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      1 // Copyright (c) 2011 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_ICON_LOADER_H_
      6 #define CHROME_BROWSER_ICON_LOADER_H_
      7 #pragma once
      8 
      9 #include "build/build_config.h"
     10 
     11 #include <string>
     12 
     13 #include "base/basictypes.h"
     14 #include "base/memory/ref_counted.h"
     15 #include "base/memory/scoped_ptr.h"
     16 #include "base/message_loop_proxy.h"
     17 #include "ui/gfx/image.h"
     18 
     19 #if defined(TOOLKIT_USES_GTK)
     20 #include "base/file_path.h"
     21 #endif
     22 
     23 #if defined(OS_WIN)
     24 // On Windows, we group files by their extension, with several exceptions:
     25 // .dll, .exe, .ico. See IconManager.h for explanation.
     26 typedef std::wstring IconGroupID;
     27 #elif defined(OS_POSIX)
     28 // On POSIX, we group files by MIME type.
     29 typedef std::string IconGroupID;
     30 #endif
     31 
     32 ////////////////////////////////////////////////////////////////////////////////
     33 //
     34 // A facility to read a file containing an icon asynchronously in the IO
     35 // thread. Returns the icon in the form of an SkBitmap.
     36 //
     37 ////////////////////////////////////////////////////////////////////////////////
     38 class IconLoader : public base::RefCountedThreadSafe<IconLoader> {
     39  public:
     40   enum IconSize {
     41     SMALL = 0,  // 16x16
     42     NORMAL,     // 32x32
     43     LARGE
     44   };
     45 
     46   class Delegate {
     47    public:
     48     // Invoked when an icon has been read. |source| is the IconLoader. If the
     49     // icon has been successfully loaded, result is non-null. This method must
     50     // return true if it is taking ownership of the returned bitmap.
     51     virtual bool OnImageLoaded(IconLoader* source, gfx::Image* result) = 0;
     52 
     53    protected:
     54     virtual ~Delegate() {}
     55   };
     56 
     57   IconLoader(const IconGroupID& group, IconSize size, Delegate* delegate);
     58 
     59   // Start reading the icon on the file thread.
     60   void Start();
     61 
     62  private:
     63   friend class base::RefCountedThreadSafe<IconLoader>;
     64 
     65   virtual ~IconLoader();
     66 
     67   void ReadIcon();
     68 
     69   void NotifyDelegate();
     70 
     71   // The message loop object of the thread in which we notify the delegate.
     72   scoped_refptr<base::MessageLoopProxy> target_message_loop_;
     73 
     74   IconGroupID group_;
     75 
     76   IconSize icon_size_;
     77 
     78   scoped_ptr<gfx::Image> image_;
     79 
     80   Delegate* delegate_;
     81 
     82 #if defined(TOOLKIT_USES_GTK)
     83   // On X11 we use gdk's pixbuf loader, which has to execute on the UI
     84   // thread, so we only read the file on the background thread and parse it
     85   // on the main thread.
     86   void ParseIcon();
     87   FilePath filename_;
     88   std::string icon_data_;
     89 #endif
     90 
     91   DISALLOW_COPY_AND_ASSIGN(IconLoader);
     92 };
     93 
     94 #endif  // CHROME_BROWSER_ICON_LOADER_H_
     95