问SerialPort检查CTS

EN

[DllImport("kernel32.dll")]
static extern bool SetCommMask(IntPtr hFile, uint dwEvtMask);
[DllImport("kernel32.dll")]
static extern bool WaitCommEvent(IntPtr hFile, out uint lpEvtMask, IntPtr lpOverlapped);

SerialPort _port = null;
bool _exit;

public Form1()
{
    InitializeComponent();

    _port = new SerialPort("COM2");
    _port.Open();

    // getting handle is tricky
    var handle = ((SafeFileHandle)_port.BaseStream.GetType().GetField("_handle", BindingFlags.NonPublic | BindingFlags.Instance).GetValue(_port.BaseStream)).DangerousGetHandle();

    // set mask to listen to change of CTS signal
    if (!SetCommMask(handle, 0x0008)) // EV_CTS
        throw ...

    // start listener
    Task.Run(() =>
    {
        while (!_exit)
        {
            uint mask = 0;
            if (WaitCommEvent(handle, out mask, IntPtr.Zero))
                if ((mask & 0x0008) != 0)
                    Task.Run(() => MessageBox.Show("smth happenz"));
        });
        _port.Close();
    }
}

private void Form1_FormClosing(object sender, FormClosingEventArgs e)
{
    _exit = true;
}