using System.Drawing;using System.IO;using System.Drawing.Imaging;        private void AddTextToImg(string fileName,string text)        {            if(!File.Exists(MapPath(fileName)))            {                throw new FileNotFoundException("The file don‘t exist!");            }                        if( text == string.Empty )            {                return;            }            //还需要判断文件类型是否为图像类型，这里就不赘述了            System.Drawing.Image image = System.Drawing.Image.FromFile(MapPath(fileName));            Bitmap bitmap = new Bitmap(image,image.Width,image.Height);            Graphics g = Graphics.FromImage(bitmap);            float fontSize = 12.0f;             //字体大小            float textWidth = text.Length*fontSize;  //文本的长度            //下面定义一个矩形区域，以后在这个矩形里画上白底黑字            float rectX = 0;                    float rectY = 0;            float rectWidth = text.Length*(fontSize+8);            float rectHeight = fontSize+8;            //声明矩形域            RectangleF textArea = new RectangleF(rectX,rectY,rectWidth,rectHeight);            Font font = new Font("宋体",fontSize);   //定义字体            Brush whiteBrush = new SolidBrush(Color.White);   //白笔刷，画文字用            Brush blackBrush = new SolidBrush(Color.Black);   //黑笔刷，画背景用            g.FillRectangle(blackBrush,rectX,rectY,rectWidth,rectHeight);                        g.DrawString(text,font,whiteBrush,textArea);            MemoryStream ms = new MemoryStream( );            //保存为Jpg类型            bitmap.Save(ms,ImageFormat.Jpeg);            //输出处理后的图像，这里为了演示方便，我将图片显示在页面中了            Response.Clear();            Response.ContentType = "image/jpeg";            Response.BinaryWrite( ms.ToArray() );            g.Dispose();            bitmap.Dispose();            image.Dispose();        }