Experiments/Generator/Generators/Project/Templates/public/content/javascripts/dragdrop.js

   1 // Copyright (c) 2005 Thomas Fuchs (http://script.aculo.us, http://mir.aculo.us)
   2 //           (c) 2005 Sammi Williams (http://www.oriontransfer.co.nz, sammi@oriontransfer.co.nz)
   3 //
   4 // See scriptaculous.js for full license.
   5
   6 /*--------------------------------------------------------------------------*/
   7
   8 var Droppables = {
   9   drops: [],
  10
  11   remove: function(element) {
  12     this.drops = this.drops.reject(function(d) { return d.element==$(element) });
  13   },
  14
  15   add: function(element) {
  16     element = $(element);
  17     var options = Object.extend({
  18       greedy:     true,
  19       hoverclass: null,
  20       tree:       false
  21     }, arguments[1] || {});
  22
  23     // cache containers
  24     if(options.containment) {
  25       options._containers = [];
  26       var containment = options.containment;
  27       if((typeof containment == 'object') &&
  28         (containment.constructor == Array)) {
  29         containment.each( function(c) { options._containers.push($(c)) });
  30       } else {
  31         options._containers.push($(containment));
  32       }
  33     }
  34
  35     if(options.accept) options.accept = [options.accept].flatten();
  36
  37     Element.makePositioned(element); // fix IE
  38     options.element = element;
  39
  40     this.drops.push(options);
  41   },
  42
  43   findDeepestChild: function(drops) {
  44     deepest = drops[0];
  45
  46     for (i = 1; i < drops.length; ++i)
  47       if (Element.isParent(drops[i].element, deepest.element))
  48         deepest = drops[i];
  49
  50     return deepest;
  51   },
  52
  53   isContained: function(element, drop) {
  54     var containmentNode;
  55     if(drop.tree) {
  56       containmentNode = element.treeNode;
  57     } else {
  58       containmentNode = element.parentNode;
  59     }
  60     return drop._containers.detect(function(c) { return containmentNode == c });
  61   },
  62
  63   isAffected: function(point, element, drop) {
  64     return (
  65       (drop.element!=element) &&
  66       ((!drop._containers) ||
  67         this.isContained(element, drop)) &&
  68       ((!drop.accept) ||
  69         (Element.classNames(element).detect(
  70           function(v) { return drop.accept.include(v) } ) )) &&
  71       Position.within(drop.element, point[0], point[1]) );
  72   },
  73
  74   deactivate: function(drop) {
  75     if(drop.hoverclass)
  76       Element.removeClassName(drop.element, drop.hoverclass);
  77     this.last_active = null;
  78   },
  79
  80   activate: function(drop) {
  81     if(drop.hoverclass)
  82       Element.addClassName(drop.element, drop.hoverclass);
  83     this.last_active = drop;
  84   },
  85
  86   show: function(point, element) {
  87     if(!this.drops.length) return;
  88     var affected = [];
  89
  90     if(this.last_active) this.deactivate(this.last_active);
  91     this.drops.each( function(drop) {
  92       if(Droppables.isAffected(point, element, drop))
  93         affected.push(drop);
  94     });
  95
  96     if(affected.length>0) {
  97       drop = Droppables.findDeepestChild(affected);
  98       Position.within(drop.element, point[0], point[1]);
  99       if(drop.onHover)
 100         drop.onHover(element, drop.element, Position.overlap(drop.overlap, drop.element));
 101
 102       Droppables.activate(drop);
 103     }
 104   },
 105
 106   fire: function(event, element) {
 107     if(!this.last_active) return;
 108     Position.prepare();
 109
 110     if (this.isAffected([Event.pointerX(event), Event.pointerY(event)], element, this.last_active))
 111       if (this.last_active.onDrop)
 112         this.last_active.onDrop(element, this.last_active.element, event);
 113   },
 114
 115   reset: function() {
 116     if(this.last_active)
 117       this.deactivate(this.last_active);
 118   }
 119 }
 120
 121 var Draggables = {
 122   drags: [],
 123   observers: [],
 124
 125   register: function(draggable) {
 126     if(this.drags.length == 0) {
