C#生成缩略图代码

//生成缩略图    protected void RebuildImage(string oldImgPath,string newName, int intThumbWidth, int intThumbHeight)    {        try        {            //原图加载             using (System.Drawing.Image sourceImage = System.Drawing.Image.FromFile(oldImgPath))            {                //原图宽度和高度                 int width = sourceImage.Width;                int height = sourceImage.Height;                int smallWidth;                int smallHeight;                //获取第一张绘制图的大小,(比较 原图的宽/缩略图的宽 和 原图的高/缩略图的高)                 if (((decimal)width) / height <= ((decimal)intThumbWidth) / intThumbHeight)                {                    smallWidth = intThumbWidth;                    smallHeight = intThumbWidth * height / width;                }                else                {                    smallWidth = intThumbHeight * width / height;                    smallHeight = intThumbHeight;                }                //判断缩略图在当前文件夹下是否同名称文件存在                 /**                file_append = 0;                sThumbFile = sThumbExtension + System.IO.Path.GetFileNameWithoutExtension(myFile.FileName) + extendName;                while (System.IO.File.Exists(System.Web.HttpContext.Current.Server.MapPath(sSavePath + sThumbFile)))                {                    file_append++;                    sThumbFile = sThumbExtension + System.IO.Path.GetFileNameWithoutExtension(myFile.FileName) +                    file_append.ToString() + extendName;                }                 * */

                //缩略图保存的绝对路径                 string smallImagePath = System.Web.HttpContext.Current.Server.MapPath("~/cn/UploadFiles/casesmall/" + "s_" + newName);

                //新建一个图板,以最小等比例压缩大小绘制原图                 using (System.Drawing.Image bitmap = new System.Drawing.Bitmap(smallWidth, smallHeight))                {                    //绘制中间图                     using (System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap))                    {                        //高清,平滑                         g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;                        g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;                        g.Clear(Color.Black);                        g.DrawImage(                        sourceImage,                        new System.Drawing.Rectangle(0, 0, smallWidth, smallHeight),                        new System.Drawing.Rectangle(0, 0, width, height),                        System.Drawing.GraphicsUnit.Pixel                        );                    }                    //新建一个图板,以缩略图大小绘制中间图                     using (System.Drawing.Image bitmap1 = new System.Drawing.Bitmap(intThumbWidth, intThumbHeight))                    {                        //绘制缩略图                         using (System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap1))                        {                            //高清,平滑                             g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;                            g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;                            g.Clear(Color.Black);                            int lwidth = (smallWidth - intThumbWidth) / 2;                            int bheight = (smallHeight - intThumbHeight) / 2;                            g.DrawImage(bitmap, new Rectangle(0, 0, intThumbWidth, intThumbHeight), lwidth, bheight, intThumbWidth, intThumbHeight, GraphicsUnit.Pixel);                            g.Dispose();                            bitmap1.Save(smallImagePath, System.Drawing.Imaging.ImageFormat.Jpeg);                        }                    }                }            }        }        catch(Exception e)        {            Response.Write("<script>alert('"+e+"')</script>");            //出错则删除             //System.IO.File.Delete(System.Web.HttpContext.Current.Server.MapPath(sSavePath + sFilename));            //return "图片格式不正确";        }    }