关于c#画图

 private void pictureBox1_Paint(object sender, PaintEventArgs e)

        {

            Graphics g = e.Graphics;



            Pen pen = new Pen(Brushes.Blue);

            //初始半径

            float r0 = 20;

            //圆心

            float x0 = 140;

            float y0 = 140;



            //圆的宽度和高度

            float width = 0;

            float height = 0;

            float x = 100;

            float y = 100;

            //圆半径的递增数量

            float d = 2 * r0;

            //画圆

            for (int i = 0; i < 3; i++)

            {

                //计算当前圆的宽度和高度

                width = (r0 + d * i) * 2;

                height = (r0 + d * i) * 2;

                //计算当前圆的左上角顶点坐标

                x = x0 - width / 2;

                y = y0 - height / 2;

                //画圆

                g.SmoothingMode = SmoothingMode.AntiAlias;

                g.DrawEllipse(pen, x, y, width, height);

            }

            //画刻度条

            pen.Color = Color.Black;//黑笔画线

            g.DrawLine(pen, x0 - 5 * r0 - 2 * r0 / 5, y0, x0 - 3 * r0 / 5, y0);//线条

            //画刻度

            for (int j = 0; j < 8; j++)

            {

                for (int i = 0; i < 13; i++)

                {

                    if (i % 6 == 0)

                    {

                        g.DrawLine(pen, x0 - 5 * r0 - 2 * r0 / 5 + 2 * r0 * i / 5, (float)(y0 - 1.5 * r0 / 5), x0 - 5 * r0 - 2 * r0 / 5 + 2 * r0 * i / 5, (float)(y0 + 1.5 * r0 / 5));

                    }

                    else

                    {

                        g.DrawLine(pen, x0 - 5 * r0 - 2 * r0 / 5 + 2 * r0 * i / 5, y0 - r0 / 5, x0 - 5 * r0 - 2 * r0 / 5 + 2 * r0 * i / 5, y0 + r0 / 5);

                    }

                }

            }

        }