
-    // values to avoid race conditions when calling GetAnimationTransform etc.
-    // (since the above SetShadowProperties will remove animation effects).
-    if (mIsTesting) {
-      ApplyAsyncProperties(aLayerTree);
-    }
   }
   mLayerManager->NotifyShadowTreeTransaction();
 }
@@ -1210,16 +1204,15 @@ CompositorParent::ApplyAsyncProperties(LayerTransactionParent* aLayerTree)
   // true or when called from test-only methods like
   // LayerTransactionParent::RecvGetAnimationTransform.
 
-  // Synchronously update the layer tree, but only if a composite was already
-  // scehduled.
-  if (aLayerTree->GetRoot() &&
-      (mCurrentCompositeTask ||
-       (mCompositorVsyncObserver &&
-        mCompositorVsyncObserver->NeedsComposite()))) {
+  // Synchronously update the layer tree
+  if (aLayerTree->GetRoot()) {
     AutoResolveRefLayers resolve(mCompositionManager);
+    SetShadowProperties(mLayerManager->GetRoot());
+
     TimeStamp time = mIsTesting ? mTestTime : mLastCompose;
     bool requestNextFrame =
-      mCompositionManager->TransformShadowTree(time);
+      mCompositionManager->TransformShadowTree(time,
+        AsyncCompositionManager::TransformsToSkip::APZ);
     if (!requestNextFrame) {
       CancelCurrentCompositeTask();
       // Pretend we composited in case someone is waiting for this event.

gfx/layers/ipc/LayerTransactionParent.cpp

@@ -664,6 +664,8 @@ LayerTransactionParent::RecvGetOpacity(PLayerParent* aParent,
     return false;
   }
 
+  mShadowLayersManager->ApplyAsyncProperties(this);
+
   *aOpacity = layer->GetLocalOpacity();
   return true;
 }