MFC剖析：消息机制 出处：白云黄鹤 转载的一篇老文，有的放矢的说明了MFC消息流程。 首先,让我们看一下MFC的消息循环部分：（程序取自MFC源程序，由于篇幅，我删去了一些非重要的部分。） MFC的WinMain函数：
extern "C" int WINAPI
_tWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
LPTSTR lpCmdLine, int nCmdShow)
{
// call shared/exported WinMain
return AfxWinMain(hInstance, hPrevInstance, lpCmdLine, nCmdShow);
}
int AFXAPI AfxWinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
LPTSTR lpCmdLine, int nCmdShow)
{
int nReturnCode = -1;
CWinApp* pApp = AfxGetApp();
// ......
// Perform specific initializations
if (!pApp->InitInstance())
{
// ......
//初始化实例不成功，通常一个Dialog Based MFC程序必须返回FALSE
//这样就可以跳过消息循环。
nReturnCode = pApp->ExitInstance();
goto InitFailure;
}
nReturnCode = pApp->Run(); //进入消息循环部分
InitFailure:
// ......
// 程序结束
AfxWinTerm();
return nReturnCode;
}
int CWinApp::Run()
{
// ......
return CWinThread::Run(); // 消息循环被封装在CWinThread类里。
}
int CWinThread::Run()
{
BOOL bIdle = TRUE;
LONG lIdleCount = 0;
// 死循环，只有收到 WM_QUIT 消息后才会退出。
for (;;)
{
while (bIdle &&
!::PeekMessage(&m_msgCur, NULL, NULL, NULL, PM_NOREMOVE))
{
if (!OnIdle(lIdleCount++))
bIdle = FALSE;
}
// 如果消息队列中没有消息，那么就调用OnIdle函数
// 否则，发送消息
do
{
if (!PumpMessage())
// PumpMessage函数仅在收到WM_QUIT消息才返回FALSE
return ExitInstance(); // 退出死循环
if (IsIdleMessage(&m_msgCur))
{
bIdle = TRUE;
lIdleCount = 0;
}
} while (::PeekMessage(&m_msgCur, NULL, NULL, NULL, PM_NOREMOVE));
// 这段程序不仅完成了消息的发送，还实现了Idle功能。
// GetMessage函数在消息队列中没有消息时，将不会返回，
// 而是将控制权交给操作系统，直到消息队列中有消息为止。
// 这段程序在一开始就调用PeekMessage函数来检测消息队列中
// 是否有消息存在，如果存在就发送消息，
// 否则就意味着空闲，那么就调用OnIdle函数，
// 这样做，控制权永远不会交给操作系统。
// 由于Windows 95, NT都是抢占式的操作系统，
// 系统会自动进行任务切换。
// 所以不用担心别的程序不会被运行。
}
}
BOOL CWinThread::PumpMessage()
{
if (!::GetMessage(&m_msgCur, NULL, NULL, NULL))
{// 收到 WM_QUIT 消息，就返回 FALSE。
return FALSE;
}
// 否则就发送消息
if (m_msgCur.message != WM_KICKIDLE && !PreTranslateMessage(&m_msgCur)
)
{
::TranslateMessage(&m_msgCur);
::DispatchMessage(&m_msgCur);
}
return TRUE;
}
</pre>
主程序的流程：
<pre lang="text">(程序开始)
|
|
v
WinMain
|
|
v
AfxWinMain
|
|
v FALSE
CWinApp::InitInstance-------> 退出程序
|
|TRUE
|
v
CWinApp::Run
|
|
v
CWinThread::Run
|
|<----------------------------+
v FALSE |
PeekMessage------->OnIdle--------+
|TRUE |
|<-------------------------+ |
v | |
GetMessage | |
| | |
| | |
YES v | |
+-----WM_QUIT 消息？ | |
| | | |
| |NO | |
| v | |
| TranslateMessage | |
| | | |
| | | |
| v | |
| DispatchMessage | |
| | | |
| | | |
| v TRUE | |
| PeekMessage------------------>+ |
| | |
| |FALSE |
| +-----------------------------+
|
v
(程序结束)
</pre>
现在，再让我们来看一下MFC的窗口是如何响应消息的。 我们先来看一段建立一个窗口的代码.
<pre lang="c">class CMsgWnd : public CWnd
{
public:
CMsgWnd() {}
// ClassWizard generated virtual function overrides
//{{AFX_VIRTUAL(CMsgWnd)
virtual BOOL Create(CWnd* pParentWnd);
//}}AFX_VIRTUAL
virtual ~CMsgWnd() {}
protected:
//{{AFX_MSG(CMsgWnd)
afx_msg void OnPaint();
afx_msg void OnLButtonDown(UINT nFlags, CPoint point);
//}}AFX_MSG
DECLARE_MESSAGE_MAP()
};
BEGIN_MESSAGE_MAP(CMsgWnd, CWnd)
//{{AFX_MSG_MAP(CMsgWnd)
ON_WM_PAINT()
ON_WM_LBUTTONDOWN()
//}}AFX_MSG_MAP
END_MESSAGE_MAP()
BOOL CMsgWnd::Create(CWnd *pParentWnd)
{
return CWnd::Create(AfxRegisterWndClass(CS_DBLCLKS),
"Message Window", WS_VISIBLE|WS_CHILD, CRect(0,0,100,100),
pParentWnd, 12345);
}
void CMsgWnd::OnPaint()
{
CPaintDC dc(this); // device context for painting
dc.TextOut(0,0,"hello");
}
void CMsgWnd::OnLButtonDown(UINT nFlags, CPoint point)
{
MessageBox("OnLButtonDown");
CWnd::OnLButtonDown(nFlags, point);
}
</pre>
以上是一段标准的CWnd窗口类的子类实现代码. 我想大家应该是可以看的懂的. 注意到CMsgWnd类中有一句代码 DECLARE_MESSAGE_MAP() 我们来看看这个宏是如何定义的:
<pre lang="c">typedef void (AFX_MSG_CALL CCmdTarget::*AFX_PMSG)(void);
// 这是一个指向 CCmdTarget 类成员函数的指针类型.
