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   1  // script.aculo.us dragdrop.js v1.7.1_beta3, Fri May 25 17:19:41 +0200 2007
   2  
   3  // Copyright (c) 2005-2007 Thomas Fuchs (http://script.aculo.us, http://mir.aculo.us)
   4  //           (c) 2005-2007 Sammi Williams (http://www.oriontransfer.co.nz, sammi@oriontransfer.co.nz)
   5  // 
   6  // script.aculo.us is freely distributable under the terms of an MIT-style license.
   7  // For details, see the script.aculo.us web site: http://script.aculo.us/
   8  
   9  if(typeof Effect == 'undefined')
  10    throw("dragdrop.js requires including script.aculo.us' effects.js library");
  11  
  12  var Droppables = {
  13    drops: [],
  14  
  15    remove: function(element) {
  16      this.drops = this.drops.reject(function(d) { return d.element==$(element) });
  17    },
  18  
  19    add: function(element) {
  20      element = $(element);
  21      var options = Object.extend({
  22        greedy:     true,
  23        hoverclass: null,
  24        tree:       false
  25      }, arguments[1] || {});
  26  
  27      // cache containers
  28      if(options.containment) {
  29        options._containers = [];
  30        var containment = options.containment;
  31        if((typeof containment == 'object') && 
  32          (containment.constructor == Array)) {
  33          containment.each( function(c) { options._containers.push($(c)) });
  34        } else {
  35          options._containers.push($(containment));
  36        }
  37      }
  38      
  39      if(options.accept) options.accept = [options.accept].flatten();
  40  
  41      Element.makePositioned(element); // fix IE
  42      options.element = element;
  43  
  44      this.drops.push(options);
  45    },
  46    
  47    findDeepestChild: function(drops) {
  48      deepest = drops[0];
  49        
  50      for (i = 1; i < drops.length; ++i)
  51        if (Element.isParent(drops[i].element, deepest.element))
  52          deepest = drops[i];
  53      
  54      return deepest;
  55    },
  56  
  57    isContained: function(element, drop) {
  58      var containmentNode;
  59      if(drop.tree) {
  60        containmentNode = element.treeNode; 
  61      } else {
  62        containmentNode = element.parentNode;
  63      }
  64      return drop._containers.detect(function(c) { return containmentNode == c });
  65    },
  66    
  67    isAffected: function(point, element, drop) {
  68      return (
  69        (drop.element!=element) &&
  70        ((!drop._containers) ||
  71          this.isContained(element, drop)) &&
  72        ((!drop.accept) ||
  73          (Element.classNames(element).detect( 
  74            function(v) { return drop.accept.include(v) } ) )) &&
  75        Position.within(drop.element, point[0], point[1]) );
  76    },
  77  
  78    deactivate: function(drop) {
  79      if(drop.hoverclass)
  80        Element.removeClassName(drop.element, drop.hoverclass);
  81      this.last_active = null;
  82    },
  83  
  84    activate: function(drop) {
  85      if(drop.hoverclass)
  86        Element.addClassName(drop.element, drop.hoverclass);
  87      this.last_active = drop;
  88    },
  89  
  90    show: function(point, element) {
  91      if(!this.drops.length) return;
  92      var affected = [];
  93      
  94      if(this.last_active) this.deactivate(this.last_active);
  95      this.drops.each( function(drop) {
  96        if(Droppables.isAffected(point, element, drop))
  97          affected.push(drop);
  98      });
  99          
 100      if(affected.length>0) {
 101        drop = Droppables.findDeepestChild(affected);
 102        Position.within(drop.element, point[0], point[1]);
 103        if(drop.onHover)
 104          drop.onHover(element, drop.element, Position.overlap(drop.overlap, drop.element));
 105        
 106        Droppables.activate(drop);
 107      }
 108    },
 109  
 110    fire: function(event, element) {
 111      if(!this.last_active) return;
 112      Position.prepare();
 113  
 114      if (this.isAffected([Event.pointerX(event), Event.pointerY(event)], element, this.last_active))
 115        if (this.last_active.onDrop) {
 116          this.last_active.onDrop(element, this.last_active.element, event); 
 117          return true; 
 118        }
 119    },
 120  
 121    reset: function() {
 122      if(this.last_active)
 123        this.deactivate(this.last_active);
 124    }
 125  }
 126  
 127  var Draggables = {
 128    drags: [],
