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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_ICON_LOADER_H_
      6 #define CHROME_BROWSER_ICON_LOADER_H_
      7 
      8 #include "build/build_config.h"
      9 
     10 #include <string>
     11 
     12 #include "base/basictypes.h"
     13 #include "base/files/file_path.h"
     14 #include "base/memory/ref_counted.h"
     15 #include "base/memory/scoped_ptr.h"
     16 #include "base/message_loop/message_loop_proxy.h"
     17 #include "ui/gfx/image/image.h"
     18 
     19 #if defined(OS_WIN)
     20 // On Windows, we group files by their extension, with several exceptions:
     21 // .dll, .exe, .ico. See IconManager.h for explanation.
     22 typedef std::wstring IconGroupID;
     23 #elif defined(OS_POSIX)
     24 // On POSIX, we group files by MIME type.
     25 typedef std::string IconGroupID;
     26 #endif
     27 
     28 ////////////////////////////////////////////////////////////////////////////////
     29 //
     30 // A facility to read a file containing an icon asynchronously in the IO
     31 // thread. Returns the icon in the form of an ImageSkia.
     32 //
     33 ////////////////////////////////////////////////////////////////////////////////
     34 class IconLoader : public base::RefCountedThreadSafe<IconLoader> {
     35  public:
     36   enum IconSize {
     37     SMALL = 0,  // 16x16
     38     NORMAL,     // 32x32
     39     LARGE,      // Windows: 32x32, Linux: 48x48, Mac: Unsupported
     40     ALL,        // All sizes available
     41   };
     42 
     43   class Delegate {
     44    public:
     45     // Invoked when an icon group has been read, but before the icon data
     46     // is read. If the icon is already cached, this method should call and
     47     // return the results of OnImageLoaded with the cached image.
     48     virtual bool OnGroupLoaded(IconLoader* source,
     49                                const IconGroupID& group) = 0;
     50     // Invoked when an icon has been read. |source| is the IconLoader. If the
     51     // icon has been successfully loaded, result is non-null. This method must
     52     // return true if it is taking ownership of the returned image.
     53     virtual bool OnImageLoaded(IconLoader* source,
     54                                gfx::Image* result,
     55                                const IconGroupID& group) = 0;
     56 
     57    protected:
     58     virtual ~Delegate() {}
     59   };
     60 
     61   IconLoader(const base::FilePath& file_path,
     62              IconSize size,
     63              Delegate* delegate);
     64 
     65   // Start reading the icon on the file thread.
     66   void Start();
     67 
     68  private:
     69   friend class base::RefCountedThreadSafe<IconLoader>;
     70 
     71   virtual ~IconLoader();
     72 
     73   // Get the identifying string for the given file. The implementation
     74   // is in icon_loader_[platform].cc.
     75   static IconGroupID ReadGroupIDFromFilepath(const base::FilePath& path);
     76 
     77   // Some icons (exe's on windows) can change as they're loaded.
     78   static bool IsIconMutableFromFilepath(const base::FilePath& path);
     79 
     80   void ReadGroup();
     81   void OnReadGroup();
     82   void ReadIcon();
     83 
     84   void NotifyDelegate();
     85 
     86   // The message loop object of the thread in which we notify the delegate.
     87   scoped_refptr<base::MessageLoopProxy> target_message_loop_;
     88 
     89   base::FilePath file_path_;
     90 
     91   IconGroupID group_;
     92 
     93   IconSize icon_size_;
     94 
     95   scoped_ptr<gfx::Image> image_;
     96 
     97   Delegate* delegate_;
     98 
     99   DISALLOW_COPY_AND_ASSIGN(IconLoader);
    100 };
    101 
    102 #endif  // CHROME_BROWSER_ICON_LOADER_H_
    103