C# GDI+ 图像的双缓存技术

using  System;
using  System.Collections.Generic;
using  System.ComponentModel;
using  System.Data;
using  System.Drawing;
using  System.Text;
using  System.Windows.Forms;
using  System.Drawing.Drawing2D;

namespace  DoubleBuffer
{
     public   partial   class  Form1 : Form
    {
         bool  flag  =   true ;
        Brush brush;
         public  Form1()
        {
            InitializeComponent();
        }

         private   void  timerTest_Tick( object  sender, EventArgs e)
        {
             if  (rbYes.Checked) // 默认
            {
                BasicDraw();
            }
             if (rbUser.Checked) // 自己实现双缓冲原理
                UseMyImage();
             if  (rbManual.Checked) // 手动管理双缓冲
            {
                UseDoubleBuffer();
            }
            
         }
         private   void  BasicDraw()
        {
            DateTime t1  =  DateTime.Now;
            Graphics g  =   this .CreateGraphics();
            Draw(g);
            DateTime t2  =  DateTime.Now;
            TimeSpan sp  =  t2  -  t1;
             float  per  =   1000   /  sp.Milliseconds;
            lbSpeed.Text  =   " 速度： "   +  per.ToString()  +   " 帧/秒 " ;
        }
         private   void  UseMyImage()
        {
            DateTime t1  =  DateTime.Now;
            Bitmap bmp  =   new  Bitmap( 600 ,  600 );
            Graphics g  =  Graphics.FromImage(bmp);
            Draw(g);
             this .CreateGraphics().DrawImage(bmp,  0 ,  0 );
            DateTime t2  =  DateTime.Now;
            TimeSpan sp  =  t2  -  t1;
             float  per  =   1000   /  sp.Milliseconds;
            lbSpeed.Text  =   " 速度： "   +  per.ToString()  +   " 帧/秒 " ;
        }
         private   void  UseDoubleBuffer()
        {
            BufferedGraphicsContext currentContext  =  BufferedGraphicsManager.Current;
            BufferedGraphics myBuffer  =  currentContext.Allocate( this .CreateGraphics(),  this .DisplayRectangle);
            DateTime t1  =  DateTime.Now;
            Graphics g  =  myBuffer.Graphics;
            g.Clear(Button.DefaultBackColor);
            Draw(g);
            myBuffer.Render();
            DateTime t2  =  DateTime.Now;
            TimeSpan sp  =  t2  -  t1;
             float  per  =   1000   /  sp.Milliseconds;
            lbSpeed.Text  =   " 速度： "   +  per.ToString()  +   " 帧/秒 " ;
            myBuffer.Dispose(); 

        }
         private   void  Draw(Graphics g)
        {
             if  (flag)
            {
                brush  =   new  LinearGradientBrush( new  PointF( 0.0f ,  0.0f ),
                     new  PointF( 700.0f ,  300.0f ), Color.Red, Color.Blue);
                flag  =   false ;
            }
             else
            {
                brush  =   new  LinearGradientBrush( new  PointF( 0.0f ,  0.0f ),
                     new  PointF( 700.0f ,  300.0f ), Color.Blue, Color.Red);
                flag  =   true ;
            }
             for  ( int  j  =   0 ; j  <   60 ; j ++ )
            {
                 for  ( int  i  =   0 ; i  <   60 ; i ++ )
                {
                    g.FillEllipse(brush, i  *   10 , j  *   10 ,  10 ,  10 );
                }
            }
        }

         private   void  btnStart_Click( object  sender, EventArgs e)
        {
            timerTest.Enabled  =   true ;
        }

         private   void  btnStop_Click( object  sender, EventArgs e)
        {
            timerTest.Enabled  =   false ;
        }
    }
}