Bug 1006084 - Allow ThebesLayers to be recreated when the creation hint changes. r=mattwoodrow

gfx/layers/Layers.h

@@ -357,6 +357,13 @@ public:
     NONE, SCROLLABLE
   };
 
+  /**
+   * Returns true if aLayer is optimized for the given ThebesLayerCreationHint.
+   */
+  virtual bool IsOptimizedFor(ThebesLayer* aLayer,
+                              ThebesLayerCreationHint aCreationHint)
+  { return true; }
+
   /**
    * CONSTRUCTION PHASE ONLY
    * Create a ThebesLayer for this manager's layer tree.
@@ -1549,6 +1556,8 @@ public:
     ComputeEffectiveTransformForMaskLayer(aTransformToSurface);
   }
 
+  LayerManager::ThebesLayerCreationHint GetCreationHint() const { return mCreationHint; }
+
   bool UsedForReadback() { return mUsedForReadback; }
   void SetUsedForReadback(bool aUsed) { mUsedForReadback = aUsed; }
   /**
@@ -1562,9 +1571,11 @@ public:
   gfxPoint GetResidualTranslation() const { return mResidualTranslation; }
 
 protected:
-  ThebesLayer(LayerManager* aManager, void* aImplData)
+  ThebesLayer(LayerManager* aManager, void* aImplData,
+              LayerManager::ThebesLayerCreationHint aCreationHint = LayerManager::NONE)
     : Layer(aManager, aImplData)
     , mValidRegion()
+    , mCreationHint(aCreationHint)
     , mUsedForReadback(false)
     , mAllowResidualTranslation(false)
   {
@@ -1580,6 +1591,10 @@ protected:
    */
   gfxPoint mResidualTranslation;
   nsIntRegion mValidRegion;
+  /**
+   * The creation hint that was used when constructing this layer.
+   */
+  const LayerManager::ThebesLayerCreationHint mCreationHint;
   /**
    * Set when this ThebesLayer is participating in readback, i.e. some
    * ReadbackLayer (may) be getting its background from this layer.

gfx/layers/client/ClientLayerManager.h

@@ -73,6 +73,8 @@ public:
 
   virtual void Mutated(Layer* aLayer);
 
+  virtual bool IsOptimizedFor(ThebesLayer* aLayer, ThebesLayerCreationHint aHint);
+
   virtual already_AddRefed<ThebesLayer> CreateThebesLayer();
   virtual already_AddRefed<ThebesLayer> CreateThebesLayerWithHint(ThebesLayerCreationHint aHint);
   virtual already_AddRefed<ContainerLayer> CreateContainerLayer();

gfx/layers/client/ClientThebesLayer.cpp

@@ -127,6 +127,22 @@ ClientThebesLayer::RenderLayer()
   mContentClient->EndPaint();
 }
 
+bool
+ClientLayerManager::IsOptimizedFor(ThebesLayer* aLayer, ThebesLayerCreationHint aHint)
+{
+#ifdef MOZ_B2G
+  // The only creation hint is whether the layer is scrollable or not, and this
+  // is only respected on B2G, where it's used to determine whether to use
+  // tiled layers or not.
+  // There are pretty nasty performance consequences for not using tiles on
+  // large, scrollable layers, so we want the layer to be recreated in this
+  // situation.
+  return aHint == aLayer->GetCreationHint();
+#else
+  return LayerManager::IsOptimizedFor(aLayer, aHint);
+#endif
+}
+
 already_AddRefed<ThebesLayer>
 ClientLayerManager::CreateThebesLayer()
 {
@@ -150,19 +166,19 @@ ClientLayerManager::CreateThebesLayerWithHint(ThebesLayerCreationHint aHint)
     }
     if (gfxPrefs::LayersUseSimpleTiles()) {
       nsRefPtr<SimpleClientTiledThebesLayer> layer =
-        new SimpleClientTiledThebesLayer(this);
+        new SimpleClientTiledThebesLayer(this, aHint);
       CREATE_SHADOW(Thebes);
       return layer.forget();
     } else {
       nsRefPtr<ClientTiledThebesLayer> layer =
-        new ClientTiledThebesLayer(this);
+        new ClientTiledThebesLayer(this, aHint);
       CREATE_SHADOW(Thebes);
       return layer.forget();
     }
   } else
   {
     nsRefPtr<ClientThebesLayer> layer =
-      new ClientThebesLayer(this);
+      new ClientThebesLayer(this, aHint);
     CREATE_SHADOW(Thebes);
     return layer.forget();
   }