 127       this.eventMouseUp   = this.endDrag.bindAsEventListener(this);
 128       this.eventMouseMove = this.updateDrag.bindAsEventListener(this);
 129       this.eventKeypress  = this.keyPress.bindAsEventListener(this);
 130
 131       Event.observe(document, "mouseup", this.eventMouseUp);
 132       Event.observe(document, "mousemove", this.eventMouseMove);
 133       Event.observe(document, "keypress", this.eventKeypress);
 134     }
 135     this.drags.push(draggable);
 136   },
 137
 138   unregister: function(draggable) {
 139     this.drags = this.drags.reject(function(d) { return d==draggable });
 140     if(this.drags.length == 0) {
 141       Event.stopObserving(document, "mouseup", this.eventMouseUp);
 142       Event.stopObserving(document, "mousemove", this.eventMouseMove);
 143       Event.stopObserving(document, "keypress", this.eventKeypress);
 144     }
 145   },
 146
 147   activate: function(draggable) {
 148     window.focus(); // allows keypress events if window isn't currently focused, fails for Safari
 149     this.activeDraggable = draggable;
 150   },
 151
 152   deactivate: function() {
 153     this.activeDraggable = null;
 154   },
 155
 156   updateDrag: function(event) {
 157     if(!this.activeDraggable) return;
 158     var pointer = [Event.pointerX(event), Event.pointerY(event)];
 159     // Mozilla-based browsers fire successive mousemove events with
 160     // the same coordinates, prevent needless redrawing (moz bug?)
 161     if(this._lastPointer && (this._lastPointer.inspect() == pointer.inspect())) return;
 162     this._lastPointer = pointer;
 163     this.activeDraggable.updateDrag(event, pointer);
 164   },
 165
 166   endDrag: function(event) {
 167     if(!this.activeDraggable) return;
 168     this._lastPointer = null;
 169     this.activeDraggable.endDrag(event);
 170     this.activeDraggable = null;
 171   },
 172
 173   keyPress: function(event) {
 174     if(this.activeDraggable)
 175       this.activeDraggable.keyPress(event);
 176   },
 177
 178   addObserver: function(observer) {
 179     this.observers.push(observer);
 180     this._cacheObserverCallbacks();
 181   },
 182
 183   removeObserver: function(element) {  // element instead of observer fixes mem leaks
 184     this.observers = this.observers.reject( function(o) { return o.element==element });
 185     this._cacheObserverCallbacks();
 186   },
 187
 188   notify: function(eventName, draggable, event) {  // 'onStart', 'onEnd', 'onDrag'
 189     if(this[eventName+'Count'] > 0)
 190       this.observers.each( function(o) {
 191         if(o[eventName]) o[eventName](eventName, draggable, event);
 192       });
 193   },
 194
 195   _cacheObserverCallbacks: function() {
 196     ['onStart','onEnd','onDrag'].each( function(eventName) {
 197       Draggables[eventName+'Count'] = Draggables.observers.select(
 198         function(o) { return o[eventName]; }
 199       ).length;
 200     });
 201   }
 202 }
 203
 204 /*--------------------------------------------------------------------------*/
 205
 206 var Draggable = Class.create();
 207 Draggable.prototype = {
 208   initialize: function(element) {
 209     var options = Object.extend({
 210       handle: false,
 211       starteffect: function(element) {
 212         new Effect.Opacity(element, {duration:0.2, from:1.0, to:0.7});
 213       },
 214       reverteffect: function(element, top_offset, left_offset) {
 215         var dur = Math.sqrt(Math.abs(top_offset^2)+Math.abs(left_offset^2))*0.02;
 216         element._revert = new Effect.Move(element, { x: -left_offset, y: -top_offset, duration: dur});
 217       },
 218       endeffect: function(element) {
 219         new Effect.Opacity(element, {duration:0.2, from:0.7, to:1.0});
 220       },
 221       zindex: 1000,
 222       revert: false,
 223       scroll: false,
 224       scrollSensitivity: 20,
 225       scrollSpeed: 15,
 226       snap: false   // false, or xy or [x,y] or function(x,y){ return [x,y] }
 227     }, arguments[1] || {});
 228
 229     this.element = $(element);
 230
 231     if(options.handle && (typeof options.handle == 'string')) {
