/// 
        /// 复制屏幕到内存中        /// 
        /// 
     
      返回内存流
             public static MemoryStream GetScreenPng()        {            Screen sc = Screen.PrimaryScreen;//取得主屏            Rectangle rct = sc.Bounds;//得到主屏的范围            Image img = new Bitmap(rct.Width, rct.Height);            Graphics gp = Graphics.FromImage(img);            gp.CopyFromScreen(new Point(0, 0), new Point(0, 0), new Size(rct.Width, rct.Height));            //SolidBrush sb = new SolidBrush(Color.Red);            //Font ft = new System.Drawing.Font("黑体",16);            //gp.DrawString("这是什么",ft,sb,new PointF(0,rct.Height-ft.Height));            //img.Save(@"d:\截图.png");            MemoryStream stream = new MemoryStream();            img.Save(stream, System.Drawing.Imaging.ImageFormat.Png);//转化为流，此时就已经有了png格式符了            return stream;        }