SoundSoftware Code Site

// Copyright (c) 2005-2008 Thomas Fuchs (http://script.aculo.us, http://mir.aculo.us)

//           (c) 2005-2008 Sammi Williams (http://www.oriontransfer.co.nz, sammi@oriontransfer.co.nz)

//

// script.aculo.us is freely distributable under the terms of an MIT-style license.

// For details, see the script.aculo.us web site: http://script.aculo.us/

if(Object.isUndefined(Effect))

  throw("dragdrop.js requires including script.aculo.us' effects.js library");

var Droppables = {

  drops: [],

  remove: function(element) {

    this.drops = this.drops.reject(function(d) { return d.element==$(element) });

  },

  add: function(element) {

    element = $(element);

    var options = Object.extend({

      greedy:     true,

      hoverclass: null,

      tree:       false

    }, arguments[1] || { });

    // cache containers

    if(options.containment) {

      options._containers = [];

      var containment = options.containment;

      if(Object.isArray(containment)) {

        containment.each( function(c) { options._containers.push($(c)) });

      } else {

        options._containers.push($(containment));

      }

    }

    if(options.accept) options.accept = [options.accept].flatten();

    Element.makePositioned(element); // fix IE

    options.element = element;

    this.drops.push(options);

  },

  findDeepestChild: function(drops) {

    deepest = drops[0];

    for (i = 1; i < drops.length; ++i)

      if (Element.isParent(drops[i].element, deepest.element))

        deepest = drops[i];

    return deepest;

  },

  isContained: function(element, drop) {

    var containmentNode;

    if(drop.tree) {

      containmentNode = element.treeNode;

    } else {

      containmentNode = element.parentNode;

    }

    return drop._containers.detect(function(c) { return containmentNode == c });

  },

  isAffected: function(point, element, drop) {

    return (

      (drop.element!=element) &&

      ((!drop._containers) ||

        this.isContained(element, drop)) &&

      ((!drop.accept) ||

        (Element.classNames(element).detect(

          function(v) { return drop.accept.include(v) } ) )) &&

      Position.within(drop.element, point[0], point[1]) );

  },

  deactivate: function(drop) {

    if(drop.hoverclass)

      Element.removeClassName(drop.element, drop.hoverclass);

    this.last_active = null;

  },

  activate: function(drop) {

    if(drop.hoverclass)

      Element.addClassName(drop.element, drop.hoverclass);

    this.last_active = drop;

  },

  show: function(point, element) {

    if(!this.drops.length) return;

    var drop, affected = [];

    this.drops.each( function(drop) {

      if(Droppables.isAffected(point, element, drop))

        affected.push(drop);

    });

    if(affected.length>0)

      drop = Droppables.findDeepestChild(affected);

    if(this.last_active && this.last_active != drop) this.deactivate(this.last_active);

    if (drop) {

      Position.within(drop.element, point[0], point[1]);

      if(drop.onHover)

        drop.onHover(element, drop.element, Position.overlap(drop.overlap, drop.element));

      if (drop != this.last_active) Droppables.activate(drop);

    }

  },

  fire: function(event, element) {

    if(!this.last_active) return;

    Position.prepare();

    if (this.isAffected([Event.pointerX(event), Event.pointerY(event)], element, this.last_active))

      if (this.last_active.onDrop) {

        this.last_active.onDrop(element, this.last_active.element, event);

        return true;

      }

  },

  reset: function() {

    if(this.last_active)

      this.deactivate(this.last_active);

  }

};

var Draggables = {

  drags: [],

  observers: [],

  register: function(draggable) {

    if(this.drags.length == 0) {

      this.eventMouseUp   = this.endDrag.bindAsEventListener(this);

      this.eventMouseMove = this.updateDrag.bindAsEventListener(this);

      this.eventKeypress  = this.keyPress.bindAsEventListener(this);

      Event.observe(document, "mouseup", this.eventMouseUp);

