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 "content/public/browser/notification_observer.h"
  14 #include "content/public/browser/notification_registrar.h"
  15 #include "extensions/common/extension_icon_set.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   ~IconImage() override;
  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   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  // EXTENSIONS_BROWSER_EXTENSION_ICON_IMAGE_H_