 129    observers: [],
 130    
 131    register: function(draggable) {
 132      if(this.drags.length == 0) {
 133        this.eventMouseUp   = this.endDrag.bindAsEventListener(this);
 134        this.eventMouseMove = this.updateDrag.bindAsEventListener(this);
 135        this.eventKeypress  = this.keyPress.bindAsEventListener(this);
 136        
 137        Event.observe(document, "mouseup", this.eventMouseUp);
 138        Event.observe(document, "mousemove", this.eventMouseMove);
 139        Event.observe(document, "keypress", this.eventKeypress);
 140      }
 141      this.drags.push(draggable);
 142    },
 143    
 144    unregister: function(draggable) {
 145      this.drags = this.drags.reject(function(d) { return d==draggable });
 146      if(this.drags.length == 0) {
 147        Event.stopObserving(document, "mouseup", this.eventMouseUp);
 148        Event.stopObserving(document, "mousemove", this.eventMouseMove);
 149        Event.stopObserving(document, "keypress", this.eventKeypress);
 150      }
 151    },
 152    
 153    activate: function(draggable) {
 154      if(draggable.options.delay) { 
 155        this._timeout = setTimeout(function() { 
 156          Draggables._timeout = null; 
 157          window.focus(); 
 158          Draggables.activeDraggable = draggable; 
 159        }.bind(this), draggable.options.delay); 
 160      } else {
 161        window.focus(); // allows keypress events if window isn't currently focused, fails for Safari
 162        this.activeDraggable = draggable;
 163      }
 164    },
 165    
 166    deactivate: function() {
 167      this.activeDraggable = null;
 168    },
 169    
 170    updateDrag: function(event) {
 171      if(!this.activeDraggable) return;
 172      var pointer = [Event.pointerX(event), Event.pointerY(event)];
 173      // Mozilla-based browsers fire successive mousemove events with
 174      // the same coordinates, prevent needless redrawing (moz bug?)
 175      if(this._lastPointer && (this._lastPointer.inspect() == pointer.inspect())) return;
 176      this._lastPointer = pointer;
 177      
 178      this.activeDraggable.updateDrag(event, pointer);
 179    },
 180    
 181    endDrag: function(event) {
 182      if(this._timeout) { 
 183        clearTimeout(this._timeout); 
 184        this._timeout = null; 
 185      }
 186      if(!this.activeDraggable) return;
 187      this._lastPointer = null;
 188      this.activeDraggable.endDrag(event);
 189      this.activeDraggable = null;
 190    },
 191    
 192    keyPress: function(event) {
 193      if(this.activeDraggable)
 194        this.activeDraggable.keyPress(event);
 195    },
 196    
 197    addObserver: function(observer) {
 198      this.observers.push(observer);
 199      this._cacheObserverCallbacks();
 200    },
 201    
 202    removeObserver: function(element) {  // element instead of observer fixes mem leaks
 203      this.observers = this.observers.reject( function(o) { return o.element==element });
 204      this._cacheObserverCallbacks();
 205    },
 206    
 207    notify: function(eventName, draggable, event) {  // 'onStart', 'onEnd', 'onDrag'
 208      if(this[eventName+'Count'] > 0)
 209        this.observers.each( function(o) {
 210          if(o[eventName]) o[eventName](eventName, draggable, event);
 211        });
 212      if(draggable.options[eventName]) draggable.options[eventName](draggable, event);
 213    },
 214    
 215    _cacheObserverCallbacks: function() {
 216      ['onStart','onEnd','onDrag'].each( function(eventName) {
 217        Draggables[eventName+'Count'] = Draggables.observers.select(
 218          function(o) { return o[eventName]; }
 219        ).length;
 220      });
 221    }
 222  }
 223  
 224  /*--------------------------------------------------------------------------*/
 225  
 226  var Draggable = Class.create();
 227  Draggable._dragging    = {};
 228  
 229  Draggable.prototype = {
 230    initialize: function(element) {
 231      var defaults = {
 232        handle: false,
 233        reverteffect: function(element, top_offset, left_offset) {
 234          var dur = Math.sqrt(Math.abs(top_offset^2)+Math.abs(left_offset^2))*0.02;
 235          new Effect.Move(element, { x: -left_offset, y: -top_offset, duration: dur,
 236            queue: {scope:'_draggable', position:'end'}
 237          });
 238        },
 239        endeffect: function(element) {
 240          var toOpacity = typeof element._opacity == 'number' ? element._opacity : 1.0;
