Bug 1294857 - Compositor uses page's background color to clear in Fennec r=kats

gfx/layers/Compositor.cpp

@@ -35,6 +35,13 @@ Compositor::Compositor(widget::CompositorWidget* aWidget,
   , mScreenRotation(ROTATION_0)
   , mWidget(aWidget)
   , mIsDestroyed(false)
+#if defined(MOZ_WIDGET_ANDROID)
+  // If the default color isn't white for Fennec, there is a black
+  // flash before the first page of a tab is loaded.
+  , mBeginFrameClearColor(1.0, 1.0, 1.0, 1.0)
+#else
+  , mBeginFrameClearColor(0.0, 0.0, 0.0, 0.0)
+#endif
 {
 }
 

gfx/layers/Compositor.h

@@ -349,6 +349,10 @@ public:
                     const gfx::IntRect& aClipRect = gfx::IntRect(),
                     const gfx::Matrix4x4& aTransform = gfx::Matrix4x4());
 
+  void SetBeginFrameClearColor(const gfx::Color& aColor) {
+    mBeginFrameClearColor = aColor;
+  }
+
   /*
    * Clear aRect on current render target.
    */
@@ -634,6 +638,8 @@ protected:
   FenceHandle mReleaseFenceHandle;
 #endif
 
+  gfx::Color mBeginFrameClearColor;
+
 private:
   static LayersBackend sBackend;
 

gfx/layers/Layers.cpp

@@ -150,6 +150,32 @@ LayerManager::GetScrollableLayers(nsTArray<Layer*>& aArray)
   }
 }
 
+LayerMetricsWrapper
+LayerManager::GetRootContentLayer()
+{
+  if (!mRoot) {
+    return LayerMetricsWrapper();
+  }
+
+  nsTArray<Layer*> queue = { mRoot };
+  while (!queue.IsEmpty()) {
+    Layer* layer = queue[0];
+    queue.RemoveElementAt(0);
+
+    for (uint32_t i = 0; i < layer->GetScrollMetadataCount(); i++) {
+      if (layer->GetFrameMetrics(i).IsRootContent()) {
+        return LayerMetricsWrapper(layer, i);
+      }
+    }
+
+    for (Layer* child = layer->GetFirstChild(); child; child = child->GetNextSibling()) {
+      queue.AppendElement(child);
+    }
+  }
+
+  return LayerMetricsWrapper();
+}
+
 already_AddRefed<DrawTarget>
 LayerManager::CreateOptimalDrawTarget(const gfx::IntSize &aSize,
                                       SurfaceFormat aFormat)

gfx/layers/Layers.h

@@ -354,6 +354,12 @@ public:
    */
   void GetScrollableLayers(nsTArray<Layer*>& aArray);
 
+  /**
+   * Returns a LayerMetricsWrapper containing the Root
+   * Content Documents layer.
+   */
+  LayerMetricsWrapper GetRootContentLayer();
+
   /**
    * CONSTRUCTION PHASE ONLY
    * Called when a managee has mutated.

gfx/layers/composite/LayerManagerComposite.cpp

@@ -929,6 +929,12 @@ LayerManagerComposite::Render(const nsIntRegion& aInvalidRegion, const nsIntRegi
   CompositorBench(mCompositor, bounds);
 
   MOZ_ASSERT(mRoot->GetOpacity() == 1);
+#if defined(MOZ_WIDGET_ANDROID)
+  LayerMetricsWrapper wrapper = GetRootContentLayer();
+  if (wrapper) {
+    mCompositor->SetBeginFrameClearColor(wrapper.Metadata().GetBackgroundColor());
+  }
+#endif
   if (mRoot->GetClipRect()) {
     clipRect = *mRoot->GetClipRect();
     IntRect rect(clipRect.x, clipRect.y, clipRect.width, clipRect.height);
@@ -996,6 +1002,13 @@ LayerManagerComposite::Render(const nsIntRegion& aInvalidRegion, const nsIntRegi
   mCompositor->GetWidget()->PostRender(this);
 
   RecordFrame();
+
+#if defined(MOZ_WIDGET_ANDROID)
+  // Reset the clear color to white so that if a page is loaded with a different background
+  // color, the page will be white while the new page is loading instead of the background
+  // color of the previous page.
+  mCompositor->SetBeginFrameClearColor(gfx::Color(1.0, 1.0, 1.0, 1.0));
+#endif
 }
 
 #if defined(MOZ_WIDGET_ANDROID) || defined(MOZ_WIDGET_GONK)

gfx/layers/opengl/CompositorOGL.cpp

@@ -707,7 +707,7 @@ CompositorOGL::BeginFrame(const nsIntRegion& aInvalidRegion,
     aClipRectOut->SetRect(0, 0, width, height);
   }
 
-  mGLContext->fClearColor(0.0, 0.0, 0.0, 0.0);
+  mGLContext->fClearColor(mBeginFrameClearColor.r, mBeginFrameClearColor.g, mBeginFrameClearColor.b, mBeginFrameClearColor.a);
   mGLContext->fClear(LOCAL_GL_COLOR_BUFFER_BIT | LOCAL_GL_DEPTH_BUFFER_BIT);
 }