ui/gfx/win/singleton_hwnd_observer.h

   1 // Copyright 2015 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 UI_GFX_WIN_SINGLETON_HWND_OBSERVER_H_
   6 #define UI_GFX_WIN_SINGLETON_HWND_OBSERVER_H_
   7
   8 #include <windows.h>
   9
  10 #include "base/callback.h"
  11 #include "base/macros.h"
  12 #include "ui/gfx/gfx_export.h"
  13
  14 namespace gfx {
  15
  16 class SingletonHwnd;
  17
  18 // Singleton lifetime management is tricky. This observer handles the correct
  19 // cleanup if either the SingletonHwnd or forwarded object is destroyed first.
  20 class GFX_EXPORT SingletonHwndObserver {
  21  public:
  22   typedef base::Callback<void(HWND, UINT, WPARAM, LPARAM)> WndProc;
  23
  24   explicit SingletonHwndObserver(const WndProc& wnd_proc);
  25   ~SingletonHwndObserver();
  26
  27  private:
  28   friend class SingletonHwnd;
  29
  30   void ClearWndProc();
  31   void OnWndProc(HWND hwnd, UINT message, WPARAM wparam, LPARAM lparam);
  32
  33   WndProc wnd_proc_;
  34
  35   DISALLOW_COPY_AND_ASSIGN(SingletonHwndObserver);
  36 };
  37
  38 }  // namespace gfx
  39
  40 #endif  // UI_GFX_WIN_SINGLETON_HWND_OBSERVER_H_