 232       var h = Element.childrenWithClassName(this.element, options.handle, true);
 233       if(h.length>0) this.handle = h[0];
 234     }
 235     if(!this.handle) this.handle = $(options.handle);
 236     if(!this.handle) this.handle = this.element;
 237
 238     if(options.scroll && !options.scroll.scrollTo && !options.scroll.outerHTML)
 239       options.scroll = $(options.scroll);
 240
 241     Element.makePositioned(this.element); // fix IE
 242
 243     this.delta    = this.currentDelta();
 244     this.options  = options;
 245     this.dragging = false;
 246
 247     this.eventMouseDown = this.initDrag.bindAsEventListener(this);
 248     Event.observe(this.handle, "mousedown", this.eventMouseDown);
 249
 250     Draggables.register(this);
 251   },
 252
 253   destroy: function() {
 254     Event.stopObserving(this.handle, "mousedown", this.eventMouseDown);
 255     Draggables.unregister(this);
 256   },
 257
 258   currentDelta: function() {
 259     return([
 260       parseInt(Element.getStyle(this.element,'left') || '0'),
 261       parseInt(Element.getStyle(this.element,'top') || '0')]);
 262   },
 263
 264   initDrag: function(event) {
 265     if(Event.isLeftClick(event)) {
 266       // abort on form elements, fixes a Firefox issue
 267       var src = Event.element(event);
 268       if(src.tagName && (
 269         src.tagName=='INPUT' ||
 270         src.tagName=='SELECT' ||
 271         src.tagName=='OPTION' ||
 272         src.tagName=='BUTTON' ||
 273         src.tagName=='TEXTAREA')) return;
 274
 275       if(this.element._revert) {
 276         this.element._revert.cancel();
 277         this.element._revert = null;
 278       }
 279
 280       var pointer = [Event.pointerX(event), Event.pointerY(event)];
 281       var pos     = Position.cumulativeOffset(this.element);
 282       this.offset = [0,1].map( function(i) { return (pointer[i] - pos[i]) });
 283
 284       Draggables.activate(this);
 285       Event.stop(event);
 286     }
 287   },
 288
 289   startDrag: function(event) {
 290     this.dragging = true;
 291
 292     if(this.options.zindex) {
 293       this.originalZ = parseInt(Element.getStyle(this.element,'z-index') || 0);
 294       this.element.style.zIndex = this.options.zindex;
 295     }
 296
 297     if(this.options.ghosting) {
 298       this._clone = this.element.cloneNode(true);
 299       Position.absolutize(this.element);
 300       this.element.parentNode.insertBefore(this._clone, this.element);
 301     }
 302
 303     if(this.options.scroll) {
 304       if (this.options.scroll == window) {
 305         var where = this._getWindowScroll(this.options.scroll);
 306         this.originalScrollLeft = where.left;
 307         this.originalScrollTop = where.top;
 308       } else {
 309         this.originalScrollLeft = this.options.scroll.scrollLeft;
 310         this.originalScrollTop = this.options.scroll.scrollTop;
 311       }
 312     }
 313
 314     Draggables.notify('onStart', this, event);
 315     if(this.options.starteffect) this.options.starteffect(this.element);
 316   },
 317
 318   updateDrag: function(event, pointer) {
 319     if(!this.dragging) this.startDrag(event);
 320     Position.prepare();
 321     Droppables.show(pointer, this.element);
 322     Draggables.notify('onDrag', this, event);
 323     this.draw(pointer);
 324     if(this.options.change) this.options.change(this);
 325
 326     if(this.options.scroll) {
 327       this.stopScrolling();
 328
 329       var p;
 330       if (this.options.scroll == window) {
 331         with(this._getWindowScroll(this.options.scroll)) { p = [ left, top, left+width, top+height ]; }
 332       } else {
 333         p = Position.page(this.options.scroll);
 334         p[0] += this.options.scroll.scrollLeft;
 335         p[1] += this.options.scroll.scrollTop;
 336         p.push(p[0]+this.options.scroll.offsetWidth);
 337         p.push(p[1]+this.options.scroll.offsetHeight);
 338       }
 339       var speed = [0,0];
 340       if(pointer[0] < (p[0]+this.options.scrollSensitivity)) speed[0] = pointer[0]-(p[0]+this.options.scrollSensitivity);
 341       if(pointer[1] < (p[1]+this.options.scrollSensitivity)) speed[1] = pointer[1]-(p[1]+this.options.scrollSensitivity);
