js 自适应控制图片的大小
<script language="javascript">
var flag=false;
function DrawImage(ImgD){
var image=new Image();
image.src=ImgD.src;
if(image.width>0 && image.height>0){
flag=true;
if(image.width/image.height>=500/400){
if(image.width>500){
ImgD.width=500;
ImgD.height=(image.height*500)/image.width;
}else{
ImgD.width=image.width;
ImgD.height=image.height;
}
}
else{
if(image.height>400){
ImgD.height=400;
ImgD.width=(image.width*400)/image.height;
}else{
ImgD.width=image.width;
ImgD.height=image.height;
}
}
}
}
</script>
调用方式（img是显示图片的html代 ） <IMG src= "temp.jpg" border=0 onload="javascript：DrawImage(this);">
修改后：
<script language="javascript">
var flag=false; //控制小图
function DrawImage(ImgD,maxwidth,maxheight){
var image=new Image();
image.src=ImgD.src;
if(image.width>0 && image.height>0){
flag=true;
if(image.width/image.height>=maxwidth/maxheight){
if(image.width>maxwidth){
ImgD.width=maxwidth;
ImgD.height=(image.height*maxwidth)/image.width;
}else{
ImgD.width=image.width;
ImgD.height=image.height;
}
}
else{
if(image.height>maxheight){
ImgD.height=maxheight;
ImgD.width=(image.width*maxheight)/image.height;
}else{
ImgD.width=image.width;
ImgD.height=image.height;
}
}
}
}
</script>
呵呵，多了两个参数，也就是你能够接受的最大宽度maxwidth与最大高度maxheight
调用方式当然也变了，请看 <IMG src= "temp.jpg" border=0 onload="javascript：DrawImage(this,300,240);">