 241          new Effect.Opacity(element, {duration:0.2, from:0.7, to:toOpacity, 
 242            queue: {scope:'_draggable', position:'end'},
 243            afterFinish: function(){ 
 244              Draggable._dragging[element] = false 
 245            }
 246          }); 
 247        },
 248        zindex: 1000,
 249        revert: false,
 250        quiet: false,
 251        scroll: false,
 252        scrollSensitivity: 20,
 253        scrollSpeed: 15,
 254        snap: false,  // false, or xy or [x,y] or function(x,y){ return [x,y] }
 255        delay: 0
 256      };
 257      
 258      if(!arguments[1] || typeof arguments[1].endeffect == 'undefined')
 259        Object.extend(defaults, {
 260          starteffect: function(element) {
 261            element._opacity = Element.getOpacity(element);
 262            Draggable._dragging[element] = true;
 263            new Effect.Opacity(element, {duration:0.2, from:element._opacity, to:0.7}); 
 264          }
 265        });
 266      
 267      var options = Object.extend(defaults, arguments[1] || {});
 268  
 269      this.element = $(element);
 270      
 271      if(options.handle && (typeof options.handle == 'string'))
 272        this.handle = this.element.down('.'+options.handle, 0);
 273      
 274      if(!this.handle) this.handle = $(options.handle);
 275      if(!this.handle) this.handle = this.element;
 276      
 277      if(options.scroll && !options.scroll.scrollTo && !options.scroll.outerHTML) {
 278        options.scroll = $(options.scroll);
 279        this._isScrollChild = Element.childOf(this.element, options.scroll);
 280      }
 281  
 282      Element.makePositioned(this.element); // fix IE    
 283  
 284      this.delta    = this.currentDelta();
 285      this.options  = options;
 286      this.dragging = false;   
 287  
 288      this.eventMouseDown = this.initDrag.bindAsEventListener(this);
 289      Event.observe(this.handle, "mousedown", this.eventMouseDown);
 290      
 291      Draggables.register(this);
 292    },
 293    
 294    destroy: function() {
 295      Event.stopObserving(this.handle, "mousedown", this.eventMouseDown);
 296      Draggables.unregister(this);
 297    },
 298    
 299    currentDelta: function() {
 300      return([
 301        parseInt(Element.getStyle(this.element,'left') || '0'),
 302        parseInt(Element.getStyle(this.element,'top') || '0')]);
 303    },
 304    
 305    initDrag: function(event) {
 306      if(typeof Draggable._dragging[this.element] != 'undefined' &&
 307        Draggable._dragging[this.element]) return;
 308      if(Event.isLeftClick(event)) {    
 309        // abort on form elements, fixes a Firefox issue
 310        var src = Event.element(event);
 311        if((tag_name = src.tagName.toUpperCase()) && (
 312          tag_name=='INPUT' ||
 313          tag_name=='SELECT' ||
 314          tag_name=='OPTION' ||
 315          tag_name=='BUTTON' ||
 316          tag_name=='TEXTAREA')) return;
 317          
 318        var pointer = [Event.pointerX(event), Event.pointerY(event)];
 319        var pos     = Position.cumulativeOffset(this.element);
 320        this.offset = [0,1].map( function(i) { return (pointer[i] - pos[i]) });
 321        
 322        Draggables.activate(this);
 323        Event.stop(event);
 324      }
 325    },
 326    
 327    startDrag: function(event) {
 328      this.dragging = true;
 329      
 330      if(this.options.zindex) {
 331        this.originalZ = parseInt(Element.getStyle(this.element,'z-index') || 0);
 332        this.element.style.zIndex = this.options.zindex;
 333      }
 334      
 335      if(this.options.ghosting) {
 336        this._clone = this.element.cloneNode(true);
 337        Position.absolutize(this.element);
 338        this.element.parentNode.insertBefore(this._clone, this.element);
 339      }
 340      
 341      if(this.options.scroll) {
 342        if (this.options.scroll == window) {
 343          var where = this._getWindowScroll(this.options.scroll);
 344          this.originalScrollLeft = where.left;
 345          this.originalScrollTop = where.top;
 346        } else {
 347          this.originalScrollLeft = this.options.scroll.scrollLeft;
 348          this.originalScrollTop = this.options.scroll.scrollTop;
 349        }
 350      }
 351      
 352      Draggables.notify('onStart', this, event);
 353          
 354      if(this.options.starteffect) this.options.starteffect(this.element);
 355    },
 356    
 357    updateDrag: function(event, pointer) {
