chromeos: Fix pixelated icons in app list and launcher (part 2) (by xiyuan)

chrome/browser/extensions/extension_icon_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.
+
+#ifndef CHROME_BROWSER_EXTENSIONS_EXTENSION_ICON_IMAGE_H_
+#define CHROME_BROWSER_EXTENSIONS_EXTENSION_ICON_IMAGE_H_
+
+#include <map>
+#include <string>
+
+#include "base/basictypes.h"
+#include "chrome/browser/extensions/image_loading_tracker.h"
+#include "chrome/common/extensions/extension_icon_set.h"
+#include "content/public/browser/notification_observer.h"
+#include "content/public/browser/notification_registrar.h"
+#include "ui/gfx/image/image_skia.h"
+
+namespace extensions {
+class Extension;
+}
+
+namespace gfx {
+class Size;
+}
+
+namespace extensions {
+
+// A class that provides an ImageSkia for UI code to use. It handles extension
+// icon resource loading, screen scale factor change etc. UI code that uses
+// extension icon should host this class and be its observer. ExtensionIconImage
+// should be outlived by the observer. In painting code, UI code paints with the
+// ImageSkia provided by this class. If required extension icon resource is not
+// present, this class uses ImageLoadingTracker to load it and call on its
+// observer interface when the resource is loaded.
+class IconImage : public ImageLoadingTracker::Observer,
+                  public content::NotificationObserver {
+ public:
+  class Observer {
+   public:
+    // Invoked when a new image rep for an additional scale factor
+    // is loaded and added to |image|.
+    virtual void OnExtensionIconImageChanged(IconImage* image) = 0;
+
+    // Invoked when the icon image couldn't be loaded.
+    virtual void OnIconImageLoadFailed(IconImage* image,
+                                       ui::ScaleFactor scale_factor) = 0;
+
+   protected:
+    virtual ~Observer() {}
+  };
+
+  IconImage(const Extension* extension,
+            const ExtensionIconSet& icon_set,
+            int resource_size_in_dip,
+            Observer* observer);
+  virtual ~IconImage();
+
+  const gfx::ImageSkia& image_skia() const { return image_skia_; }
+
+ private:
+  class Source;
+
+  typedef std::map<int, ui::ScaleFactor> LoadMap;
+
+  // Loads bitmap for additional scale factor.
+  void LoadImageForScaleFactor(ui::ScaleFactor scale_factor);
+
+  // ImageLoadingTracker::Observer overrides:
+  virtual void OnImageLoaded(const gfx::Image& image,
+                             const std::string& extension_id,
+                             int index) OVERRIDE;
+
+  // content::NotificationObserver overrides:
+  virtual void Observe(int type,
+                       const content::NotificationSource& source,
+                       const content::NotificationDetails& details) OVERRIDE;
+
+  const Extension* extension_;
+  const ExtensionIconSet& icon_set_;
+  const int resource_size_in_dip_;
+  const gfx::Size desired_size_in_dip_;
+
+  Observer* observer_;
+
+  Source* source_;  // Owned by ImageSkia storage.
+  gfx::ImageSkia image_skia_;
+
+  ImageLoadingTracker tracker_;
+  content::NotificationRegistrar registrar_;
+
+  LoadMap load_map_;
+
+  DISALLOW_COPY_AND_ASSIGN(IconImage);
+};
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_ICON_IMAGE_H_