public partial class UserLine : UserControl
    {
        private Point lineStart;
        private Point lineEnd;
        private int lineWidth;
        private Color lineColor;
        private Pen pen;

        public UserLine()
        {
            InitializeComponent();
        }
        public Point LineStart
        {
            get
            {
                return lineStart;
            }
            set
            {
                this.lineStart=new Point(value.X,value.Y);
            }
        }
        public Point LineEnd
        {
            get
            {
                return lineEnd;
            }
            set
            {
                this.lineEnd = new Point(value.X, value.Y);
            }
        }
        public int LineWidth
        {
            get
            {
                return lineWidth;
            }
            set
            {
                this.lineWidth = value;
            }
        }
        public Color  LineColor
        {
            get
            {
                return lineColor;
            }
            set
            {
                this.lineColor = value;
            }
        }

        protected override void OnPaint(PaintEventArgs e)
        {
            pen=new Pen(LineColor,LineWidth);
            base.OnPaint(e);
            e.Graphics.DrawLine(pen,LineStart,LineEnd);
        }
        int i = 0;
        private void UserLine_MouseDown(object sender, MouseEventArgs e)
        {
            if (((e.Y - lineStart.X) / (e.X - lineStart.X)) == ((lineEnd.Y - lineStart.Y) / (lineEnd.X - lineStart.X)))
            {
                if (e.Button == MouseButtons.Left)
                {
                    i++;
                    if (i == 2)
                    {
                        this.LineColor = Color.Red;
                        this.LineWidth = 6;
                        i = 0;
                    }
                    else
                        this.LineColor = Color.Yellow;
                }
            }
            this.Invalidate();
        }
        
    }