struct AFX_MSGMAP_ENTRY // 消息映射表之消息入口
{
UINT nMessage; // 消息
UINT nCode; // 控制码或者是 WM_NOTIFY 消息的通知码
UINT nID; // 控件的ID,如果是窗口消息则为0
UINT nLastID; // 如果是一个范围的消息,那么这是最后一个控件的ID
UINT nSig; // 消息处理类型
AFX_PMSG pfn; // 消息处理函数
};
struct AFX_MSGMAP // 消息映射表
{
#ifdef _AFXDLL // 如果MFC是动态连接的,
// 就是编译时选择 Use MFC in a shared DLL
const AFX_MSGMAP* (PASCAL* pfnGetBaseMap)();
#else // MFC是静态连接的,编译时选择 Use MFC in a static library.
const AFX_MSGMAP* pBaseMap;
#endif
// 如果MFC是动态连接的, 就用pfnGetBaseMap函数返回基类的消息映射表
// 否则 pBaseBap 指向基类的消息映射表
const AFX_MSGMAP_ENTRY* lpEntries; // 指向消息入口的指针
};
#ifdef _AFXDLL // 如果MFC是动态连接的
#define DECLARE_MESSAGE_MAP() \
private: \
static const AFX_MSGMAP_ENTRY _messageEntries[]; \ // 消息入口
protected: \
static AFX_DATA const AFX_MSGMAP messageMap; \ // 消息映射表
static const AFX_MSGMAP* PASCAL _GetBaseMessageMap(); \
// 该函数返回基类的消息映射表
virtual const AFX_MSGMAP* GetMessageMap() const; \
// 该函数返回当前类的消息映射表
#else // 静态连接的
#define DECLARE_MESSAGE_MAP() \
private: \
static const AFX_MSGMAP_ENTRY _messageEntries[]; \
protected: \
static AFX_DATA const AFX_MSGMAP messageMap; \
virtual const AFX_MSGMAP* GetMessageMap() const; \
#endif
//^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
// 以上这段代码实际上是嵌入在你的类中.
在 .CPP 文件中我们看到还有这段宏,
BEGIN_MESSAGE_MAP(CMsgWnd, CWnd)
//{{AFX_MSG_MAP(CMsgWnd)
ON_WM_PAINT()
ON_WM_LBUTTONDOWN()
//}}AFX_MSG_MAP
END_MESSAGE_MAP()
现在我们再来看看它是被如何定义的.
#ifdef _AFXDLL
#define BEGIN_MESSAGE_MAP(theClass, baseClass) \
const AFX_MSGMAP* PASCAL theClass::_GetBaseMessageMap() \
{ return &baseClass::messageMap; } \ // 返回基类的消息映射表
^^^^^^^^^^^^^^^^^^^^^^
const AFX_MSGMAP* theClass::GetMessageMap() const \
{ return &theClass::messageMap; } \ // 返回当前类的消息映射表
AFX_DATADEF const AFX_MSGMAP theClass::messageMap = \ // 消息映射表
{ &theClass::_GetBaseMessageMap, &theClass::_messageEntries[0] }; \
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
const AFX_MSGMAP_ENTRY theClass::_messageEntries[] = \
{ \
#else
#define BEGIN_MESSAGE_MAP(theClass, baseClass) \
const AFX_MSGMAP* theClass::GetMessageMap() const \
{ return &theClass::messageMap; } \ // 返回当前类的消息映射表
AFX_DATADEF const AFX_MSGMAP theClass::messageMap = \ // 消息映射表
{ &baseClass::messageMap, &theClass::_messageEntries[0] }; \
^^^^^^^^^^^^^^^^^^^^^^ 可以看到这是 MFC 动态连接与静态连接的区别所在
动态连接时使用函数 _GetBaseMessageMap 返回 &baseClass::messageMap
而静态连接是直接使用.至于Microsoft为什么要这样做,
好像没有什么很好的理由.
当然这个并不重要,我们暂且不用理会.
const AFX_MSGMAP_ENTRY theClass::_messageEntries[] = \
//开始初始化消息入口
{ \
#endif
#define END_MESSAGE_MAP() \
{0, 0, 0, 0, AfxSig_end, (AFX_PMSG)0 } \
}; \ ^^^^^^^^^^^^^^^^^^^^^^ 指示消息映射结束.
在这两个宏之间还有
ON_WM_PAINT()
ON_WM_LBUTTONDOWN()
它们是我们在ClassWizard中选择了WM_PAINT和WM_LBUTTONDOWN消息后,
MFC自动加入的,那么这两个又是如何定义的呢?
......
#define ON_WM_PAINT() \
{ WM_PAINT, 0, 0, 0, AfxSig_vv, \
^^^^^^^^ ^ ^ ^ ^
| | | | +------------- 消息处理类型
| | | +------------------- LastID
| | +---------------------- ID=0, 窗口消息
| +------------------------- 控制码
+-------------------------------- WM_PAINT 消息
(AFX_PMSG)(AFX_PMSGW)(void (AFX_MSG_CALL CWnd::*)
(void))&OnPaint },
^^^^^^^^^^^^^^^ 消息处理函数
.....
