在WPF中实现全局快捷键功能

    static class Hotkey
    {
        #region 系统api
        [DllImport("user32.dll")]
        [return: MarshalAs(UnmanagedType.Bool)]
        static extern bool RegisterHotKey(IntPtr hWnd, int id, HotkeyModifiers fsModifiers, uint vk);

        [DllImport("user32.dll")]
        static extern bool UnregisterHotKey(IntPtr hWnd, int id);
        #endregion

        /// <summary>
        /// 注册快捷键
        /// </summary>
        /// <param name="window">持有快捷键窗口</param>
        /// <param name="fsModifiers">组合键</param>
        /// <param name="key">快捷键</param>
        /// <param name="callBack">回调函数</param>
        public static void Regist(Window window, HotkeyModifiers fsModifiers, Key key, HotKeyCallBackHanlder callBack)
        {
            var hwnd = new WindowInteropHelper(window).Handle;
            var _hwndSource = HwndSource.FromHwnd(hwnd);
            _hwndSource.AddHook(WndProc);

            int id = keyid++;

            var vk = KeyInterop.VirtualKeyFromKey(key);
            if (!RegisterHotKey(hwnd, id, fsModifiers, (uint)vk))
                throw new Exception("regist hotkey fail.");
            keymap[id] = callBack;
        }

        /// <summary>
        /// 快捷键消息处理
        /// </summary>
        static IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
        {
            if (msg == WM_HOTKEY)
            {
                int id = wParam.ToInt32();
                if (keymap.TryGetValue(id, out var callback))
                {
                    callback();
                }
            }
            return IntPtr.Zero;
        }

        /// <summary>
        /// 注销快捷键
        /// </summary>
        /// <param name="hWnd">持有快捷键窗口的句柄</param>
        /// <param name="callBack">回调函数</param>
        public static void UnRegist(IntPtr hWnd, HotKeyCallBackHanlder callBack)
        {
            foreach (KeyValuePair<int, HotKeyCallBackHanlder> var in keymap)
            {
                if (var.Value == callBack)
                    UnregisterHotKey(hWnd, var.Key);
            }
        }


        const int WM_HOTKEY = 0x312;
        static int keyid = 10;
        static Dictionary<int, HotKeyCallBackHanlder> keymap = new Dictionary<int, HotKeyCallBackHanlder>();

        public delegate void HotKeyCallBackHanlder();
    }

    enum HotkeyModifiers
    {
        MOD_ALT = 0x1,
        MOD_CONTROL = 0x2,
        MOD_SHIFT = 0x4,
        MOD_WIN = 0x8
    }

protected override void OnSourceInitialized(EventArgs e)
{
    Hotkey.Regist(this, HotkeyModifiers.MOD_ALT, Key.T, () =>
    {
        MessageBox.Show("hello");
    });

    _context = new MainContext();
    this.DataContext = _context;
    _context.Process();
}