Added new class gfx::ImageFamily.

ui/gfx/image/image_family.h

+// Copyright 2013 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_FAMILY_H_
+#define UI_GFX_IMAGE_IMAGE_FAMILY_H_
+
+#include <iterator>
+#include <map>
+#include <utility>
+
+#include "ui/base/ui_export.h"
+#include "ui/gfx/image/image.h"
+
+namespace gfx {
+class ImageSkia;
+
+// A collection of images at different sizes. The images should be different
+// representations of the same basic concept (for example, an icon) at various
+// sizes and (optionally) aspect ratios. A method is provided for finding the
+// most appropriate image to fit in a given rectangle.
+class UI_EXPORT ImageFamily {
+ public:
+  // Type for iterating over all images in the family, in order.
+  // Dereferencing this iterator returns a gfx::Image.
+  class const_iterator;
+
+  ImageFamily();
+  ~ImageFamily();
+
+  // Gets an iterator to the first image.
+  inline const_iterator begin() const { return const_iterator(map_.begin()); }

[Robert Sesek, 2013/03/27 17:42:50]

Remove the |inline| keywords throughout this file. The compiler will be smart
enough to figure this otu.

[Matt Giuca, 2013/03/28 03:54:03]

Done.

+  // Gets an iterator to one after the last image.
+  inline const_iterator end() const { return const_iterator(map_.end()); }
+
+  // Determines whether the image family has no images in it.
+  inline bool empty() const { return map_.empty(); }
+
+  // Removes all images from the family.
+  inline void clear() { return map_.clear(); }
+
+  // Adds an image to the family. If another image is already present at the
+  // same size, it will be overwritten.
+  void Add(const gfx::Image& image);
+
+  // Adds an image to the family. If another image is already present at the
+  // same size, it will be overwritten.
+  void Add(const gfx::ImageSkia& image_skia);
+
+  // Gets the best image to use in a rectangle of |width|x|height|.
+  // Gets an image at the same aspect ratio as |width|:|height|, if possible, or
+  // if not, the closest aspect ratio. Among images of that aspect ratio,
+  // returns the smallest image with both its width and height bigger or equal
+  // to the requested size. If none exists, returns the largest image of that
+  // aspect ratio. If there are no images in the family, returns NULL.
+  const gfx::Image* Get(int width, int height) const;
+
+  // An <aspect ratio, width> pair.
+  // A 0x0 image has aspect ratio 1.0. 0xN and Nx0 images are treated as 0x0.
+  // If the image contains high-DPI bitmaps, the width refers to the width at

[pkotwicz, 2013/03/27 19:04:53]

Nit: An <aspect ratio, DIP width> pair.
"DIP width of image" means width of the image's 1x representation.

[Matt Giuca, 2013/03/28 03:54:03]

Done.

+  // the 100% representation.
+  struct MapKey : std::pair<float, int> {
+    MapKey(float aspect, int width)
+        : std::pair<float, int>(aspect, width) {}
+
+    inline float aspect() const { return first; }
+
+    inline float width() const { return second; }
+  };
+
+  class const_iterator :
+    std::iterator<std::bidirectional_iterator_tag, const gfx::Image> {
+   public:
+    inline const_iterator() {}
+
+    inline const_iterator& operator++() {

[Robert Sesek, 2013/03/27 17:42:50]

Do all these definitions have to be in the header? I think you can move them
into the .cc file but keep the |inline| attribute.

[Matt Giuca, 2013/03/28 03:54:03]

But they are used (and expected to be inlined) externally to this module. (Not
in the current CL, but ImageFamily is designed to be iterated over by external
users.) As far as I'm aware, you can't inline a function defined in a .cc file;
see http://www.parashift.com/c++-faq-lite/inline-member-fns.html.

I'm happy to move these definitions out of the class declaration and into the
bottom of the file, if you think that will make things more readable.

+      ++map_iterator_;
+      return *this;
+    }
+
+    inline const_iterator operator++(int /*unused*/) {
+      const_iterator result(*this);
+      ++(*this);
+      return result;
+    }
+
+    inline const_iterator& operator--() {
+      --map_iterator_;
+      return *this;
+    }
+
+    inline const_iterator operator--(int /*unused*/) {
+      const_iterator result(*this);
+      --(*this);
+      return result;
+    }
+
+    inline bool operator==(const const_iterator& other) const {
+      return map_iterator_ == other.map_iterator_;
+    }
+
+    inline bool operator!=(const const_iterator& other) const {
+      return map_iterator_ != other.map_iterator_;
+    }
+
+    inline const gfx::Image& operator*() const {
+      return map_iterator_->second;
+    }
+
+    inline const gfx::Image* operator->() const {
+      return &**this;
+    }
+
+   private:
+    explicit const_iterator(
+        const std::map<MapKey, gfx::Image>::const_iterator& other);
+
+    std::map<MapKey, gfx::Image>::const_iterator map_iterator_;
+
+    friend class ImageFamily;
+  };
+
+ private:
+  // Map from (aspect ratio, width) to image.
+  std::map<MapKey, gfx::Image> map_;
+};
+
+}  // namespace gfx
+
+#endif  // UI_GFX_IMAGE_IMAGE_FAMILY_H_