ozone: dri: Composite to intermediate surface & copy

ui/gfx/ozone/surface_ozone_canvas.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_GFX_OZONE_SURFACE_OZONE_CANVAS_H_
 #define UI_GFX_OZONE_SURFACE_OZONE_CANVAS_H_
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "skia/ext/refptr.h"
@@ skipping 10 matching lines @@
 // for use when no EGL/GLES2 acceleration is possible.
 // This class owns any bits that the ozone implementation needs freed when
 // the software output is destroyed.
 class GFX_EXPORT SurfaceOzoneCanvas {
  public:
   virtual ~SurfaceOzoneCanvas() {}
 
   // Returns an SkCanvas for drawing on the window.
   virtual skia::RefPtr<SkCanvas> GetCanvas() = 0;
 
-  // Attempts to resize the canvas to match the viewport size. Returns true if
-  // resizing was successful, otherwise false (platforms may require a fixed
-  // size canvas). After resizing, the compositor must call GetCanvas() to get
-  // the next canvas.
-  virtual bool ResizeCanvas(const gfx::Size& viewport_size) = 0;
+  // Attempts to resize the canvas to match the viewport size. After
+  // resizing, the compositor must call GetCanvas() to get the next
+  // canvas - this invalidates any previous canvas from GetCanvas().
+  virtual void ResizeCanvas(const gfx::Size& viewport_size) = 0;
 
-  // Present the current canvas. After presenting, the compositor must call
-  // GetCanvas() to get the next canvas.
-  virtual bool PresentCanvas() = 0;
+  // Present the current canvas. After presenting, the compositor must
+  // call GetCanvas() to get the next canvas - this invalidates any
+  // previous canvas from GetCanvas().
+  //
+  // The implementation may assume that any pixels outside the damage
+  // rectangle are unchanged since the previous call to PresentCanvas().
+  virtual void PresentCanvas(const gfx::Rect& damage) = 0;
 
   // Returns a gfx::VsyncProvider for this surface. Note that this may be
   // called after we have entered the sandbox so if there are operations (e.g.
   // opening a file descriptor providing vsync events) that must be done
   // outside of the sandbox, they must have been completed in
   // InitializeHardware. Returns an empty scoped_ptr on error.
   virtual scoped_ptr<gfx::VSyncProvider> CreateVSyncProvider() = 0;
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_OZONE_SURFACE_OZONE_CANVAS_H_