如何创建“全局”wpf应用程序热键

using System.Runtime.InteropServices;
using System.Windows.Input;

private const int MOD_ALT = 0x0001;
private const int MOD_CONTROL = 0x0002;
private const int MOD_SHIFT = 0x0004;
private const int MOD_WIN = 0x0008;
private const int WM_HOTKEY = 0x0312;

[DllImport("user32.dll")]
private static extern bool RegisterHotKey(IntPtr hWnd, int id, int fsModifiers, int vk);

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

protected override void OnSourceInitialized(EventArgs e)
{
    base.OnSourceInitialized(e);
    IntPtr handle = new WindowInteropHelper(this).Handle;
    HwndSource source = HwndSource.FromHwnd(handle);
    source.AddHook(HwndHook);
    RegisterHotKey(handle, 1, MOD_CONTROL | MOD_SHIFT, KeyInterop.VirtualKeyFromKey(Key.A));
}

private IntPtr HwndHook(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
{
    if (msg == WM_HOTKEY)
    {
        // 处理热键触发事件
        // 在这里执行你想要的操作
        handled = true;
    }
    return IntPtr.Zero;
}

protected override void OnClosed(EventArgs e)
{
    base.OnClosed(e);
    UnregisterHotKey(new WindowInteropHelper(this).Handle, 1);
}

public MainWindow()
{
    InitializeComponent();
    Loaded += (sender, e) => { Keyboard.Focus(this); };
}

private IntPtr HwndHook(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
{
    if (msg == WM_HOTKEY)
    {
        if (wParam.ToInt32() == 1)
        {
            MessageBox.Show("热键触发！");
            handled = true;
        }
    }
    return IntPtr.Zero;
}