      Event.observe(document, "mousemove", this.eventMouseMove);

      Event.observe(document, "keypress", this.eventKeypress);

    }

    this.drags.push(draggable);

  },

  unregister: function(draggable) {

    this.drags = this.drags.reject(function(d) { return d==draggable });

    if(this.drags.length == 0) {

      Event.stopObserving(document, "mouseup", this.eventMouseUp);

      Event.stopObserving(document, "mousemove", this.eventMouseMove);

      Event.stopObserving(document, "keypress", this.eventKeypress);

    }

  },

  activate: function(draggable) {

    if(draggable.options.delay) {

      this._timeout = setTimeout(function() {

        Draggables._timeout = null;

        window.focus();

        Draggables.activeDraggable = draggable;

      }.bind(this), draggable.options.delay);

    } else {

      window.focus(); // allows keypress events if window isn't currently focused, fails for Safari

      this.activeDraggable = draggable;

    }

  },

  deactivate: function() {

    this.activeDraggable = null;

  },

  updateDrag: function(event) {

    if(!this.activeDraggable) return;

    var pointer = [Event.pointerX(event), Event.pointerY(event)];

    // Mozilla-based browsers fire successive mousemove events with

    // the same coordinates, prevent needless redrawing (moz bug?)

    if(this._lastPointer && (this._lastPointer.inspect() == pointer.inspect())) return;

    this._lastPointer = pointer;

    this.activeDraggable.updateDrag(event, pointer);

  },

  endDrag: function(event) {

    if(this._timeout) {

      clearTimeout(this._timeout);

      this._timeout = null;

    }

    if(!this.activeDraggable) return;

    this._lastPointer = null;

    this.activeDraggable.endDrag(event);

    this.activeDraggable = null;

  },

  keyPress: function(event) {

    if(this.activeDraggable)

      this.activeDraggable.keyPress(event);

  },

  addObserver: function(observer) {

    this.observers.push(observer);

    this._cacheObserverCallbacks();

  },

  removeObserver: function(element) {  // element instead of observer fixes mem leaks

    this.observers = this.observers.reject( function(o) { return o.element==element });

    this._cacheObserverCallbacks();

  },

  notify: function(eventName, draggable, event) {  // 'onStart', 'onEnd', 'onDrag'

    if(this[eventName+'Count'] > 0)

      this.observers.each( function(o) {

        if(o[eventName]) o[eventName](eventName, draggable, event);

      });

    if(draggable.options[eventName]) draggable.options[eventName](draggable, event);

  },

  _cacheObserverCallbacks: function() {

    ['onStart','onEnd','onDrag'].each( function(eventName) {

      Draggables[eventName+'Count'] = Draggables.observers.select(

        function(o) { return o[eventName]; }

      ).length;

    });

  }

};

/*--------------------------------------------------------------------------*/

var Draggable = Class.create({

  initialize: function(element) {

    var defaults = {

      handle: false,

      reverteffect: function(element, top_offset, left_offset) {

        var dur = Math.sqrt(Math.abs(top_offset^2)+Math.abs(left_offset^2))*0.02;

        new Effect.Move(element, { x: -left_offset, y: -top_offset, duration: dur,

          queue: {scope:'_draggable', position:'end'}

        });

      },

      endeffect: function(element) {

        var toOpacity = Object.isNumber(element._opacity) ? element._opacity : 1.0;

        new Effect.Opacity(element, {duration:0.2, from:0.7, to:toOpacity,

          queue: {scope:'_draggable', position:'end'},

          afterFinish: function(){

            Draggable._dragging[element] = false

          }

        });

      },

      zindex: 1000,

      revert: false,

      quiet: false,

      scroll: false,

      scrollSensitivity: 20,

      scrollSpeed: 15,

      snap: false,  // false, or xy or [x,y] or function(x,y){ return [x,y] }

      delay: 0

    };

    if(!arguments[1] || Object.isUndefined(arguments[1].endeffect))

