Optionally clear PlatformCanvas instances.

skia/ext/platform_device.h

 // Copyright (c) 2011 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_PLATFORM_DEVICE_H_
 #define SKIA_EXT_PLATFORM_DEVICE_H_
 #pragma once
 
 #include "build/build_config.h"
 
@@ skipping 80 matching lines @@
 // A SkDevice is basically a wrapper around SkBitmap that provides a surface for
 // SkCanvas to draw into. PlatformDevice provides a surface Windows can also
 // write to. It also provides functionality to play well with GDI drawing
 // functions. This class is abstract and must be subclassed. It provides the
 // basic interface to implement it either with or without a bitmap backend.
 //
 // PlatformDevice provides an interface which sub-classes of SkDevice can also
 // provide to allow for drawing by the native platform into the device.
 class SK_API PlatformDevice {
  public:
+  enum PlatformDeviceFlags {
+    FLAGS_NONE = 0,
+    FLAGS_OPAQUE = 1,
+    FLAGS_INITIALIZED = 2
+  };
+  static int GetDefaultFlags(bool is_opaque);
+
   virtual ~PlatformDevice() {}
 
 #if defined(OS_MACOSX)
   // The CGContext that corresponds to the bitmap, used for CoreGraphics
   // operations drawing into the bitmap. This is possibly heavyweight, so it
   // should exist only during one pass of rendering.
   virtual CGContextRef GetBitmapContext() = 0;
 #endif
 
   // The DC that corresponds to the bitmap, used for GDI operations drawing
@@ skipping 60 matching lines @@
 #elif defined(OS_MACOSX)
   // Loads the specified Skia transform into the device context
   static void LoadTransformToCGContext(CGContextRef context,
                                        const SkMatrix& matrix);
 #endif
 };
 
 }  // namespace skia
 
 #endif  // SKIA_EXT_PLATFORM_DEVICE_H_