From

[codx]

using System;
using System.Drawing;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }


        Rectangle re = new Rectangle(0, 0, 20, 20);   //小球初始的坐标和大小
        int setpX = 5;
        int setpY = 5;


        private void timer1_Tick(object sender, EventArgs e)
        {
            Show(this);
        }



        public void Show(Control ctl)
        {

            
            Graphics g = ctl.CreateGraphics(); //这是要绘图的控件的Graphics

            BufferedGraphicsContext dc = new BufferedGraphicsContext();

            BufferedGraphics bg = dc.Allocate(g, new Rectangle(new Point(0, 

0), ctl.Size));//根据控件的Graphics初始缓冲Graphics

            Graphics gBuff = bg.Graphics;    //这是缓冲Graphics

          
            ///以下是绘图代码
            re.X += setpX;
            re.Y += setpY;

            if (re.X >= ctl.Width)
            {
                setpX = -setpX;
            }
            if (re.X <= 0)
            {
                setpX = -setpX;
            }

            if (re.Y >= ctl.Height)
            {

                setpY = -setpY;
            }
            if (re.Y <= 0)
            {
                setpY = Math.Abs(setpY);
            }

             SolidBrush sb = new SolidBrush(Color.Red);
             gBuff.FillEllipse(sb,re);
             gBuff.DrawEllipse(new Pen(Color.Blue), 0, 0, re.X - 2, re.Y - 

2);
             gBuff.DrawEllipse(new Pen(Color.Yellow), 0, 0, re.X - 4, re.Y 

- 4);
             gBuff.DrawEllipse(new Pen(Color.Tan), 0, 0, re.X - 6, re.Y - 

6);

            //把缓冲Graphics的图一次性绘制到控件的Graphics
            bg.Render(g);


            sb.Dispose();
            bg.Dispose();
            g.Dispose();

        }
    }
}

[Justin-Liu]

问题是什么。。。