Bug 651858 - Part 3: Add layers API for creating an optimal DrawTarget. r=roc

gfx/layers/Layers.cpp

@@ -48,6 +48,7 @@
 #include "mozilla/Util.h"
 
 using namespace mozilla::layers;
+using namespace mozilla::gfx;
 
 typedef FrameMetrics::ViewID ViewID;
 const ViewID FrameMetrics::NULL_SCROLL_ID = 0;
@@ -210,6 +211,14 @@ LayerManager::CreateOptimalSurface(const gfxIntSize &aSize,
     CreateOffscreenSurface(aSize, gfxASurface::ContentFromFormat(aFormat));
 }
 
+TemporaryRef<DrawTarget>
+LayerManager::CreateDrawTarget(const IntSize &aSize,
+                               SurfaceFormat aFormat)
+{
+  // Right now this doesn't work on the general layer manager.
+  return NULL;
+}
+
 #ifdef DEBUG
 void
 LayerManager::Mutated(Layer* aLayer)

gfx/layers/Layers.h

@@ -49,6 +49,8 @@
 #include "gfxColor.h"
 #include "gfxPattern.h"
 
+#include "mozilla/gfx/2D.h"
+
 #if defined(DEBUG) || defined(PR_LOGGING)
 #  include <stdio.h>            // FILE
 #  include "prlog.h"
@@ -424,6 +426,15 @@ public:
     CreateOptimalSurface(const gfxIntSize &aSize,
                          gfxASurface::gfxImageFormat imageFormat);
 
+  /**
+   * Creates a DrawTarget which is optimized for inter-operating with this
+   * layermanager.
+   */
+  virtual TemporaryRef<mozilla::gfx::DrawTarget>
+    CreateDrawTarget(const mozilla::gfx::IntSize &aSize,
+                     mozilla::gfx::SurfaceFormat aFormat);
+
+
   /**
    * Return the name of the layer manager's backend.
    */