Bug 1444432 - Add Compositor::GetWindowRenderTarget() and implement it for CompositorOGL. r=jrmuizel

MozReview-Commit-ID: d0vBM6g2pM

--HG--
extra : rebase_source : d16ad9a58c04c146cd4ef2d95d7eb2ec2cff1593

gfx/layers/Compositor.h

@@ -302,6 +302,14 @@ public:
    */
   virtual CompositingRenderTarget* GetCurrentRenderTarget() const = 0;
 
+  /**
+   * Returns a render target which contains the entire window's drawing.
+   * On platforms where no such render target is used during compositing (e.g.
+   * with buffered BasicCompositor, where only the invalid area is drawn to a
+   * render target), this will return null.
+   */
+  virtual CompositingRenderTarget* GetWindowRenderTarget() const { return nullptr; }
+
   /**
    * Mostly the compositor will pull the size from a widget and this method will
    * be ignored, but compositor implementations are free to use it if they like.

gfx/layers/opengl/CompositorOGL.cpp

@@ -682,6 +682,12 @@ CompositorOGL::GetCurrentRenderTarget() const
   return mCurrentRenderTarget;
 }
 
+CompositingRenderTarget*
+CompositorOGL::GetWindowRenderTarget() const
+{
+  return mWindowRenderTarget;
+}
+
 already_AddRefed<AsyncReadbackBuffer>
 CompositorOGL::CreateAsyncReadbackBuffer(const IntSize& aSize)
 {
@@ -816,10 +822,7 @@ CompositorOGL::BeginFrame(const nsIntRegion& aInvalidRegion,
     CompositingRenderTargetOGL::RenderTargetForWindow(this,
                                                       IntSize(width, height));
   SetRenderTarget(rt);
-
-#ifdef DEBUG
   mWindowRenderTarget = mCurrentRenderTarget;
-#endif
 
   if (aClipRectOut && !aClipRectIn) {
     aClipRectOut->SetRect(0, 0, width, height);
@@ -1752,11 +1755,13 @@ CompositorOGL::EndFrame()
   if (mTarget) {
     CopyToTarget(mTarget, mTargetBounds.TopLeft(), Matrix());
     mGLContext->fBindBuffer(LOCAL_GL_ARRAY_BUFFER, 0);
+    mWindowRenderTarget = nullptr;
     mCurrentRenderTarget = nullptr;
     Compositor::EndFrame();
     return;
   }
 
+  mWindowRenderTarget = nullptr;
   mCurrentRenderTarget = nullptr;
 
   if (mTexturePool) {

gfx/layers/opengl/CompositorOGL.h

@@ -157,6 +157,7 @@ public:
 
   virtual void SetRenderTarget(CompositingRenderTarget *aSurface) override;
   virtual CompositingRenderTarget* GetCurrentRenderTarget() const override;
+  virtual CompositingRenderTarget* GetWindowRenderTarget() const override;
 
   virtual bool
   ReadbackRenderTarget(CompositingRenderTarget* aSource,
@@ -290,9 +291,8 @@ private:
 
   /** Currently bound render target */
   RefPtr<CompositingRenderTargetOGL> mCurrentRenderTarget;
-#ifdef DEBUG
+
   CompositingRenderTargetOGL* mWindowRenderTarget;
-#endif
 
   /**
    * VBO that has some basics in it for a textured quad, including vertex