 358      if(!this.dragging) this.startDrag(event);
 359      
 360      if(!this.options.quiet){
 361        Position.prepare();
 362        Droppables.show(pointer, this.element);
 363      }
 364      
 365      Draggables.notify('onDrag', this, event);
 366      
 367      this.draw(pointer);
 368      if(this.options.change) this.options.change(this);
 369      
 370      if(this.options.scroll) {
 371        this.stopScrolling();
 372        
 373        var p;
 374        if (this.options.scroll == window) {
 375          with(this._getWindowScroll(this.options.scroll)) { p = [ left, top, left+width, top+height ]; }
 376        } else {
 377          p = Position.page(this.options.scroll);
 378          p[0] += this.options.scroll.scrollLeft + Position.deltaX;
 379          p[1] += this.options.scroll.scrollTop + Position.deltaY;
 380          p.push(p[0]+this.options.scroll.offsetWidth);
 381          p.push(p[1]+this.options.scroll.offsetHeight);
 382        }
 383        var speed = [0,0];
 384        if(pointer[0] < (p[0]+this.options.scrollSensitivity)) speed[0] = pointer[0]-(p[0]+this.options.scrollSensitivity);
 385        if(pointer[1] < (p[1]+this.options.scrollSensitivity)) speed[1] = pointer[1]-(p[1]+this.options.scrollSensitivity);
 386        if(pointer[0] > (p[2]-this.options.scrollSensitivity)) speed[0] = pointer[0]-(p[2]-this.options.scrollSensitivity);
 387        if(pointer[1] > (p[3]-this.options.scrollSensitivity)) speed[1] = pointer[1]-(p[3]-this.options.scrollSensitivity);
 388        this.startScrolling(speed);
 389      }
 390      
 391      // fix AppleWebKit rendering
 392      if(Prototype.Browser.WebKit) window.scrollBy(0,0);
 393      
 394      Event.stop(event);
 395    },
 396    
 397    finishDrag: function(event, success) {
 398      this.dragging = false;
 399      
 400      if(this.options.quiet){
 401        Position.prepare();
 402        var pointer = [Event.pointerX(event), Event.pointerY(event)];
 403        Droppables.show(pointer, this.element);
 404      }
 405  
 406      if(this.options.ghosting) {
 407        Position.relativize(this.element);
 408        Element.remove(this._clone);
 409        this._clone = null;
 410      }
 411  
 412      var dropped = false; 
 413      if(success) { 
 414        dropped = Droppables.fire(event, this.element); 
 415        if (!dropped) dropped = false; 
 416      }
 417      if(dropped && this.options.onDropped) this.options.onDropped(this.element);
 418      Draggables.notify('onEnd', this, event);
 419  
 420      var revert = this.options.revert;
 421      if(revert && typeof revert == 'function') revert = revert(this.element);
 422      
 423      var d = this.currentDelta();
 424      if(revert && this.options.reverteffect) {
 425        if (dropped == 0 || revert != 'failure')
 426          this.options.reverteffect(this.element,
 427            d[1]-this.delta[1], d[0]-this.delta[0]);
 428      } else {
 429        this.delta = d;
 430      }
 431  
 432      if(this.options.zindex)
 433        this.element.style.zIndex = this.originalZ;
 434  
 435      if(this.options.endeffect) 
 436        this.options.endeffect(this.element);
 437        
 438      Draggables.deactivate(this);
 439      Droppables.reset();
 440    },
 441    
 442    keyPress: function(event) {
 443      if(event.keyCode!=Event.KEY_ESC) return;
 444      this.finishDrag(event, false);
 445      Event.stop(event);
 446    },
 447    
 448    endDrag: function(event) {
 449      if(!this.dragging) return;
 450      this.stopScrolling();
 451      this.finishDrag(event, true);
 452      Event.stop(event);
 453    },
 454    
 455    draw: function(point) {
 456      var pos = Position.cumulativeOffset(this.element);
 457      if(this.options.ghosting) {
 458        var r   = Position.realOffset(this.element);
 459        pos[0] += r[0] - Position.deltaX; pos[1] += r[1] - Position.deltaY;
 460      }
 461      
 462      var d = this.currentDelta();
 463      pos[0] -= d[0]; pos[1] -= d[1];
 464      
 465      if(this.options.scroll && (this.options.scroll != window && this._isScrollChild)) {
 466        pos[0] -= this.options.scroll.scrollLeft-this.originalScrollLeft;
 467        pos[1] -= this.options.scroll.scrollTop-this.originalScrollTop;
 468      }
 469      
 470      var p = [0,1].map(function(i){ 
 471        return (point[i]-pos[i]-this.offset[i]) 
 472      }.bind(this));
 473      
 474      if(this.options.snap) {
