icon_loader.h

   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 "content/public/browser/browser_thread.h"
  18 #include "ui/gfx/image/image.h"
  19
  20 #if defined(OS_WIN)
  21 // On Windows, we group files by their extension, with several exceptions:
  22 // .dll, .exe, .ico. See IconManager.h for explanation.
  23 typedef std::wstring IconGroupID;
  24 #elif defined(OS_POSIX)
  25 // On POSIX, we group files by MIME type.
  26 typedef std::string IconGroupID;
  27 #endif
  28
  29 ////////////////////////////////////////////////////////////////////////////////
  30 //
  31 // A facility to read a file containing an icon asynchronously in the IO
  32 // thread. Returns the icon in the form of an ImageSkia.
  33 //
  34 ////////////////////////////////////////////////////////////////////////////////
  35 class IconLoader : public base::RefCountedThreadSafe<IconLoader> {
  36  public:
  37   enum IconSize {
  38     SMALL = 0,  // 16x16
  39     NORMAL,     // 32x32
  40     LARGE,      // Windows: 32x32, Linux: 48x48, Mac: Unsupported
  41     ALL,        // All sizes available
  42   };
  43
  44   class Delegate {
  45    public:
  46     // Invoked when an icon group has been read, but before the icon data
  47     // is read. If the icon is already cached, this method should call and
  48     // return the results of OnImageLoaded with the cached image.
  49     virtual bool OnGroupLoaded(IconLoader* source,
  50                                const IconGroupID& group) = 0;
  51     // Invoked when an icon has been read. |source| is the IconLoader. If the
  52     // icon has been successfully loaded, result is non-null. This method must
  53     // return true if it is taking ownership of the returned image.
  54     virtual bool OnImageLoaded(IconLoader* source,
  55                                gfx::Image* result,
  56                                const IconGroupID& group) = 0;
  57
  58    protected:
  59     virtual ~Delegate() {}
  60   };
  61
  62   IconLoader(const base::FilePath& file_path,
  63              IconSize size,
  64              Delegate* delegate);
  65
  66   // Start reading the icon on the file thread.
  67   void Start();
  68
  69  private:
  70   friend class base::RefCountedThreadSafe<IconLoader>;
  71
  72   virtual ~IconLoader();
  73
  74   // Get the identifying string for the given file. The implementation
  75   // is in icon_loader_[platform].cc.
  76   static IconGroupID ReadGroupIDFromFilepath(const base::FilePath& path);
  77
  78   // Some icons (exe's on windows) can change as they're loaded.
  79   static bool IsIconMutableFromFilepath(const base::FilePath& path);
  80
  81   // The thread ReadIcon() should be called on.
  82   static content::BrowserThread::ID ReadIconThreadID();
  83
  84   void ReadGroup();
  85   void OnReadGroup();
  86   void ReadIcon();
  87
  88   void NotifyDelegate();
  89
  90   // The message loop object of the thread in which we notify the delegate.
  91   scoped_refptr<base::MessageLoopProxy> target_message_loop_;
  92
  93   base::FilePath file_path_;
  94
  95   IconGroupID group_;
  96
  97   IconSize icon_size_;
  98
  99   scoped_ptr<gfx::Image> image_;
 100
 101   Delegate* delegate_;
 102
 103   DISALLOW_COPY_AND_ASSIGN(IconLoader);
 104 };
 105
 106 #endif  // CHROME_BROWSER_ICON_LOADER_H_