      Object.extend(defaults, {

        starteffect: function(element) {

          element._opacity = Element.getOpacity(element);

          Draggable._dragging[element] = true;

          new Effect.Opacity(element, {duration:0.2, from:element._opacity, to:0.7});

        }

      });

    var options = Object.extend(defaults, arguments[1] || { });

    this.element = $(element);

    if(options.handle && Object.isString(options.handle))

      this.handle = this.element.down('.'+options.handle, 0);

    if(!this.handle) this.handle = $(options.handle);

    if(!this.handle) this.handle = this.element;

    if(options.scroll && !options.scroll.scrollTo && !options.scroll.outerHTML) {

      options.scroll = $(options.scroll);

      this._isScrollChild = Element.childOf(this.element, options.scroll);

    }

    Element.makePositioned(this.element); // fix IE

    this.options  = options;

    this.dragging = false;

    this.eventMouseDown = this.initDrag.bindAsEventListener(this);

    Event.observe(this.handle, "mousedown", this.eventMouseDown);

    Draggables.register(this);

  },

  destroy: function() {

    Event.stopObserving(this.handle, "mousedown", this.eventMouseDown);

    Draggables.unregister(this);

  },

  currentDelta: function() {

    return([

      parseInt(Element.getStyle(this.element,'left') || '0'),

      parseInt(Element.getStyle(this.element,'top') || '0')]);

  },

  initDrag: function(event) {

    if(!Object.isUndefined(Draggable._dragging[this.element]) &&

      Draggable._dragging[this.element]) return;

    if(Event.isLeftClick(event)) {

      // abort on form elements, fixes a Firefox issue

      var src = Event.element(event);

      if((tag_name = src.tagName.toUpperCase()) && (

        tag_name=='INPUT' ||

        tag_name=='SELECT' ||

        tag_name=='OPTION' ||

        tag_name=='BUTTON' ||

        tag_name=='TEXTAREA')) return;

      var pointer = [Event.pointerX(event), Event.pointerY(event)];

      var pos     = Position.cumulativeOffset(this.element);

      this.offset = [0,1].map( function(i) { return (pointer[i] - pos[i]) });

      Draggables.activate(this);

      Event.stop(event);

    }

  },

  startDrag: function(event) {

    this.dragging = true;

    if(!this.delta)

      this.delta = this.currentDelta();

    if(this.options.zindex) {

      this.originalZ = parseInt(Element.getStyle(this.element,'z-index') || 0);

      this.element.style.zIndex = this.options.zindex;

    }

    if(this.options.ghosting) {

      this._clone = this.element.cloneNode(true);

      this._originallyAbsolute = (this.element.getStyle('position') == 'absolute');

      if (!this._originallyAbsolute)

        Position.absolutize(this.element);

      this.element.parentNode.insertBefore(this._clone, this.element);

    }

    if(this.options.scroll) {

      if (this.options.scroll == window) {

        var where = this._getWindowScroll(this.options.scroll);

        this.originalScrollLeft = where.left;

        this.originalScrollTop = where.top;

      } else {

        this.originalScrollLeft = this.options.scroll.scrollLeft;

        this.originalScrollTop = this.options.scroll.scrollTop;

      }

    }

    Draggables.notify('onStart', this, event);

    if(this.options.starteffect) this.options.starteffect(this.element);

  },

  updateDrag: function(event, pointer) {

    if(!this.dragging) this.startDrag(event);

    if(!this.options.quiet){

      Position.prepare();

      Droppables.show(pointer, this.element);

    }

    Draggables.notify('onDrag', this, event);

    this.draw(pointer);

    if(this.options.change) this.options.change(this);

    if(this.options.scroll) {

      this.stopScrolling();

      var p;

      if (this.options.scroll == window) {

        with(this._getWindowScroll(this.options.scroll)) { p = [ left, top, left+width, top+height ]; }