 475        if(typeof this.options.snap == 'function') {
 476          p = this.options.snap(p[0],p[1],this);
 477        } else {
 478        if(this.options.snap instanceof Array) {
 479          p = p.map( function(v, i) {
 480            return Math.round(v/this.options.snap[i])*this.options.snap[i] }.bind(this))
 481        } else {
 482          p = p.map( function(v) {
 483            return Math.round(v/this.options.snap)*this.options.snap }.bind(this))
 484        }
 485      }}
 486      
 487      var style = this.element.style;
 488      if((!this.options.constraint) || (this.options.constraint=='horizontal'))
 489        style.left = p[0] + "px";
 490      if((!this.options.constraint) || (this.options.constraint=='vertical'))
 491        style.top  = p[1] + "px";
 492      
 493      if(style.visibility=="hidden") style.visibility = ""; // fix gecko rendering
 494    },
 495    
 496    stopScrolling: function() {
 497      if(this.scrollInterval) {
 498        clearInterval(this.scrollInterval);
 499        this.scrollInterval = null;
 500        Draggables._lastScrollPointer = null;
 501      }
 502    },
 503    
 504    startScrolling: function(speed) {
 505      if(!(speed[0] || speed[1])) return;
 506      this.scrollSpeed = [speed[0]*this.options.scrollSpeed,speed[1]*this.options.scrollSpeed];
 507      this.lastScrolled = new Date();
 508      this.scrollInterval = setInterval(this.scroll.bind(this), 10);
 509    },
 510    
 511    scroll: function() {
 512      var current = new Date();
 513      var delta = current - this.lastScrolled;
 514      this.lastScrolled = current;
 515      if(this.options.scroll == window) {
 516        with (this._getWindowScroll(this.options.scroll)) {
 517          if (this.scrollSpeed[0] || this.scrollSpeed[1]) {
 518            var d = delta / 1000;
 519            this.options.scroll.scrollTo( left + d*this.scrollSpeed[0], top + d*this.scrollSpeed[1] );
 520          }
 521        }
 522      } else {
 523        this.options.scroll.scrollLeft += this.scrollSpeed[0] * delta / 1000;
 524        this.options.scroll.scrollTop  += this.scrollSpeed[1] * delta / 1000;
 525      }
 526      
 527      Position.prepare();
 528      Droppables.show(Draggables._lastPointer, this.element);
 529      Draggables.notify('onDrag', this);
 530      if (this._isScrollChild) {
 531        Draggables._lastScrollPointer = Draggables._lastScrollPointer || $A(Draggables._lastPointer);
 532        Draggables._lastScrollPointer[0] += this.scrollSpeed[0] * delta / 1000;
 533        Draggables._lastScrollPointer[1] += this.scrollSpeed[1] * delta / 1000;
 534        if (Draggables._lastScrollPointer[0] < 0)
 535          Draggables._lastScrollPointer[0] = 0;
 536        if (Draggables._lastScrollPointer[1] < 0)
 537          Draggables._lastScrollPointer[1] = 0;
 538        this.draw(Draggables._lastScrollPointer);
 539      }
 540      
 541      if(this.options.change) this.options.change(this);
 542    },
 543    
 544    _getWindowScroll: function(w) {
 545      var T, L, W, H;
 546      with (w.document) {
 547        if (w.document.documentElement && documentElement.scrollTop) {
 548          T = documentElement.scrollTop;
 549          L = documentElement.scrollLeft;
 550        } else if (w.document.body) {
 551          T = body.scrollTop;
 552          L = body.scrollLeft;
 553        }
 554        if (w.innerWidth) {
 555          W = w.innerWidth;
 556          H = w.innerHeight;
 557        } else if (w.document.documentElement && documentElement.clientWidth) {
 558          W = documentElement.clientWidth;
 559          H = documentElement.clientHeight;
 560        } else {
 561          W = body.offsetWidth;
 562          H = body.offsetHeight
 563        }
 564      }
 565      return { top: T, left: L, width: W, height: H };
 566    }
 567  }
 568  
 569  /*--------------------------------------------------------------------------*/
 570  
 571  var SortableObserver = Class.create();
 572  SortableObserver.prototype = {
 573    initialize: function(element, observer) {
 574      this.element   = $(element);
 575      this.observer  = observer;
 576      this.lastValue = Sortable.serialize(this.element);
 577    },
 578    
 579    onStart: function() {
 580      this.lastValue = Sortable.serialize(this.element);
 581    },
 582    
 583    onEnd: function() {
 584      Sortable.unmark();
 585      if(this.lastValue != Sortable.serialize(this.element))
 586        this.observer(this.element)
 587    }
 588  }
