javascript控制图片自适应大小

//图片自适应大小
//id为img控件的id
//width与height为img父控件的宽高——即img的最大宽高
//示例：<imgid="dd"src="ee.jpg"onload="imgFit('dd',100,200)"/>"
functionimgFit(id,width,height)
...{
varimageArr=document.getElementById(id);
if(imageArr.offsetWidth>width||imageArr.offsetHeight>height)
...{
imageRate1=parseInt(imageArr.offsetWidth)/width;
imageRate2=parseInt(imageArr.offsetHeight)/height;
if(imageRate2>imageRate1)
imageArr.style.height=imageArr.offsetHeight/imageRate2+"px";
else
imageArr.style.width=imageArr.offsetWidth/imageRate1+"px";
}
}
添加居中处理：

functionimgFit(imageArr,width,height)
...{
//varimageArr=document.getElementById(id);
//if(imageArr.offsetWidth>width||imageArr.offsetHeight>height)
//{
//alert(imageArr.style.marginTop);
sWidth=imageArr.offsetWidth;
sHeight=imageArr.offsetHeight;
imageRate1=parseInt(imageArr.offsetWidth)/width;
imageRate2=parseInt(imageArr.offsetHeight)/height;
if(imageRate2>imageRate1)
...{
imageArr.style.height=sHeight/imageRate2+"px";
imageArr.style.marginLeft=(width-sWidth/imageRate2)/2+"px";
}
else
...{
imageArr.style.width=sWidth/imageRate1+"px";
imageArr.style.marginTop=(height-sHeight/imageRate1)/2+"px";
}
//alert(imageArr.offsetWidth+":"+imageArr.offsetHeight);
//}
}