base/win/message_window.h

   1 // Copyright 2013 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 BASE_WIN_MESSAGE_WINDOW_H_
   6 #define BASE_WIN_MESSAGE_WINDOW_H_
   7
   8 #include <windows.h>
   9
  10 #include "base/base_export.h"
  11 #include "base/basictypes.h"
  12 #include "base/callback.h"
  13 #include "base/compiler_specific.h"
  14 #include "base/strings/string16.h"
  15 #include "base/threading/non_thread_safe.h"
  16
  17 namespace base {
  18 namespace win {
  19
  20 // Implements a message-only window.
  21 class BASE_EXPORT MessageWindow : public base::NonThreadSafe {
  22  public:
  23   // Used to register a process-wide message window class.
  24   class WindowClass;
  25
  26   // Implement this callback to handle messages received by the message window.
  27   // If the callback returns |false|, the first four parameters are passed to
  28   // DefWindowProc(). Otherwise, |*result| is returned by the window procedure.
  29   typedef base::Callback<bool(UINT message,
  30                               WPARAM wparam,
  31                               LPARAM lparam,
  32                               LRESULT* result)> MessageCallback;
  33
  34   MessageWindow();
  35   ~MessageWindow();
  36
  37   // Creates a message-only window. The incoming messages will be passed by
  38   // |message_callback|. |message_callback| must outlive |this|.
  39   bool Create(const MessageCallback& message_callback);
  40
  41   // Same as Create() but assigns the name to the created window.
  42   bool CreateNamed(const MessageCallback& message_callback,
  43                    const string16& window_name);
  44
  45   HWND hwnd() const { return window_; }
  46
  47   // Retrieves a handle of the first message-only window with matching
  48   // |window_name|.
  49   static HWND FindWindow(const string16& window_name);
  50
  51  private:
  52   // Give |WindowClass| access to WindowProc().
  53   friend class WindowClass;
  54
  55   // Contains the actual window creation code.
  56   bool DoCreate(const MessageCallback& message_callback,
  57                 const wchar_t* window_name);
  58
  59   // Invoked by the OS to process incoming window messages.
  60   static LRESULT CALLBACK WindowProc(HWND hwnd, UINT message, WPARAM wparam,
  61                                      LPARAM lparam);
  62
  63   // Invoked to handle messages received by the window.
  64   MessageCallback message_callback_;
  65
  66   // Handle of the input window.
  67   HWND window_;
  68
  69   DISALLOW_COPY_AND_ASSIGN(MessageWindow);
  70 };
  71
  72 }  // namespace win
  73 }  // namespace base
  74
  75 #endif  // BASE_WIN_MESSAGE_WINDOW_H_