原文网址:http://blog.csdn.net/hyhnoproblem/article/details/6182646
本例通过在单文档程序的视图中添加WM_LBUTTONCLICK消息处理函数,来解释一般窗口消息的投递流程。 基于VS 2005
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- BEGIN_MESSAGE_MAP(CMyView, CView)
- ON_WM_LBUTTONDBLCLK()
- END_MESSAGE_MAP()
- // ON_WM_LBUTTONDBLCLK宏展开
- #define ON_WM_LBUTTONDBLCLK() /
- { WM_LBUTTONDBLCLK, 0, 0, 0, AfxSig_vwp, /
- (AFX_PMSG)(AFX_PMSGW) /
- (static_cast< void (AFX_MSG_CALL CWnd::*)(UINT, CPoint) > ( &ThisClass :: OnLButtonDblClk)) },
从上面的代码可以看出WM_LBUTTONCLICK消息的类型标签是AfxSig_vwp, 在afxmsg_.h中有一个枚举类型AfxSig,消息标签主要用于区分消息处理函数的类型。该类型中定义了AfxSig_vwp的值:
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- enum AfxSig
- {
- //...
- AfxSig_vWp = AfxSig_v_W_p
- //...
- }
在AfxWndProc中,将消息中的句柄映射成窗口类指针,这个指针指向CMyView。AfxWndProc调用AfxCallWndProc,AfxCallWndProc调用CWnd::WindowProc,CWnd::WindowProc调用CWnd::OnWndMsg,CWnd::OnWndMsg完成对消息的处理。
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- // wincore.cpp 1746
- BOOL CWnd::OnWndMsg(UINT message, WPARAM wParam, LPARAM lParam, LRESULT* pResult)
- {
- // ...
- // GetMessageMap是个虚函数,因为当前指针是指向CMyView,所以取到的是CMyView的消息映射表
- const AFX_MSGMAP* pMessageMap; pMessageMap = GetMessageMap();
- UINT iHash; iHash = (LOWORD((DWORD_PTR)pMessageMap) ^ message) & (iHashMax-1);
- winMsgLock.Lock(CRIT_WINMSGCACHE);
- // 全局消息散列缓存,查找缓存
- AFX_MSG_CACHE* pMsgCache; pMsgCache = &_afxMsgCache[iHash];
- const AFX_MSGMAP_ENTRY* lpEntry;
- if (message == pMsgCache->nMsg && pMessageMap == pMsgCache->pMessageMap)
- {
- // cache hit
- lpEntry = pMsgCache->lpEntry;
- winMsgLock.Unlock();
- if (lpEntry == NULL)
- return FALSE;
- // cache hit, and it needs to be handled
- if (message < 0xC000)
- goto LDispatch; // 系统消息?
- else
- goto LDispatchRegistered; // 已注册消息?
- }
- else
- {
- // not in cache, look for it
- pMsgCache->nMsg = message;
- pMsgCache->pMessageMap = pMessageMap;
- for (/* pMessageMap already init‘ed */; pMessageMap->pfnGetBaseMap != NULL;
- pMessageMap = (*pMessageMap->pfnGetBaseMap)())
- {
- // Note: catch not so common but fatal mistake!!
- // BEGIN_MESSAGE_MAP(CMyWnd, CMyWnd)
- ASSERT(pMessageMap != (*pMessageMap->pfnGetBaseMap)());
- if (message < 0xC000)
- {
- // constant window message
- if ((lpEntry = AfxFindMessageEntry(pMessageMap->lpEntries,
- message, 0, 0)) != NULL)
- {
- pMsgCache->lpEntry = lpEntry;
- winMsgLock.Unlock();
- goto LDispatch;
- }
- }
- else
- {
- // registered windows message
- lpEntry = pMessageMap->lpEntries;
- while ((lpEntry = AfxFindMessageEntry(lpEntry, 0xC000, 0, 0)) != NULL)
- {
- UINT* pnID = (UINT*)(lpEntry->nSig);
- ASSERT(*pnID >= 0xC000 || *pnID == 0);
- // must be successfully registered
- if (*pnID == message)
- {
- pMsgCache->lpEntry = lpEntry;
- winMsgLock.Unlock();
- goto LDispatchRegistered;
- }
- lpEntry++; // keep looking past this one
- }
- }
- }
- pMsgCache->lpEntry = NULL;
- winMsgLock.Unlock();
- return FALSE;
- }
- // ...
- LDispatch:
- mmf.pfn = lpEntry->pfn;
- switch (lpEntry->nSig)
- {
- //...
- case AfxSig_v_u_p: // 消息标签
- {
- CPoint point(lParam);
- (this->*mmf.pfn_v_u_p)(static_cast<UINT>(wParam), point);
- }
- break;
- //...
- }
- //...
- LDispatchRegistered: // for registered windows messages
- ASSERT(message >= 0xC000);
- ASSERT(sizeof(mmf) == sizeof(mmf.pfn));
- mmf.pfn = lpEntry->pfn;
- lResult = (this->*mmf.pfn_l_w_l)(wParam, lParam);
- }
- // 消息处理函数类型枚举
- union MessageMapFunctions
- {
- AFX_PMSG pfn; // generic member function pointer
- // ...
- LRESULT (AFX_MSG_CALL CWnd::*pfn_l_w_l)(WPARAM, LPARAM);
- };
时间: 2024-10-05 12:20:26