消息反射

</pre><pre name="code" class="cpp">代碼如下：
BOOL CWnd::OnNotify(WPARAM, LPARAM lParam, LRESULT* pResult)
{
ASSERT(pResult != NULL);
NMHDR* pNMHDR = (NMHDR*)lParam;
HWND hWndCtrl = pNMHDR->hwndFrom;
// get the child ID from the window itself
UINT nID = _AfxGetDlgCtrlID(hWndCtrl);
int nCode = pNMHDR->code;
ASSERT(hWndCtrl != NULL);
ASSERT(::IsWindow(hWndCtrl));
if (_afxThreadState->m_hLockoutNotifyWindow == m_hWnd)
return TRUE;        // locked out - ignore control notification
// reflect notification to child window control
if (ReflectLastMsg(hWndCtrl, pResult))
return TRUE;        // eaten by child
AFX_NOTIFY notify;
notify.pResult = pResult;
notify.pNMHDR = pNMHDR;
return OnCmdMsg(nID, MAKELONG(nCode, WM_NOTIFY), ?ify, NULL);
}
BOOL PASCAL CWnd::ReflectLastMsg(HWND hWndChild, LRESULT* pResult)
{
// get the map, and if no map, then this message does not need reflection
CHandleMap* pMap = afxMapHWND();
if (pMap == NULL)
return FALSE;
// check if in permanent map, if it is reflect it (could be OLE control)
CWnd* pWnd = (CWnd*)pMap->LookupPermanent(hWndChild);
ASSERT(pWnd == NULL || pWnd->m_hWnd == hWndChild);
if (pWnd == NULL)
{
#ifndef _AFX_NO_OCC_SUPPORT
// check if the window is an OLE control
CWnd* pWndParent = (CWnd*)pMap->LookupPermanent(::GetParent(hWndChild));
if (pWndParent != NULL && pWndParent->m_pCtrlCont != NULL)
{
// If a matching control site exists, it''s an OLE control
COleControlSite* pSite = (COleControlSite*)pWndParent->
m_pCtrlCont->m_siteMap.GetValueAt(hWndChild);
if (pSite != NULL)
{
CWnd wndTemp(hWndChild);
wndTemp.m_pCtrlSite = pSite;
LRESULT lResult = wndTemp.SendChildNotifyLastMsg(pResult);
wndTemp.m_hWnd = NULL;
return lResult;
}
}
#endif //!_AFX_NO_OCC_SUPPORT
return FALSE;
}
BOOL PASCAL CWnd::ReflectLastMsg(HWND hWndChild, LRESULT* pResult)
{
// get the map, and if no map, then this message does not need reflection
CHandleMap* pMap = afxMapHWND();
if (pMap == NULL)
return FALSE;
// check if in permanent map, if it is reflect it (could be OLE control)
CWnd* pWnd = (CWnd*)pMap->LookupPermanent(hWndChild);
ASSERT(pWnd == NULL || pWnd->m_hWnd == hWndChild);
if (pWnd == NULL)
{
#ifndef _AFX_NO_OCC_SUPPORT
// check if the window is an OLE control
CWnd* pWndParent = (CWnd*)pMap->LookupPermanent(::GetParent(hWndChild));
if (pWndParent != NULL && pWndParent->m_pCtrlCont != NULL)
{
// If a matching control site exists, it''s an OLE control
COleControlSite* pSite = (COleControlSite*)pWndParent->
m_pCtrlCont->m_siteMap.GetValueAt(hWndChild);
if (pSite != NULL)
{
CWnd wndTemp(hWndChild);
wndTemp.m_pCtrlSite = pSite;
LRESULT lResult = wndTemp.SendChildNotifyLastMsg(pResult);
wndTemp.m_hWnd = NULL;
return lResult;
}
}
#endif //!_AFX_NO_OCC_SUPPORT
return FALSE;
}
// only OLE controls and permanent windows will get reflected msgs
ASSERT(pWnd != NULL);
return pWnd->SendChildNotifyLastMsg(pResult);
}
注意紅色代碼！此時調用的是子控件的SendChildNotifyLastMsg()
BOOL CWnd::SendChildNotifyLastMsg(LRESULT* pResult)
{
_AFX_THREAD_STATE* pThreadState = _afxThreadState.GetData();
return OnChildNotify(pThreadState->m_lastSentMsg.message,
pThreadState->m_lastSentMsg.wParam, pThreadState->m_lastSentMsg.lParam, pResult);
}
調用子控件的虛函數OnChildNotify函數，進行處理。 如果沒有處理，則調用ReflectChildNotify(...)函數進行標準的反射消息的消息映射處理。  如果在ReflectChildNotify(...)中此消息還沒被處理，就返回到CWnd::OnNotify(...)中調用OnCmdMsg(...)處理，這樣，父窗口就可以響應此消息了。