      } else {

        p = Position.page(this.options.scroll);

        p[0] += this.options.scroll.scrollLeft + Position.deltaX;

        p[1] += this.options.scroll.scrollTop + Position.deltaY;

        p.push(p[0]+this.options.scroll.offsetWidth);

        p.push(p[1]+this.options.scroll.offsetHeight);

      }

      var speed = [0,0];

      if(pointer[0] < (p[0]+this.options.scrollSensitivity)) speed[0] = pointer[0]-(p[0]+this.options.scrollSensitivity);

      if(pointer[1] < (p[1]+this.options.scrollSensitivity)) speed[1] = pointer[1]-(p[1]+this.options.scrollSensitivity);

      if(pointer[0] > (p[2]-this.options.scrollSensitivity)) speed[0] = pointer[0]-(p[2]-this.options.scrollSensitivity);

      if(pointer[1] > (p[3]-this.options.scrollSensitivity)) speed[1] = pointer[1]-(p[3]-this.options.scrollSensitivity);

      this.startScrolling(speed);

    }

    // fix AppleWebKit rendering

    if(Prototype.Browser.WebKit) window.scrollBy(0,0);

    Event.stop(event);

  },

  finishDrag: function(event, success) {

    this.dragging = false;

    if(this.options.quiet){

      Position.prepare();

      var pointer = [Event.pointerX(event), Event.pointerY(event)];

      Droppables.show(pointer, this.element);

    }

    if(this.options.ghosting) {

      if (!this._originallyAbsolute)

        Position.relativize(this.element);

      delete this._originallyAbsolute;

      Element.remove(this._clone);

      this._clone = null;

    }

    var dropped = false;

    if(success) {

      dropped = Droppables.fire(event, this.element);

      if (!dropped) dropped = false;

    }

    if(dropped && this.options.onDropped) this.options.onDropped(this.element);

    Draggables.notify('onEnd', this, event);

    var revert = this.options.revert;

    if(revert && Object.isFunction(revert)) revert = revert(this.element);

    var d = this.currentDelta();

    if(revert && this.options.reverteffect) {

      if (dropped == 0 || revert != 'failure')

        this.options.reverteffect(this.element,

          d[1]-this.delta[1], d[0]-this.delta[0]);

    } else {

      this.delta = d;

    }

    if(this.options.zindex)

      this.element.style.zIndex = this.originalZ;

    if(this.options.endeffect)

      this.options.endeffect(this.element);

    Draggables.deactivate(this);

    Droppables.reset();

  },

  keyPress: function(event) {

    if(event.keyCode!=Event.KEY_ESC) return;

    this.finishDrag(event, false);

    Event.stop(event);

  },

  endDrag: function(event) {

    if(!this.dragging) return;

    this.stopScrolling();

    this.finishDrag(event, true);

    Event.stop(event);

  },

  draw: function(point) {

    var pos = Position.cumulativeOffset(this.element);

    if(this.options.ghosting) {

      var r   = Position.realOffset(this.element);

      pos[0] += r[0] - Position.deltaX; pos[1] += r[1] - Position.deltaY;

    }

    var d = this.currentDelta();

    pos[0] -= d[0]; pos[1] -= d[1];

    if(this.options.scroll && (this.options.scroll != window && this._isScrollChild)) {

      pos[0] -= this.options.scroll.scrollLeft-this.originalScrollLeft;

      pos[1] -= this.options.scroll.scrollTop-this.originalScrollTop;

    }

    var p = [0,1].map(function(i){

      return (point[i]-pos[i]-this.offset[i])

    }.bind(this));

    if(this.options.snap) {

      if(Object.isFunction(this.options.snap)) {

        p = this.options.snap(p[0],p[1],this);

