Introduce PlatformBitmap, which is a minimal helper class that wraps an SkBitmap

and a PlatformSurface. This is used to replace the PlatformCanvas that was being
passed to BackingStore to return pixels.

The problem to solve is that PlatformCanvas is an extension of SkCanvas, and
SkCanvas is losing the ability to have its backend specified after its
constructor (for performance reasons).

The BackingStore interface only needs to return a copy of its pixels, and offer
a platform-specific way to draw into it (i.e. BitBlt). The PlatformSurface is
sufficient for this, so the larger infrastructure of PlatformCanvas/PlatformDevice
is not required.
Review URL: https://codereview.chromium.org/11031055

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@161163 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 23 insertions, 0 deletions

diff --git a/skia/ext/platform_canvas.h b/skia/ext/platform_canvas.h
index e030ad7..4d2b0c0 100644
--- a/skia/ext/platform_canvas.h
+++ b/skia/ext/platform_canvas.h
@@ -7,6 +7,7 @@
 
 // The platform-specific device will include the necessary platform headers
 // to get the surface type.
+#include "base/basictypes.h"
 #include "skia/ext/platform_device.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 
@@ -151,6 +152,28 @@ class SK_API ScopedPlatformPaint {
   ScopedPlatformPaint& operator=(const ScopedPlatformPaint&);
 };
 
+class SK_API PlatformBitmap {
+ public:
+  PlatformBitmap();
+  ~PlatformBitmap();
+
+  // Returns true if the bitmap was able to allocate its surface.
+  bool Allocate(int width, int height, bool is_opaque);
+
+  // Returns the platform surface, or 0 if Allocate() did not return true.
+  PlatformSurface GetSurface() { return surface_; }
+
+  // Return the skia bitmap, which will be empty if Allocate() did not
+  // return true.
+  const SkBitmap& GetBitmap() { return bitmap_; }
+
+ private:
+  SkBitmap bitmap_;
+  PlatformSurface surface_;
+
+  DISALLOW_COPY_AND_ASSIGN(PlatformBitmap);
+};
+
 }  // namespace skia
 
 #endif  // SKIA_EXT_PLATFORM_CANVAS_H_