不要同时限定图片的宽和高,
它就会按原图比例显示<html>
<body bgcolor=cccccc >
<img id=img1 src="http://jkisjk.vip.sina.com/Buddha.jpg" onclick="alert(this.offsetWidth)">
<p>
<input type=button value="2:1缩小" onclick="img1.style.width=img1.offsetWidth/2;">
<input type=button value="1:2放大" onclick="img1.style.width=img1.offsetWidth*2;">
</body>
</html>
它就会按原图比例显示<html>
<body bgcolor=cccccc >
<img id=img1 src="http://jkisjk.vip.sina.com/Buddha.jpg" onclick="alert(this.offsetWidth)">
<p>
<input type=button value="2:1缩小" onclick="img1.style.width=img1.offsetWidth/2;">
<input type=button value="1:2放大" onclick="img1.style.width=img1.offsetWidth*2;">
</body>
</html>
<!--
#idDiv {
position: absolute;
height: 400;
width: 400;
filter: progid:DXImageTransform.Microsoft.AlphaImageLoader(src='csdn.gif',sizingMethod='scale');
}
//-->
</style>
</head><body>
<div id="idDiv" align="" width="200" height="100"></div>
</body>