JavaScript
//图片按比例缩放var flag=false;function DrawImage(ImgD,iwidth,iheight){ ???//参数(图片,允许的宽度,允许的高度) ???var image=new Image(); ???image.src=ImgD.src; ???if(image.width>0 && image.height>0){ ???flag=true; ???if(image.width/image.height>= iwidth/iheight){ ???????if(image.width>iwidth){ ?????????ImgD.width=iwidth; ???????ImgD.height=(image.height*iwidth)/image.width; ???????}else{ ???????ImgD.width=image.width; ?????????ImgD.height=image.height; ???????} ???????ImgD.alt=image.width+"×"+image.height; ???????} ???else{ ???????if(image.height>iheight){ ?????????ImgD.height=iheight; ???????ImgD.width=(image.width*iheight)/image.height; ???????????????}else{ ???????ImgD.width=image.width; ?????????ImgD.height=image.height; ???????} ???????ImgD.alt=image.width+"×"+image.height; ???????} ???}}
html
<img src="images/toplogo.gif" onload="javascript:DrawImage(this,100,100)">JS等比例缩放图片,限定最大宽度和最大高度
原文地址：https://www.cnblogs.com/thatme/p/10208248.html