gfx/layers/client/ClientThebesLayer.h

@@ -27,15 +27,17 @@ class CompositableClient;
 class ShadowableLayer;
 class SpecificLayerAttributes;
 
-class ClientThebesLayer : public ThebesLayer, 
+class ClientThebesLayer : public ThebesLayer,
                           public ClientLayer {
 public:
   typedef RotatedContentBuffer::PaintState PaintState;
   typedef RotatedContentBuffer::ContentType ContentType;
 
-  ClientThebesLayer(ClientLayerManager* aLayerManager) :
+  ClientThebesLayer(ClientLayerManager* aLayerManager,
+                    LayerManager::ThebesLayerCreationHint aCreationHint = LayerManager::NONE) :
     ThebesLayer(aLayerManager,
-                static_cast<ClientLayer*>(MOZ_THIS_IN_INITIALIZER_LIST())),
+                static_cast<ClientLayer*>(MOZ_THIS_IN_INITIALIZER_LIST()),
+                aCreationHint),
     mContentClient(nullptr)
   {
     MOZ_COUNT_CTOR(ClientThebesLayer);

gfx/layers/client/ClientTiledThebesLayer.cpp

@@ -29,9 +29,11 @@ namespace mozilla {
 namespace layers {
 
 
-ClientTiledThebesLayer::ClientTiledThebesLayer(ClientLayerManager* const aManager)
+ClientTiledThebesLayer::ClientTiledThebesLayer(ClientLayerManager* const aManager,
+                                               ClientLayerManager::ThebesLayerCreationHint aCreationHint)
   : ThebesLayer(aManager,
-                static_cast<ClientLayer*>(MOZ_THIS_IN_INITIALIZER_LIST()))
+                static_cast<ClientLayer*>(MOZ_THIS_IN_INITIALIZER_LIST()),
+                aCreationHint)
   , mContentClient()
 {
   MOZ_COUNT_CTOR(ClientTiledThebesLayer);

gfx/layers/client/ClientTiledThebesLayer.h

@@ -41,7 +41,8 @@ class ClientTiledThebesLayer : public ThebesLayer,
   typedef ThebesLayer Base;
 
 public:
-  ClientTiledThebesLayer(ClientLayerManager* const aManager);
+  ClientTiledThebesLayer(ClientLayerManager* const aManager,
+                         ClientLayerManager::ThebesLayerCreationHint aCreationHint = LayerManager::NONE);
   ~ClientTiledThebesLayer();
 
   // Override name to distinguish it from ClientThebesLayer in layer dumps

gfx/layers/client/SimpleTiledContentClient.cpp

@@ -247,9 +247,11 @@ SimpleTiledContentClient::UseTiledLayerBuffer()
   mTiledBuffer.ClearPaintedRegion();
 }
 
-SimpleClientTiledThebesLayer::SimpleClientTiledThebesLayer(ClientLayerManager* aManager)
+SimpleClientTiledThebesLayer::SimpleClientTiledThebesLayer(ClientLayerManager* aManager,
+                                                           ClientLayerManager::ThebesLayerCreationHint aCreationHint)
   : ThebesLayer(aManager,
-                static_cast<ClientLayer*>(MOZ_THIS_IN_INITIALIZER_LIST()))
+                static_cast<ClientLayer*>(MOZ_THIS_IN_INITIALIZER_LIST()),
+                aCreationHint)
   , mContentClient()
 {
   MOZ_COUNT_CTOR(SimpleClientTiledThebesLayer);

gfx/layers/client/SimpleTiledContentClient.h

@@ -159,7 +159,8 @@ class SimpleClientTiledThebesLayer : public ThebesLayer,
   typedef ThebesLayer Base;
 
 public:
-  SimpleClientTiledThebesLayer(ClientLayerManager* const aManager);
+  SimpleClientTiledThebesLayer(ClientLayerManager* const aManager,
+                               ClientLayerManager::ThebesLayerCreationHint aCreationHint = LayerManager::NONE);
   ~SimpleClientTiledThebesLayer();
 