 589  
 590  var Sortable = {
 591    SERIALIZE_RULE: /^[^_\-](?:[A-Za-z0-9\-\_]*)[_](.*)$/,
 592    
 593    sortables: {},
 594    
 595    _findRootElement: function(element) {
 596      while (element.tagName.toUpperCase() != "BODY") {  
 597        if(element.id && Sortable.sortables[element.id]) return element;
 598        element = element.parentNode;
 599      }
 600    },
 601  
 602    options: function(element) {
 603      element = Sortable._findRootElement($(element));
 604      if(!element) return;
 605      return Sortable.sortables[element.id];
 606    },
 607    
 608    destroy: function(element){
 609      var s = Sortable.options(element);
 610      
 611      if(s) {
 612        Draggables.removeObserver(s.element);
 613        s.droppables.each(function(d){ Droppables.remove(d) });
 614        s.draggables.invoke('destroy');
 615        
 616        delete Sortable.sortables[s.element.id];
 617      }
 618    },
 619  
 620    create: function(element) {
 621      element = $(element);
 622      var options = Object.extend({ 
 623        element:     element,
 624        tag:         'li',       // assumes li children, override with tag: 'tagname'
 625        dropOnEmpty: false,
 626        tree:        false,
 627        treeTag:     'ul',
 628        overlap:     'vertical', // one of 'vertical', 'horizontal'
 629        constraint:  'vertical', // one of 'vertical', 'horizontal', false
 630        containment: element,    // also takes array of elements (or id's); or false
 631        handle:      false,      // or a CSS class
 632        only:        false,
 633        delay:       0,
 634        hoverclass:  null,
 635        ghosting:    false,
 636        quiet:       false, 
 637        scroll:      false,
 638        scrollSensitivity: 20,
 639        scrollSpeed: 15,
 640        format:      this.SERIALIZE_RULE,
 641        
 642        // these take arrays of elements or ids and can be 
 643        // used for better initialization performance
 644        elements:    false,
 645        handles:     false,
 646  
 647        onChange:    Prototype.emptyFunction,
 648        onUpdate:    Prototype.emptyFunction
 649      }, arguments[1] || {});
 650  
 651      // clear any old sortable with same element
 652      this.destroy(element);
 653  
 654      // build options for the draggables
 655      var options_for_draggable = {
 656        revert:      true,
 657        quiet:       options.quiet,
 658        scroll:      options.scroll,
 659        scrollSpeed: options.scrollSpeed,
 660        scrollSensitivity: options.scrollSensitivity,
 661        delay:       options.delay,
 662        ghosting:    options.ghosting,
 663        constraint:  options.constraint,
 664        handle:      options.handle };
 665  
 666      if(options.starteffect)
 667        options_for_draggable.starteffect = options.starteffect;
 668  
 669      if(options.reverteffect)
 670        options_for_draggable.reverteffect = options.reverteffect;
 671      else
 672        if(options.ghosting) options_for_draggable.reverteffect = function(element) {
 673          element.style.top  = 0;
 674          element.style.left = 0;
 675        };
 676  
 677      if(options.endeffect)
 678        options_for_draggable.endeffect = options.endeffect;
 679  
 680      if(options.zindex)
 681        options_for_draggable.zindex = options.zindex;
 682  
 683      // build options for the droppables  
 684      var options_for_droppable = {
 685        overlap:     options.overlap,
 686        containment: options.containment,
 687        tree:        options.tree,
 688        hoverclass:  options.hoverclass,
 689        onHover:     Sortable.onHover
 690      }
 691      
 692      var options_for_tree = {
 693        onHover:      Sortable.onEmptyHover,
 694        overlap:      options.overlap,
 695        containment:  options.containment,
 696        hoverclass:   options.hoverclass
 697      }
 698  
 699      // fix for gecko engine
 700      Element.cleanWhitespace(element); 
 701  
 702      options.draggables = [];
 703      options.droppables = [];
 704  
 705      // drop on empty handling
 706      if(options.dropOnEmpty || options.tree) {
 707        Droppables.add(element, options_for_tree);
 708        options.droppables.push(element);
 709      }
 710  
 711      (options.elements || this.findElements(element, options) || []).each( function(e,i) {
 712        var handle = options.handles ? $(options.handles[i]) :