 342       if(pointer[0] > (p[2]-this.options.scrollSensitivity)) speed[0] = pointer[0]-(p[2]-this.options.scrollSensitivity);
 343       if(pointer[1] > (p[3]-this.options.scrollSensitivity)) speed[1] = pointer[1]-(p[3]-this.options.scrollSensitivity);
 344       this.startScrolling(speed);
 345     }
 346
 347     // fix AppleWebKit rendering
 348     if(navigator.appVersion.indexOf('AppleWebKit')>0) window.scrollBy(0,0);
 349
 350     Event.stop(event);
 351   },
 352
 353   finishDrag: function(event, success) {
 354     this.dragging = false;
 355
 356     if(this.options.ghosting) {
 357       Position.relativize(this.element);
 358       Element.remove(this._clone);
 359       this._clone = null;
 360     }
 361
 362     if(success) Droppables.fire(event, this.element);
 363     Draggables.notify('onEnd', this, event);
 364
 365     var revert = this.options.revert;
 366     if(revert && typeof revert == 'function') revert = revert(this.element);
 367
 368     var d = this.currentDelta();
 369     if(revert && this.options.reverteffect) {
 370       this.options.reverteffect(this.element,
 371         d[1]-this.delta[1], d[0]-this.delta[0]);
 372     } else {
 373       this.delta = d;
 374     }
 375
 376     if(this.options.zindex)
 377       this.element.style.zIndex = this.originalZ;
 378
 379     if(this.options.endeffect)
 380       this.options.endeffect(this.element);
 381
 382     Draggables.deactivate(this);
 383     Droppables.reset();
 384   },
 385
 386   keyPress: function(event) {
 387     if(event.keyCode!=Event.KEY_ESC) return;
 388     this.finishDrag(event, false);
 389     Event.stop(event);
 390   },
 391
 392   endDrag: function(event) {
 393     if(!this.dragging) return;
 394     this.stopScrolling();
 395     this.finishDrag(event, true);
 396     Event.stop(event);
 397   },
 398
 399   draw: function(point) {
 400     var pos = Position.cumulativeOffset(this.element);
 401     var d = this.currentDelta();
 402     pos[0] -= d[0]; pos[1] -= d[1];
 403
 404     if(this.options.scroll && (this.options.scroll != window)) {
 405       pos[0] -= this.options.scroll.scrollLeft-this.originalScrollLeft;
 406       pos[1] -= this.options.scroll.scrollTop-this.originalScrollTop;
 407     }
 408
 409     var p = [0,1].map(function(i){
 410       return (point[i]-pos[i]-this.offset[i])
 411     }.bind(this));
 412
 413     if(this.options.snap) {
 414       if(typeof this.options.snap == 'function') {
 415         p = this.options.snap(p[0],p[1]);
 416       } else {
 417       if(this.options.snap instanceof Array) {
 418         p = p.map( function(v, i) {
 419           return Math.round(v/this.options.snap[i])*this.options.snap[i] }.bind(this))
 420       } else {
 421         p = p.map( function(v) {
 422           return Math.round(v/this.options.snap)*this.options.snap }.bind(this))
 423       }
 424     }}
 425
 426     var style = this.element.style;
 427     if((!this.options.constraint) || (this.options.constraint=='horizontal'))
 428       style.left = p[0] + "px";
 429     if((!this.options.constraint) || (this.options.constraint=='vertical'))
 430       style.top  = p[1] + "px";
 431     if(style.visibility=="hidden") style.visibility = ""; // fix gecko rendering
 432   },
 433
 434   stopScrolling: function() {
 435     if(this.scrollInterval) {
 436       clearInterval(this.scrollInterval);
 437       this.scrollInterval = null;
 438       Draggables._lastScrollPointer = null;
 439     }
 440   },
 441
 442   startScrolling: function(speed) {
 443     this.scrollSpeed = [speed[0]*this.options.scrollSpeed,speed[1]*this.options.scrollSpeed];
 444     this.lastScrolled = new Date();
 445     this.scrollInterval = setInterval(this.scroll.bind(this), 10);
 446   },
 447
 448   scroll: function() {
 449     var current = new Date();
 450     var delta = current - this.lastScrolled;
 451     this.lastScrolled = current;
 452     if(this.options.scroll == window) {
 453       with (this._getWindowScroll(this.options.scroll)) {
 454         if (this.scrollSpeed[0] || this.scrollSpeed[1]) {
 455           var d = delta / 1000;
