mfc消息循环

MFC消息传递（单文档与对话框） 收藏
先针对单文档程序进行分析：

//首先进入_tWinMain函数，函数中调用AfxWinMain()；

extern "C" int WINAPI
_tWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
LPTSTR lpCmdLine, int nCmdShow)
{
// call shared/exported WinMain
return AfxWinMain(hInstance, hPrevInstance, lpCmdLine, nCmdShow);
}

//下面是AfxWinMain函数的说明：

int AFXAPI AfxWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
LPTSTR lpCmdLine, int nCmdShow)
{
........

int nReturnCode = -1;
CWinThread* pThread = AfxGetThread();
CWinApp* pApp = AfxGetApp();

// AFX internal initialization

//AFX的内部初始化：
if (!AfxWinInit(hInstance, hPrevInstance, lpCmdLine, nCmdShow))
goto InitFailure;

// App global initializations (rare)

//App全局的初始化：
if (pApp != NULL && !pApp->InitApplication())
goto InitFailure;

// Perform specific initializations

//进行指定的初始化：
if (!pThread->InitInstance())
{
if (pThread->m_pMainWnd != NULL)
{
TRACE0("Warning: Destroying non-NULL m_pMainWnd/n");
pThread->m_pMainWnd->DestroyWindow();
}
nReturnCode = pThread->ExitInstance();
goto InitFailure;
}

//进程运行：
nReturnCode = pThread->Run();

InitFailure:
.......

AfxWinTerm();
return nReturnCode;
}

//CWinThread的子类CWinApp的Run函数重写

int CWinApp::Run()
{
if (m_pMainWnd == NULL && AfxOleGetUserCtrl())
{
// Not launched /Embedding or /Automation, but has no main window!
TRACE0("Warning: m_pMainWnd is NULL in CWinApp::Run - quitting application./n");
AfxPostQuitMessage(0);
}
return CWinThread::Run();
}

首先调用InitialInstance()

BOOL CSingleDocumentApp::InitInstance()
{
..........

//初始化文档模板，即添加文档类，主框架类，视图类三个动态类

//添加文档模板，多文档程序中需要多个模板。

CSingleDocTemplate* pDocTemplate;
pDocTemplate = new CSingleDocTemplate(
IDR_MAINFRAME,
RUNTIME_CLASS(CSingleDocumentDoc),
RUNTIME_CLASS(CMainFrame), // main SDI frame window
RUNTIME_CLASS(CSingleDocumentView));
AddDocTemplate(pDocTemplate);

//控制台消息处理

// Parse command line for standard shell commands, DDE, file open
CCommandLineInfo cmdInfo;
ParseCommandLine(cmdInfo);

// Dispatch commands specified on the command line
if (!ProcessShellCommand(cmdInfo))
return FALSE;

//窗口显示

// The one and only window has been initialized, so show and update it.
m_pMainWnd->ShowWindow(SW_SHOW);
m_pMainWnd->UpdateWindow();

return TRUE;
}

//这里就进入了比较重要的地方了：

int CWinThread::Run()
{
ASSERT_VALID(this);

// for tracking the idle time state
BOOL bIdle = TRUE;
LONG lIdleCount = 0;

// acquire and dispatch messages until a WM_QUIT message is received.

//一个“无限循环”
for (;;)
{
// phase1: check to see if we can do idle work

//如果是idle状态且没有其他的消息，系统会进行相关的内存释放？？？
while (bIdle &&
!::PeekMessage(&m_msgCur, NULL, NULL, NULL, PM_NOREMOVE))
{
// call OnIdle while in bIdle state
if (!OnIdle(lIdleCount++))
bIdle = FALSE; // assume "no idle" state
}

// phase2: pump messages while available

//第二阶段，消息泵函数调用：
do
{
// pump message, but quit on WM_QUIT
if (!PumpMessage())
return ExitInstance();

// reset "no idle" state after pumping "normal" message
if (IsIdleMessage(&m_msgCur))
{
bIdle = TRUE;
lIdleCount = 0;
}

} while (::PeekMessage(&m_msgCur, NULL, NULL, NULL, PM_NOREMOVE));
}

ASSERT(FALSE); // not reachable
}

//下面就进入了关键的消息泵函数了，核心啊：

BOOL CWinThread::PumpMessage()
{
ASSERT_VALID(this);

//GetMessage函数会从消息队列中取走消息，与带指定参数PM_NOREMOVE的PeekMessage函数不一样

if (!::GetMessage(&m_msgCur, NULL, NULL, NULL))
{
........

