The Tor Browser: dom/tests/mochitest/ajax/scriptaculous/src/dragdrop.js@a63d609f5ebe (annotated)

dom/tests/mochitest/ajax/scriptaculous/src/dragdrop.js@a63d609f5ebe (annotated)

dom/tests/mochitest/ajax/scriptaculous/src/dragdrop.js

Thu, 15 Jan 2015 15:55:04 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 15 Jan 2015 15:55:04 +0100
branch: TOR_BUG_9701
changeset 9: a63d609f5ebe
permissions: -rw-r--r--

Back out 97036ab72558 which inappropriately compared turds to third parties.

 // script.aculo.us dragdrop.js v1.7.1_beta2, Tue May 15 15:15:45 EDT 2007
 // Copyright (c) 2005-2007 Thomas Fuchs (http://script.aculo.us, http://mir.aculo.us)
 //           (c) 2005-2007 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(typeof Effect == 'undefined')
   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 = $(element);
     var options = Object.extend({
       greedy:     true,
       hoverclass: null,
       tree:       false
     }, arguments[1] || {});
     // cache containers
     if(options.containment) {
       options._containers = [];
       var containment = options.containment;
       if((typeof containment == 'object') &&
         (containment.constructor == Array)) {
         containment.each( function(c) { options._containers.push($(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 affected = [];
     if(this.last_active) this.deactivate(this.last_active);
     this.drops.each( function(drop) {
       if(Droppables.isAffected(point, element, drop))
         affected.push(drop);
     });
     if(affected.length>0) {
       drop = Droppables.findDeepestChild(affected);
       Position.within(drop.element, point[0], point[1]);
       if(drop.onHover)
         drop.onHover(element, drop.element, Position.overlap(drop.overlap, drop.element));
       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();
 Draggable._dragging    = {};
 Draggable.prototype = {
   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 = typeof element._opacity == 'number' ? 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] || typeof arguments[1].endeffect == 'undefined')
       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 && (typeof options.handle == 'string'))
       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.delta    = this.currentDelta();
     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(typeof Draggable._dragging[this.element] != 'undefined' &&
       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.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);
       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) {
       Position.relativize(this.element);
       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 && typeof revert == 'function') 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(typeof this.options.snap == 'function') {
         p = this.options.snap(p[0],p[1],this);
       } else {
       if(this.options.snap instanceof Array) {
         p = p.map( function(v, i) {
           return Math.round(v/this.options.snap[i])*this.options.snap[i] }.bind(this))
       } else {
         p = p.map( function(v) {
           return Math.round(v/this.options.snap)*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 };
   }
 }
 /*--------------------------------------------------------------------------*/
 var SortableObserver = Class.create();
 SortableObserver.prototype = {
   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){
     var s = Sortable.options(element);
     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).getElementsByClassName(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')];
 }