jquery插件－放大镜效果代码

</style>
<script src="js/jquery-1.5.2.min.js"></script>
<script >

(function ($) {
    $.fn.imageLens = function (options) {

        var defaults = {
            lensSize: 100,
            borderSize: 4,
            borderColor: "#888"
        };
        var options = $.extend(defaults, options);
        var lensStyle = "background-position: 0px 0px;width: " + String(options.lensSize) + "px;height: " + String(options.lensSize)
            + "px;float: left;display: none;border-radius: " + String(options.lensSize / 2 + options.borderSize)
            + "px;border: " + String(options.borderSize) + "px solid " + options.borderColor
            + ";background-repeat: no-repeat;position: absolute;";

        return this.each(function () {
            obj = $(this);

            var offset = $(this).offset();

            // Creating lens
            var target = $("<div style='" + lensStyle + "' class='" + options.lensCss + "'>&nbsp;</div>").appendTo($(this).parent());
            var targetSize = target.size();

            // Calculating actual size of image
            var imageSrc = options.imageSrc ? options.imageSrc : $(this).attr("src");
            var imageTag = "<img style='display:none;' src='" + imageSrc + "' />";

            var widthRatio = 0;
            var heightRatio = 0;

            $(imageTag).load(function () {
                widthRatio = $(this).width() / obj.width();
                heightRatio = $(this).height() / obj.height();
            }).appendTo($(this).parent());

            target.css({ backgroundImage: "url('" + imageSrc + "')" });

            target.mousemove(setPosition);
            $(this).mousemove(setPosition);

            function setPosition(e) {

                var leftPos = parseInt(e.pageX - offset.left);
                var topPos = parseInt(e.pageY - offset.top);

                if (leftPos < 0 || topPos < 0 || leftPos > obj.width() || topPos > obj.height()) {
                    target.hide();
                }
                else {
                    target.show();

                    leftPos = String(((e.pageX - offset.left) * widthRatio - target.width() / 2) * (-1));
                    topPos = String(((e.pageY - offset.top) * heightRatio - target.height() / 2) * (-1));
                    target.css({ backgroundPosition: leftPos + 'px ' + topPos + 'px' });

                    leftPos = String(e.pageX - target.width() / 2);
                    topPos = String(e.pageY - target.height() / 2);
                    target.css({ left: leftPos + 'px', top: topPos + 'px' });
                }
            }
        });
    };
})(jQuery);
</script>
<script >

$(document).ready(function(){
    $('#img_01').imageLens(); // default initialization
    $('#img_02').imageLens({ lensSize: 200 }); // set lens size
    $('#img_03').imageLens({ lensSize: 200, imageSrc: 'data_images/img5.jpg' }); // lens size + custom image
    $('#img_04').imageLens({ borderSize: 8, borderColor: '#f00' }); // new border size and color
});

</script>

<div class="example">
    <h3><a href="#">imageLens samples</a></h3>

    <img id="img_01" src="data_images/img1.jpg" width="350" height="262" />
    <img id="img_02" src="data_images/img2.jpg" width="350" height="262" />
    <img id="img_03" src="data_images/img3.jpg" width="350" height="262" />
    <img id="img_04" src="data_images/img4.jpg" width="350" height="262" />
</div>