      } else {

      if(Object.isArray(this.options.snap)) {

        p = p.map( function(v, i) {

          return (v/this.options.snap[i]).round()*this.options.snap[i] }.bind(this));

      } else {

        p = p.map( function(v) {

          return (v/this.options.snap).round()*this.options.snap }.bind(this));

      }

    }}

    var style = this.element.style;

    if((!this.options.constraint) || (this.options.constraint=='horizontal'))

      style.left = p[0] + "px";

    if((!this.options.constraint) || (this.options.constraint=='vertical'))

      style.top  = p[1] + "px";

    if(style.visibility=="hidden") style.visibility = ""; // fix gecko rendering

  },

  stopScrolling: function() {

    if(this.scrollInterval) {

      clearInterval(this.scrollInterval);

      this.scrollInterval = null;

      Draggables._lastScrollPointer = null;

    }

  },

  startScrolling: function(speed) {

    if(!(speed[0] || speed[1])) return;

    this.scrollSpeed = [speed[0]*this.options.scrollSpeed,speed[1]*this.options.scrollSpeed];

    this.lastScrolled = new Date();

    this.scrollInterval = setInterval(this.scroll.bind(this), 10);

  },

  scroll: function() {

    var current = new Date();

    var delta = current - this.lastScrolled;

    this.lastScrolled = current;

    if(this.options.scroll == window) {

      with (this._getWindowScroll(this.options.scroll)) {

        if (this.scrollSpeed[0] || this.scrollSpeed[1]) {

          var d = delta / 1000;

          this.options.scroll.scrollTo( left + d*this.scrollSpeed[0], top + d*this.scrollSpeed[1] );

        }

      }

    } else {

      this.options.scroll.scrollLeft += this.scrollSpeed[0] * delta / 1000;

      this.options.scroll.scrollTop  += this.scrollSpeed[1] * delta / 1000;

    }

    Position.prepare();

    Droppables.show(Draggables._lastPointer, this.element);

    Draggables.notify('onDrag', this);

    if (this._isScrollChild) {

      Draggables._lastScrollPointer = Draggables._lastScrollPointer || $A(Draggables._lastPointer);

      Draggables._lastScrollPointer[0] += this.scrollSpeed[0] * delta / 1000;

      Draggables._lastScrollPointer[1] += this.scrollSpeed[1] * delta / 1000;

      if (Draggables._lastScrollPointer[0] < 0)

        Draggables._lastScrollPointer[0] = 0;

      if (Draggables._lastScrollPointer[1] < 0)

        Draggables._lastScrollPointer[1] = 0;

      this.draw(Draggables._lastScrollPointer);

    }

    if(this.options.change) this.options.change(this);

  },

  _getWindowScroll: function(w) {

    var T, L, W, H;

    with (w.document) {

      if (w.document.documentElement && documentElement.scrollTop) {

        T = documentElement.scrollTop;

        L = documentElement.scrollLeft;

      } else if (w.document.body) {

        T = body.scrollTop;

        L = body.scrollLeft;

      }

      if (w.innerWidth) {

        W = w.innerWidth;

        H = w.innerHeight;

      } else if (w.document.documentElement && documentElement.clientWidth) {

        W = documentElement.clientWidth;

        H = documentElement.clientHeight;

      } else {

        W = body.offsetWidth;

        H = body.offsetHeight;

      }

    }

    return { top: T, left: L, width: W, height: H };

  }

});

Draggable._dragging = { };

/*--------------------------------------------------------------------------*/

var SortableObserver = Class.create({

  initialize: function(element, observer) {

    this.element   = $(element);

    this.observer  = observer;

    this.lastValue = Sortable.serialize(this.element);

  },

  onStart: function() {

    this.lastValue = Sortable.serialize(this.element);

  },

  onEnd: function() {

    Sortable.unmark();

    if(this.lastValue != Sortable.serialize(this.element))

      this.observer(this.element)

