supposition.js

/*
 * Supposition v0.2 - an optional enhancer for Superfish jQuery menu widget.
 *
 * Copyright (c) 2008 Joel Birch - based mostly on work by Jesse Klaasse and credit goes largely to him.
 * Special thanks to Karl Swedberg for valuable input.
 *
 * Dual licensed under the MIT and GPL licenses:
 *  http://www.opensource.org/licenses/mit-license.php
 *  http://www.gnu.org/licenses/gpl.html
 */
/*
 * This is not the original jQuery Supposition plugin.
 * Please refer to the README for more information.
 */

(function($){
  $.fn.supposition = function(){
    var $w = $(window), /*do this once instead of every onBeforeShow call*/
    _offset = function(dir) {
      return window[dir == 'y' ? 'pageYOffset' : 'pageXOffset']
      || document.documentElement && document.documentElement[dir=='y' ? 'scrollTop' : 'scrollLeft']
      || document.body[dir=='y' ? 'scrollTop' : 'scrollLeft'];
    },
    onHide = function(){
      this.css({bottom:''});
    },
    onBeforeShow = function(){
      this.each(function(){
        var $u = $(this);
        $u.css('display','block');
        var $mul = $u.closest('.sf-menu'),
        level = $u.parents('ul').length,
        menuWidth = $u.width(),
        menuParentWidth = $u.closest('li').outerWidth(true),
        menuParentLeft = $u.closest('li').offset().left,
        totalRight = $w.width() + _offset('x'),
        menuRight = $u.offset().left + menuWidth,
        exactMenuWidth = (menuRight > (menuParentWidth + menuParentLeft)) ? menuWidth - (menuRight - (menuParentWidth + menuParentLeft)) : menuWidth;
        if ($u.parents('.sf-js-enabled').hasClass('rtl')) {
          if (menuParentLeft < exactMenuWidth) {
            if (($mul.hasClass('sf-horizontal') && level == 1) || ($mul.hasClass('sf-navbar') && level == 2)){
              $u.css({left:0,right:'auto'});
            }
            else {
              $u.css({left:menuParentWidth + 'px',right:'auto'});
            }
            $u.parent().addClass('sf-supposition-active');
          }
        }
        else {
          if (menuRight > totalRight && menuParentLeft > menuWidth) {
            if (($mul.hasClass('sf-horizontal') && level == 1) || ($mul.hasClass('sf-navbar') && level == 2)){
              $u.css({right:0,left:'auto'});
            }
            else {
              $u.css({right:menuParentWidth + 'px',left:'auto'});
            }
            $u.parent().addClass('sf-supposition-active');
          }
        }
        var windowHeight = $w.height(),
        offsetTop = $u.offset().top,
        menuParentShadow = ($mul.hasClass('sf-shadow') && $u.css('padding-bottom').length > 0) ? parseInt($u.css('padding-bottom').slice(0,-2)) : 0,
        menuParentHeight = ($mul.hasClass('sf-vertical')) ? '-' + menuParentShadow : $u.parent().outerHeight(true) - menuParentShadow,
        menuHeight = $u.height(),
        baseline = windowHeight + _offset('y');
        var expandUp = ((offsetTop + menuHeight > baseline) && (offsetTop > menuHeight));
        if (expandUp) {
          $u.css({bottom:menuParentHeight + 'px',top:'auto'});
        }
        $u.css('display','none');
      });
    };

    return this.each(function() {
      var o = $.fn.superfish.o[this.serial]; /* get this menu's options */

      /* if callbacks already set, store them */
      var _onBeforeShow = o.onBeforeShow,
      _onHide = o.onHide;

      $.extend($.fn.superfish.o[this.serial],{
        onBeforeShow: function() {
          onBeforeShow.call(this); /* fire our Supposition callback */
          _onBeforeShow.call(this); /* fire stored callbacks */
        },
        onHide: function() {
          onHide.call(this); /* fire our Supposition callback */
          _onHide.call(this); /* fire stored callbacks */
        }
      });
    });
  };
})(jQuery);