原理：图片加载完后把图片的尺寸固定在一个固定的范围之内。。
JS Code：
<script type="text/javascript">
var proMaxHeight=100;
var proMaxWidth=100;
function ImgAuto(ImgD)
{
var image=new Image();
image.src=ImgD.src;
image.onload = function(){
if(image.width>0&&image.height>0)
{
var rate=(proMaxWidth/image.width<proMaxHeight/image.height)?proMaxWidth/image.width:proMaxHeight/image.height;
if(rate<=1)
{
ImgD.width=image.width*rate;
ImgD.height=image.height*rate
}
else
{
ImgD.width=image.width;
ImgD.height=image.height;
}
}
};
image.onload();
};
</script>
HTML Code:
<body>
<img src="http://s3.knowsky.com/l/45001-55000/200952916491584421395.jpg" onload="ImgAuto(this)" id="test"/>
<script type="text/javascript" src="img.js"></script>
</body>