  }

});

var Sortable = {

  SERIALIZE_RULE: /^[^_\-](?:[A-Za-z0-9\-\_]*)[_](.*)$/,

  sortables: { },

  _findRootElement: function(element) {

    while (element.tagName.toUpperCase() != "BODY") {

      if(element.id && Sortable.sortables[element.id]) return element;

      element = element.parentNode;

    }

  },

  options: function(element) {

    element = Sortable._findRootElement($(element));

    if(!element) return;

    return Sortable.sortables[element.id];

  },

  destroy: function(element){

    element = $(element);

    var s = Sortable.sortables[element.id];

    if(s) {

      Draggables.removeObserver(s.element);

      s.droppables.each(function(d){ Droppables.remove(d) });

      s.draggables.invoke('destroy');

      delete Sortable.sortables[s.element.id];

    }

  },

  create: function(element) {

    element = $(element);

    var options = Object.extend({

      element:     element,

      tag:         'li',       // assumes li children, override with tag: 'tagname'

      dropOnEmpty: false,

      tree:        false,

      treeTag:     'ul',

      overlap:     'vertical', // one of 'vertical', 'horizontal'

      constraint:  'vertical', // one of 'vertical', 'horizontal', false

      containment: element,    // also takes array of elements (or id's); or false

      handle:      false,      // or a CSS class

      only:        false,

      delay:       0,

      hoverclass:  null,

      ghosting:    false,

      quiet:       false,

      scroll:      false,

      scrollSensitivity: 20,

      scrollSpeed: 15,

      format:      this.SERIALIZE_RULE,

      // these take arrays of elements or ids and can be

      // used for better initialization performance

      elements:    false,

      handles:     false,

      onChange:    Prototype.emptyFunction,

      onUpdate:    Prototype.emptyFunction

    }, arguments[1] || { });

    // clear any old sortable with same element

    this.destroy(element);

    // build options for the draggables

    var options_for_draggable = {

      revert:      true,

      quiet:       options.quiet,

      scroll:      options.scroll,

      scrollSpeed: options.scrollSpeed,

      scrollSensitivity: options.scrollSensitivity,

      delay:       options.delay,

      ghosting:    options.ghosting,

      constraint:  options.constraint,

      handle:      options.handle };

    if(options.starteffect)

      options_for_draggable.starteffect = options.starteffect;

    if(options.reverteffect)

      options_for_draggable.reverteffect = options.reverteffect;

    else

      if(options.ghosting) options_for_draggable.reverteffect = function(element) {

        element.style.top  = 0;

        element.style.left = 0;

      };

    if(options.endeffect)

      options_for_draggable.endeffect = options.endeffect;

    if(options.zindex)

      options_for_draggable.zindex = options.zindex;

    // build options for the droppables

    var options_for_droppable = {

      overlap:     options.overlap,

      containment: options.containment,

      tree:        options.tree,

      hoverclass:  options.hoverclass,

      onHover:     Sortable.onHover

    };

    var options_for_tree = {

      onHover:      Sortable.onEmptyHover,

      overlap:      options.overlap,

      containment:  options.containment,

      hoverclass:   options.hoverclass

    };

    // fix for gecko engine

    Element.cleanWhitespace(element);

    options.draggables = [];

    options.droppables = [];

    // drop on empty handling

    if(options.dropOnEmpty || options.tree) {

      Droppables.add(element, options_for_tree);

      options.droppables.push(element);

    }

    (options.elements || this.findElements(element, options) || []).each( function(e,i) {

      var handle = options.handles ? $(options.handles[i]) :

        (options.handle ? $(e).select('.' + options.handle)[0] : e);

      options.draggables.push(

        new Draggable(e, Object.extend(options_for_draggable, { handle: handle })));

      Droppables.add(e, options_for_droppable);

      if(options.tree) e.treeNode = element;

      options.droppables.push(e);