   // Thebes Layer

layout/base/FrameLayerBuilder.cpp

@@ -1446,74 +1446,85 @@ ContainerState::CreateOrRecycleThebesLayer(const nsIFrame* aAnimatedGeometryRoot
   // We need a new thebes layer
   nsRefPtr<ThebesLayer> layer;
   ThebesDisplayItemLayerUserData* data;
+  bool layerRecycled = false;
 #ifndef MOZ_ANDROID_OMTC
   bool didResetScrollPositionForLayerPixelAlignment = false;
 #endif
+
+  // Check whether the layer will be scrollable. This is used as a hint to
+  // influence whether tiled layers are used or not.
+  LayerManager::ThebesLayerCreationHint creationHint = LayerManager::NONE;
+  nsIFrame* animatedGeometryRootParent = aAnimatedGeometryRoot->GetParent();
+  if (animatedGeometryRootParent &&
+      animatedGeometryRootParent->GetType() == nsGkAtoms::scrollFrame) {
+    creationHint = LayerManager::SCROLLABLE;
+  }
+
   if (mNextFreeRecycledThebesLayer < mRecycledThebesLayers.Length()) {
-    // Recycle a layer
+    // Try to recycle a layer
     layer = mRecycledThebesLayers[mNextFreeRecycledThebesLayer];
     ++mNextFreeRecycledThebesLayer;
-    // Clear clip rect and mask layer so we don't accidentally stay clipped.
-    // We will reapply any necessary clipping.
-    layer->SetMaskLayer(nullptr);
 
-    data = static_cast<ThebesDisplayItemLayerUserData*>
-        (layer->GetUserData(&gThebesDisplayItemLayerUserData));
-    NS_ASSERTION(data, "Recycled ThebesLayers must have user data");
+    // Check if the layer hint has changed and whether or not the layer should
+    // be recreated because of it.
+    if (mManager->IsOptimizedFor(layer->AsThebesLayer(), creationHint)) {
+      layerRecycled = true;
 
