使用js和css讲图片的现实控制在固定的区域内，大于这个区域的等比例缩放，小于这个区域的居中显示。
<!doctype html public "-//w3c//dtd xhtml 1.0 strict//en" "http://www.w3.org/tr/xhtml1/dtd/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="content-type" content="text/html; charset=gb2312" />
<title>css+js完美控制图片大小</title>
<script type="text/javascript" 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>= 400/400){
if(image.width>400){
imgd.width=400;
imgd.height=(image.height*400)/image.width;
}else{
imgd.width=image.width;
imgd.height=image.height;
}
imgd.alt=image.width+"x"+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;
}
imgd.alt=image.width+"x"+image.height;
}
}
}
//-->
</script>
<style type="text/css">
<!--
* {
margin:0;
padding:0;
}
li {
list-style:none;
}
img {
border:0;
}
.group_head {
width:400px;
height:400px;
line-height:400px;
border:1px solid #ccc;
overflow:hidden;
position:relative;
text-align:center;
float:left;
margin-right:10px;
}
.group_head p {
position:static;
+position:absolute;
top:50%;
vertical-align:middle
}
.group_head img {
position:static;
+position:relative;
top:-50%;left:-50%;
vertical-align:middle
}
-->
</style>
</head>
<body>
<ul class="jobgroup">
<li><a href="http://www.jb51.net">
<div class="group_head">
<p>
<img width="400" height="400" src="http://www.baidu.com/img/baidu_logo.gif" onload="drawimage(this);"/>
</p>
</div>
</a>
</li>
</ul>
</body>
</html>
以上就是css+javascript如何控制图片大小的示例代码分享的详细内容。