对话框的消息循环,MFC源码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 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); UpdateWindow(); bShowIdle = FALSE; } 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)); }ExitModal: m_nFlags &= ~(WF_MODALLOOP|WF_CONTINUEMODAL); return m_nModalResult; }
应该看看DoModal的代码
{
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
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);
UpdateWindow();
bShowIdle = FALSE;
} 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));
}ExitModal:
m_nFlags &= ~(WF_MODALLOOP|WF_CONTINUEMODAL);
return m_nModalResult;
}