extensions/browser/extension_icon_image.h

   1 // Copyright 2014 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 EXTENSIONS_BROWSER_EXTENSION_ICON_IMAGE_H_
   6 #define EXTENSIONS_BROWSER_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 "base/observer_list.h"
  14 #include "content/public/browser/notification_observer.h"
  15 #include "content/public/browser/notification_registrar.h"
  16 #include "extensions/common/extension_icon_set.h"
  17 #include "ui/base/layout.h"
  18 #include "ui/gfx/image/image.h"
  19 #include "ui/gfx/image/image_skia.h"
  20
  21 namespace content {
  22 class BrowserContext;
  23 }
  24
  25 namespace extensions {
  26 class Extension;
  27 }
  28
  29 namespace gfx {
  30 class Size;
  31 class Image;
  32 }
  33
  34 namespace extensions {
  35
  36 // A class that provides an ImageSkia for UI code to use. It handles extension
  37 // icon resource loading, screen scale factor change etc. UI code that uses
  38 // extension icon should host this class. In painting code, UI code paints with
  39 // the ImageSkia provided by this class. If the required extension icon resource
  40 // is not already present, this class tries to load it and calls its observer
  41 // interface when the image get updated. Until the resource is loaded, the UI
  42 // code will be provided with a blank, transparent image.
  43 // If the requested resource doesn't exist or can't be loaded and a default
  44 // icon was supplied in the constructor, icon image will be updated with the
  45 // default icon's resource.
  46 // The default icon doesn't need to be supplied, but in that case, icon image
  47 // representation will be left blank if the resource loading fails.
  48 // If default icon is supplied, it is assumed that it contains or can
  49 // synchronously create (when |GetRepresentation| is called on it)
  50 // representations for all the scale factors supported by the current platform.
  51 // Note that |IconImage| is not thread safe.
  52 class IconImage : public content::NotificationObserver {
  53  public:
  54   class Observer {
  55    public:
  56     // Invoked when a new image rep for an additional scale factor
  57     // is loaded and added to |image|.
  58     virtual void OnExtensionIconImageChanged(IconImage* image) = 0;
  59
  60     // Called when this object is deleted. Objects should observe this if there
  61     // is a question about the lifetime of the icon image vs observer.
  62     virtual void OnExtensionIconImageDestroyed(IconImage* image) {}
  63
  64    protected:
  65     virtual ~Observer() {}
  66   };
  67
  68   // |context| is required by the underlying implementation to retrieve the
  69   // |ImageLoader| instance associated with the given context. |ImageLoader| is
  70   // used to perform the asynchronous image load work.
  71   IconImage(content::BrowserContext* context,
  72             const Extension* extension,
  73             const ExtensionIconSet& icon_set,
  74             int resource_size_in_dip,
  75             const gfx::ImageSkia& default_icon,
  76             Observer* observer);
  77   ~IconImage() override;
  78
  79   gfx::Image image() const { return image_; }
  80   const gfx::ImageSkia& image_skia() const { return image_skia_; }
  81
  82   void AddObserver(Observer* observer);
  83   void RemoveObserver(Observer* observer);
  84
  85  private:
  86   class Source;
  87
  88   // Loads an image representation for the scale factor.
  89   // If the representation gets loaded synchronously, it is returned by this
  90   // method.
  91   // If representation loading is asynchronous, an empty image
  92   // representation is returned. When the representation gets loaded the
  93   // observers' OnExtensionIconImageLoaded() will be called.
  94   gfx::ImageSkiaRep LoadImageForScaleFactor(ui::ScaleFactor scale_factor);
  95
  96   void OnImageLoaded(float scale_factor, const gfx::Image& image);
  97
  98   // content::NotificationObserver overrides:
  99   void Observe(int type,
 100                const content::NotificationSource& source,
 101                const content::NotificationDetails& details) override;
 102
 103   content::BrowserContext* browser_context_;
 104   const Extension* extension_;
 105   const ExtensionIconSet& icon_set_;
 106   const int resource_size_in_dip_;
 107
 108   base::ObserverList<Observer> observers_;
 109
 110   Source* source_;  // Owned by ImageSkia storage.
 111   gfx::ImageSkia image_skia_;
 112   // The icon with whose representation |image_skia_| should be updated if
 113   // its own representation load fails.
 114   gfx::ImageSkia default_icon_;
 115
 116   // The image wrapper around |image_skia_|.
 117   // Note: this is reset each time a new representation is loaded.
 118   gfx::Image image_;
 119
 120   content::NotificationRegistrar registrar_;
 121
 122   base::WeakPtrFactory<IconImage> weak_ptr_factory_;
 123
 124   DISALLOW_COPY_AND_ASSIGN(IconImage);
 125 };
 126
 127 }  // namespace extensions
 128
 129 #endif  // EXTENSIONS_BROWSER_EXTENSION_ICON_IMAGE_H_