this.SetStyle(ControlStyles.OptimizedDoubleBuffer|ControlStyles.ResizeRedraw|ControlStyles.AllPaintingInWmPaint,true);

Bitmap bmp=null;
Graphics g_bmp=null;
bmp=new Bitmap(this.Width,this.Height);
g_bmp=Graphics.FromImage(bmp);
g_bmp.Clear(this.BackColor);
g_bmp.DrawString("重绘",this.Font,new SolidBrush(this.ForeColor),this.Location.X+1,this.Location.Y+1);
this.Refresh();//在OnPaint方法中实现下面代码
private void this_Paint(object sender,PaintEventArgs e)
{Graphics g=e.Graphics;if(g==null) return;if(g_bmp!=null){g.DrawImage((Image)bmp,0,0);}
}

BufferedGraphicsContext current = BufferedGraphicsManager.Current; //(1)
BufferedGraphics bg;
bg = current.Allocate(this.CreateGraphics(),this.DisplayRectangle); //(2)
Graphics g = bg.Graphics;//(3)
//随机 宽400 高400

System.Random rnd = new Random();
int x,y,w,h,r,i;
for (i = 0; i < 10000; i++)
{x = rnd.Next(400);y = rnd.Next(400);r = rnd.Next(20);w = rnd.Next(10);h = rnd.Next(10);g.DrawEllipse(Pens.Blue, x, y, w, h);
}
bg.Render();//(4)
//bg.Render(this.CreateGraphics());
bg.Dispose();//(5)

Bitmap bt = new Bitmap(400, 400);
Graphics bg = Graphics.FromImage(bt);
System.Random rnd = new Random();
int x, y, w, h, r, i;
for (i = 0; i < 10000; i++)
{ x = rnd.Next(400); y = rnd.Next(400); r = rnd.Next(20); w = rnd.Next(10); h = rnd.Next(10); bg.DrawEllipse(Pens.Blue, x, y, w, h); }
this.CreateGraphics().DrawImage(bt, new Point(0, 0)); 

Rectangle rect = e.ClipRectangle;
Bitmap bufferimage = new Bitmap(this.Width, this.Height);
Graphics g = Graphics.FromImage(bufferimage);
g.Clear(this.BackColor);
g.SmoothingMode = SmoothingMode.HighQuality; //高质量
g.PixelOffsetMode = PixelOffsetMode.HighQuality; //高像素偏移质量
foreach (IShape drawobject in doc.drawObjectList){if (rect.IntersectsWith(drawobject.Rect)){drawobject.Draw(g);if (drawobject.TrackerState == config.Module.Core.TrackerState.Selected&& this.CurrentOperator == Enum.Operator.Transfrom)//仅当编辑节点操作时显示图元热点
               {drawobject.DrawTracker(g);}}}
using (Graphics tg = e.Graphics)
{tg.DrawImage(bufferimage, 0, 0);//把画布贴到画面上
}

Rectangle rect = e.ClipRectangle;
BufferedGraphicsContext currentContext = BufferedGraphicsManager.Current;
BufferedGraphics myBuffer = currentContext.Allocate(e.Graphics, e.ClipRectangle);
Graphics g = myBuffer.Graphics;
g.SmoothingMode = SmoothingMode.HighQuality;
g.PixelOffsetMode = PixelOffsetMode.HighSpeed;
g.Clear(this.BackColor);
foreach (IShape drawobject in doc.drawObjectList)
{if (rect.IntersectsWith(drawobject.Rect)){drawobject.Draw(g);if (drawobject.TrackerState == config.Module.Core.TrackerState.Selected&& this.CurrentOperator == Enum.Operator.Transfrom)//仅当编辑节点操作时显示图元热点
        {drawobject.DrawTracker(g);}}
}
myBuffer.Render(e.Graphics);
myBuffer.Dispose();//释放资源

Bitmap currentMap;
bool first = true;
private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
{if (zoom == 0){if (e.Button == MouseButtons.Left) //draggingmousedrag = e.Location;Image myImage = myMap.GetMap();currentMap = new Bitmap(myImage);first = false;}
}
private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
{if (zoom == 0&&!first){Image img = new Bitmap(Size.Width, Size.Height);Graphics g = Graphics.FromImage(img);g.Clear(Color.Transparent);//图片移动后显示的底色g.SmoothingMode = SmoothingMode.HighQuality; //高质量g.PixelOffsetMode = PixelOffsetMode.HighQuality; //高像素偏移质量g.DrawImageUnscaled(currentMap, new System.Drawing.Point(e.Location.X - mousedrag.X, e.Location.Y - mousedrag.Y));//在g中移动图片，原图在（0，0）画的，所以直接用new System.Drawing.Point(e.Location.X - mousedrag.X, e.Location.Y - mousedrag.Y）就好。
            g.Dispose();pictureBox1.Image = img;//img是在鼠标这个位置时生成被移动后的暂时的图片
    }
}
private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
{if (zoom == 0){System.Drawing.Point pnt = new System.Drawing.Point(Width / 2 + (mousedrag.X - e.Location.X),Height / 2 + (mousedrag.Y - e.Location.Y));myMap.Center = myMap.ImageToWorld(pnt);pictureBox1.Image = myMap.GetMap();first = true;}
}

