text: // 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 "base/memory/weak_ptr.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"
  
  class Profile;
  
  namespace extensions {
  class Extension;
  }
  
  namespace gfx {
  class Size;
  class Image;
  }
  
  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
  // already present, this class tries to load it and calls its observer interface
  // when the image get updated. Until the resource is loaded, the UI code will be
  // provided with blank, transparent image.
  // If the requested resource doesn't exist or can't be loaded and a default
  // icon was supplied in the constructor, icon image will be updated with the
  // default icon's resource.
  // The default icon doesn't need to be supplied, but in that case, icon image
  // representation will be left blank if the resource loading fails.
  // If default icon is supplied, it is assumed that it contains or can
  // synchronously create (when |GetRepresentation| is called on it)
  // representations for all the scale factors supported by the current platform.
  // Note that |IconImage| is not thread safe.
  class IconImage : 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;
  
     protected:
      virtual ~Observer() {}
    };
  
    // |profile| is required by the underlying implementation to retrieve the
    // |ImageLoader| instance associated with the given profile. |ImageLoader| is
    // used to perform the asynchronous image load work.
    IconImage(Profile* profile,
              const Extension* extension,
              const ExtensionIconSet& icon_set,
              int resource_size_in_dip,
              const gfx::ImageSkia& default_icon,
              Observer* observer);
    virtual ~IconImage();
  
    const gfx::ImageSkia& image_skia() const { return image_skia_; }
  
   private:
    class Source;
  
    // Loads an image representation for the scale factor.
    // If the representation gets loaded synchronously, it is returned by this
    // method.
    // If representation loading is asynchronous, an empty image
    // representation is returned. When the representation gets loaded the
    // observer's |OnExtensionIconImageLoaded| will be called.
    gfx::ImageSkiaRep LoadImageForScaleFactor(ui::ScaleFactor scale_factor);
  
    void OnImageLoaded(ui::ScaleFactor scale_factor, const gfx::Image& image);
  
    // content::NotificationObserver overrides:
    virtual void Observe(int type,
                         const content::NotificationSource& source,
                         const content::NotificationDetails& details) OVERRIDE;
  
    Profile* profile_;
    const Extension* extension_;
    const ExtensionIconSet& icon_set_;
    const int resource_size_in_dip_;
  
    Observer* observer_;
  
    Source* source_;  // Owned by ImageSkia storage.
    gfx::ImageSkia image_skia_;
    // The icon with whose representation |image_skia_| should be updated if
    // its own representation load fails.
    gfx::ImageSkia default_icon_;
  
    content::NotificationRegistrar registrar_;
  
    base::WeakPtrFactory<IconImage> weak_ptr_factory_;
  
    DISALLOW_COPY_AND_ASSIGN(IconImage);
  };
  
  }  // namespace extensions
  
  #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_ICON_IMAGE_H_
  