internal static void GetScreenShot( )
{
  //获得当前屏幕的大小 
  Rectangle rect = new Rectangle();
  rect = Screen.AllScreens[0].WorkingArea;
   
  //计算图片的大小，因为图片的长和宽有可能超过目前屏幕的大小 
  //创建一个以当前屏幕为模板的图象 
  Control ctl = new Control();
  Graphics g1 = ctl.CreateGraphics();
  //创建以屏幕大小为标准的位图 
  Image MyImage = new Bitmap(rect.Width ,rect .Height, g1);

  Graphics g2 = Graphics.FromImage(MyImage);
  //得到屏幕的DC 
  IntPtr dc1 = g1.GetHdc();
  //得到Bitmap的DC 
  IntPtr dc2 = g2.GetHdc();
  //调用此API函数，实现屏幕捕获 

  BitBlt(dc2, 0, 0, rect.Width, rect.Height, dc1, 0, 0, 13369376);
  //释放掉屏幕的DC 
  g1.ReleaseHdc(dc1);
  //释放掉Bitmap的DC 
  g2.ReleaseHdc(dc2);
  //以JPG文件格式来保存 
  //Image.GetThumbnailImageAbort myCallback = new Image.GetThumbnailImageAbort(ThumbnailCallback);
  //return MyImage.GetThumbnailImage(control.Width, control.Height, myCallback, IntPtr.Zero);
  MyImage.Save("D:\\aa.jpg");
 
}
[System.Runtime.InteropServices.DllImportAttribute("gdi32.dll")]
private static extern bool BitBlt(
 IntPtr hdcDest,  //目标设备的句柄
 int nXDest,    //目标对象的左上角的X坐标
 int nYDest,    //目标对象的左上角的X坐标
 int nWidth,    //目标对象的矩形的宽度
 int nHeight,    //目标对象的矩形的长度
 IntPtr hdcSrc,   //源设备的句柄
 int nXSrc,     //源对象的左上角的X坐标
 int nYSrc,     //源对象的左上角的X坐标
 System.Int32 dwRop //光栅的操作值
);