jquery等比例控制图片宽高

$(function() {
$(".dvcontent img").each(function() {
var maxwidth = 520;
if ($(this).width() > maxwidth) {
var oldwidth = $(this).width();
var oldheight = $(this).height();
var newheight = maxwidth/oldwidth*oldheight;
$(this).css({width:maxwidth+"px",height:newheight+"px",cursor:"pointer"});
$(this).attr("title","点击查看原图");
$(this).click(function(){window.open($(this).attr("src"))});
}
});
});