    });

    if(options.tree) {

      (Sortable.findTreeElements(element, options) || []).each( function(e) {

        Droppables.add(e, options_for_tree);

        e.treeNode = element;

        options.droppables.push(e);

      });

    }

    // keep reference

    this.sortables[element.id] = options;

    // for onupdate

    Draggables.addObserver(new SortableObserver(element, options.onUpdate));

  },

  // return all suitable-for-sortable elements in a guaranteed order

  findElements: function(element, options) {

    return Element.findChildren(

      element, options.only, options.tree ? true : false, options.tag);

  },

  findTreeElements: function(element, options) {

    return Element.findChildren(

      element, options.only, options.tree ? true : false, options.treeTag);

  },

  onHover: function(element, dropon, overlap) {

    if(Element.isParent(dropon, element)) return;

    if(overlap > .33 && overlap < .66 && Sortable.options(dropon).tree) {

      return;

    } else if(overlap>0.5) {

      Sortable.mark(dropon, 'before');

      if(dropon.previousSibling != element) {

        var oldParentNode = element.parentNode;

        element.style.visibility = "hidden"; // fix gecko rendering

        dropon.parentNode.insertBefore(element, dropon);

        if(dropon.parentNode!=oldParentNode)

          Sortable.options(oldParentNode).onChange(element);

        Sortable.options(dropon.parentNode).onChange(element);

      }

    } else {

      Sortable.mark(dropon, 'after');

      var nextElement = dropon.nextSibling || null;

      if(nextElement != element) {

        var oldParentNode = element.parentNode;

        element.style.visibility = "hidden"; // fix gecko rendering

        dropon.parentNode.insertBefore(element, nextElement);

        if(dropon.parentNode!=oldParentNode)

          Sortable.options(oldParentNode).onChange(element);

        Sortable.options(dropon.parentNode).onChange(element);

      }

    }

  },

  onEmptyHover: function(element, dropon, overlap) {

    var oldParentNode = element.parentNode;

    var droponOptions = Sortable.options(dropon);

    if(!Element.isParent(dropon, element)) {

      var index;

      var children = Sortable.findElements(dropon, {tag: droponOptions.tag, only: droponOptions.only});

      var child = null;

      if(children) {

        var offset = Element.offsetSize(dropon, droponOptions.overlap) * (1.0 - overlap);

        for (index = 0; index < children.length; index += 1) {

          if (offset - Element.offsetSize (children[index], droponOptions.overlap) >= 0) {

            offset -= Element.offsetSize (children[index], droponOptions.overlap);

          } else if (offset - (Element.offsetSize (children[index], droponOptions.overlap) / 2) >= 0) {

            child = index + 1 < children.length ? children[index + 1] : null;

            break;

          } else {

            child = children[index];

            break;

          }

        }

      }

      dropon.insertBefore(element, child);

      Sortable.options(oldParentNode).onChange(element);

      droponOptions.onChange(element);

    }

  },

  unmark: function() {

    if(Sortable._marker) Sortable._marker.hide();

  },

  mark: function(dropon, position) {

    // mark on ghosting only

    var sortable = Sortable.options(dropon.parentNode);

    if(sortable && !sortable.ghosting) return;

    if(!Sortable._marker) {

      Sortable._marker =

        ($('dropmarker') || Element.extend(document.createElement('DIV'))).

          hide().addClassName('dropmarker').setStyle({position:'absolute'});

      document.getElementsByTagName("body").item(0).appendChild(Sortable._marker);

    }

    var offsets = Position.cumulativeOffset(dropon);

    Sortable._marker.setStyle({left: offsets[0]+'px', top: offsets[1] + 'px'});

    if(position=='after')

      if(sortable.overlap == 'horizontal')

        Sortable._marker.setStyle({left: (offsets[0]+dropon.clientWidth) + 'px'});

      else

        Sortable._marker.setStyle({top: (offsets[1]+dropon.clientHeight) + 'px'});