#define ON_WM_LBUTTONDOWN() \
{ WM_LBUTTONDOWN, 0, 0, 0, AfxSig_vwp, \
^^^^^^^^^^^^^^ WM_LBUTTON 消息
(AFX_PMSG)(AFX_PMSGW)(void (AFX_MSG_CALL CWnd::*)
(UINT, CPoint))&OnLButtonDown },
^^^^^^^^^^^^^ 消息处理函数
......
现在我们差不多可以看得出来了,消息处理函数可以
靠_messageEntries来找到每个消息的处理函数.
我们可以再看看CWnd类来验证我们的想法.
先看一下窗口的建立过程:
BOOL CWnd::Create(LPCTSTR lpszClassName,
LPCTSTR lpszWindowName, DWORD dwStyle,
const RECT& rect,
CWnd* pParentWnd, UINT nID,
CCreateContext* pContext)
{
// can't use for desktop or pop-up windows (use CreateEx instead)
ASSERT(pParentWnd != NULL);
ASSERT((dwStyle & WS_POPUP) == 0);
return CreateEx(0, lpszClassName, lpszWindowName,
dwStyle | WS_CHILD,
rect.left, rect.top,
rect.right - rect.left, rect.bottom - rect.top,
pParentWnd->GetSafeHwnd(), (HMENU)nID, (LPVOID)pContext);
}
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;
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);
^^^^^^^^^^^^^^^^^^^^^^^^^^ 函数见后
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);
if (!AfxUnhookWindowCreate())
PostNcDestroy(); // cleanup if CreateWindowEx fails too soon
if (hWnd == NULL)
return FALSE;
ASSERT(hWnd == m_hWnd); // should have been set in send msg hook
return TRUE;
}
// for child windows
BOOL CWnd::PreCreateWindow(CREATESTRUCT& cs)
{
if (cs.lpszClass == NULL)
{
// make sure the default window class is registered
if (!AfxDeferRegisterClass(AFX_WND_REG))
return FALSE;
// no WNDCLASS provided - use child window default
ASSERT(cs.style & WS_CHILD);
cs.lpszClass = _afxWnd;
}
return TRUE;
}
void AFXAPI AfxHookWindowCreate(CWnd* pWnd)
{
_AFX_THREAD_STATE* pThreadState = _afxThreadState.GetData();
if (pThreadState->m_pWndInit == pWnd)
return;
if (pThreadState->m_hHookOldCbtFilter == NULL)
{
pThreadState->m_hHookOldCbtFilter = ::SetWindowsHookEx(WH_CBT,
^^^^^^
Computer-based Training,当建立、删除、移动、最大化、最小化
窗口时，将会调用钩子函数。
_AfxCbtFilterHook, NULL, ::GetCurrentThreadId());
^^^^^^^^^^^^^^^^^ 钩子函数
if (pThreadState->m_hHookOldCbtFilter == NULL)
AfxThrowMemoryException();
}
ASSERT(pThreadState->m_hHookOldCbtFilter != NULL);
ASSERT(pWnd != NULL);
ASSERT(pWnd->m_hWnd == NULL); // only do once
ASSERT(pThreadState->m_pWndInit == NULL); // hook not already in progr
ess
pThreadState->m_pWndInit = pWnd;
}
BOOL AFXAPI AfxUnhookWindowCreate()
{
_AFX_THREAD_STATE* pThreadState = _afxThreadState.GetData();
#ifndef _AFXDLL
if (afxContextIsDLL && pThreadState->m_hHookOldCbtFilter != NULL)
{
::UnhookWindowsHookEx(pThreadState->m_hHookOldCbtFilter);
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
删除钩子函数
pThreadState->m_hHookOldCbtFilter = NULL;
}
#endif
if (pThreadState->m_pWndInit != NULL)
{
pThreadState->m_pWndInit = NULL;
return FALSE; // was not successfully hooked
}
return TRUE;
}
// Window creation hooks
LRESULT CALLBACK
_AfxCbtFilterHook(int code, WPARAM wParam, LPARAM lParam)
{
_AFX_THREAD_STATE* pThreadState = _afxThreadState.GetData();
if (code != HCBT_CREATEWND)
{ ^^^^^^^^^^^^^^^^^^^^^^ 是要建立窗口吗？
// wait for HCBT_CREATEWND just pass others on...
return CallNextHookEx(pThreadState->m_hHookOldCbtFilter, code,
wParam, lParam);
}
ASSERT(lParam != NULL);
LPCREATESTRUCT lpcs = ((LPCBT_CREATEWND)lParam)->lpcs;
ASSERT(lpcs != NULL);
// this hook exists to set the SendMessage hook on window creations
// (but this is only done for MFC windows or non-child windows)
// the subclassing cannot be done at this point because on Win32s
// the window does not have the WNDPROC set yet
CWnd* pWndInit = pThreadState->m_pWndInit;
if (pWndInit != NULL || (!(lpcs->style & WS_CHILD) && !afxContextIsDLL
))
{
ASSERT(wParam != NULL); // should be non-NULL HWND
HWND hWnd = (HWND)wParam;
WNDPROC oldWndProc;
if (pWndInit != NULL)
{ ^^^^^^^^^^^^^^^^ 窗口建立来自一个CWnd?
