MFC将大部分函数都进行了封装，程序员只要改写部分重要的virtual函数即可，这往往使初学者摸不着头脑，连个WinMain函数都看不到，程序从哪开始从哪结束？基本的条理搞不清，永远也不会有提高。下面简单讲下基运行过程.
1,CMyWinApp theApp 程序从这里开始
2,_tWinMain() 在APPMODUL.CPP 它实际上只调用AfxWinMain函数
3,AfxWinMain() WINAMIN.CPP，去掉一些次要信息，它作的事就是：
int AFXAPI AfxWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
LPTSTR lpCmdLine, int nCmdShow)
{
int nReturnCode = -1;
CWinThread* pThread = AfxGetThread();
CWinApp* pApp = AfxGetApp(); ->实际上就是取得CMyWinApp对象指针
AfxWinInit(hInstance, hPrevInstance, lpCmdLine, nCmdShow)
pApp->InitApplication()
pThread->InitInstance()
pThread->Run();
AfxWinTerm();
return nReturnCode;
}
其中:
AfxGetApp(); AFXWIN.CPP中
InitApplication() AFXWIN.CPP中
InitInstance() AFXWIN.CPP中
实际上AfxWinMainy就是调用：
CWinApp::InitApplication 因为我们程序没有改写它
CMyWinApp::InitInstance 我们改写了它且必须改写它,为什么？看源码就能证明一切
BOOL CWinApp::InitInstance() APPCORE.CPP中
{
return TRUE;
}
看到了吧，它什么也没干，直接return TRUE;
CWinApp::Run();
4:AfxWinInit() AFX内部初始化操作,APPINIT.CPP中,贴下源码,如下：
BOOL AFXAPI AfxWinInit(HINSTANCE hInstance, HINSTANCE hPrevInstance,
LPTSTR lpCmdLine, int nCmdShow)
{
..,去掉部分
pModuleState->m_hCurrentInstanceHandle = hInstance;
pModuleState->m_hCurrentResourceHandle = hInstance;
CWinApp* pApp = AfxGetApp();
if (pApp != NULL)
{
// Windows specific initialization (not done if no CWinApp)
pApp->m_hInstance = hInstance;
pApp->m_hPrevInstance = hPrevInstance;
pApp->m_lpCmdLine = lpCmdLine;
pApp->m_nCmdShow = nCmdShow;
pApp->SetCurrentHandles();
}
if (!afxContextIsDLL)
AfxInitThread();
return TRUE;
}
可以看到。它主要进行一些初始化工作.其中：
AfxInitThread() 在THRDCORE.CPP中
5:CWinApp::InitApplication() APPCORE.CPP中,
BOOL CWinApp::InitApplication()
{
if (CDocManager::pStaticDocManager != NULL)
{
if (m_pDocManager == NULL)
m_pDocManager = CDocManager::pStaticDocManager;
CDocManager::pStaticDocManager = NULL;
}
if (m_pDocManager != NULL)
m_pDocManager->AddDocTemplate(NULL);
else
CDocManager::bStaticInit = FALSE;
return TRUE;
}
5:CMyWinApp::InitInstance() 继InitApplication后就是InitInstance调用了。在我们改写的InitStance函数中,将是我们的主窗口的生命,在这里我们会有这样的操作：
m_pMainWnd=new CMyFrameWnd();开始我们的主窗口，创建主窗口，MDI程序采取的是LoadFrame，大家可以看CFrameWnd::LoadFrame()(WNDFRM.CPP中），实际还是做了一样的事，大家不防看下源码。
6:CFrameWnd::Create()
BOOL CFrameWnd::Create(LPCTSTR lpszClassName, 类名
LPCTSTR lpszWindowName, 窗口名
DWORD dwStyle, 样式
const RECT& rect, 区域，默认:rectDefault
CWnd* pParentWnd, 父窗口
LPCTSTR lpszMenuName, 菜单
DWORD dwExStyle, 扩展样式
CCreateContext* pContext)
{
HMENU hMenu = NULL;
if (lpszMenuName != NULL)
{
HINSTANCE hInst = AfxFindResourceHandle(lpszMenuName, RT_MENU);
if ((hMenu = ::LoadMenu(hInst, lpszMenuName)) == NULL)
{
TRACE0("Warning: failed to load menu for CFrameWnd.\n");
PostNcDestroy(); // perhaps delete the C++ object
return FALSE;
}
}
m_strTitle = lpszWindowName; // save title for later
if (!CreateEx(dwExStyle, lpszClassName, lpszWindowName, dwStyle,
rect.left, rect.top, rect.right - rect.left, rect.bottom - rect.top,
pParentWnd->GetSafeHwnd(), hMenu, (LPVOID)pContext))
{
TRACE0("Warning: failed to create CFrameWnd.\n");
if (hMenu != NULL)
DestroyMenu(hMenu);
return FALSE;
}
return TRUE;
}
7:CWnd::CreateEx() 可以看到CFrameWnd::Create，只是调用了CreateEx 函数，CFrameWnd没有改字CreateEx 函数，所以它调用的是CWnd 类的函数.