 456           this.options.scroll.scrollTo( left + d*this.scrollSpeed[0], top + d*this.scrollSpeed[1] );
 457         }
 458       }
 459     } else {
 460       this.options.scroll.scrollLeft += this.scrollSpeed[0] * delta / 1000;
 461       this.options.scroll.scrollTop  += this.scrollSpeed[1] * delta / 1000;
 462     }
 463
 464     Position.prepare();
 465     Droppables.show(Draggables._lastPointer, this.element);
 466     Draggables.notify('onDrag', this);
 467     Draggables._lastScrollPointer = Draggables._lastScrollPointer || $A(Draggables._lastPointer);
 468     Draggables._lastScrollPointer[0] += this.scrollSpeed[0] * delta / 1000;
 469     Draggables._lastScrollPointer[1] += this.scrollSpeed[1] * delta / 1000;
 470     if (Draggables._lastScrollPointer[0] < 0)
 471       Draggables._lastScrollPointer[0] = 0;
 472     if (Draggables._lastScrollPointer[1] < 0)
 473       Draggables._lastScrollPointer[1] = 0;
 474     this.draw(Draggables._lastScrollPointer);
 475
 476     if(this.options.change) this.options.change(this);
 477   },
 478
 479   _getWindowScroll: function(w) {
 480     var T, L, W, H;
 481     with (w.document) {
 482       if (w.document.documentElement && documentElement.scrollTop) {
 483         T = documentElement.scrollTop;
 484         L = documentElement.scrollLeft;
 485       } else if (w.document.body) {
 486         T = body.scrollTop;
 487         L = body.scrollLeft;
 488       }
 489       if (w.innerWidth) {
 490         W = w.innerWidth;
 491         H = w.innerHeight;
 492       } else if (w.document.documentElement && documentElement.clientWidth) {
 493         W = documentElement.clientWidth;
 494         H = documentElement.clientHeight;
 495       } else {
 496         W = body.offsetWidth;
 497         H = body.offsetHeight
 498       }
 499     }
 500     return { top: T, left: L, width: W, height: H };
 501   }
 502 }
 503
 504 /*--------------------------------------------------------------------------*/
 505
 506 var SortableObserver = Class.create();
 507 SortableObserver.prototype = {
 508   initialize: function(element, observer) {
 509     this.element   = $(element);
 510     this.observer  = observer;
 511     this.lastValue = Sortable.serialize(this.element);
 512   },
 513
 514   onStart: function() {
 515     this.lastValue = Sortable.serialize(this.element);
 516   },
 517
 518   onEnd: function() {
 519     Sortable.unmark();
 520     if(this.lastValue != Sortable.serialize(this.element))
 521       this.observer(this.element)
 522   }
 523 }
 524
 525 var Sortable = {
 526   sortables: {},
 527
 528   _findRootElement: function(element) {
 529     while (element.tagName != "BODY") {
 530       if(element.id && Sortable.sortables[element.id]) return element;
 531       element = element.parentNode;
 532     }
 533   },
 534
 535   options: function(element) {
 536     element = Sortable._findRootElement($(element));
 537     if(!element) return;
 538     return Sortable.sortables[element.id];
 539   },
 540
 541   destroy: function(element){
 542     var s = Sortable.options(element);
 543
 544     if(s) {
 545       Draggables.removeObserver(s.element);
 546       s.droppables.each(function(d){ Droppables.remove(d) });
 547       s.draggables.invoke('destroy');
 548
 549       delete Sortable.sortables[s.element.id];
 550     }
 551   },
 552
 553   create: function(element) {
 554     element = $(element);
 555     var options = Object.extend({
 556       element:     element,
 557       tag:         'li',       // assumes li children, override with tag: 'tagname'
 558       dropOnEmpty: false,
 559       tree:        false,
 560       treeTag:     'ul',
 561       overlap:     'vertical', // one of 'vertical', 'horizontal'
 562       constraint:  'vertical', // one of 'vertical', 'horizontal', false
 563       containment: element,    // also takes array of elements (or id's); or false
 564       handle:      false,      // or a CSS class
 565       only:        false,
 566       hoverclass:  null,
 567       ghosting:    false,
 568       scroll:      false,
 569       scrollSensitivity: 20,
 570       scrollSpeed: 15,