// the window should not be in the permanent map at this time
ASSERT(CWnd::FromHandlePermanent(hWnd) == NULL);
// connect the HWND to pWndInit...
pWndInit->Attach(hWnd);
// allow other subclassing to occur first
pWndInit->PreSubclassWindow();
WNDPROC *pOldWndProc = pWndInit->GetSuperWndProcAddr();
ASSERT(pOldWndProc != NULL);
#ifndef _MAC
_AFX_CTL3D_STATE* pCtl3dState;
DWORD dwFlags;
if (!afxData.bWin4 && !afxContextIsDLL &&
(pCtl3dState = _afxCtl3dState.GetDataNA()) != NULL &&
pCtl3dState->m_pfnSubclassDlgEx != NULL &&
(dwFlags = AfxCallWndProc(pWndInit, hWnd, WM_QUERY3DCONTROLS)) != 0)
{
// was the class registered with AfxWndProc?
WNDPROC afxWndProc = AfxGetAfxWndProc();
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
函数见后
BOOL bAfxWndProc = ((WNDPROC)
GetWindowLong(hWnd, GWL_WNDPROC) == afxWndProc);
pCtl3dState->m_pfnSubclassDlgEx(hWnd, dwFlags);
// subclass the window if not already wired to AfxWndProc
if (!bAfxWndProc)
{
// subclass the window with standard AfxWndProc
oldWndProc = (WNDPROC)SetWindowLong(hWnd, GWL_WNDPROC,
(DWORD)afxWndProc); // 修改窗口的WndProc!!!
ASSERT(oldWndProc != NULL);
*pOldWndProc = oldWndProc;
}
}
else
#endif
{
// subclass the window with standard AfxWndProc
WNDPROC afxWndProc = AfxGetAfxWndProc();
oldWndProc = (WNDPROC)SetWindowLong(hWnd, GWL_WNDPROC,
(DWORD)afxWndProc);
ASSERT(oldWndProc != NULL);
if (oldWndProc != afxWndProc)
*pOldWndProc = oldWndProc;
}
pThreadState->m_pWndInit = NULL;
}
else
{
ASSERT(!afxContextIsDLL); // should never get here
// subclass the window with the proc which does gray backgrounds
oldWndProc = (WNDPROC)GetWindowLong(hWnd, GWL_WNDPROC);
if (oldWndProc != NULL)
{
ASSERT(GetProp(hWnd, szAfxOldWndProc) == NULL);
SetProp(hWnd, szAfxOldWndProc, oldWndProc);
if ((WNDPROC)GetProp(hWnd, szAfxOldWndProc) == oldWndProc)
{
SetWindowLong(hWnd, GWL_WNDPROC,
(DWORD)(pThreadState->m_bDlgCreate ?
_AfxGrayBackgroundWndProc : _AfxActivationWndProc));
ASSERT(oldWndProc != NULL);
}
}
}
}
LRESULT lResult = CallNextHookEx(pThreadState->m_hHookOldCbtFilter, co
de,
wParam, lParam);
#ifndef _AFXDLL
if (afxContextIsDLL)
{
::UnhookWindowsHookEx(pThreadState->m_hHookOldCbtFilter);
pThreadState->m_hHookOldCbtFilter = NULL;
}
#endif
return lResult;
}
// always indirectly accessed via AfxGetAfxWndProc
WNDPROC AFXAPI AfxGetAfxWndProc()
{
#ifdef _AFXDLL
return AfxGetModuleState()->m_pfnAfxWndProc;
// 如果MFC是动态连入，返回的地址是AfxWndProcBase
#else
return &AfxWndProc; // 否则返回AfxWndProc
#endif
}
// The WndProc for all CWnd's and derived classes
LRESULT CALLBACK
AfxWndProc(HWND hWnd, UINT nMsg, WPARAM wParam, LPARAM lParam)
{
// special message which identifies the window as using AfxWndProc
if (nMsg == WM_QUERYAFXWNDPROC)
^^^^^^^^^^^^^^^^^^ 查询是否为AFX的窗口过程
return 1;
// all other messages route through message map
CWnd* pWnd = CWnd::FromHandlePermanent(hWnd);
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
FromHandlePermanent函数用于返回一个和hWnd句柄对应的
永久的CWnd类，所谓永久的，就是CWnd调用了Attach函数
连上了一个窗口句柄。
ASSERT(pWnd != NULL);
ASSERT(pWnd->m_hWnd == hWnd);
return AfxCallWndProc(pWnd, hWnd, nMsg, wParam, lParam);
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 函数见后
}
#ifdef _AFXDLL
#undef AfxWndProc
LRESULT CALLBACK
AfxWndProcBase(HWND hWnd, UINT nMsg, WPARAM wParam, LPARAM lParam)
{
AFX_MANAGE_STATE(_afxBaseModuleState.GetData());
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
// 由于MFC是动态连入的，所以必须要这条语句！
return AfxWndProc(hWnd, nMsg, wParam, lParam);
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
调用MFC静态连入时使用的函数
}
#endif
// 微软官方规定的发送消息给CWnd的函数
LRESULT AFXAPI AfxCallWndProc(CWnd* pWnd, HWND hWnd, UINT nMsg,
WPARAM wParam = 0, LPARAM lParam = 0)
{
_AFX_THREAD_STATE* pThreadState = _afxThreadState.GetData();
MSG oldState = pThreadState->m_lastSentMsg; // save for nesting
pThreadState->m_lastSentMsg.hwnd = hWnd;
pThreadState->m_lastSentMsg.message = nMsg;
pThreadState->m_lastSentMsg.wParam = wParam;
pThreadState->m_lastSentMsg.lParam = lParam;
#ifdef _DEBUG
if (afxTraceFlags & traceWinMsg)
_AfxTraceMsg(_T("WndProc"), &pThreadState->m_lastSentMsg);
#endif
// Catch exceptions thrown outside the scope of a callback
// in debug builds and warn the user.
