深入解析钩子和动态链接库（下）

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/*****************************************************************                             clearMyHook* Inputs:*       HWND hWnd: Window whose hook is to be cleared* Result: BOOL*       TRUE if the hook is properly unhooked*       FALSE if you gave the wrong parameter* Effect:*       Removes the hook that has been set.****************************************************************/__declspec(dllexport) BOOL clearMyHook(HWND hWnd)   {    if(hWnd != hWndServer)       return FALSE;    BOOL unhooked = UnhookWindowsHookEx(hook);    if(unhooked)       hWndServer = NULL;    return unhooked;   }/*****************************************************************                              msghook* Inputs:*       int nCode: Code value*       WPARAM wParam: parameter*       LPARAM lParam: parameter* Result: LRESULT** Effect:*       If the message is a mouse-move message, posts it back to*       the server window with the mouse coordinates* Notes:*       This must be a CALLBACK function or it will not work!****************************************************************/ static LRESULT CALLBACK msghook(int nCode, WPARAM wParam, LPARAM lParam)   {    // If the value of nCode is 0, just pass it on and return 0    // this is required by the specification of hook handlers    if(nCode 0)      { /* pass it on */       CallNextHookEx(hook, nCode,                   wParam, lParam);       return 0;      } /* pass it on */     // Read the documentation to discover what WPARAM and LPARAM    // mean. For a WH_MESSAGE hook, LPARAM is specified as being    // a pointer to a MSG structure, so the code below makes that    // structure available     LPMSG msg = (LPMSG)lParam;     // If it is a mouse-move message, either in the client area or    // the non-client area, we want to notify the parent that it has    // occurred. Note the use of PostMessage instead of SendMessage    if(msg-message == WM_MOUSEMOVE ||       msg-message == WM_NCMOUSEMOVE)      PostMessage(hWndServer,                  UWM_MOUSEMOVE,                     0, 0);      // Pass the message on to the next hook    return CallNextHookEx(hook, nCode,                        wParam, lParam);   } // msghookThe server application
在头文件中，将下面的增加到类的protected段：

afx_msg LRESULT OnMyMouseMove(WPARAM,LPARAM);在application 文件中, 增加以下代码到文件前部。

UINT UWM_MOUSEMOVE = ::RegisterWindowMessage(UWM_MOUSEMOVE_MSG);在 MESSAGE_MAP, 增加以下代码

 //{AFX_MSG comments:

ON_REGISTERED_MESSAGE(UWM_MOUSEMOVE, OnMyMouseMove)In your application file, add the following function:

LRESULT CMyClass::OnMyMouseMove(WPARAM, LPARAM)   {    // ...do stuff here    return 0;   }        上面是我写的一个小程序。既然我为了钩子花了n+1st 时间，我干脆给它一个好的用户界面。 猫在窗口之内盯着老鼠。小心! 当老鼠足够接近猫时并且它将捉住老鼠!

你可以下载这个项目并建立它。 真正的关键是DLL 子工程项目; 其他的都不过是陪衬。有几个其它的技术被用在这个例子里，包括各种各样的图画技术， ClipCursor 和 SetCapture的用法，区域选择、屏幕更新等等。，因此除了展示钩子函数的使用以外，对初级程序员掌握窗口样式设计编程也有一些价值。