    Sortable._marker.show();

  },

  _tree: function(element, options, parent) {

    var children = Sortable.findElements(element, options) || [];

    for (var i = 0; i < children.length; ++i) {

      var match = children[i].id.match(options.format);

      if (!match) continue;

      var child = {

        id: encodeURIComponent(match ? match[1] : null),

        element: element,

        parent: parent,

        children: [],

        position: parent.children.length,

        container: $(children[i]).down(options.treeTag)

      };

      /* Get the element containing the children and recurse over it */

      if (child.container)

        this._tree(child.container, options, child);

      parent.children.push (child);

    }

    return parent;

  },

  tree: function(element) {

    element = $(element);

    var sortableOptions = this.options(element);

    var options = Object.extend({

      tag: sortableOptions.tag,

      treeTag: sortableOptions.treeTag,

      only: sortableOptions.only,

      name: element.id,

      format: sortableOptions.format

    }, arguments[1] || { });

    var root = {

      id: null,

      parent: null,

      children: [],

      container: element,

      position: 0

    };

    return Sortable._tree(element, options, root);

  },

  /* Construct a [i] index for a particular node */

  _constructIndex: function(node) {

    var index = '';

    do {

      if (node.id) index = '[' + node.position + ']' + index;

    } while ((node = node.parent) != null);

    return index;

  },

  sequence: function(element) {

    element = $(element);

    var options = Object.extend(this.options(element), arguments[1] || { });

    return $(this.findElements(element, options) || []).map( function(item) {

      return item.id.match(options.format) ? item.id.match(options.format)[1] : '';

    });

  },

  setSequence: function(element, new_sequence) {

    element = $(element);

    var options = Object.extend(this.options(element), arguments[2] || { });

    var nodeMap = { };

    this.findElements(element, options).each( function(n) {

        if (n.id.match(options.format))

            nodeMap[n.id.match(options.format)[1]] = [n, n.parentNode];

        n.parentNode.removeChild(n);

    });

    new_sequence.each(function(ident) {

      var n = nodeMap[ident];

      if (n) {

        n[1].appendChild(n[0]);

        delete nodeMap[ident];

      }

    });

  },

  serialize: function(element) {

    element = $(element);

    var options = Object.extend(Sortable.options(element), arguments[1] || { });

    var name = encodeURIComponent(

      (arguments[1] && arguments[1].name) ? arguments[1].name : element.id);

    if (options.tree) {

      return Sortable.tree(element, arguments[1]).children.map( function (item) {

        return [name + Sortable._constructIndex(item) + "[id]=" +

                encodeURIComponent(item.id)].concat(item.children.map(arguments.callee));

      }).flatten().join('&');

    } else {

      return Sortable.sequence(element, arguments[1]).map( function(item) {

        return name + "[]=" + encodeURIComponent(item);

      }).join('&');

    }

  }

};

// Returns true if child is contained within element

Element.isParent = function(child, element) {

  if (!child.parentNode || child == element) return false;

  if (child.parentNode == element) return true;

  return Element.isParent(child.parentNode, element);

};

Element.findChildren = function(element, only, recursive, tagName) {

  if(!element.hasChildNodes()) return null;

  tagName = tagName.toUpperCase();

  if(only) only = [only].flatten();

  var elements = [];

  $A(element.childNodes).each( function(e) {

    if(e.tagName && e.tagName.toUpperCase()==tagName &&

      (!only || (Element.classNames(e).detect(function(v) { return only.include(v) }))))

        elements.push(e);

    if(recursive) {

      var grandchildren = Element.findChildren(e, only, recursive, tagName);

      if(grandchildren) elements.push(grandchildren);

    }

  });

  return (elements.length>0 ? elements.flatten() : []);

};

Element.offsetSize = function (element, type) {

  return element['offset' + ((type=='vertical' || type=='height') ? 'Height' : 'Width')];

};