Winform上面使用线笔画图

 

 

 public partial class Form1 : Form
    {
        int startX, startY;
        Graphics g;

        private void Form1_MouseDown(object sender, MouseEventArgs e)
        {
            startX = e.X;
            startY = e.Y;
        }

       
        private void Form1_MouseUp(object sender, MouseEventArgs e)
        {
            g = this.CreateGraphics();
            Pen p = new Pen(Color.Black, 2);
            if (radioButton1.Checked == true)
            {
                g.DrawLine(p, startX, startY, e.X, e.Y);
            }
        }

        private void Form1_MouseMove(object sender, MouseEventArgs e)
        {
            g = this.CreateGraphics();
            Pen p = new Pen(Color.Black, 1);
            if (radioButton1.Checked == true)
            {
                g.DrawRectangle(p, e.X, e.Y, 1, 1);
            }
        }

        public Form1()
        {
            InitializeComponent();
        }
    }