 571       format:      /^[^_]*_(.*)$/,
 572       onChange:    Prototype.emptyFunction,
 573       onUpdate:    Prototype.emptyFunction
 574     }, arguments[1] || {});
 575
 576     // clear any old sortable with same element
 577     this.destroy(element);
 578
 579     // build options for the draggables
 580     var options_for_draggable = {
 581       revert:      true,
 582       scroll:      options.scroll,
 583       scrollSpeed: options.scrollSpeed,
 584       scrollSensitivity: options.scrollSensitivity,
 585       ghosting:    options.ghosting,
 586       constraint:  options.constraint,
 587       handle:      options.handle };
 588
 589     if(options.starteffect)
 590       options_for_draggable.starteffect = options.starteffect;
 591
 592     if(options.reverteffect)
 593       options_for_draggable.reverteffect = options.reverteffect;
 594     else
 595       if(options.ghosting) options_for_draggable.reverteffect = function(element) {
 596         element.style.top  = 0;
 597         element.style.left = 0;
 598       };
 599
 600     if(options.endeffect)
 601       options_for_draggable.endeffect = options.endeffect;
 602
 603     if(options.zindex)
 604       options_for_draggable.zindex = options.zindex;
 605
 606     // build options for the droppables
 607     var options_for_droppable = {
 608       overlap:     options.overlap,
 609       containment: options.containment,
 610       tree:        options.tree,
 611       hoverclass:  options.hoverclass,
 612       onHover:     Sortable.onHover
 613       //greedy:      !options.dropOnEmpty
 614     }
 615
 616     var options_for_tree = {
 617       onHover:      Sortable.onEmptyHover,
 618       overlap:      options.overlap,
 619       containment:  options.containment,
 620       hoverclass:   options.hoverclass
 621     }
 622
 623     // fix for gecko engine
 624     Element.cleanWhitespace(element);
 625
 626     options.draggables = [];
 627     options.droppables = [];
 628
 629     // drop on empty handling
 630     if(options.dropOnEmpty || options.tree) {
 631       Droppables.add(element, options_for_tree);
 632       options.droppables.push(element);
 633     }
 634
 635     (this.findElements(element, options) || []).each( function(e) {
 636       // handles are per-draggable
 637       var handle = options.handle ?
 638         Element.childrenWithClassName(e, options.handle)[0] : e;
 639       options.draggables.push(
 640         new Draggable(e, Object.extend(options_for_draggable, { handle: handle })));
 641       Droppables.add(e, options_for_droppable);
 642       if(options.tree) e.treeNode = element;
 643       options.droppables.push(e);
 644     });
 645
 646     if(options.tree) {
 647       (Sortable.findTreeElements(element, options) || []).each( function(e) {
 648         Droppables.add(e, options_for_tree);
 649         e.treeNode = element;
 650         options.droppables.push(e);
 651       });
 652     }
 653
 654     // keep reference
 655     this.sortables[element.id] = options;
 656
 657     // for onupdate
 658     Draggables.addObserver(new SortableObserver(element, options.onUpdate));
 659
 660   },
 661
 662   // return all suitable-for-sortable elements in a guaranteed order
 663   findElements: function(element, options) {
 664     return Element.findChildren(
 665       element, options.only, options.tree ? true : false, options.tag);
 666   },
 667
 668   findTreeElements: function(element, options) {
 669     return Element.findChildren(
 670       element, options.only, options.tree ? true : false, options.treeTag);
 671   },
 672
 673   onHover: function(element, dropon, overlap) {
 674     if(Element.isParent(dropon, element)) return;
 675
 676     if(overlap > .33 && overlap < .66 && Sortable.options(dropon).tree) {
 677       return;
 678     } else if(overlap>0.5) {
 679       Sortable.mark(dropon, 'before');
 680       if(dropon.previousSibling != element) {
 681         var oldParentNode = element.parentNode;
 682         element.style.visibility = "hidden"; // fix gecko rendering
 683         dropon.parentNode.insertBefore(element, dropon);
 684         if(dropon.parentNode!=oldParentNode)
