int CWnd::RunModalLoop(DWORD dwFlags)
{
ASSERT(::IsWindow(m_hWnd)); // window must be created
ASSERT(!(m_nFlags & WF_MODALLOOP)); // window must not already be in modal state
// for tracking the idle time state
BOOL bIdle = TRUE;
LONG lIdleCount = 0;
BOOL bShowIdle = (dwFlags & MLF_SHOWONIDLE) && !(GetStyle() & WS_VISIBLE);
HWND hWndParent = ::GetParent(m_hWnd);
m_nFlags |= (WF_MODALLOOP|WF_CONTINUEMODAL);
MSG* pMsg = &AfxGetThread()->m_msgCur;
// acquire and dispatch messages until the modal state is done
for (;;)
{
ASSERT(ContinueModal());
// phase1: check to see if we can do idle work
while (bIdle &&
!::PeekMessage(pMsg, NULL, NULL, NULL, PM_NOREMOVE))
{
ASSERT(ContinueModal());
// show the dialog when the message queue goes idle
if (bShowIdle)
{
ShowWindow(SW_SHOWNORMAL);
UpdateWindow();
bShowIdle = FALSE;
}
// call OnIdle while in bIdle state
if (!(dwFlags & MLF_NOIDLEMSG) && hWndParent != NULL && lIdleCount == 0)
{
// send WM_ENTERIDLE to the parent
::SendMessage(hWndParent, WM_ENTERIDLE, MSGF_DIALOGBOX, (LPARAM)m_hWnd);
}
if ((dwFlags & MLF_NOKICKIDLE) ||
!SendMessage(WM_KICKIDLE, MSGF_DIALOGBOX, lIdleCount++))
{
// stop idle processing next time
bIdle = FALSE;
}
}
// phase2: pump messages while available
do
{
ASSERT(ContinueModal());
// pump message, but quit on WM_QUIT
//PumpMessage(消息泵)的實(shí)現(xiàn)和上面講的差不多。都是派送消息到窗口。
if (!AfxGetThread()->PumpMessage())
{
AfxPostQuitMessage(0);
return -1;
}
// show the window when certain special messages rec'd
if (bShowIdle &&
(pMsg->message == 0x118 || pMsg->message == WM_SYSKEYDOWN))
{
ShowWindow(SW_SHOWNORMAL);
消息分為隊(duì)列消息(進(jìn)入線程的消息隊(duì)列)和非隊(duì)列消息(不進(jìn)入線程的消息隊(duì)列)。對于隊(duì)列消息，最常見的是鼠標(biāo)和鍵盤觸發(fā)的消息，例如 WM_MOUSERMOVE,WM_CHAR等消息；還有例如：WM_PAINT、WM_TIMER和WM_QUIT。當(dāng)鼠標(biāo)、鍵盤事件被觸發(fā)后，相應(yīng)的鼠標(biāo)或鍵盤驅(qū)動(dòng)程序就會(huì)把這些事件轉(zhuǎn)換成相應(yīng)的消息，然后輸送到系統(tǒng)消息隊(duì)列，由Windows系統(tǒng)負(fù)責(zé)把消息加入到相應(yīng)線程的消息隊(duì)列中，于是就有了消息循環(huán)(從消息隊(duì)列中讀取并派送消息)。還有一種是非隊(duì)列消息，他繞過系統(tǒng)隊(duì)列和消息隊(duì)列，直接將消息發(fā)送到窗口過程。例如,當(dāng)用戶激活一個(gè)窗口系統(tǒng)發(fā)送 WM_ACTIVATE, WM_SETFOCUS, and WM_SETCURSOR。創(chuàng)建窗口時(shí)發(fā)送WM_CREATE消息。
BOOL CWinThread::PumpMessage()
{
ASSERT_VALID(this);
//如果是WM_QUIT就退出函數(shù)(return FALSE)，這將導(dǎo)致程序結(jié)束.
