Load 2x resources on demand

ui/gfx/image/image_skia.h

 // Copyright (c) 2012 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 UI_GFX_IMAGE_IMAGE_SKIA_H_
 #define UI_GFX_IMAGE_IMAGE_SKIA_H_
 
 #include <vector>
 
 #include "base/basictypes.h"
@@ skipping 19 matching lines @@
 // ImageSkia is cheap to copy and intentionally supports copy semantics.
 class UI_EXPORT ImageSkia {
  public:
   typedef std::vector<ImageSkiaRep> ImageSkiaReps;
 
   // Creates an instance with no bitmaps.
   ImageSkia();
 
   // Creates an instance that will use the |source| to get the image
   // for scale factors. |size| specifes the size of the image in DIP.
+  // ImageSkia owns |source|.
   ImageSkia(ImageSkiaSource* source, const gfx::Size& size);
 
   // Adds ref to passed in bitmap.
   // DIP width and height are set based on scale factor of 1x.
   // TODO(pkotwicz): This is temporary till conversion to gfx::ImageSkia is
   // done.
   ImageSkia(const SkBitmap& bitmap);
 
   ImageSkia(const gfx::ImageSkiaRep& image_rep);
 
@@ skipping 63 matching lines @@
   // TODO(pkotwicz): Return null SkBitmap when the object has no 1x bitmap.
   const SkBitmap* bitmap() const { return &GetBitmap(); }
 
   // Returns a vector with the image reps contained in this object.
   // There is no guarantee that this will return all images rep for
   // supported scale factors.
   // TODO(oshima): Update all use of this API and make this to fail
   // when source is used.
   std::vector<gfx::ImageSkiaRep> image_reps() const;
 
+  // Delete the ImageSkiaSource if any. It will make GetRepresentation
+  // thread safe because it will no longer update the storage.
+  void DeleteSource();
+
+  // When the soruce is available, generates all ImageReps for
+  // supported scale factors. This method is defined as const as
+  // the state change in the storage is agnostic to the caller.
+  void EnsureRepsForSupportedScaleFactors() const;
+
  private:
   // Initialize ImageSkiaStorage with passed in parameters.
   // If the image rep's bitmap is empty, ImageStorage is set to NULL.
   void Init(const gfx::ImageSkiaRep& image_rep);
 
   SkBitmap& GetBitmap() const;
 
   // A refptr so that ImageRepSkia can be copied cheaply.
   scoped_refptr<internal::ImageSkiaStorage> storage_;
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_IMAGE_IMAGE_SKIA_H_