Properly use data when creating a bitmap platform canvas

skia/ext/bitmap_platform_device_mac.h

 // Copyright (c) 2006-2008 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 SKIA_EXT_BITMAP_PLATFORM_DEVICE_MAC_H_
 #define SKIA_EXT_BITMAP_PLATFORM_DEVICE_MAC_H_
 
 #include "skia/ext/platform_device_mac.h"
 
 namespace skia {
 
 // A device is basically a wrapper around SkBitmap that provides a surface for
 // SkCanvas to draw into. Our device provides a surface CoreGraphics can also
 // write to. BitmapPlatformDevice creates a bitmap using
 // CGCreateBitmapContext() in a format that Skia supports and can then use this
 // to draw text into, etc. This pixel data is provided to the bitmap that the
 // device contains so that it can be shared.
 //
 // The device owns the pixel data, when the device goes away, the pixel data
 // also becomes invalid. THIS IS DIFFERENT THAN NORMAL SKIA which uses
 // reference counting for the pixel data. In normal Skia, you could assign
 // another bitmap to this device's bitmap and everything will work properly.
 // For us, that other bitmap will become invalid as soon as the device becomes
 // invalid, which may lead to subtle bugs. Therefore, DO NOT ASSIGN THE
 // DEVICE'S PIXEL DATA TO ANOTHER BITMAP, make sure you copy instead.
 class BitmapPlatformDevice : public PlatformDevice {
  public:
-  // Factory function. The screen DC is used to create the bitmap, and will not
-  // be stored beyond this function. is_opaque should be set if the caller
-  // knows the bitmap will be completely opaque and allows some optimizations.
-  //
-  // The shared_section parameter is optional (pass NULL for default behavior).
-  // If shared_section is non-null, then it must be a handle to a file-mapping
-  // object returned by CreateFileMapping.  See CreateDIBSection for details.
-  static BitmapPlatformDevice* Create(CGContextRef context,
-                                      int width,
-                                      int height,
-                                      bool is_opaque);
+  // |context| may be NULL.
+  static BitmapPlatformDevice* CreateWithContext(CGContextRef context,
+                                                 int width, int height,
+                                                 bool is_opaque);
+
+  // Creates a context for |data| and calls CreateWithContext.
+  static BitmapPlatformDevice* CreateWithData(uint8_t* data,
+                                              int width, int height,
+                                              bool is_opaque);
 
   // Copy constructor. When copied, devices duplicate their internal data, so
   // stay linked. This is because their implementation is very heavyweight
   // (lots of memory and CoreGraphics state). If a device has been copied, both
   // clip rects and other state will stay in sync.
   //
   // This means it will NOT work to duplicate a device and assign it to a
   // canvas, because the two canvases will each set their own clip rects, and
   // the resulting CoreGraphics drawing state will be unpredictable.
   //
@@ skipping 35 matching lines @@
                              adjustAlpha adjustor);
 
   // Data associated with this device, guaranteed non-null. We hold a reference
   // to this object.
   BitmapPlatformDeviceData* data_;
 };
 
 }  // namespace skia
 
 #endif  // SKIA_EXT_BITMAP_PLATFORM_DEVICE_MAC_H_