Makes ImageSkia more like SkBitmap

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_
 #pragma once
 
 #include <vector>
 
 #include "base/basictypes.h"
+#include "base/memory/ref_counted.h"
+#include "ui/base/ui_export.h"
 #include "third_party/skia/include/core/SkBitmap.h"
-#include "ui/gfx/canvas.h"
-#include "ui/gfx/size.h"
 
 namespace gfx {
 
+namespace internal {
+class ImageSkiaStorage;
+}  // namespace internal
+
 // Container for the same image at different densities, similar to NSImage.
 // Smallest image is assumed to represent 1x density.
-
-// ImageSkia should be used for caching and drawing images of different
-// densities. It should not be used as an SkBitmap wrapper.
+//
+// ImageSkia should be used whenever possible instead of SkBitmap.
+// Functions which mutate the image should operate on the SkBitmap returned
+// from ImageSkia::GetBitmapForScale, not on ImageSkia.
+//
+// ImageSkia supports copy semantics as legacy from SkBitmap. Ideally, this

[sky, 2012/05/04 20:12:25]

This comment isn't right, we want copy semantics.

[pkotwicz, 2012/05/04 22:35:36]

Do you have a suggestion for a good comment? Copy semantics make it easier to
port from SkBitmap. It also hides memory management.

[sky, 2012/05/04 23:41:42]

I agree. My point is your comment makes it sounds like we're doing this for
legacy reasons, which isn't true. How about:

// ImageSkia is cheap to copy and intentionally supports copy semantics.

+// would not be necessary and all classes which add a ref to ImageSkia would
+// hold a ref_ptr.
 class UI_EXPORT ImageSkia {
  public:
+  // Creates null instance.

[sky, 2012/05/04 20:12:25]

null instance -> instance with no images.

+  ImageSkia();
+
+  // 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);
+
+  // Adds ref to passed in bitmap.
+  // DIP width and height are set based on |dip_scale_factor|.
+  ImageSkia(const SkBitmap& bitmap, float dip_scale_factor);
+
+  // Takes ownership of passed in bitmap.
+  // Caller should not assume that |bitmap| will be valid after constructor
+  // is called.
+  // DIP width and height are set based on scale factor of 1x.
+  // TODO(pkotwicz): This is temporary till conversion to gfx::ImageSkia is
+  // done.
   explicit ImageSkia(const SkBitmap* bitmap);
-  explicit ImageSkia(const std::vector<const SkBitmap*>& bitmaps);
+
+  // Copies a reference to |other|'s storage.
+  ImageSkia(const ImageSkia& other);
+
+  // Copies a reference to |other|'s storage.
+  ImageSkia& operator=(const ImageSkia& other);
+
+  // Converts from SkBitmap.
+  // 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& operator=(const SkBitmap& other);
+
+  // Converts to SkBitmap.
+  // TODO(pkotwicz): This is temporary till conversion to gfx::ImageSkia is
+  // done.
+  operator SkBitmap&() const;
+
   ~ImageSkia();
 
-  // Build mipmap at time of next call to |DrawToCanvasInt|.
-  void BuildMipMap();
+  // Adds |bitmap| for |dip_scale_factor| to bitmaps contained by this object.
+  // Adds ref to passed in bitmap.
+  // DIP width and height are set based on |dip_scale_factor|.
+  void AddBitmapForScale(const SkBitmap& bitmap, float dip_scale_factor);
 
-  // Draws the image with the origin at the specified location. The upper left
-  // corner of the image is rendered at the specified location.
-  void DrawToCanvasInt(Canvas* canvas, int x, int y);
+  // Finds the |bitmap| whose density best matches |x_scale_factor| and
+  // |y_scale_factor|.
+  // |bitmap_scale_factor| is set to the scale factor of the returned bitmap.
+  // Returns true if a bitmap was found.
+  bool GetBitmapForScale(float x_scale_factor,
+                         float y_scale_factor,
+                         const SkBitmap** bitmap,
+                         float* bitmap_scale_factor) const;
 
-  // Draws the image with the origin at the specified location, using the
-  // specified paint. The upper left corner of the image is rendered at the
-  // specified location.
-  void DrawToCanvasInt(Canvas* canvas,
-                       int x, int y,
-                       const SkPaint& paint);
+  // Returns true if object is null or |size_| is empty.
+  bool empty() const;
 
-  // Draws a portion of the image in the specified location. The src parameters
-  // correspond to the region of the image to draw in the region defined
-  // by the dest coordinates.
-  //
-  // If the width or height of the source differs from that of the destination,
-  // the image will be scaled. When scaling down, it is highly recommended
-  // that you call BuildMipMap() on your image to ensure that it has
-  // a mipmap, which will result in much higher-quality output. Set |filter| to
-  // use filtering for bitmaps, otherwise the nearest-neighbor algorithm is used
-  // for resampling.
-  //
-  // An optional custom SkPaint can be provided.
-  void DrawToCanvasInt(Canvas* canvas,
-                       int src_x, int src_y, int src_w, int src_h,
-                       int dest_x, int dest_y, int dest_w, int dest_h,
-                       bool filter);
-  void DrawToCanvasInt(Canvas* canvas,
-                       int src_x, int src_y, int src_w, int src_h,
-                       int dest_x, int dest_y, int dest_w, int dest_h,
-                       bool filter,
-                       const SkPaint& paint);
-
-  // Returns true if |size_| is empty.
-  bool IsZeroSized() const { return size_.IsEmpty(); }
+  // 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.
-  int width() const { return size_.width(); }
-  int height() const { return size_.height(); }
+  int width() const;
+  int height() const;
+
+  // Wrapper function for SkBitmap::extractBitmap.
+  // Operates on bitmap at index 0 if available.
+  // TODO(pkotwicz): This is temporary till conversion to gfx::ImageSkia is
+  // done.
+  bool extractSubset(ImageSkia* dst, SkIRect& subset) const;
 
   // Returns a vector with the SkBitmaps contained in this object.
-  const std::vector<const SkBitmap*>& bitmaps() const { return bitmaps_; }
+  const std::vector<SkBitmap>& bitmaps() const;
 
  private:
-  // Returns the bitmap whose density best matches |x_scale_factor| and
-  // |y_scale_factor|.
-  const SkBitmap* GetBitmapForScale(float x_scale_factor,
-                                    float y_scale_factor) const;
+  // Initialize ImageStorage with passed in parameters.
+  // If |bitmap.isNull()|, ImageStorage is set to NULL.
+  // Scale factor is set based on default scale factor of 1x.
+  // TODO(pkotwicz): This is temporary till conversion to gfx::ImageSkia is
+  // done.
+  void Init(const SkBitmap& bitmap);
 
-  std::vector<const SkBitmap*> bitmaps_;
-  gfx::Size size_;
-  bool mip_map_build_pending_;
+  // Initialize ImageStorage with passed in parameters.
+  // If |bitmap.isNull()|, ImageStorage is set to NULL.
+  void Init(const SkBitmap& bitmap, float scale_factor);
 
-  DISALLOW_COPY_AND_ASSIGN(ImageSkia);
+  // A refptr so that ImageRepSkia can be copied cheaply.
+  scoped_refptr<internal::ImageSkiaStorage> storage_;
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_IMAGE_IMAGE_SKIA_H_