 685           Sortable.options(oldParentNode).onChange(element);
 686         Sortable.options(dropon.parentNode).onChange(element);
 687       }
 688     } else {
 689       Sortable.mark(dropon, 'after');
 690       var nextElement = dropon.nextSibling || null;
 691       if(nextElement != element) {
 692         var oldParentNode = element.parentNode;
 693         element.style.visibility = "hidden"; // fix gecko rendering
 694         dropon.parentNode.insertBefore(element, nextElement);
 695         if(dropon.parentNode!=oldParentNode)
 696           Sortable.options(oldParentNode).onChange(element);
 697         Sortable.options(dropon.parentNode).onChange(element);
 698       }
 699     }
 700   },
 701
 702   onEmptyHover: function(element, dropon, overlap) {
 703     var oldParentNode = element.parentNode;
 704     var droponOptions = Sortable.options(dropon);
 705
 706     if(!Element.isParent(dropon, element)) {
 707       var index;
 708
 709       var children = Sortable.findElements(dropon, {tag: droponOptions.tag});
 710       var child = null;
 711
 712       if(children) {
 713         var offset = Element.offsetSize(dropon, droponOptions.overlap) * (1.0 - overlap);
 714
 715         for (index = 0; index < children.length; index += 1) {
 716           if (offset - Element.offsetSize (children[index], droponOptions.overlap) >= 0) {
 717             offset -= Element.offsetSize (children[index], droponOptions.overlap);
 718           } else if (offset - (Element.offsetSize (children[index], droponOptions.overlap) / 2) >= 0) {
 719             child = index + 1 < children.length ? children[index + 1] : null;
 720             break;
 721           } else {
 722             child = children[index];
 723             break;
 724           }
 725         }
 726       }
 727
 728       dropon.insertBefore(element, child);
 729
 730       Sortable.options(oldParentNode).onChange(element);
 731       droponOptions.onChange(element);
 732     }
 733   },
 734
 735   unmark: function() {
 736     if(Sortable._marker) Element.hide(Sortable._marker);
 737   },
 738
 739   mark: function(dropon, position) {
 740     // mark on ghosting only
 741     var sortable = Sortable.options(dropon.parentNode);
 742     if(sortable && !sortable.ghosting) return;
 743
 744     if(!Sortable._marker) {
 745       Sortable._marker = $('dropmarker') || document.createElement('DIV');
 746       Element.hide(Sortable._marker);
 747       Element.addClassName(Sortable._marker, 'dropmarker');
 748       Sortable._marker.style.position = 'absolute';
 749       document.getElementsByTagName("body").item(0).appendChild(Sortable._marker);
 750     }
 751     var offsets = Position.cumulativeOffset(dropon);
 752     Sortable._marker.style.left = offsets[0] + 'px';
 753     Sortable._marker.style.top = offsets[1] + 'px';
 754
 755     if(position=='after')
 756       if(sortable.overlap == 'horizontal')
 757         Sortable._marker.style.left = (offsets[0]+dropon.clientWidth) + 'px';
 758       else
 759         Sortable._marker.style.top = (offsets[1]+dropon.clientHeight) + 'px';
 760
 761     Element.show(Sortable._marker);
 762   },
 763
 764   _tree: function(element, options, parent) {
 765     var children = Sortable.findElements(element, options) || [];
 766
 767     for (var i = 0; i < children.length; ++i) {
 768       var match = children[i].id.match(options.format);
 769
 770       if (!match) continue;
 771
 772       var child = {
 773         id: encodeURIComponent(match ? match[1] : null),
 774         element: element,
 775         parent: parent,
 776         children: new Array,
 777         position: parent.children.length,
 778         container: Sortable._findChildrenElement(children[i], options.treeTag.toUpperCase())
 779       }
 780
 781       /* Get the element containing the children and recurse over it */
 782       if (child.container)
 783         this._tree(child.container, options, child)
 784
 785       parent.children.push (child);
 786     }
 787
 788     return parent;
 789   },
 790
 791   /* Finds the first element of the given tag type within a parent element.