 713          (options.handle ? $(e).getElementsByClassName(options.handle)[0] : e); 
 714        options.draggables.push(
 715          new Draggable(e, Object.extend(options_for_draggable, { handle: handle })));
 716        Droppables.add(e, options_for_droppable);
 717        if(options.tree) e.treeNode = element;
 718        options.droppables.push(e);      
 719      });
 720      
 721      if(options.tree) {
 722        (Sortable.findTreeElements(element, options) || []).each( function(e) {
 723          Droppables.add(e, options_for_tree);
 724          e.treeNode = element;
 725          options.droppables.push(e);
 726        });
 727      }
 728  
 729      // keep reference
 730      this.sortables[element.id] = options;
 731  
 732      // for onupdate
 733      Draggables.addObserver(new SortableObserver(element, options.onUpdate));
 734  
 735    },
 736  
 737    // return all suitable-for-sortable elements in a guaranteed order
 738    findElements: function(element, options) {
 739      return Element.findChildren(
 740        element, options.only, options.tree ? true : false, options.tag);
 741    },
 742    
 743    findTreeElements: function(element, options) {
 744      return Element.findChildren(
 745        element, options.only, options.tree ? true : false, options.treeTag);
 746    },
 747  
 748    onHover: function(element, dropon, overlap) {
 749      if(Element.isParent(dropon, element)) return;
 750  
 751      if(overlap > .33 && overlap < .66 && Sortable.options(dropon).tree) {
 752        return;
 753      } else if(overlap>0.5) {
 754        Sortable.mark(dropon, 'before');
 755        if(dropon.previousSibling != element) {
 756          var oldParentNode = element.parentNode;
 757          element.style.visibility = "hidden"; // fix gecko rendering
 758          dropon.parentNode.insertBefore(element, dropon);
 759          if(dropon.parentNode!=oldParentNode) 
 760            Sortable.options(oldParentNode).onChange(element);
 761          Sortable.options(dropon.parentNode).onChange(element);
 762        }
 763      } else {
 764        Sortable.mark(dropon, 'after');
 765        var nextElement = dropon.nextSibling || null;
 766        if(nextElement != element) {
 767          var oldParentNode = element.parentNode;
 768          element.style.visibility = "hidden"; // fix gecko rendering
 769          dropon.parentNode.insertBefore(element, nextElement);
 770          if(dropon.parentNode!=oldParentNode) 
 771            Sortable.options(oldParentNode).onChange(element);
 772          Sortable.options(dropon.parentNode).onChange(element);
 773        }
 774      }
 775    },
 776    
 777    onEmptyHover: function(element, dropon, overlap) {
 778      var oldParentNode = element.parentNode;
 779      var droponOptions = Sortable.options(dropon);
 780          
 781      if(!Element.isParent(dropon, element)) {
 782        var index;
 783        
 784        var children = Sortable.findElements(dropon, {tag: droponOptions.tag, only: droponOptions.only});
 785        var child = null;
 786              
 787        if(children) {
 788          var offset = Element.offsetSize(dropon, droponOptions.overlap) * (1.0 - overlap);
 789          
 790          for (index = 0; index < children.length; index += 1) {
 791            if (offset - Element.offsetSize (children[index], droponOptions.overlap) >= 0) {
 792              offset -= Element.offsetSize (children[index], droponOptions.overlap);
 793            } else if (offset - (Element.offsetSize (children[index], droponOptions.overlap) / 2) >= 0) {
 794              child = index + 1 < children.length ? children[index + 1] : null;
 795              break;
 796            } else {
 797              child = children[index];
 798              break;
 799            }
 800          }
 801        }
 802        
 803        dropon.insertBefore(element, child);
 804        
 805        Sortable.options(oldParentNode).onChange(element);
 806        droponOptions.onChange(element);
 807      }
 808    },
 809  
 810    unmark: function() {
 811      if(Sortable._marker) Sortable._marker.hide();
 812    },
 813  
 814    mark: function(dropon, position) {
 815      // mark on ghosting only
 816      var sortable = Sortable.options(dropon.parentNode);
 817      if(sortable && !sortable.ghosting) return; 
 818  
 819      if(!Sortable._marker) {
 820        Sortable._marker = 
 821          ($('dropmarker') || Element.extend(document.createElement('DIV'))).
