Optionally clear PlatformCanvas instances.

skia/ext/bitmap_platform_device_android.h

Index: skia/ext/bitmap_platform_device_android.h
===================================================================
--- skia/ext/bitmap_platform_device_android.h	(revision 126621)
+++ skia/ext/bitmap_platform_device_android.h	(working copy)
@@ -20,9 +20,18 @@
 // -----------------------------------------------------------------------------
 class BitmapPlatformDevice : public PlatformDevice, public SkDevice {
  public:
+  // Construct a BitmapPlatformDevice. |is_opaque| should be set if the caller
+  // knows the bitmap will be completely opaque and allows some optimizations.
+  // The bitmap is not initialized.
   static BitmapPlatformDevice* Create(int width, int height, bool is_opaque);
 
-  // This doesn't take ownership of |data|
+  // Construct a BitmapPlatformDevice, as above.
+  // If |is_opaque| is false, the bitmap is initialized to 0.
+  static BitmapPlatformDevice* CreateAndClear(int width, int height,

[msw, 2012/03/16 07:13:22]

nit: one line per arg if they don't all fit (here and elsewhere).
it seems like that rule isn't popular here; ignore me if i'm wrong.

[Jeff Timanus, 2012/03/16 15:52:42]

I'd prefer to keep with the existing style in this file.  In general, the
skia/ext code doesn't always follow the coding standards consistently.

+                                              bool is_opaque);
+
+  // This doesn't take ownership of |data|. If |data| is null, the bitmap

[msw, 2012/03/16 07:13:22]

It appears the bitmap is not initialized regardless of |data|'s value.

[Jeff Timanus, 2012/03/16 15:52:42]

If |data| is non-null, the bitmap has the pixel data of |data|.  The old
behaviour would clear the bitmap to 0.  The comment makes it very explicit that
if you don't give an initial value, the contents are undefined.

+  // is not initialized to 0.
   static BitmapPlatformDevice* Create(int width, int height, bool is_opaque,
                                       uint8_t* data);