按比例缩放图片

/**//// <summary>
        /// 按比例缩放图片
        /// </summary>
        /// <param name="imgUrl">图片的路径</param>
        /// <param name="imgHeight">图片的高度</param>
        /// <param name="imgWidth">图片的宽度</param>
        /// <returns></returns>
        public static string GetImageSize(string imgUrl,int imgHeight,int imgWidth)
        {
            string fileName = System.Web.HttpContext.Current.Server.MapPath(imgUrl);
            string strResult = string.Empty;
            if(System.IO.File.Exists(fileName) && imgHeight != 0 && imgWidth != 0)
            {
                decimal desWidth;decimal desHeight;                                            //目标宽高
                System.Drawing.Image objImage = System.Drawing.Image.FromFile(fileName);
                decimal radioAct = (decimal)objImage.Width/(decimal)objImage.Height;        //原始图片的宽高比
                decimal radioLoc = (decimal)imgWidth/(decimal)imgHeight;                    //图片位的宽高比
                if(radioAct > radioLoc)                                                        //原始图片比图片位宽
                {       
                    decimal dcmZoom = (decimal)imgWidth/(decimal)objImage.Width;
                    desHeight = objImage.Height*dcmZoom;
                    desWidth = imgWidth;
                }
                else
                {
                    decimal dcmZoom = (decimal)imgHeight/(decimal)objImage.Height;
                    desWidth = objImage.Width*dcmZoom;
                    desHeight = imgHeight;
                }
                objImage.Dispose();                //释放资源
                strResult = "width=/"" + Convert.ToString((int)desWidth) + "/" height=/""
                    + Convert.ToString((int)desHeight) + "/" ";
            }
            return strResult;
        }

 

 

function resizeImage(obj, MaxW, MaxH)
{
var imageObject = obj;
var state = imageObject.readyState;
if(state!='complete')
{
setTimeout("resizeImage("+imageObject+","+MaxW+","+MaxH+")",50);
return;
}
var oldImage = new Image();
oldImage.src = imageObject.src;
var dW = oldImage.width;
var dH = oldImage.height;
if(dW>MaxW || dH>MaxH)
{
a = dW/MaxW; b = dH/MaxH;
if( b>a ) a = b;
dW = dW/a; dH = dH/a;
}
if(dW > 0 && dH > 0)
{
imageObject.width = dW;
imageObject.height = dH;
}
}