 822            hide().addClassName('dropmarker').setStyle({position:'absolute'});
 823        document.getElementsByTagName("body").item(0).appendChild(Sortable._marker);
 824      }    
 825      var offsets = Position.cumulativeOffset(dropon);
 826      Sortable._marker.setStyle({left: offsets[0]+'px', top: offsets[1] + 'px'});
 827      
 828      if(position=='after')
 829        if(sortable.overlap == 'horizontal') 
 830          Sortable._marker.setStyle({left: (offsets[0]+dropon.clientWidth) + 'px'});
 831        else
 832          Sortable._marker.setStyle({top: (offsets[1]+dropon.clientHeight) + 'px'});
 833      
 834      Sortable._marker.show();
 835    },
 836    
 837    _tree: function(element, options, parent) {
 838      var children = Sortable.findElements(element, options) || [];
 839    
 840      for (var i = 0; i < children.length; ++i) {
 841        var match = children[i].id.match(options.format);
 842  
 843        if (!match) continue;
 844        
 845        var child = {
 846          id: encodeURIComponent(match ? match[1] : null),
 847          element: element,
 848          parent: parent,
 849          children: [],
 850          position: parent.children.length,
 851          container: $(children[i]).down(options.treeTag)
 852        }
 853        
 854        /* Get the element containing the children and recurse over it */
 855        if (child.container)
 856          this._tree(child.container, options, child)
 857        
 858        parent.children.push (child);
 859      }
 860  
 861      return parent; 
 862    },
 863  
 864    tree: function(element) {
 865      element = $(element);
 866      var sortableOptions = this.options(element);
 867      var options = Object.extend({
 868        tag: sortableOptions.tag,
 869        treeTag: sortableOptions.treeTag,
 870        only: sortableOptions.only,
 871        name: element.id,
 872        format: sortableOptions.format
 873      }, arguments[1] || {});
 874      
 875      var root = {
 876        id: null,
 877        parent: null,
 878        children: [],
 879        container: element,
 880        position: 0
 881      }
 882      
 883      return Sortable._tree(element, options, root);
 884    },
 885  
 886    /* Construct a [i] index for a particular node */
 887    _constructIndex: function(node) {
 888      var index = '';
 889      do {
 890        if (node.id) index = '[' + node.position + ']' + index;
 891      } while ((node = node.parent) != null);
 892      return index;
 893    },
 894  
 895    sequence: function(element) {
 896      element = $(element);
 897      var options = Object.extend(this.options(element), arguments[1] || {});
 898      
 899      return $(this.findElements(element, options) || []).map( function(item) {
 900        return item.id.match(options.format) ? item.id.match(options.format)[1] : '';
 901      });
 902    },
 903  
 904    setSequence: function(element, new_sequence) {
 905      element = $(element);
 906      var options = Object.extend(this.options(element), arguments[2] || {});
 907      
 908      var nodeMap = {};
 909      this.findElements(element, options).each( function(n) {
 910          if (n.id.match(options.format))
 911              nodeMap[n.id.match(options.format)[1]] = [n, n.parentNode];
 912          n.parentNode.removeChild(n);
 913      });
 914     
 915      new_sequence.each(function(ident) {
 916        var n = nodeMap[ident];
 917        if (n) {
 918          n[1].appendChild(n[0]);
 919          delete nodeMap[ident];
 920        }
 921      });
 922    },
 923    
 924    serialize: function(element) {
 925      element = $(element);
 926      var options = Object.extend(Sortable.options(element), arguments[1] || {});
 927      var name = encodeURIComponent(
 928        (arguments[1] && arguments[1].name) ? arguments[1].name : element.id);
 929      
 930      if (options.tree) {
 931        return Sortable.tree(element, arguments[1]).children.map( function (item) {
 932          return [name + Sortable._constructIndex(item) + "[id]=" + 
 933                  encodeURIComponent(item.id)].concat(item.children.map(arguments.callee));
 934        }).flatten().join('&');
 935      } else {
 936        return Sortable.sequence(element, arguments[1]).map( function(item) {
 937          return name + "[]=" + encodeURIComponent(item);
 938        }).join('&');
 939      }
 940    }
 941  }
 942  
 943  // Returns true if child is contained within element
 944  Element.isParent = function(child, element) {
 945    if (!child.parentNode || child == element) return false;
 946    if (child.parentNode == element) return true;
 947    return Element.isParent(child.parentNode, element);
 948  }
 949  
 950  Element.findChildren = function(element, only, recursive, tagName) {    
 951    if(!element.hasChildNodes()) return null;
 952    tagName = tagName.toUpperCase();
 953    if(only) only = [only].flatten();
 954    var elements = [];
 955    $A(element.childNodes).each( function(e) {
 956      if(e.tagName && e.tagName.toUpperCase()==tagName &&
 957        (!only || (Element.classNames(e).detect(function(v) { return only.include(v) }))))
 958          elements.push(e);
 959      if(recursive) {
 960        var grandchildren = Element.findChildren(e, only, recursive, tagName);
 961        if(grandchildren) elements.push(grandchildren);
 962      }
 963    });
 964  
 965    return (elements.length>0 ? elements.flatten() : []);
 966  }
 967  
 968  Element.offsetSize = function (element, type) {
 969    return element['offset' + ((type=='vertical' || type=='height') ? 'Height' : 'Width')];
 970  }