C# file

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.IO.Ports;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Runtime.InteropServices;

namespace Arduino_W
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        Boolean act = false;
        private void Form1_Load(object sender, EventArgs e)
        {
            string[] ports = SerialPort.GetPortNames();
            portBox.Items.AddRange(ports);
            brBox.SelectedIndex = 0;
        }

        private void startstopBtn_Click(object sender, EventArgs e)
        {
            if(startstopBtn.Text == "Start")
            {
                try
                {
                    sp.PortName = portBox.Text;
                    sp.BaudRate = Int32.Parse(brBox.Text);
                    sp.Open();
                }
                catch(Exception ex)
                {
                    MessageBox.Show(ex.Message, "Message", MessageBoxButtons.OK, MessageBoxIcon.Error);
                }
                if(sp.IsOpen)
                {
                    act = true;
                    startstopBtn.Text = "Stop";
                    sendBtn.Enabled = true;
                }
            }
            else
            {
                act = false;
                startstopBtn.Text = "Start";
                if(sp.IsOpen)
                {
                    sp.Close();
                }
            }
        }

        private void portBox_SelectedIndexChanged(object sender, EventArgs e)
        {
            if(portBox.Text != "") startstopBtn.Enabled = true;
        }

        private void sp_DataReceived(object sender, SerialDataReceivedEventArgs e)
        {
            string data = sp.ReadLine();

            if(data[0] == 'k') //key
            {
                SendKeys.SendWait(data.Substring(2, data.Length - 2));
            }
            else if(data[0] == 'm') //mouse
            {
                string ev = data.Substring(2, data.Length - 2);

                switch (ev) {
                    case "lu":
                        MouseOperations.MouseEvent(MouseOperations.MouseEventFlags.LeftUp); break;
                    case "ld":
                        MouseOperations.MouseEvent(MouseOperations.MouseEventFlags.LeftDown); break;
                    case "mu":
                        MouseOperations.MouseEvent(MouseOperations.MouseEventFlags.MiddleUp); break;
                    case "md":
                        MouseOperations.MouseEvent(MouseOperations.MouseEventFlags.MiddleDown); break;
                    case "ru":
                        MouseOperations.MouseEvent(MouseOperations.MouseEventFlags.RightUp); break;
                    case "rd":
                        MouseOperations.MouseEvent(MouseOperations.MouseEventFlags.RightDown); break;
                }
            }
        }
        private void sendBtn_Click(object sender, EventArgs e)
        {
            sp.WriteLine(sendTxt.Text);
            sendTxt.Text = "";
        }

        private void button1_Click(object sender, EventArgs e)
        {
            portBox.Items.AddRange(SerialPort.GetPortNames());
        }

        private void showtimeBox_CheckedChanged(object sender, EventArgs e)
        {

        }

        private void readWnd_TextChanged(object sender, EventArgs e)
        {

        }
    }
    public class MouseOperations
    {
        [Flags]
        public enum MouseEventFlags
        {
            LeftDown = 0x00000002,
            LeftUp = 0x00000004,
            MiddleDown = 0x00000020,
            MiddleUp = 0x00000040,
            Move = 0x00000001,
            Absolute = 0x00008000,
            RightDown = 0x00000008,
            RightUp = 0x00000010
        }

        [DllImport("user32.dll", EntryPoint = "SetCursorPos")]
        [return: MarshalAs(UnmanagedType.Bool)]
        private static extern bool SetCursorPos(int x, int y);

        [DllImport("user32.dll")]
        [return: MarshalAs(UnmanagedType.Bool)]
        private static extern bool GetCursorPos(out MousePoint lpMousePoint);

        [DllImport("user32.dll")]
        private static extern void mouse_event(int dwFlags, int dx, int dy, int dwData, int dwExtraInfo);

        public static void SetCursorPosition(int x, int y)
        {
            SetCursorPos(x, y);
        }

        public static void SetCursorPosition(MousePoint point)
        {
            SetCursorPos(point.X, point.Y);
        }

        public static MousePoint GetCursorPosition()
        {
            MousePoint currentMousePoint;
            var gotPoint = GetCursorPos(out currentMousePoint);
            if (!gotPoint) { currentMousePoint = new MousePoint(0, 0); }
            return currentMousePoint;
        }

        public static void MouseEvent(MouseEventFlags value)
        {
            MousePoint position = GetCursorPosition();

            mouse_event
                ((int)value,
                 position.X,
                 position.Y,
                 0,
                 0)
                ;
        }

        [StructLayout(LayoutKind.Sequential)]
        public struct MousePoint
        {
            public int X;
            public int Y;

            public MousePoint(int x, int y)
            {
                X = x;
                Y = y;
            }
        }
    }
}