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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef CHROME_BROWSER_EXTENSIONS_EXTENSION_ICON_IMAGE_H_
      6 #define CHROME_BROWSER_EXTENSIONS_EXTENSION_ICON_IMAGE_H_
      7 
      8 #include <map>
      9 #include <string>
     10 
     11 #include "base/basictypes.h"
     12 #include "base/memory/weak_ptr.h"
     13 #include "chrome/common/extensions/extension_icon_set.h"
     14 #include "content/public/browser/notification_observer.h"
     15 #include "content/public/browser/notification_registrar.h"
     16 #include "ui/base/layout.h"
     17 #include "ui/gfx/image/image_skia.h"
     18 
     19 namespace content {
     20 class BrowserContext;
     21 }
     22 
     23 namespace extensions {
     24 class Extension;
     25 }
     26 
     27 namespace gfx {
     28 class Size;
     29 class Image;
     30 }
     31 
     32 namespace extensions {
     33 
     34 // A class that provides an ImageSkia for UI code to use. It handles extension
     35 // icon resource loading, screen scale factor change etc. UI code that uses
     36 // extension icon should host this class and be its observer. ExtensionIconImage
     37 // should be outlived by the observer. In painting code, UI code paints with the
     38 // ImageSkia provided by this class. If required extension icon resource is not
     39 // already present, this class tries to load it and calls its observer interface
     40 // when the image get updated. Until the resource is loaded, the UI code will be
     41 // provided with blank, transparent image.
     42 // If the requested resource doesn't exist or can't be loaded and a default
     43 // icon was supplied in the constructor, icon image will be updated with the
     44 // default icon's resource.
     45 // The default icon doesn't need to be supplied, but in that case, icon image
     46 // representation will be left blank if the resource loading fails.
     47 // If default icon is supplied, it is assumed that it contains or can
     48 // synchronously create (when |GetRepresentation| is called on it)
     49 // representations for all the scale factors supported by the current platform.
     50 // Note that |IconImage| is not thread safe.
     51 class IconImage : public content::NotificationObserver {
     52  public:
     53   class Observer {
     54    public:
     55     // Invoked when a new image rep for an additional scale factor
     56     // is loaded and added to |image|.
     57     virtual void OnExtensionIconImageChanged(IconImage* image) = 0;
     58 
     59    protected:
     60     virtual ~Observer() {}
     61   };
     62 
     63   // |context| is required by the underlying implementation to retrieve the
     64   // |ImageLoader| instance associated with the given context. |ImageLoader| is
     65   // used to perform the asynchronous image load work.
     66   IconImage(content::BrowserContext* context,
     67             const Extension* extension,
     68             const ExtensionIconSet& icon_set,
     69             int resource_size_in_dip,
     70             const gfx::ImageSkia& default_icon,
     71             Observer* observer);
     72   virtual ~IconImage();
     73 
     74   const gfx::ImageSkia& image_skia() const { return image_skia_; }
     75 
     76  private:
     77   class Source;
     78 
     79   // Loads an image representation for the scale factor.
     80   // If the representation gets loaded synchronously, it is returned by this
     81   // method.
     82   // If representation loading is asynchronous, an empty image
     83   // representation is returned. When the representation gets loaded the
     84   // observer's |OnExtensionIconImageLoaded| will be called.
     85   gfx::ImageSkiaRep LoadImageForScaleFactor(ui::ScaleFactor scale_factor);
     86 
     87   void OnImageLoaded(float scale_factor, const gfx::Image& image);
     88 
     89   // content::NotificationObserver overrides:
     90   virtual void Observe(int type,
     91                        const content::NotificationSource& source,
     92                        const content::NotificationDetails& details) OVERRIDE;
     93 
     94   content::BrowserContext* browser_context_;
     95   const Extension* extension_;
     96   const ExtensionIconSet& icon_set_;
     97   const int resource_size_in_dip_;
     98 
     99   Observer* observer_;
    100 
    101   Source* source_;  // Owned by ImageSkia storage.
    102   gfx::ImageSkia image_skia_;
    103   // The icon with whose representation |image_skia_| should be updated if
    104   // its own representation load fails.
    105   gfx::ImageSkia default_icon_;
    106 
    107   content::NotificationRegistrar registrar_;
    108 
    109   base::WeakPtrFactory<IconImage> weak_ptr_factory_;
    110 
    111   DISALLOW_COPY_AND_ASSIGN(IconImage);
    112 };
    113 
    114 }  // namespace extensions
    115 
    116 #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_ICON_IMAGE_H_
    117