BOOL CWnd::CreateEx(DWORD dwExStyle, LPCTSTR lpszClassName,
LPCTSTR lpszWindowName, DWORD dwStyle,
int x, int y, int nWidth, int nHeight,
HWND hWndParent, HMENU nIDorHMenu, LPVOID lpParam)
{
// allow modification of several common create parameters
CREATESTRUCT cs; 用过SDK写程序的朋友一定知道这是想做什么
cs.dwExStyle = dwExStyle;
cs.lpszClass = lpszClassName;
cs.lpszName = lpszWindowName;
cs.style = dwStyle;
cs.x = x;
cs.y = y;
cs.cx = nWidth;
cs.cy = nHeight;
cs.hwndParent = hWndParent;
cs.hMenu = nIDorHMenu;
cs.hInstance = AfxGetInstanceHandle();
cs.lpCreateParams = lpParam;
if (!PreCreateWindow(cs))
{
PostNcDestroy();
return FALSE;
}
AfxHookWindowCreate(this);
HWND hWnd = ::CreateWindowEx(cs.dwExStyle, cs.lpszClass,
cs.lpszName, cs.style, cs.x, cs.y, cs.cx, cs.cy,
cs.hwndParent, cs.hMenu, cs.hInstance, cs.lpCreateParams);
...
}
此函数又调用了PreCreateWindow,CreateWindowEx,
8：CFrameWnd::PreCreateWindow()， PreCreateWindow是个virtual，由于this 指针的原故，这里是调用CFrameWnd的PreCreateWindow.一般我们的程序都会改写些函数，在此设定窗口的一些样式。
BOOL CFrameWnd::PreCreateWindow(CREATESTRUCT& cs) --->WINFRM.CPP
{
if (cs.lpszClass == NULL)
{
VERIFY(AfxDeferRegisterClass(AFX_WNDFRAMEORVIEW_REG));
cs.lpszClass = _afxWndFrameOrView; // COLOR_WINDOW background
}
...
}
#define AfxDeferRegisterClass(fClass) AfxEndDeferRegisterClass(fClass)
AfxEndDeferRegisterClass() --->WINCORE.CPP,在这个函数中，调用RegisterWithIcon(实际上还是要调用AfxRegisterClass),和AfxRegisterClass,会我们注五个窗口类.在non-Unicode下使用MFC动态链接版和谳试版，五个类为：
"AfxWnd42d"
"AfxControlBar42d"
"AfxMDIFrame42d"
"AfxFrameOrView42d"
"AfxOleControl42d"
在Uncode中使用静态和调试版，是：
"AfxWnd42sud"
"AfxControlBar42sud"
"AfxMDIFrame42sud"
"AfxFrameOrView42sud"
"AfxOleControl42sud"
大家可以看到了。PreCreateWindow是在窗口产生前被调用，用来注册窗口类，如果我们指定的窗口类为NULL,则会用系统默认的。可以来看下不同功能的窗口使用的窗口类:
BOOL CWnd::PreCreateWindow(CREATESTRUCT& cs) -->WINCORE.CPP
{
if (cs.lpszClass == NULL)
{
...
cs.lpszClass = _afxWnd; file://使用_afxWnd窗口类
}
}
BOOL CFrameWnd::PreCreateWindow(CREATESTRUCT& cs) -->WINFRM.CPP
{
if (cs.lpszClass == NULL)
{
...
cs.lpszClass = _afxWndFrameOrView; // COLOR_WINDOW background
}
}
BOOL CMDIFrameWnd::PreCreateWindow(CREATESTRUCT& cs) -->WINMDI.CPP
{
if (cs.lpszClass == NULL)
{
...
cs.lpszClass = _afxWndMDIFrame; file://使用_afxWndMDIFrame 窗口类
}
return TRUE;
}
...
9:CWinApp::Run() 程序到这里，窗口类注册好了。并显示出来了。UpDateWindow函数将会调用，并产生一个WM_PAINTIITH，等待处理。便进入了RUN函数，
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(); // 调用CWinThread::Run()
}
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.
for (;;)
{
// phase1: check to see if we can do idle work
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
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
}
如果没有消息，则调用OnIdle()，空闲处理，否则PumpMessage(),看下它做了什么？
BOOL CWinThread::PumpMessage()
{
ASSERT_VALID(this);
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);
::DispatchMessage(&m_msgCur);
}
return TRUE;
}
呵，和SDK程序做法一样，GetMessage,TranslateMessage(),DisptchMessage()
好了。进入到Run （）这里，程序就活动起来了。它会对一系列的消息进行处理。并在收到WM_CLOSE 消息时退出.默认函数对WM_CLOSE的处理是是调用::DestroyWindow(),关因而发出WM_DESTROY消息，默认的的WM_DESTROY处理方式是调用::PostQuitMessage(),因此发出WM_QUIT,Run收到WM_QUIT时，就结束消息循环，调用ExitInstance,最后在AfxWinMain中执行AfxWinTerm结束程序.