-    // This gets called on recycled ThebesLayers that are going to be in the
-    // final layer tree, so it's a convenient time to invalidate the
-    // content that changed where we don't know what ThebesLayer it belonged
-    // to, or if we need to invalidate the entire layer, we can do that.
-    // This needs to be done before we update the ThebesLayer to its new
-    // transform. See nsGfxScrollFrame::InvalidateInternal, where
-    // we ensure that mInvalidThebesContent is updated according to the
-    // scroll position as of the most recent paint.
-    if (!FuzzyEqual(data->mXScale, mParameters.mXScale, 0.00001f) ||
-        !FuzzyEqual(data->mYScale, mParameters.mYScale, 0.00001f) ||
-        data->mAppUnitsPerDevPixel != mAppUnitsPerDevPixel) {
+      // Clear clip rect and mask layer so we don't accidentally stay clipped.
+      // We will reapply any necessary clipping.
+      layer->SetMaskLayer(nullptr);
+
+      data = static_cast<ThebesDisplayItemLayerUserData*>
+          (layer->GetUserData(&gThebesDisplayItemLayerUserData));
+      NS_ASSERTION(data, "Recycled ThebesLayers must have user data");
+
+      // This gets called on recycled ThebesLayers that are going to be in the
+      // final layer tree, so it's a convenient time to invalidate the
+      // content that changed where we don't know what ThebesLayer it belonged
+      // to, or if we need to invalidate the entire layer, we can do that.
+      // This needs to be done before we update the ThebesLayer to its new
+      // transform. See nsGfxScrollFrame::InvalidateInternal, where
+      // we ensure that mInvalidThebesContent is updated according to the
+      // scroll position as of the most recent paint.
+      if (!FuzzyEqual(data->mXScale, mParameters.mXScale, 0.00001f) ||
+          !FuzzyEqual(data->mYScale, mParameters.mYScale, 0.00001f) ||
+          data->mAppUnitsPerDevPixel != mAppUnitsPerDevPixel) {
 #ifdef MOZ_DUMP_PAINTING
-    if (nsLayoutUtils::InvalidationDebuggingIsEnabled()) {
-      printf_stderr("Recycled layer %p changed scale\n", layer.get());
-    }
+      if (nsLayoutUtils::InvalidationDebuggingIsEnabled()) {
+        printf_stderr("Recycled layer %p changed scale\n", layer.get());
+      }
 #endif
-      InvalidateEntireThebesLayer(layer, aAnimatedGeometryRoot);
+        InvalidateEntireThebesLayer(layer, aAnimatedGeometryRoot);
 #ifndef MOZ_ANDROID_OMTC
-      didResetScrollPositionForLayerPixelAlignment = true;
+        didResetScrollPositionForLayerPixelAlignment = true;
 #endif
-    }
-    if (!data->mRegionToInvalidate.IsEmpty()) {
-#ifdef MOZ_DUMP_PAINTING
-      if (nsLayoutUtils::InvalidationDebuggingIsEnabled()) {
-        printf_stderr("Invalidating deleted frame content from layer %p\n", layer.get());
       }
-#endif
-      layer->InvalidateRegion(data->mRegionToInvalidate);
+      if (!data->mRegionToInvalidate.IsEmpty()) {
 #ifdef MOZ_DUMP_PAINTING
-      if (nsLayoutUtils::InvalidationDebuggingIsEnabled()) {
-        nsAutoCString str;
-        AppendToString(str, data->mRegionToInvalidate);
-        printf_stderr("Invalidating layer %p: %s\n", layer.get(), str.get());
-      }
+        if (nsLayoutUtils::InvalidationDebuggingIsEnabled()) {
+          printf_stderr("Invalidating deleted frame content from layer %p\n", layer.get());
+        }
 #endif
-      data->mRegionToInvalidate.SetEmpty();
-    }
+        layer->InvalidateRegion(data->mRegionToInvalidate);
+#ifdef MOZ_DUMP_PAINTING
+        if (nsLayoutUtils::InvalidationDebuggingIsEnabled()) {
+          nsAutoCString str;
+          AppendToString(str, data->mRegionToInvalidate);
+          printf_stderr("Invalidating layer %p: %s\n", layer.get(), str.get());
+        }
+#endif
+        data->mRegionToInvalidate.SetEmpty();
+      }
 
-    // We do not need to Invalidate these areas in the widget because we
-    // assume the caller of InvalidateThebesLayerContents has ensured
-    // the area is invalidated in the widget.
-  } else {
-    // Check whether the layer will be scrollable. This is used as a hint to
-    // influence whether tiled layers are used or not.
-    bool canScroll = false;
-    nsIFrame* animatedGeometryRootParent = aAnimatedGeometryRoot->GetParent();
-    if (animatedGeometryRootParent &&
-        animatedGeometryRootParent->GetType() == nsGkAtoms::scrollFrame) {
-      canScroll = true;
+      // We do not need to Invalidate these areas in the widget because we
+      // assume the caller of InvalidateThebesLayerContents has ensured
+      // the area is invalidated in the widget.
     }
+  }
+
+  if (!layerRecycled) {
     // Create a new thebes layer
-    layer = mManager->CreateThebesLayerWithHint(canScroll ? LayerManager::SCROLLABLE :
-                                                            LayerManager::NONE);
+    layer = mManager->CreateThebesLayerWithHint(creationHint);
     if (!layer)
       return nullptr;
     // Mark this layer as being used for Thebes-painting display items