[C#] 모니터 off 하기

public partial class MainForm : Form
    {
 
        const int WM_SYSCOMMAND = 0x0112;
        const int SC_MONITORPOWER = 0xF170;
 
        const int MONITOR_ON = -1;
        const int MONITOR_OFF = 2;
        const int MONITOR_STANBY = 1;
 
        [DllImport("user32.dll")]
        private static extern int SendMessage(int hWnd, int hMsg, int wParam, int lParam);
 
        public MainForm()
        {
            InitializeComponent();
        }
 
        private void MainForm_Load(object sender, EventArgs e)
        {
            Console.WriteLine(this.Handle.ToInt32());
 
            int ScreenHeight = 0;
            System.Windows.Forms.Screen[] screens = System.Windows.Forms.Screen.AllScreens;
 
            if (screens.Length >= 1)
            {
                foreach (Screen screen in screens)
                {
                    if (screen.Primary)
                    {
                        ScreenHeight = screen.Bounds.Height;
                        Console.WriteLine(ScreenHeight);
                    }
 
                     
                }
            }
            else
            {
                ScreenHeight = screens[0].Bounds.Height;
            }
        }
 
        //  모니터 Off
        private void button1_Click(object sender, EventArgs e)
        {
            SendMessage(this.Handle.ToInt32(), WM_SYSCOMMAND, SC_MONITORPOWER, MONITOR_OFF);
        }
 
    }