if (!::GetMessage(&m_msgCur, NULL, NULL, NULL)) {
#ifdef _DEBUG
if (afxTraceFlags & traceAppMsg)
TRACE0("CWinThread::PumpMessage - Received WM_QUIT.\n");
m_nDisablePumpCount++; // application must die
// Note: prevents calling message loop things in 'ExitInstance'
// will never be decremented
#endif
return FALSE;
}
#ifdef _DEBUG
if (m_nDisablePumpCount != 0)
{
TRACE0("Error: CWinThread::PumpMessage called when not permitted.\n");
ASSERT(FALSE);
}
#endif
#ifdef _DEBUG
if (afxTraceFlags & traceAppMsg)
_AfxTraceMsg(_T("PumpMessage"), &m_msgCur);
#endif
// process this message
if (m_msgCur.message != WM_KICKIDLE && !PreTranslateMessage(&m_msgCur))
{
::TranslateMessage(&m_msgCur); //鍵轉(zhuǎn)換
::DispatchMessage(&m_msgCur); //派送消息
}
return TRUE;
}
BOOL CWinThread::PreTranslateMessage(MSG* pMsg)
{
ASSERT_VALID(this);
// 如果是線程消息，那么將會(huì)在消息映射表中找到消息入口，調(diào)用線程消息的處理函數(shù)
if (pMsg->hwnd == NULL && DispatchThreadMessageEx(pMsg))
return TRUE;
// walk from target to main window
CWnd* pMainWnd = AfxGetMainWnd();
if (CWnd::WalkPreTranslateTree(pMainWnd->GetSafeHwnd(), pMsg))
return TRUE;
// in case of modeless dialogs, last chance route through main
// window's accelerator table
if (pMainWnd != NULL)
{
CWnd* pWnd = CWnd::FromHandle(pMsg->hwnd);
if (pWnd->GetTopLevelParent() != pMainWnd)
return pMainWnd->PreTranslateMessage(pMsg);
}
return FALSE; // no special processing
}
注：1.一般用PostThreadMessage函數(shù)發(fā)送線程之間的消息，他和窗口消息不同，需要指定線程id,消息激被系統(tǒng)放入到目標(biāo)線程的消息隊(duì)列中；用 ON_THREAD_MESSAGE( message, memberFxn )宏可以映射線程消息和他的處理函數(shù)。這個(gè)宏必須在應(yīng)用程序類(從CWinThread繼承)中，因?yàn)橹挥袘?yīng)用程序類才處理線程消息。如果你在別的類(比如視圖類)中用這個(gè)宏，線程消息的消息處理函數(shù)將得不到線程消息。
2.消息的目標(biāo)窗口的PreTranslateMessage函數(shù)首先得到消息處理權(quán)，如果函數(shù)返回FALSE，那么他的父窗口將得到消息的處理權(quán)，直到主窗口；如果函數(shù)返回TRUE(表示消息已經(jīng)被處理了)，那么就不需要調(diào)用父類的PreTranslateMessage函數(shù)。這樣，保證了消息的目標(biāo)窗口以及他的父窗口都可以有機(jī)會(huì)調(diào)用PreTranslateMessage,如果你想要消息不傳遞給父類進(jìn)行處理的話，返回TRUE就行了
//對話框程序的消息循環(huán)
int CWnd::RunModalLoop(DWORD dwFlags)
{
ASSERT(::IsWindow(m_hWnd)); // window must be created
ASSERT(!(m_nFlags & WF_MODALLOOP)); // window must not already be in modal state
// for tracking the idle time state
BOOL bIdle = TRUE;
LONG lIdleCount = 0;
BOOL bShowIdle = (dwFlags & MLF_SHOWONIDLE) && !(GetStyle() & WS_VISIBLE);
HWND hWndParent = ::GetParent(m_hWnd);
m_nFlags |= (WF_MODALLOOP|WF_CONTINUEMODAL);
MSG* pMsg = &AfxGetThread()->m_msgCur;
// acquire and dispatch messages until the modal state is done
for (;;)
{
ASSERT(ContinueModal());
// phase1: check to see if we can do idle work
while (bIdle &&
!::PeekMessage(pMsg, NULL, NULL, NULL, PM_NOREMOVE))
{
ASSERT(ContinueModal());
// show the dialog when the message queue goes idle
if (bShowIdle)
{
ShowWindow(SW_SHOWNORMAL);
UpdateWindow();
bShowIdle = FALSE;
}
// call OnIdle while in bIdle state
if (!(dwFlags & MLF_NOIDLEMSG) && hWndParent != NULL && lIdleCount == 0)
{
// send WM_ENTERIDLE to the parent
::SendMessage(hWndParent, WM_ENTERIDLE, MSGF_DIALOGBOX, (LPARAM)m_hWnd);
}
if ((dwFlags & MLF_NOKICKIDLE) ||
!SendMessage(WM_KICKIDLE, MSGF_DIALOGBOX, lIdleCount++))
//發(fā)送WM_KICKIDLE消息，如果對話框中有狀態(tài)欄或是工具欄等，靠這個(gè)消息更新狀態(tài)，相當(dāng)于OnIdle
{
// stop idle processing next time
bIdle = FALSE;
}
}
// phase2: pump messages while available
do
{
ASSERT(ContinueModal());
// pump message, but quit on WM_QUIT
//PumpMessage(消息泵)的實(shí)現(xiàn)和上面講的差不多。都是派送消息到窗口。
if (!AfxGetThread()->PumpMessage())
{
AfxPostQuitMessage(0);
return -1;
}
// 消息為WM_SYSTIMER或者WM_SYSKEYDOWN,并且空閑顯示標(biāo)志為真的話，就顯示窗口并通知窗口立刻重繪。
if (bShowIdle &&
(pMsg->message == 0x118 || pMsg->message == WM_SYSKEYDOWN))
{
ShowWindow(SW_SHOWNORMAL);
UpdateWindow();
bShowIdle = FALSE;
}
// 檢測對話框是否還是模式狀態(tài)，如果不是則退出
if (!ContinueModal())
goto ExitModal;
// reset "no idle" state after pumping "normal" message
if (AfxGetThread()->IsIdleMessage(pMsg))
{
bIdle = TRUE;
lIdleCount = 0;
}
} while (::PeekMessage(pMsg, NULL, NULL, NULL, PM_NOREMOVE));
} //無限循環(huán)
ExitModal:
m_nFlags &= ~(WF_MODALLOOP|WF_CONTINUEMODAL);
return m_nModalResult;
}
posted on 2008-09-02 23:16
黑色天使 閱讀(651)
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