WTL客户的窗口消息函数分析

window窗口程序，必须提供一个windowproc回调函数。

原型：

LRESULT CALLBACK WindowProc(
  HWND hwnd,      // handle to window
  UINT uMsg,      // message identifier
  WPARAM wParam,  // first message parameter
  LPARAM lParam   // second message parameter
);

第一种 ：写成全局函数

第二种：写成static函数

WTL中的格式：

LRESULT CALLBACK CWindowImplBaseT< TBase, TWinTraits >::WindowProc(
	_In_ HWND hWnd,
	_In_ UINT uMsg,
	_In_ WPARAM wParam,
	_In_ LPARAM lParam)
{
	CWindowImplBaseT< TBase, TWinTraits >* pThis = (CWindowImplBaseT< TBase, TWinTraits >*)hWnd;
	// set a ptr to this message and save the old value
	_ATL_MSG msg(pThis->m_hWnd, uMsg, wParam, lParam);
	const _ATL_MSG* pOldMsg = pThis->m_pCurrentMsg;
	pThis->m_pCurrentMsg = &msg;
	// pass to the message map to process
	LRESULT lRes = 0;
	BOOL bRet = pThis->ProcessWindowMessage(pThis->m_hWnd, uMsg, wParam, lParam, lRes, 0);
	// restore saved value for the current message
	ATLASSERT(pThis->m_pCurrentMsg == &msg);

	// do the default processing if message was not handled
	if(!bRet)
	{
		if(uMsg != WM_NCDESTROY)
			lRes = pThis->DefWindowProc(uMsg, wParam, lParam);
		else
		{
			// unsubclass, if needed
			LONG_PTR pfnWndProc = ::GetWindowLongPtr(pThis->m_hWnd, GWLP_WNDPROC);
			lRes = pThis->DefWindowProc(uMsg, wParam, lParam);
			if(pThis->m_pfnSuperWindowProc != ::DefWindowProc && ::GetWindowLongPtr(pThis->m_hWnd, GWLP_WNDPROC) == pfnWndProc)
				::SetWindowLongPtr(pThis->m_hWnd, GWLP_WNDPROC, (LONG_PTR)pThis->m_pfnSuperWindowProc);
			// mark window as destryed
			pThis->m_dwState |= WINSTATE_DESTROYED;
		}
	}
	if((pThis->m_dwState & WINSTATE_DESTROYED) && pOldMsg== NULL)
	{
		// clear out window handle
		HWND hWndThis = pThis->m_hWnd;
		pThis->m_hWnd = NULL;
		pThis->m_dwState &= ~WINSTATE_DESTROYED;
		// clean up after window is destroyed
		pThis->m_pCurrentMsg = pOldMsg;
		pThis->OnFinalMessage(hWndThis);
	}else {
		pThis->m_pCurrentMsg = pOldMsg;
	}
	return lRes;
}

最主要的代码1：

BOOL bRet = pThis->ProcessWindowMessage(pThis->m_hWnd, uMsg, wParam, lParam, lRes, 0);

这个函数，可以处理消息，每个窗口中都要实现这个函数：

窗口消毁后，的处理：

uMsg  == WM_NCDESTROY

这里，// mark window as destryed
            pThis->m_dwState |= WINSTATE_DESTROYED;

处理一些函数，变量的销毁工作。

参考这些代码的实现 。我自己在封装窗口代码时可以做为参考。

窗口中其它proc函数：

virtual DLGPROC GetDialogProc()
    {
        return DialogProc;
    }
    static INT_PTR CALLBACK StartDialogProc(
        _In_ HWND hWnd,
        _In_ UINT uMsg,
        _In_ WPARAM wParam,
        _In_ LPARAM lParam);
    static INT_PTR CALLBACK DialogProc(
        _In_ HWND hWnd,
        _In_ UINT uMsg,
        _In_ WPARAM wParam,
        _In_ LPARAM lParam);

  
    // has no meaning for a dialog, but needed for handlers that use it
    LRESULT DefWindowProc()
    {
        return 0;
    }