// process this message

if (m_msgCur.message != WM_KICKIDLE && !PreTranslateMessage(&m_msgCur))

//TranslateMessage用于对键盘的输入的转换

//DispatchMessage用于消息的指派给各个反应单元了
{
::TranslateMessage(&m_msgCur);
::DispatchMessage(&m_msgCur);
}
return TRUE;
}

对于对话框应该注意到在APP类中的InitInstance中

//不管如何处理，最后都会返回一个FALSE

BOOL CDialogApp::InitInstance()
{
AfxEnableControlContainer();

// Standard initialization
// If you are not using these features and wish to reduce the size
// of your final executable, you should remove from the following
// the specific initialization routines you do not need.

#ifdef _AFXDLL
Enable3dControls(); // Call this when using MFC in a shared DLL
#else
Enable3dControlsStatic(); // Call this when linking to MFC statically
#endif

CDialogDlg dlg;
m_pMainWnd = &dlg;
int nResponse = dlg.DoModal();
if (nResponse == IDOK)
{
// TODO: Place code here to handle when the dialog is
// dismissed with OK
}
else if (nResponse == IDCANCEL)
{
// TODO: Place code here to handle when the dialog is
// dismissed with Cancel
}

// Since the dialog has been closed, return FALSE so that we exit the
// application, rather than start the application's message pump.
return FALSE;
}

那么在WinMain中调用InitInstace函数之后就会跳过调用pThread->Run()，消息泵进不去了，怎么办？

int CDialog::DoModal()
{
// can be constructed with a resource template or InitModalIndirect
ASSERT(m_lpszTemplateName != NULL || m_hDialogTemplate != NULL ||
m_lpDialogTemplate != NULL);

// load resource as necessary
LPCDLGTEMPLATE lpDialogTemplate = m_lpDialogTemplate;
HGLOBAL hDialogTemplate = m_hDialogTemplate;
HINSTANCE hInst = AfxGetResourceHandle();
if (m_lpszTemplateName != NULL)
{
hInst = AfxFindResourceHandle(m_lpszTemplateName, RT_DIALOG);
HRSRC hResource = ::FindResource(hInst, m_lpszTemplateName, RT_DIALOG);
hDialogTemplate = LoadResource(hInst, hResource);
}
if (hDialogTemplate != NULL)
lpDialogTemplate = (LPCDLGTEMPLATE)LockResource(hDialogTemplate);

// return -1 in case of failure to load the dialog template resource
if (lpDialogTemplate == NULL)
return -1;

// disable parent (before creating dialog)
HWND hWndParent = PreModal();
AfxUnhookWindowCreate();
BOOL bEnableParent = FALSE;
if (hWndParent != NULL && ::IsWindowEnabled(hWndParent))
{
::EnableWindow(hWndParent, FALSE);
bEnableParent = TRUE;
}

TRY
{
// create modeless dialog
AfxHookWindowCreate(this);
if (CreateDlgIndirect(lpDialogTemplate,
CWnd::FromHandle(hWndParent), hInst))
{
if (m_nFlags & WF_CONTINUEMODAL)
{
// enter modal loop
DWORD dwFlags = MLF_SHOWONIDLE;
if (GetStyle() & DS_NOIDLEMSG)
dwFlags |= MLF_NOIDLEMSG;
VERIFY(RunModalLoop(dwFlags) == m_nModalResult);
}

// hide the window before enabling the parent, etc.
if (m_hWnd != NULL)
SetWindowPos(NULL, 0, 0, 0, 0, SWP_HIDEWINDOW|
SWP_NOSIZE|SWP_NOMOVE|SWP_NOACTIVATE|SWP_NOZORDER);
}
}
CATCH_ALL(e)
{
DELETE_EXCEPTION(e);
m_nModalResult = -1;
}
END_CATCH_ALL

if (bEnableParent)
::EnableWindow(hWndParent, TRUE);
if (hWndParent != NULL && ::GetActiveWindow() == m_hWnd)
::SetActiveWindow(hWndParent);

// destroy modal window
DestroyWindow();
PostModal();

// unlock/free resources as necessary
if (m_lpszTemplateName != NULL || m_hDialogTemplate != NULL)
UnlockResource(hDialogTemplate);
if (m_lpszTemplateName != NULL)
FreeResource(hDialogTemplate);

return m_nModalResult;
}

//哇嘎嘎，在这里进行消息的传递的啊

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;
}



本文来自CSDN博客，转载请标明出处：http://blog.csdn.net/pizi0475/archive/2010/04/01/5441791.aspx