vendor/rails/actionpack/lib/action_view/helpers/javascripts/dragdrop.js

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