JS自动生成等比例缩略图的函数

函数部分
<script language="javascript" type="text/javascript">
<!--
function vvvvv(obj,ww,hh)
  {
    var w = obj.width, h = obj.height;
    if(w>ww){h=ww*h/w;w=ww;}
    if(h>hh){w=hh*w/h;h=hh;}
    obj.width = w;
    obj.height = h;
  }
-->
</script>

调用部分
<img src='图片地址' onload="javascript:vvvvv(this,100,100);" />