效果：
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>按比例缩放图片</title>
<script language="JavaScript" type="text/javascript">
<!--
function DrawImage(ImgD,FitWidth,FitHeight){
var image=new Image();
image.src=ImgD.src;
if(image.width>0 && image.height>0){
if(image.width/image.height>= FitWidth/FitHeight){
if(image.width>FitWidth){
ImgD.width=FitWidth;
ImgD.height=(image.height*FitWidth)/image.width;
}else{
ImgD.width=image.width;
ImgD.height=image.height;
}
} else{
if(image.height>FitHeight){
ImgD.height=FitHeight;
ImgD.width=(image.width*FitHeight)/image.height;
}else{
ImgD.width=image.width;
ImgD.height=image.height;
}
}
}
}
//-->
</script>
</head>
<body>
按比例缩小：
<p><img src="/jscss/demoimg/wall7.jpg" onload="DrawImage(this,100,100)" border="0"></a>
</p>按比例放大：（实际上不能放大，只是显示图片的最原始尺寸）
<p><img src="/jscss/demoimg/wall7.jpg" onload="DrawImage(this,500,500)" border="0"></a>
</p>
</body>
</html>
效果：
