如何在C#中访问我的触控板？

[DllImport("user32.dll")]
private static extern IntPtr GetForegroundWindow();

[DllImport("user32.dll")]
private static extern bool RegisterRawInputDevices(RAWINPUTDEVICE[] pRawInputDevices, uint uiNumDevices, uint cbSize);

const int WM_INPUT = 0x00FF;

protected override void WndProc(ref Message m)
{
    if (m.Msg == WM_INPUT)
    {
        // 处理触控板输入数据
    }
    base.WndProc(ref m);
}

public void StartTouchpad()
{
    RAWINPUTDEVICE[] rawInputDevices = new RAWINPUTDEVICE[1];
    rawInputDevices[0].usUsagePage = 0x0D; // 触控板设备的使用页面
    rawInputDevices[0].usUsage = 0x04; // 触控板设备的使用标识
    rawInputDevices[0].dwFlags = 0x00000100; // 输入数据将被异步发送到窗口
    rawInputDevices[0].hwndTarget = this.Handle;

    if (!RegisterRawInputDevices(rawInputDevices, (uint)rawInputDevices.Length, (uint)Marshal.SizeOf(typeof(RAWINPUTDEVICE))))
    {
        // 注册失败，处理错误
    }
}