c# 键盘勾子

来源：互联网发布：众品集团怎么样知乎编辑：程序博客网时间：2024/04/29 04:37

PowerPoint在放映模式下，如果用户按Esc键，PowerPoint直接退出放映模式。在查看了相关PowerPoint API没有找到PowerPoint退出放映模式前的事件，只好使用键盘勾子去捕获Esc按键。

    public class KeyboardHookDll    {        //Hook结构         [StructLayout(LayoutKind.Sequential)]        public class HookStruct        {            public int vkCode;            public int scanCode;            public int flags;            public int time;            public int dwExtraInfo;        }        //键盘         private const int WH_KEYBOARD_LL = 13;         //接收SetWindowsHookEx返回值        private static int _hHookValue = 0;        //钩子程序处理事件          private HookHandle _KeyBoardHookProcedure;        //外部调用的键盘处理事件         private static ProcessKeyHandle _clientMethod = null;        private IntPtr _hookWindowPtr = IntPtr.Zero;                     //键盘处理事件委托 ,当捕获键盘输入时调用定义该委托的方法.          private delegate int HookHandle(int nCode, int wParam, IntPtr lParam);        //客户端键盘处理事件           public delegate void ProcessKeyHandle(HookStruct param, out bool handle);                       //设置钩子        [DllImport("user32.dll")]        private static extern int SetWindowsHookEx(int idHook, HookHandle lpfn, IntPtr hInstance, int threadId);        //取消钩子           [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]        private static extern bool UnhookWindowsHookEx(int idHook);        //调用下一个钩子           [DllImport("user32.dll")]        private static extern int CallNextHookEx(int idHook, int nCode, int wParam, IntPtr lParam);        //获取当前线程ID          [DllImport("kernel32.dll")]        private static extern int GetCurrentThreadId();        //得到模块的句柄         [DllImport("kernel32.dll")]        private static extern IntPtr GetModuleHandle(string name);        //构造器          public KeyboardHookDll() { }         /// <summary>         /// 安装勾子          /// </summary>        /// <param name="hookProcess">外部调用的键盘处理事件</param>        public void InstallHook(ProcessKeyHandle clientMethod)        {            _clientMethod = clientMethod;            // 安装键盘钩子              if (_hHookValue == 0)            {                _KeyBoardHookProcedure = new HookHandle(OnHookProc);                _hookWindowPtr = GetModuleHandle(Process.GetCurrentProcess().MainModule.ModuleName);                _hHookValue = SetWindowsHookEx(                    WH_KEYBOARD_LL,                    _KeyBoardHookProcedure,                    _hookWindowPtr,                    0);                //如果设置钩子失败.                  if (_hHookValue == 0)                {                    UninstallHook();                }            }        }        /// <summary>        /// 取消钩子事件        /// </summary>        public void UninstallHook()        {            if (_hHookValue != 0)            {                bool ret = UnhookWindowsHookEx(_hHookValue);                if (ret)                {                    _hHookValue = 0;                }            }        }        /// <summary>        /// 钩子事件内部调用,调用_clientMethod方法转发到客户端应用        /// </summary>        /// <param name="nCode"></param>        /// <param name="wParam"></param>        /// <param name="lParam"></param>        /// <returns></returns>        private static int OnHookProc(int nCode, int wParam, IntPtr lParam)        {            if (nCode >= 0)            {                //转换结构                HookStruct hookStruct = (HookStruct)Marshal.PtrToStructure(lParam, typeof(HookStruct));                if (_clientMethod != null)                {                    bool handle = false;                    //调用客户提供的事件处理程序。                      _clientMethod(hookStruct, out handle);                    //1:表示拦截键盘,return 退出                       if (handle)                    {                        return 1;                    }                }            }            return CallNextHookEx(_hHookValue, nCode, wParam, lParam);        }    }

安装键盘勾子

    KeyboardHookDll hook = new KeyboardHookDll();    hook.InstallHook(this.OnKeyPress);

客户端键盘捕捉事件

    public void OnKeyPress(KeyboardHookDll.HookStruct hookStruct, out bool handle)    {        handle = false; //预设不拦截任何键          if (hookStruct.vkCode == 27) // 截获ESC          {            handle = true;            //程序后续代码          }    }

取消键盘勾子

    if (hook != null)    {        hook.UninstallHook();    }