LRESULT lResult;
TRY
{
#ifndef _AFX_NO_OCC_SUPPORT
// special case for WM_DESTROY
if ((nMsg == WM_DESTROY) && (pWnd->m_pCtrlCont != NULL))
pWnd->m_pCtrlCont->OnUIActivate(NULL);
#endif
// special case for WM_INITDIALOG
CRect rectOld;
DWORD dwStyle;
if (nMsg == WM_INITDIALOG)
_AfxPreInitDialog(pWnd, &rectOld, &dwStyle);
// delegate to object's WindowProc
lResult = pWnd->WindowProc(nMsg, wParam, lParam);
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
调用CWnd类的WindowProc函数,函数见后
// more special case for WM_INITDIALOG
if (nMsg == WM_INITDIALOG)
_AfxPostInitDialog(pWnd, rectOld, dwStyle);
}
CATCH_ALL(e)
{
lResult = AfxGetThread()->ProcessWndProcException(e, &pThreadState->m_
lastSentMsg);
TRACE1("Warning: Uncaught exception in WindowProc (returning %ld).\n",
lResult);
DELETE_EXCEPTION(e);
}
END_CATCH_ALL
pThreadState->m_lastSentMsg = oldState;
return lResult;
}
消息处理转入CWnd类了,
LRESULT CWnd::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
{
// OnWndMsg does most of the work, except for DefWindowProc call
LRESULT lResult = 0;
if (!OnWndMsg(message, wParam, lParam, &lResult))
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
处理窗口消息
lResult = DefWindowProc(message, wParam, lParam);
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
如果没有处理，就调用DefWindowProc，
呵呵，和我们以前用C写Windows程序一样！！
return lResult;
}
BOOL CWnd::OnWndMsg(UINT message, WPARAM wParam, LPARAM lParam, LRESUL
T* pResult)
{
LRESULT lResult = 0;
// special case for commands
if (message == WM_COMMAND)
{ ^^^^^^^^^^ WM_COMMAND消息？
if (OnCommand(wParam, lParam))
{ ^^^^^^^^^^^^^^^^^^^^^^^^^
调用OnCommand函数，这是一个虚函数
lResult = 1;
goto LReturnTrue;
}
return FALSE;
}
// special case for notifies
if (message == WM_NOTIFY)
{ ^^^^^^^^^ 通告消息？
NMHDR* pNMHDR = (NMHDR*)lParam;
if (pNMHDR->hwndFrom != NULL &&
OnNotify(wParam, lParam, &lResult))
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
调用OnNotify函数，也是一个虚函数
goto LReturnTrue;
return FALSE;
}
// special case for activation
if (message == WM_ACTIVATE)
_AfxHandleActivate(this, wParam, CWnd::FromHandle((HWND)lParam));
// special case for set cursor HTERROR
if (message == WM_SETCURSOR &&
_AfxHandleSetCursor(this, (short)LOWORD(lParam), HIWORD(lParam)))
{
lResult = 1;
goto LReturnTrue;
}
const AFX_MSGMAP* pMessageMap; pMessageMap = GetMessageMap();
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
GetMessageMap返回当前类的消息映射表
UINT iHash; iHash = (LOWORD((DWORD)pMessageMap) ^ message) & (iHashMax
-1);
AfxLockGlobals(CRIT_WINMSGCACHE);
AFX_MSG_CACHE* pMsgCache; pMsgCache = &_afxMsgCache[iHash];
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
为了查找消息更快，微软实现了一个消息cache！
const AFX_MSGMAP_ENTRY* lpEntry;
if (message == pMsgCache->nMsg && pMessageMap == pMsgCache->pMessageMa
p)
{
// 消息在cache里，命中
lpEntry = pMsgCache->lpEntry;
AfxUnlockGlobals(CRIT_WINMSGCACHE);
if (lpEntry == NULL)
return FALSE;
// cache hit, and it needs to be handled
if (message < 0xC000)
goto LDispatch;
else
goto LDispatchRegistered;
}
else
{
// 不在cache里面，只好查找整个消息映射表
pMsgCache->nMsg = message;
pMsgCache->pMessageMap = pMessageMap;
#ifdef _AFXDLL
for (/* pMessageMap already init'ed */; pMessageMap != NULL;
pMessageMap = (*pMessageMap->pfnGetBaseMap)())
#else
for (/* pMessageMap already init'ed */; pMessageMap != NULL;
pMessageMap = pMessageMap->pBaseMap)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
从最高层类一层一层往下找
#endif
{
// Note: catch not so common but fatal mistake!!
