功能要求  在一个平面画半径连续的圆！即圆心位置不变！！
 我的代码圆心一直在变，求修改！！！
 Pen mypen = new Pen(Color.Red, 2);
        Graphics g;
        private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                timer1.Start();
                g = this.pictureBox1.CreateGraphics();
            }

        }
        int x = 0;
            
        private void timer1_Tick(object sender, EventArgs e)
        {
            g.DrawEllipse(mypen, 100 + x / 2, 100 + x / 2,  2*x, 2*x);
                x+=10;
            if (x>pictureBox1.Width/4)
                timer1.Stop();
           
            }

这个下代码应该做你想：

g.DrawEllipse(mypen, 100 - x, 100 - x,  2*x, 2*x);