WPF获得全局窗体句柄,并响应全局键盘事件

场景

wpf窗体运行后,只能捕获当前Active窗体的按键事件,如果要监听windows全局事件,并对当前窗口事件响应.

第一步:导入Winows API

    public class Win32
    {
        [DllImport("User32.Dll")]
        public static extern void SetWindowText(int h, String s);

        /// <summary>
        /// 如果函数执行成功，返回值不为0。
        /// 如果函数执行失败，返回值为0。要得到扩展错误信息，调用GetLastError。.NET方法:Marshal.GetLastWin32Error()
        /// </summary>
        /// <param name="hWnd">要定义热键的窗口的句柄</param>
        /// <param name="id">定义热键ID（不能与其它ID重复）  </param>
        /// <param name="fsModifiers">标识热键是否在按Alt、Ctrl、Shift、Windows等键时才会生效</param>
        /// <param name="vk">定义热键的内容,WinForm中可以使用Keys枚举转换，
        /// WPF中Key枚举是不正确的,应该使用System.Windows.Forms.Keys枚举，或者自定义正确的枚举或int常量</param>
        /// <returns></returns>
        [DllImport("user32.dll", SetLastError = true)]
        public static extern bool RegisterHotKey(
            IntPtr hWnd,
            int id,
            KeyModifiers fsModifiers,
            int vk
            );

        /// <summary>
        /// 取消注册热键
        /// </summary>
        /// <param name="hWnd">要取消热键的窗口的句柄</param>
        /// <param name="id">要取消热键的ID</param>
        /// <returns></returns>
        [DllImport("user32.dll", SetLastError = true)]
        public static extern bool UnregisterHotKey(
            IntPtr hWnd,
            int id
            );

        /// <summary>
        /// 向全局原子表添加一个字符串，并返回这个字符串的唯一标识符,成功则返回值为新创建的原子ID,失败返回0
        /// </summary>
        /// <param name="lpString"></param>
        /// <returns></returns>
        [DllImport("kernel32", SetLastError = true)]
        public static extern short GlobalAddAtom(string lpString);

        [DllImport("kernel32", SetLastError = true)]
        public static extern short GlobalDeleteAtom(short nAtom);

        /// <summary>
        /// 定义了辅助键的名称（将数字转变为字符以便于记忆，也可去除此枚举而直接使用数值）
        /// </summary>
        [Flags()]
        public enum KeyModifiers
        {
            None = 0,
            Alt = 1,
            Ctrl = 2,
            Shift = 4,
            WindowsKey = 8
        }
        /// <summary>
        /// 热键的对应的消息ID
        /// </summary>
        public const int WmHotkey = 0x312;
    }

 第二步:注册快捷键

        /// <summary>
        /// 注册快捷集合
        /// </summary>
        readonly Dictionary<string, short> hotKeyDic = new Dictionary<string, short>();

        public MainWindow()
        {
            InitializeComponent();

            this.Loaded += (sender, e) =>
            {
                var wpfHwnd = new WindowInteropHelper(this).Handle;

                var hWndSource = HwndSource.FromHwnd(wpfHwnd);
                //添加处理程序
                if (hWndSource != null) hWndSource.AddHook(MainWindowProc);

                hotKeyDic.Add("Alt-S", Win32.GlobalAddAtom("Alt-S"));
                hotKeyDic.Add("Alt-D", Win32.GlobalAddAtom("Alt-D"));
                Win32.RegisterHotKey(wpfHwnd, hotKeyDic["Alt-S"], Win32.KeyModifiers.Alt, (int)System.Windows.Forms.Keys.S);
                Win32.RegisterHotKey(wpfHwnd, hotKeyDic["Alt-D"], Win32.KeyModifiers.Alt, (int)System.Windows.Forms.Keys.D);
            };
        }

第三步:响应快捷键事件

        /// <summary>
        /// 响应快捷键事件
        /// </summary>
        /// <param name="hwnd"></param>
        /// <param name="msg"></param>
        /// <param name="wParam"></param>
        /// <param name="lParam"></param>
        /// <param name="handled"></param>
        /// <returns></returns>
        private IntPtr MainWindowProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
        {
            switch (msg)
            {
                case Win32.WmHotkey:
                    {
                        int sid = wParam.ToInt32();
                        if (sid == hotKeyDic["Alt-S"])
                        {
                            MessageBox.Show("按下Alt+S");
                        }
                        else if (sid == hotKeyDic["Alt-D"])
                        {
                            MessageBox.Show("按下Alt+D");
                        }
                        handled = true;
                        break;
                    }
            }

            return IntPtr.Zero;
        }