KeyboardHook.cs

using System;
using System.Diagnostics;
using System.Linq;
using System.Runtime.InteropServices;
using WindowsInput;

namespace PocketTDPControl
{
    class KeyboardHook
    {
        // 键盘
        private const int WH_KEYBOARD_LL = 13; 
        // 键盘处理事件委托
        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);
        // 接收SetWindowsHookEx返回值
        private static int _hHookValue = 0;
        // 勾子程序处理事件
        private HookHandle _KeyBoardHookProcedure;

        // Hook结构
        [StructLayout(LayoutKind.Sequential)]
        public class HookStruct
        {
            public int vkCode;
            public int scanCode;
            public int flags;
            public int time;
            public int dwExtraInfo;
        }

        // 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();

        [DllImport("kernel32.dll")]
        private static extern IntPtr GetModuleHandle(string name);
        private IntPtr _hookWindowPtr = IntPtr.Zero;

        // 构造器
        public KeyboardHook() { }

        // 外部调用的键盘处理事件
        private static ProcessKeyHandle _clientMethod = null;

        /// <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(GetHookProc);
                _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();
            }
        }

        // 取消钩子事件
        public void UninstallHook()
        {
            if (_hHookValue != 0)
            {
                bool ret = UnhookWindowsHookEx(_hHookValue);
                if (ret) _hHookValue = 0;
            }
        }


        // 钩子事件内部调用,调用_clientMethod方法转发到客户端应用。
        private static int GetHookProc(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);
                    if (handle) return 0; //1:表示拦截键盘,return 退出
                }
            }
            return CallNextHookEx(_hHookValue, nCode, wParam, lParam);
        }

    }
}