add SkImage::newSurface

src/image/SkImage_Gpu.cpp

Index: src/image/SkImage_Gpu.cpp
diff --git a/src/image/SkImage_Gpu.cpp b/src/image/SkImage_Gpu.cpp
index de49d1e33973f6f3e3dbd3f33e291fe4213ae931..b337c101c7208084c870181b70ed909924b1bca0 100644
--- a/src/image/SkImage_Gpu.cpp
+++ b/src/image/SkImage_Gpu.cpp
@@ -9,6 +9,7 @@
 #include "SkImagePriv.h"
 #include "SkBitmap.h"
 #include "SkCanvas.h"
+#include "SkSurface.h"
 #include "GrContext.h"
 #include "GrTexture.h"
 
@@ -19,19 +20,20 @@ public:
     explicit SkImage_Gpu(const SkBitmap&);
     virtual ~SkImage_Gpu();
 
-    virtual void onDraw(SkCanvas*, SkScalar x, SkScalar y, const SkPaint*) const SK_OVERRIDE;
-    virtual void onDrawRect(SkCanvas*, const SkRect* src, const SkRect& dst,
-                                  const SkPaint*) const SK_OVERRIDE;
-    virtual GrTexture* onGetTexture() const SK_OVERRIDE;
-    virtual bool getROPixels(SkBitmap*) const SK_OVERRIDE;
+    void onDraw(SkCanvas*, SkScalar x, SkScalar y, const SkPaint*) const SK_OVERRIDE;
+    void onDrawRect(SkCanvas*, const SkRect* src, const SkRect& dst,
+                    const SkPaint*) const SK_OVERRIDE;
+    SkSurface* onNewSurface(const SkImageInfo&, const SkSurfaceProps&) const SK_OVERRIDE;
+    GrTexture* onGetTexture() const SK_OVERRIDE;
+    bool getROPixels(SkBitmap*) const SK_OVERRIDE;
 
     GrTexture* getTexture() const { return fBitmap.getTexture(); }
 
-    virtual SkShader* onNewShader(SkShader::TileMode,
+    SkShader* onNewShader(SkShader::TileMode,
                                   SkShader::TileMode,
                                   const SkMatrix* localMatrix) const SK_OVERRIDE;
 
-    virtual bool isOpaque() const SK_OVERRIDE;
+    bool isOpaque() const SK_OVERRIDE;
 
 private:
     SkBitmap    fBitmap;
@@ -66,6 +68,12 @@ void SkImage_Gpu::onDrawRect(SkCanvas* canvas, const SkRect* src, const SkRect&
     canvas->drawBitmapRectToRect(fBitmap, src, dst, paint);
 }
 
+SkSurface* SkImage_Gpu::onNewSurface(const SkImageInfo& info, const SkSurfaceProps& props) const {
+    GrContext* ctx = this->getTexture()->getContext();
+    const int sampleCount = 0;  // TODO: extract this from this image...
+    return SkSurface::NewRenderTarget(ctx, info, sampleCount, &props);
+}
+
 GrTexture* SkImage_Gpu::onGetTexture() const {
     return fBitmap.getTexture();
 }