JQuery插件第三十五个：在指定范围内水平垂直居中浮动层

//常量：浮动层的生成时的初始位置坐标,数据来自操作台的坐标与窗口坐标的距离
var DIV_X_DIFFERENCE = 194;
var DIV_Y_DIFFERENCE = 167;
//设置层的坐标
(function($) {
    $.fn.point = function(options) {
        var defaults = { X: 0, Y: 0 };         //坐标对象
        var opts = $.extend(defaults, options);
        //主要执行过程
        return this.each(function() {
            $(this).css({ "left": parseInt(opts.X), "top": parseInt(opts.Y) });
        });
    };
})(jQuery);

//让当前层水平垂直居中
(function($) {
    $.fn.positionCenter = function(options) {
        var defaults = { box: null };          //操作台box
        var opts = $.extend(defaults, options);
        if (opts.box == null) return;
        var w = $(this).width();
        var h = $(this).height();
        var marginLeft = parseInt(w / 2);
        var marginTop = parseInt(h / 2);
        var winWidth = parseInt(opts.box.width() / 2);
        var winHeight = parseInt(opts.box.height() / 2);
        var left = winWidth - marginLeft;
        var top = winHeight - marginTop;
        var cp = { X: left + DIV_X_DIFFERENCE, Y: top + DIV_Y_DIFFERENCE };

        //主要执行过程
        $(this).point(cp);
    };
})(jQuery);