// BEGIN_MESSAGE_MAP(CMyWnd, CMyWnd)
#ifdef _AFXDLL
ASSERT(pMessageMap != (*pMessageMap->pfnGetBaseMap)());
#else
ASSERT(pMessageMap != pMessageMap->pBaseMap);
#endif
if (message < 0xC000)
{
// constant window message
if ((lpEntry = AfxFindMessageEntry(pMessageMap->lpEntries,
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
这是一个汇编写的查找消息处理入口的函数
message, 0, 0)) != NULL)
{
pMsgCache->lpEntry = lpEntry;
AfxUnlockGlobals(CRIT_WINMSGCACHE);
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;
AfxUnlockGlobals(CRIT_WINMSGCACHE);
goto LDispatchRegistered;
}
lpEntry++; // keep looking past this one
}
}
}
pMsgCache->lpEntry = NULL;
AfxUnlockGlobals(CRIT_WINMSGCACHE);
return FALSE;
}
ASSERT(FALSE); // not reached
LDispatch: //消息处理函数找到了就转到此处了
ASSERT(message < 0xC000);
union MessageMapFunctions mmf;
mmf.pfn = lpEntry->pfn;
// if we've got WM_SETTINGCHANGE / WM_WININICHANGE, we need to
// decide if we're going to call OnWinIniChange() or OnSettingChange()
int nSig;
nSig = lpEntry->nSig;
^^^^^^^^^^^^^^^^^^^^
if (lpEntry->nID == WM_SETTINGCHANGE)
{
DWORD dwVersion = GetVersion();
if (LOBYTE(LOWORD(dwVersion)) >= 4)
nSig = AfxSig_vws;
else
nSig = AfxSig_vs;
}
switch (nSig)
{// nSig为消息参数类型,详细解释见后
default:
ASSERT(FALSE);
break;
case AfxSig_bD:
lResult = (this->*mmf.pfn_bD)(CDC::FromHandle((HDC)wParam));
^^^ mmf就是我们在Message Map里面设的消息处理函数
它是一个共用体（union），其中定义了
带有各种不同参数形式的函数。
break;
case AfxSig_bb: // AfxSig_bb, AfxSig_bw, AfxSig_bh
lResult = (this->*mmf.pfn_bb)((BOOL)wParam);
break;
case AfxSig_bWww: // really AfxSig_bWiw
lResult = (this->*mmf.pfn_bWww)(CWnd::FromHandle((HWND)wParam),
(short)LOWORD(lParam), HIWORD(lParam));
break;
case AfxSig_bWCDS:
lResult = (this->*mmf.pfn_bWCDS)(CWnd::FromHandle((HWND)lParam),
(COPYDATASTRUCT*) lParam);
break;
case AfxSig_bHELPINFO:
lResult = (this->*mmf.pfn_bHELPINFO)((HELPINFO*)lParam);
break;
case AfxSig_hDWw:
{
// special case for OnCtlColor to avoid too many temporary objects
ASSERT(message == WM_CTLCOLOR);
AFX_CTLCOLOR* pCtl = (AFX_CTLCOLOR*)lParam;
CDC dcTemp; dcTemp.m_hDC = pCtl->hDC;
CWnd wndTemp; wndTemp.m_hWnd = pCtl->hWnd;
UINT nCtlType = pCtl->nCtlType;
// if not coming from a permanent window, use stack temporary
CWnd* pWnd = CWnd::FromHandlePermanent(wndTemp.m_hWnd);
if (pWnd == NULL)
{
#ifndef _AFX_NO_OCC_SUPPORT
// determine the site of the OLE control if it is one
COleControlSite* pSite;
if (m_pCtrlCont != NULL && (pSite = (COleControlSite*)
m_pCtrlCont->m_siteMap.GetValueAt(wndTemp.m_hWnd)) != NULL)
{
wndTemp.m_pCtrlSite = pSite;
}
#endif
pWnd = &wndTemp;
}
HBRUSH hbr = (this->*mmf.pfn_hDWw)(&dcTemp, pWnd, nCtlType);
// fast detach of temporary objects
dcTemp.m_hDC = NULL;
wndTemp.m_hWnd = NULL;
lResult = (LRESULT)hbr;
}
break;
case AfxSig_hDw:
{
// special case for CtlColor to avoid too many temporary objects
ASSERT(message == WM_REFLECT_BASE+WM_CTLCOLOR);
AFX_CTLCOLOR* pCtl = (AFX_CTLCOLOR*)lParam;
CDC dcTemp; dcTemp.m_hDC = pCtl->hDC;
UINT nCtlType = pCtl->nCtlType;
HBRUSH hbr = (this->*mmf.pfn_hDw)(&dcTemp, nCtlType);
// fast detach of temporary objects
dcTemp.m_hDC = NULL;
lResult = (LRESULT)hbr;
}
break;
case AfxSig_iwWw:
lResult = (this->*mmf.pfn_iwWw)(LOWORD(wParam),
CWnd::FromHandle((HWND)lParam), HIWORD(wParam));
break;
case AfxSig_iww:
lResult = (this->*mmf.pfn_iww)(LOWORD(wParam), HIWORD(wParam));
break;
case AfxSig_iWww: // really AfxSig_iWiw
lResult = (this->*mmf.pfn_iWww)(CWnd::FromHandle((HWND)wParam),
(short)LOWORD(lParam), HIWORD(lParam));
break;
case AfxSig_is:
lResult = (this->*mmf.pfn_is)((LPTSTR)lParam);
