C / C++ / MFC

LRESULT CALLBACK WndProc( HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam )
{
    return DefWindowProc(hwnd, uMsg, wParam, lParam); 
}
  
WNDCLASSEX wndClass;
wndClass.cbClsExtra    = NULL;
wndClass.cbSize        = sizeof(WNDCLASSEX);
wndClass.cbWndExtra    = NULL;
wndClass.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
wndClass.hCursor       = ::LoadCursor(NULL, IDC_ARROW);
wndClass.hIcon         = ::LoadIcon(NULL, IDI_APPLICATION);
wndClass.hIconSm       = ::LoadIcon(NULL, IDI_APPLICATION);
wndClass.hInstance     = AfxGetInstanceHandle();
wndClass.lpfnWndProc   = WndProc;
wndClass.lpszClassName = "MyWndClass";
wndClass.lpszMenuName  = NULL;
wndClass.style         = CS_CLASSDC;
  
RegisterClassEx(&wndClass);
  
HWND mHWnd = CreateWindowEx(0, "MyWndClass", "MyTitle", 
                            WS_CAPTION | WS_MAXIMIZEBOX | WS_MINIMIZEBOX | WS_SYSMENU | WS_VISIBLE,
                            CW_USEDEFAULT, CW_USEDEFAULT, 800, 600, 
                            NULL, NULL, AfxGetInstanceHandle(), this);

LRESULT CALLBACK Window::msgRouter(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
	//NOTE: The following messages may need to be handled here explicitly as they are sent
	//before CreateWindow() returns - WM_NCCREATE, WM_GETMINMAXINFO, WM_CREATE.
	
	if(msg == WM_NCCREATE)
	{
		//A window was created. Set the user data of the handle to the pointer passed in the call to createWindow()
		Window *window = reinterpret_cast<Window*>(reinterpret_cast<LPCREATESTRUCT>(lParam)->lpCreateParams);
		SetWindowLongPtr(hWnd, GWLP_USERDATA, reinterpret_cast<long>(window));
		return TRUE;
	}
	else
	{
		Window *window = (Window*)GetWindowLongPtr(hWnd, GWLP_USERDATA);

		if(window)
		{
			return window->wndProc(msg, wParam, lParam);
		}

		return DefWindowProc(hWnd, msg, wParam, lParam);
	}

	return DefWindowProc(hWnd, msg, wParam, lParam);
}

LRESULT CALLBACK Window::wndProc(UINT msg, WPARAM wParam, LPARAM lParam)
{
	switch(msg)
	{
	case WM_CLOSE:
	case WM_DESTROY:
		PostQuitMessage(0);
		return 0;
	case WM_KEYDOWN:
		switch(wParam)
		{
		case VK_ESCAPE:
			PostQuitMessage(0);
			return 0;
		default:
			break;
		}
		break;
	default:
		break;
	}

	return DefWindowProc(mHWnd, msg, wParam, lParam);
}

LRESULT CALLBACK Window::msgRouter(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
	//NOTE: The following messages may need to be handled here explicitly as they are sent
	//before CreateWindow() returns - WM_NCCREATE, WM_GETMINMAXINFO, WM_CREATE.
	
	if(msg == WM_CREATE)
	{
		//A window was created. Set the user data of the handle to the pointer passed in the call to createWindow()
		Window *window = reinterpret_cast<Window*>(reinterpret_cast<LPCREATESTRUCT>(lParam)->lpCreateParams);
		SetWindowLongPtr(hWnd, GWLP_USERDATA, reinterpret_cast<long>(window));
		return TRUE;
	}
	else
	{
		Window *window = (Window*)GetWindowLongPtr(hWnd, GWLP_USERDATA);

		if(window)
		{
			return window->wndProc(msg, wParam, lParam);
		}
	}

	return DefWindowProc(hWnd, msg, wParam, lParam);
}