 792     Used for finding the first LI[ST] within a L[IST]I[TEM].*/
 793   _findChildrenElement: function (element, containerTag) {
 794     if (element && element.hasChildNodes)
 795       for (var i = 0; i < element.childNodes.length; ++i)
 796         if (element.childNodes[i].tagName == containerTag)
 797           return element.childNodes[i];
 798
 799     return null;
 800   },
 801
 802   tree: function(element) {
 803     element = $(element);
 804     var sortableOptions = this.options(element);
 805     var options = Object.extend({
 806       tag: sortableOptions.tag,
 807       treeTag: sortableOptions.treeTag,
 808       only: sortableOptions.only,
 809       name: element.id,
 810       format: sortableOptions.format
 811     }, arguments[1] || {});
 812
 813     var root = {
 814       id: null,
 815       parent: null,
 816       children: new Array,
 817       container: element,
 818       position: 0
 819     }
 820
 821     return Sortable._tree (element, options, root);
 822   },
 823
 824   /* Construct a [i] index for a particular node */
 825   _constructIndex: function(node) {
 826     var index = '';
 827     do {
 828       if (node.id) index = '[' + node.position + ']' + index;
 829     } while ((node = node.parent) != null);
 830     return index;
 831   },
 832
 833   sequence: function(element) {
 834     element = $(element);
 835     var options = Object.extend(this.options(element), arguments[1] || {});
 836
 837     return $(this.findElements(element, options) || []).map( function(item) {
 838       return item.id.match(options.format) ? item.id.match(options.format)[1] : '';
 839     });
 840   },
 841
 842   setSequence: function(element, new_sequence) {
 843     element = $(element);
 844     var options = Object.extend(this.options(element), arguments[2] || {});
 845
 846     var nodeMap = {};
 847     this.findElements(element, options).each( function(n) {
 848         if (n.id.match(options.format))
 849             nodeMap[n.id.match(options.format)[1]] = [n, n.parentNode];
 850         n.parentNode.removeChild(n);
 851     });
 852
 853     new_sequence.each(function(ident) {
 854       var n = nodeMap[ident];
 855       if (n) {
 856         n[1].appendChild(n[0]);
 857         delete nodeMap[ident];
 858       }
 859     });
 860   },
 861
 862   serialize: function(element) {
 863     element = $(element);
 864     var options = Object.extend(Sortable.options(element), arguments[1] || {});
 865     var name = encodeURIComponent(
 866       (arguments[1] && arguments[1].name) ? arguments[1].name : element.id);
 867
 868     if (options.tree) {
 869       return Sortable.tree(element, arguments[1]).children.map( function (item) {
 870         return [name + Sortable._constructIndex(item) + "=" +
 871                 encodeURIComponent(item.id)].concat(item.children.map(arguments.callee));
 872       }).flatten().join('&');
 873     } else {
 874       return Sortable.sequence(element, arguments[1]).map( function(item) {
 875         return name + "[]=" + encodeURIComponent(item);
 876       }).join('&');
 877     }
 878   }
 879 }
 880
 881 /* Returns true if child is contained within element */
 882 Element.isParent = function(child, element) {
 883   if (!child.parentNode || child == element) return false;
 884
 885   if (child.parentNode == element) return true;
 886
 887   return Element.isParent(child.parentNode, element);
 888 }
 889
 890 Element.findChildren = function(element, only, recursive, tagName) {
 891   if(!element.hasChildNodes()) return null;
 892   tagName = tagName.toUpperCase();
 893   if(only) only = [only].flatten();
 894   var elements = [];
 895   $A(element.childNodes).each( function(e) {
 896     if(e.tagName && e.tagName.toUpperCase()==tagName &&
 897       (!only || (Element.classNames(e).detect(function(v) { return only.include(v) }))))
 898         elements.push(e);
 899     if(recursive) {
 900       var grandchildren = Element.findChildren(e, only, recursive, tagName);
 901       if(grandchildren) elements.push(grandchildren);
 902     }
 903   });
 904
 905   return (elements.length>0 ? elements.flatten() : []);
 906 }
 907
 908 Element.offsetSize = function (element, type) {
 909   if (type == 'vertical' || type == 'height')
 910     return element.offsetHeight;
 911   else
 912     return element.offsetWidth;
 913 }