JS实现按比例缩放图片的方法(附C#版代码)_javascript技巧

本文实例讲述了JS实现按比例缩放图片的方法。分享给大家供大家参考，具体如下：

js版本：

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;
 }
}

使用很简单： /// <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; }