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:<img src="../pic.jpg" onload='resizeImage(this,60,90)> 就OK了;
注:等比例放缩的时候会出现抖动的情况,处理方法很简单,你在img的属性先设置它的widht和height,这样的话加载的时候绝对不会超过这个尺寸,等你js运行好之后就会调到你所规定的比例,绝对不会以下撑到很大。
同时也附上C#版本的
C#版本---海东兄 http://www.cnblogs.com/ghd258/archive/2005/11/07/270447.html
1
/// <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
else25
{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
} 
