Add support for PNG representation in gfx::Image

ui/gfx/image/image.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.
 
 // An Image wraps an image any flavor, be it platform-native GdkBitmap/NSImage,
 // or a SkBitmap. This also provides easy conversion to other image types
 // through operator overloading. It will cache the converted representations
 // internally to prevent double-conversion.
 //
 // The lifetime of both the initial representation and any converted ones are
@@ skipping 18 matching lines @@
 #include "ui/gfx/native_widget_types.h"
 
 class SkBitmap;
 
 namespace {
 class ImageTest;
 class ImageMacTest;
 }
 
 namespace gfx {
+class ImagePNG;

[Robert Sesek, 2012/07/20 21:03:01]

Remove

[cjhopman, 2012/07/24 01:44:13]

Done.

 class ImageSkia;
 class ImageSkiaRep;
 
 #if defined(TOOLKIT_GTK)
 class CairoCachedSurface;
 #endif
 
 namespace internal {
 class ImageRep;
 class ImageStorage;
 }
 
 class UI_EXPORT Image {
  public:
   enum RepresentationType {
     kImageRepGdk,
     kImageRepCocoa,
     kImageRepCairo,
     kImageRepSkia,
+    kImageRepPNG,
   };
 
   typedef std::map<RepresentationType, internal::ImageRep*> RepresentationMap;
 
   // Creates an empty image with no representations.
   Image();
 
+  // Creates a new image by copying the png-encoded input for use as the default
+  // representation.
+  Image(const unsigned char* png, size_t input_size);
+  explicit Image(const std::vector<unsigned char>& png);

[Robert Sesek, 2012/07/20 21:03:01]

I wonder if you even need this constructor. A client that has a vector can
always use .front() and .size() to the constructor above.

What do you think?

[cjhopman, 2012/07/24 01:44:13]

Agreed. Done.

+
   // Creates a new image by copying the ImageSkia for use as the default
   // representation.
   explicit Image(const ImageSkia& image);
 
   // Creates a new image by copying the image rep for use as the default
   // representation.
   explicit Image(const ImageSkiaRep& image_rep);
 
   // Creates a new image by copying the bitmap for use as the default
   // representation.
@@ skipping 16 matching lines @@
   // Copies a reference to |other|'s storage.
   Image& operator=(const Image& other);
 
   // Deletes the image and, if the only owner of the storage, all of its cached
   // representations.
   ~Image();
 
   // Converts the Image to the desired representation and stores it internally.
   // The returned result is a weak pointer owned by and scoped to the life of
   // the Image.
+  const std::vector<unsigned char>* ToImagePNG() const;

[Robert Sesek, 2012/07/20 21:03:01]

I'm wondering if this should return a const ref. Reasons against are that it's a
difference in the API from all the other To*() functions, and it makes it easier
to perform a vector copy.

[cjhopman, 2012/07/24 01:44:13]

I think my preference would be to keep it consistent with the other To*()
functions, but I'm not really opposed to changing it if you'd prefer it as a
reference.

[Robert Sesek, 2012/07/24 18:59:17]

Agree. Let's keep these as pointers.

   const SkBitmap* ToSkBitmap() const;
   const ImageSkia* ToImageSkia() const;
 #if defined(TOOLKIT_GTK)
   GdkPixbuf* ToGdkPixbuf() const;
   CairoCachedSurface* const ToCairo() const;
 #elif defined(OS_MACOSX)
   NSImage* ToNSImage() const;
 #endif
 
   // Performs a conversion, like above, but returns a copy of the result rather
   // than a weak pointer. The caller is responsible for deleting the result.
   // Note that the result is only a copy in terms of memory management; the
   // backing pixels are shared amongst all copies (a fact of each of the
   // converted representations, rather than a limitation imposed by Image) and
   // so the result should be considered immutable.
+  std::vector<unsigned char>* CopyImagePNG() const;
   ImageSkia* CopyImageSkia() const;
   SkBitmap* CopySkBitmap() const;
 #if defined(TOOLKIT_GTK)
   GdkPixbuf* CopyGdkPixbuf() const;
 #elif defined(OS_MACOSX)
   NSImage* CopyNSImage() const;
 #endif
 
   // DEPRECATED ----------------------------------------------------------------
   // Conversion handlers. These wrap the ToType() variants.
@@ skipping 30 matching lines @@
   // be cheaply copied.
   scoped_refptr<internal::ImageStorage> storage_;
 
   friend class ::ImageTest;
   friend class ::ImageMacTest;
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_IMAGE_IMAGE_H_