JavaScript实现图片放大与缩小的两种方案

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Image.aspx.cs" Inherits="ImageZoom.Image" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
  <title></title>
  <style type="text/css">
    img
    {
      border:#000000 1px solid;
    }
  </style>
  <script language="JavaScript" type="text/javascript">
    //兼容IE和火狐
    function ImageChange(args) {
      var oImg = document.getElementById("img1");
      if (args) {
        oImg.width = oImg.width * 1.2;
        oImg.height = oImg.height * 1.2;
      }
      else {
        oImg.width = oImg.width / 1.2;
        oImg.height = oImg.height / 1.2;
      }
    }
   </script>
</head>
<body>
  <form id="form1" runat="server">
  <div>
    <img id="img1" alt="图片" src="images/img1.gif" mce_src="images/img1.gif"/>
    <br />
    <input id="btn1" type="button" value="放大" onclick="ImageChange(true)" />
    <input id="btn2" type="button" value="缩小" onclick="ImageChange(false)" />
  </div>
  </form>
</body>
</html>

var oImg = document.getElementById("img1");
oImg.style.zoom = parseInt(oImg.style.zoom) + (args ? +20 : -20) + '%';