break;
case AfxSig_lwl:
lResult = (this->*mmf.pfn_lwl)(wParam, lParam);
break;
case AfxSig_lwwM:
lResult = (this->*mmf.pfn_lwwM)((UINT)LOWORD(wParam),
(UINT)HIWORD(wParam), (CMenu*)CMenu::FromHandle((HMENU)lParam));
break;
case AfxSig_vv:
(this->*mmf.pfn_vv)();
break;
case AfxSig_vw: // AfxSig_vb, AfxSig_vh
(this->*mmf.pfn_vw)(wParam);
break;
case AfxSig_vww:
(this->*mmf.pfn_vww)((UINT)wParam, (UINT)lParam);
break;
case AfxSig_vvii:
(this->*mmf.pfn_vvii)((short)LOWORD(lParam), (short)HIWORD(lParam));
break;
case AfxSig_vwww:
(this->*mmf.pfn_vwww)(wParam, LOWORD(lParam), HIWORD(lParam));
break;
case AfxSig_vwii:
(this->*mmf.pfn_vwii)(wParam, LOWORD(lParam), HIWORD(lParam));
break;
case AfxSig_vwl:
(this->*mmf.pfn_vwl)(wParam, lParam);
break;
case AfxSig_vbWW:
(this->*mmf.pfn_vbWW)(m_hWnd == (HWND)lParam,
CWnd::FromHandle((HWND)lParam),
CWnd::FromHandle((HWND)wParam));
break;
case AfxSig_vD:
(this->*mmf.pfn_vD)(CDC::FromHandle((HDC)wParam));
break;
case AfxSig_vM:
(this->*mmf.pfn_vM)(CMenu::FromHandle((HMENU)wParam));
break;
case AfxSig_vMwb:
(this->*mmf.pfn_vMwb)(CMenu::FromHandle((HMENU)wParam),
LOWORD(lParam), (BOOL)HIWORD(lParam));
break;
case AfxSig_vW:
(this->*mmf.pfn_vW)(CWnd::FromHandle((HWND)wParam));
break;
case AfxSig_vW2:
(this->*mmf.pfn_vW)(CWnd::FromHandle((HWND)lParam));
break;
case AfxSig_vWww:
(this->*mmf.pfn_vWww)(CWnd::FromHandle((HWND)wParam), LOWORD(lParam),
HIWORD(lParam));
break;
case AfxSig_vWp:
{
CPoint point((DWORD)lParam);
(this->*mmf.pfn_vWp)(CWnd::FromHandle((HWND)wParam), point);
}
break;
case AfxSig_vWh:
(this->*mmf.pfn_vWh)(CWnd::FromHandle((HWND)wParam),
(HANDLE)lParam);
break;
case AfxSig_vwW:
(this->*mmf.pfn_vwW)(wParam, CWnd::FromHandle((HWND)lParam));
break;
case AfxSig_vwWb:
(this->*mmf.pfn_vwWb)((UINT)(LOWORD(wParam)),
CWnd::FromHandle((HWND)lParam), (BOOL)HIWORD(wParam));
break;
case AfxSig_vwwW:
case AfxSig_vwwx:
{
// special case for WM_VSCROLL and WM_HSCROLL
ASSERT(message == WM_VSCROLL || message == WM_HSCROLL ||
message == WM_VSCROLL+WM_REFLECT_BASE || message == WM_HSCROLL+WM_REFL
ECT_BASE);
int nScrollCode = (short)LOWORD(wParam);
int nPos = (short)HIWORD(wParam);
if (lpEntry->nSig == AfxSig_vwwW)
(this->*mmf.pfn_vwwW)(nScrollCode, nPos,
CWnd::FromHandle((HWND)lParam));
else
(this->*mmf.pfn_vwwx)(nScrollCode, nPos);
}
break;
case AfxSig_vs:
(this->*mmf.pfn_vs)((LPTSTR)lParam);
break;
case AfxSig_vws:
(this->*mmf.pfn_vws)((UINT) wParam, (LPCTSTR)lParam);
break;
case AfxSig_vOWNER:
(this->*mmf.pfn_vOWNER)((int)wParam, (LPTSTR)lParam);
lResult = TRUE;
break;
case AfxSig_iis:
lResult = (this->*mmf.pfn_iis)((int)wParam, (LPTSTR)lParam);
break;
case AfxSig_wp:
{
CPoint point((DWORD)lParam);
lResult = (this->*mmf.pfn_wp)(point);
}
break;
case AfxSig_wv: // AfxSig_bv, AfxSig_wv
lResult = (this->*mmf.pfn_wv)();
break;
case AfxSig_vCALC:
(this->*mmf.pfn_vCALC)((BOOL)wParam, (NCCALCSIZE_PARAMS*)lParam);
break;
case AfxSig_vPOS:
(this->*mmf.pfn_vPOS)((WINDOWPOS*)lParam);
break;
case AfxSig_vwwh:
(this->*mmf.pfn_vwwh)(LOWORD(wParam), HIWORD(wParam), (HANDLE)lParam);
break;
case AfxSig_vwp:
{
CPoint point((DWORD)lParam);
(this->*mmf.pfn_vwp)(wParam, point);
break;
}
case AfxSig_vwSIZING:
(this->*mmf.pfn_vwl)(wParam, lParam);
lResult = TRUE;
break;
case AfxSig_bwsp:
lResult = (this->*mmf.pfn_bwsp)(LOWORD(wParam), (short) HIWORD(wParam)
,
CPoint(LOWORD(lParam), HIWORD(lParam)));
if (!lResult)
return FALSE;
}
goto LReturnTrue;
LDispatchRegistered: // for registered windows messages
ASSERT(message >= 0xC000);
