Add class GrGLTextureRenderTarget for GL texture/rendertarget objects

include/gpu/GrSurface.h

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #ifndef GrSurface_DEFINED
 #define GrSurface_DEFINED
 
 #include "GrTypes.h"
 #include "GrGpuResource.h"
 #include "SkImageInfo.h"
 #include "SkRect.h"
 
 class GrRenderTarget;
 class GrSurfacePriv;
 class GrTexture;
 
 class GrSurface : public GrGpuResource {
 public:
     SK_DECLARE_INST_COUNT(GrSurface);
 
     /**
      * Retrieves the width of the surface.
-     *
-     * @return the width in texels
      */
     int width() const { return fDesc.fWidth; }
 
     /**
      * Retrieves the height of the surface.
-     *
-     * @return the height in texels
      */
     int height() const { return fDesc.fHeight; }
 
     /**
      * Helper that gets the width and height of the surface as a bounding rectangle.
      */
     void getBoundsRect(SkRect* rect) const { rect->setWH(SkIntToScalar(this->width()),
                                                          SkIntToScalar(this->height())); }
 
     GrSurfaceOrigin origin() const {
@@ skipping 10 matching lines @@
     GrPixelConfig config() const { return fDesc.fConfig; }
 
     /**
      * Return the descriptor describing the surface
      */
     const GrSurfaceDesc& desc() const { return fDesc; }
 
     /**
      * @return the texture associated with the surface, may be NULL.
      */
-    virtual GrTexture* asTexture() = 0;
-    virtual const GrTexture* asTexture() const = 0;
+    virtual GrTexture* asTexture() { return NULL; }
+    virtual const GrTexture* asTexture() const { return NULL; }
 
     /**
      * @return the render target underlying this surface, may be NULL.
      */
-    virtual GrRenderTarget* asRenderTarget() = 0;
-    virtual const GrRenderTarget* asRenderTarget() const = 0;
+    virtual GrRenderTarget* asRenderTarget() { return NULL; }
+    virtual const GrRenderTarget* asRenderTarget() const { return NULL; }
 
     /**
      * Reads a rectangle of pixels from the surface.
      * @param left          left edge of the rectangle to read (inclusive)
      * @param top           top edge of the rectangle to read (inclusive)
      * @param width         width of rectangle to read in pixels.
      * @param height        height of rectangle to read in pixels.
      * @param config        the pixel config of the destination buffer
      * @param buffer        memory to read the rectangle into.
      * @param rowBytes      number of bytes between consecutive rows. Zero means rows are tightly
@@ skipping 57 matching lines @@
     , fDesc(desc) {
     }
 
     GrSurfaceDesc fDesc;
 
 private:
     typedef GrGpuResource INHERITED;
 };
 
 #endif