Load 2x resources on demand

ui/gfx/image/image_skia.h

Index: ui/gfx/image/image_skia.h
diff --git a/ui/gfx/image/image_skia.h b/ui/gfx/image/image_skia.h
index 2518b2c447c9276917833f8b48c018cdd932d23b..9b79ab61d74ba7b1be977e700a07027074f43f67 100644
--- a/ui/gfx/image/image_skia.h
+++ b/ui/gfx/image/image_skia.h
@@ -8,6 +8,7 @@
 #include <vector>
 
 #include "base/basictypes.h"
+#include "base/gtest_prod_util.h"
 #include "base/memory/ref_counted.h"
 #include "ui/base/ui_export.h"
 #include "ui/gfx/image/image_skia_rep.h"
@@ -20,6 +21,10 @@ namespace internal {
 class ImageSkiaStorage;
 }  // namespace internal
 
+namespace test {
+class TestOnThread;
+}
+
 // Container for the same image at different densities, similar to NSImage.
 // Image height and width are in DIP (Density Indepent Pixel) coordinates.
 //
@@ -37,6 +42,7 @@ class UI_EXPORT 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.
@@ -62,6 +68,15 @@ class UI_EXPORT ImageSkia {
 
   ~ImageSkia();
 
+  // Returns a deep copy of this ImageSkia which has its own storage with
+  // the ImageSkiaRep instances that this ImageSkia currently has.
+  // This can be safely passed to and manipulated by another thread.
+  // Note that this does NOT generate ImageSkiaReps from its source.
+  // If you want to create a deep copy with ImageSkiaReps for supported
+  // scale factors, you need to explicitly call
+  // |EnsureRepsForSupportedScaleFactors()| first.
+  ImageSkia DeepCopy() const;
+
   // Returns true if this object is backed by the same ImageSkiaStorage as
   // |other|. Will also return true if both images are isNull().
   bool BackedBySameObjectAs(const gfx::ImageSkia& other) const;
@@ -82,16 +97,23 @@ class UI_EXPORT ImageSkia {
   const gfx::ImageSkiaRep& GetRepresentation(
       ui::ScaleFactor scale_factor) const;
 
-#if defined(OS_MACOSX)
-  // Returns the image reps contained by this object.
-  // If the image has a source, this method will attempt to generate
-  // representations from the source for all supported scale factors.
-  // Mac only for now.
-  std::vector<ImageSkiaRep> GetRepresentations() const;
-#endif  // OS_MACOSX
+  // Make the ImageSkia instance read-only. Note that this only prevent
+  // modification from client code, and the storage may still be
+  // modified by the source if any (thus, it's not thread safe).  This
+  // detaches the storage from currently accessing thread, so its safe
+  // to pass it to other thread as long as it is accessed only by that
+  // thread. If this ImageSkia's storage will be accessed by multiple
+  // threads, use |MakeThreadSafe()| method.
+  void SetReadOnly();
+
+  // Make the image thread safe by making the storage read only and remove
+  // its source if any. All ImageSkia that shares the same storage will also
+  // become thread safe. Note that in order to make it 100% thread safe,
+  // this must be called before it's been passed to anther thread.
+  void MakeThreadSafe();
+  bool IsThreadSafe() const;
 
   // Returns true if this is a null object.
-  // TODO(pkotwicz): Merge this function into empty().
   bool isNull() const { return storage_ == NULL; }
 
   // Width and height of image in DIP coordinate system.
@@ -109,17 +131,33 @@ class UI_EXPORT ImageSkia {
   // 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;
 
+  // When the source 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:
+  friend class test::TestOnThread;
+  FRIEND_TEST_ALL_PREFIXES(ImageSkiaTest, EmptyOnThreadTest);
+  FRIEND_TEST_ALL_PREFIXES(ImageSkiaTest, StaticOnThreadTest);
+  FRIEND_TEST_ALL_PREFIXES(ImageSkiaTest, SourceOnThreadTest);
+
   // 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;
 
+  // Checks if the current thread can read/modify the ImageSkia.
+  bool CanRead() const;
+  bool CanModify() const;
+
+  // Detach the storage from the currently assinged thread
+  // so that other thread can access the storage.
+  void DetachStorageFromThread();
+
   // A refptr so that ImageRepSkia can be copied cheaply.
   scoped_refptr<internal::ImageSkiaStorage> storage_;
 };