//创建一个与窗体工作区大小相同的位图实例
// image:Image类的子类的实例引用
Bitmap localBitmap=new Bitmap(CilentRectangle.Width,CilentRectangle.Height) //创建位图实例// image:要绘制的图像  x:绘制的图像的左上角 x坐标 y:左上角y坐标
Graphics g=e.Graphics;//获取窗体画布
g.DrawImage(localBitmap,0,0);  //在窗体中绘制出内存中的图像

private void InitializeComponent()
{this.SuspendLayout();// // Form1// this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 12F);this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;this.ClientSize = new System.Drawing.Size(388, 325);this.MaximizeBox = false;this.MinimizeBox = false;this.Name = "Form1";this.Text = "双缓冲技术绘图";this.Paint += new System.Windows.Forms.PaintEventHandler(this.Form1_Paint);this.ResumeLayout(false);
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Drawing.Drawing2D;  namespace DoubleBuffer
{  public partial class Form1 : Form  {  public Form1()  {  InitializeComponent();  }  private void Form1_Paint(object sender, PaintEventArgs e)  {  Bitmap localBitmap = new Bitmap(ClientRectangle.Width, ClientRectangle.Height);  //创建位图实例  Graphics g_bmp= Graphics.FromImage(localBitmap);  g_bmp.Clear(BackColor);  g_bmp.SmoothingMode = SmoothingMode.AntiAlias;  PaintImage(g_bmp);  Graphics g = e.Graphics;//获取窗体画布  g.DrawImage(localBitmap, 0, 0); //在窗体的画布中绘画出内存中的图像
            g_bmp.Dispose();  localBitmap.Dispose();  g.Dispose();  }  private void PaintImage(Graphics g)  {  //绘图  GraphicsPath path = new GraphicsPath(new Point[]{ new Point(100,60),new Point(350,200),new Point(105,225),new Point(190,ClientRectangle.Bottom),  new Point(50,ClientRectangle.Bottom),new Point(50,180)}, new byte[]{  (byte)PathPointType.Start,  (byte)PathPointType.Bezier,  (byte)PathPointType.Bezier,  (byte)PathPointType.Bezier,  (byte)PathPointType.Line,  (byte)PathPointType.Line});  PathGradientBrush pgb = new PathGradientBrush(path);  pgb.SurroundColors = new Color[] { Color.Green, Color.Yellow, Color.Red, Color.Blue, Color.Orange, Color.LightBlue };  g.FillPath(pgb, path);  g.DrawString("双缓冲绘图", new Font("宋体", 18, FontStyle.Bold), new SolidBrush(Color.Red), new PointF(110, 20));  g.DrawBeziers(new Pen(new SolidBrush(Color.Green),2),new Point[] {new Point(120,100),new Point(120,120),new Point(120,100),new Point(120,150)});  g.DrawArc(new Pen(new SolidBrush(Color.Blue), 5), new Rectangle(new Point(120, 170), new Size(60, 60)), 0, 360);  g.DrawRectangle(new Pen(new SolidBrush(Color.Orange), 3), new Rectangle(new Point(240, 260), new Size(90, 50)));  }  }
}  

namespace DoubleBuffer
{  partial class Form1  {  /// <summary>  /// 必需的设计器变量。  /// </summary>  private System.ComponentModel.IContainer components = null;  /// <summary>  /// 清理所有正在使用的资源。  /// </summary>  /// <param name="disposing">如果应释放托管资源，为 true；否则为 false。</param>  protected override void Dispose(bool disposing)  {  if (disposing && (components != null))  {  components.Dispose();  }  base.Dispose(disposing);  }  #region Windows 窗体设计器生成的代码  /// <summary>  /// 设计器支持所需的方法 - 不要  /// 使用代码编辑器修改此方法的内容。  /// </summary>  private void InitializeComponent()  {  this.SuspendLayout();  //   // Form1  //   this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 12F);  this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;  this.ClientSize = new System.Drawing.Size(388, 325);  this.MaximizeBox = false;  this.MinimizeBox = false;  this.Name = "Form1";  this.Text = "双缓冲技术绘图";  this.Paint += new System.Windows.Forms.PaintEventHandler(this.Form1_Paint);  this.ResumeLayout(false);  }  #endregion  }
}