按比例缩放图片

/// <summary>
 2        /// 按比例缩放图片
 3        /// </summary>
 4        /// <param name="imgUrl">图片的路径</param>
 5        /// <param name="imgHeight">图片的高度</param>
 6        /// <param name="imgWidth">图片的宽度</param>
 7        /// <returns></returns>
 8          public   static   string  GetImageSize( string  imgUrl, int  imgHeight, int  imgWidth)
 9          {
10            string fileName = System.Web.HttpContext.Current.Server.MapPath(imgUrl);
11            string strResult = string.Empty;
12            if(System.IO.File.Exists(fileName) && imgHeight != 0 && imgWidth != 0)
13            {
14                decimal desWidth;decimal desHeight;                                            //目标宽高
15                System.Drawing.Image objImage = System.Drawing.Image.FromFile(fileName);
16                decimal radioAct = (decimal)objImage.Width/(decimal)objImage.Height;        //原始图片的宽高比
17                decimal radioLoc = (decimal)imgWidth/(decimal)imgHeight;                    //图片位的宽高比
18                if(radioAct > radioLoc)                                                        //原始图片比图片位宽
19                {        
20                    decimal dcmZoom = (decimal)imgWidth/(decimal)objImage.Width;
21                    desHeight = objImage.Height*dcmZoom;
22                    desWidth = imgWidth;
23                }
24                else
25                {
26                    decimal dcmZoom = (decimal)imgHeight/(decimal)objImage.Height;
27                    desWidth = objImage.Width*dcmZoom;
28                    desHeight = imgHeight;
29                }
30                objImage.Dispose();                //释放资源
31                strResult = "width=\"" + Convert.ToString((int)desWidth) + "\" height=\""
32                    + Convert.ToString((int)desHeight) + "\" ";
33            }
34            return strResult;
35        }