图片等比例放大

<!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" manifest="../manifest.mf">
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <title>北京市建设工程安全质量状况评估信息平台</title>
    <script src="../PadScript/jquery-1.7.1.min.js" type="text/javascript"></script>
    <script type="text/javascript">
        function DrawImg(boxWidth, boxHeight) {
            var imgWidth = $("#img1").width();
            var imgHeight = $("#img1").height();
            //比较imgBox的长宽比与img的长宽比大小
            if ((boxWidth / boxHeight) >= (imgWidth / imgHeight)) {
                //重新设置img的width和height
                $("#img1").width((boxHeight * imgWidth) / imgHeight);
                $("#img1").height(boxHeight);
                //让图片居中显示
                var margin = (boxWidth - $("#img1").width()) / 2;
                $("#img1").css("margin-left", margin);
            }
            else {
                //重新设置img的width和height
                $("#img1").width(boxWidth);
                $("#img1").height((boxWidth * imgHeight) / imgWidth);
                //让图片居中显示
                var margin = (boxHeight - $("#img1").height()) / 2;
                $("#img1").css("margin-top", margin);
            }
        }
    </script>
</head>
<body>
    <div id="imgBox" style=" 500px; height: 400px; background: #cccccc; overflow: hidden">
        <img id="img1" alt="" src="../PadImages/status11.png" onclick="DrawImg(500,400);" />
    </div>
</body>
</html>

原文地址:https://www.cnblogs.com/fqs123456/p/3009365.html