mmf.pfn = lpEntry->pfn;
lResult = (this->*mmf.pfn_lwl)(wParam, lParam);
LReturnTrue:
if (pResult != NULL)
*pResult = lResult;
return TRUE;
}
LRESULT CWnd::DefWindowProc(UINT nMsg, WPARAM wParam, LPARAM lParam)
{
if (m_pfnSuper != NULL)
return ::CallWindowProc(m_pfnSuper, m_hWnd, nMsg, wParam, lParam);
WNDPROC pfnWndProc;
if ((pfnWndProc = *GetSuperWndProcAddr()) == NULL)
return ::DefWindowProc(m_hWnd, nMsg, wParam, lParam);
else
return ::CallWindowProc(pfnWndProc, m_hWnd, nMsg, wParam, lParam);
}
enum AfxSig // 消息处理函数的参数类型
{
AfxSig_end = 0, // [marks end of message map]
AfxSig_bD, // BOOL (CDC*)
^^
|+--------------- D表示CDC*
+---------------- b表示返回值为bool型
AfxSig_bb, // BOOL (BOOL)
AfxSig_bWww, // BOOL (CWnd*, UINT, UINT)
AfxSig_hDWw, // HBRUSH (CDC*, CWnd*, UINT)
AfxSig_hDw, // HBRUSH (CDC*, UINT)
AfxSig_iwWw, // int (UINT, CWnd*, UINT)
AfxSig_iww, // int (UINT, UINT)
AfxSig_iWww, // int (CWnd*, UINT, UINT)
AfxSig_is, // int (LPTSTR)
AfxSig_lwl, // LRESULT (WPARAM, LPARAM)
AfxSig_lwwM, // LRESULT (UINT, UINT, CMenu*)
AfxSig_vv, // void (void)
^^^^^^^^^ 举个例子，如WM_PAINT消息，
在BEGIN_MESSAGE_MAP里面我们定义的消息处理函数为
ON_WM_PAINT()
察看我们前面剖析过程，知道
#define ON_WM_PAINT() \
{ WM_PAINT, 0, 0, 0, AfxSig_vv, \
所以处理函数的形式即为
OnPaint()
即没有参数，没有返回值。
采用这种方法，就可以避免把没用的wParam和lParam参数传给用户
AfxSig_vw, // void (UINT)
AfxSig_vww, // void (UINT, UINT)
AfxSig_vvii, // void (int, int) // wParam is ignored
AfxSig_vwww, // void (UINT, UINT, UINT)
AfxSig_vwii, // void (UINT, int, int)
AfxSig_vwl, // void (UINT, LPARAM)
AfxSig_vbWW, // void (BOOL, CWnd*, CWnd*)
AfxSig_vD, // void (CDC*)
AfxSig_vM, // void (CMenu*)
AfxSig_vMwb, // void (CMenu*, UINT, BOOL)
AfxSig_vW, // void (CWnd*)
AfxSig_vWww, // void (CWnd*, UINT, UINT)
AfxSig_vWp, // void (CWnd*, CPoint)
AfxSig_vWh, // void (CWnd*, HANDLE)
AfxSig_vwW, // void (UINT, CWnd*)
AfxSig_vwWb, // void (UINT, CWnd*, BOOL)
AfxSig_vwwW, // void (UINT, UINT, CWnd*)
AfxSig_vwwx, // void (UINT, UINT)
AfxSig_vs, // void (LPTSTR)
AfxSig_vOWNER, // void (int, LPTSTR), force return TRUE
AfxSig_iis, // int (int, LPTSTR)
AfxSig_wp, // UINT (CPoint)
AfxSig_wv, // UINT (void)
AfxSig_vPOS, // void (WINDOWPOS*)
AfxSig_vCALC, // void (BOOL, NCCALCSIZE_PARAMS*)
AfxSig_vNMHDRpl, // void (NMHDR*, LRESULT*)
AfxSig_bNMHDRpl, // BOOL (NMHDR*, LRESULT*)
AfxSig_vwNMHDRpl, // void (UINT, NMHDR*, LRESULT*)
AfxSig_bwNMHDRpl, // BOOL (UINT, NMHDR*, LRESULT*)
AfxSig_bHELPINFO, // BOOL (HELPINFO*)
AfxSig_vwSIZING, // void (UINT, LPRECT) -- return TRUE
// signatures specific to CCmdTarget
AfxSig_cmdui, // void (CCmdUI*)
AfxSig_cmduiw, // void (CCmdUI*, UINT)
AfxSig_vpv, // void (void*)
AfxSig_bpv, // BOOL (void*)
// Other aliases (based on implementation)
AfxSig_vwwh, // void (UINT, UINT, HANDLE)
AfxSig_vwp, // void (UINT, CPoint)
AfxSig_bw = AfxSig_bb, // BOOL (UINT)
AfxSig_bh = AfxSig_bb, // BOOL (HANDLE)
AfxSig_iw = AfxSig_bb, // int (UINT)
AfxSig_ww = AfxSig_bb, // UINT (UINT)
AfxSig_bv = AfxSig_wv, // BOOL (void)
AfxSig_hv = AfxSig_wv, // HANDLE (void)
AfxSig_vb = AfxSig_vw, // void (BOOL)
AfxSig_vbh = AfxSig_vww, // void (BOOL, HANDLE)
AfxSig_vbw = AfxSig_vww, // void (BOOL, UINT)
AfxSig_vhh = AfxSig_vww, // void (HANDLE, HANDLE)
AfxSig_vh = AfxSig_vw, // void (HANDLE)
AfxSig_viSS = AfxSig_vwl, // void (int, STYLESTRUCT*)
AfxSig_bwl = AfxSig_lwl,
AfxSig_vwMOVING = AfxSig_vwSIZING, // void (UINT, LPRECT) -- return TR
UE
AfxSig_vW2, // void (CWnd*) (CWnd* comes from lParam)
AfxSig_bWCDS, // BOOL (CWnd*, COPYDATASTRUCT*)
AfxSig_bwsp, // BOOL (UINT, short, CPoint)
AfxSig_vws,
};