dragdrop.js

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// Copyright (c) 2005 Thomas Fuchs (http://script.aculo.us, http://mir.aculo.us)
// 
// See scriptaculous.js for full license.

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

var Droppables = {
  drops: [],

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

  add: function(element) {
    element = $(element);
    var options = Object.extend({
      greedy:     true,
      hoverclass: null  
    }, arguments[1] || {});

    // cache containers
    if(options.containment) {
      options._containers = [];
      var containment = options.containment;
      if((typeof containment == 'object') && 
        (containment.constructor == Array)) {
        containment.each( function(c) { options._containers.push($(c)) });
      } else {
        options._containers.push($(containment));
      }
    }
    
    if(options.accept) options.accept = [options.accept].flatten();

    Element.makePositioned(element); // fix IE
    options.element = element;

    this.drops.push(options);
  },

  isContained: function(element, drop) {
    var parentNode = element.parentNode;
    return drop._containers.detect(function(c) { return parentNode == c });
  },

  isAffected: function(point, element, drop) {
    return (
      (drop.element!=element) &&
      ((!drop._containers) ||
        this.isContained(element, drop)) &&
      ((!drop.accept) ||
        (Element.classNames(element).detect( 
          function(v) { return drop.accept.include(v) } ) )) &&
      Position.within(drop.element, point[0], point[1]) );
  },

  deactivate: function(drop) {
    if(drop.hoverclass)
      Element.removeClassName(drop.element, drop.hoverclass);
    this.last_active = null;
  },

  activate: function(drop) {
    if(drop.hoverclass)
      Element.addClassName(drop.element, drop.hoverclass);
    this.last_active = drop;
  },

  show: function(point, element) {
    if(!this.drops.length) return;
    
    if(this.last_active) this.deactivate(this.last_active);
    this.drops.each( function(drop) {
      if(Droppables.isAffected(point, element, drop)) {
        if(drop.onHover)
           drop.onHover(element, drop.element, Position.overlap(drop.overlap, drop.element));
        if(drop.greedy) { 
          Droppables.activate(drop);
          throw $break;
        }
      }
    });
  },

  fire: function(event, element) {
    if(!this.last_active) return;
    Position.prepare();

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

  reset: function() {
    if(this.last_active)
      this.deactivate(this.last_active);
  }
}

var Draggables = {
  drags: [],
  observers: [],
  
  register: function(draggable) {
    if(this.drags.length == 0) {
      this.eventMouseUp   = this.endDrag.bindAsEventListener(this);
      this.eventMouseMove = this.updateDrag.bindAsEventListener(this);
      this.eventKeypress  = this.keyPress.bindAsEventListener(this);
      
      Event.observe(document, "mouseup", this.eventMouseUp);
      Event.observe(document, "mousemove", this.eventMouseMove);
      Event.observe(document, "keypress", this.eventKeypress);
    }
    this.drags.push(draggable);
  },
  
  unregister: function(draggable) {
    this.drags = this.drags.reject(function(d) { return d==draggable });
    if(this.drags.length == 0) {
      Event.stopObserving(document, "mouseup", this.eventMouseUp);
      Event.stopObserving(document, "mousemove", this.eventMouseMove);
      Event.stopObserving(document, "keypress", this.eventKeypress);
    }
  },
  
  activate: function(draggable) {
    window.focus(); // allows keypress events if window isn't currently focused, fails for Safari
    this.activeDraggable = draggable;
  },
  
  deactivate: function() {
    this.activeDraggable = null;
  },
  
  updateDrag: function(event) {
    if(!this.activeDraggable) return;
    var pointer = [Event.pointerX(event), Event.pointerY(event)];
    // Mozilla-based browsers fire successive mousemove events with
    // the same coordinates, prevent needless redrawing (moz bug?)
    if(this._lastPointer && (this._lastPointer.inspect() == pointer.inspect())) return;
    this._lastPointer = pointer;
    this.activeDraggable.updateDrag(event, pointer);
  },
  
  endDrag: function(event) {
    if(!this.activeDraggable) return;
    this._lastPointer = null;
    this.activeDraggable.endDrag(event);
    this.activeDraggable = null;
  },
  
  keyPress: function(event) {
    if(this.activeDraggable)
      this.activeDraggable.keyPress(event);
  },
  
  addObserver: function(observer) {
    this.observers.push(observer);
    this._cacheObserverCallbacks();
  },
  
  removeObserver: function(element) {  // element instead of observer fixes mem leaks
    this.observers = this.observers.reject( function(o) { return o.element==element });
    this._cacheObserverCallbacks();
  },
  
  notify: function(eventName, draggable, event) {  // 'onStart', 'onEnd', 'onDrag'
    if(this[eventName+'Count'] > 0)
      this.observers.each( function(o) {
        if(o[eventName]) o[eventName](eventName, draggable, event);
      });
  },
  
  _cacheObserverCallbacks: function() {
    ['onStart','onEnd','onDrag'].each( function(eventName) {
      Draggables[eventName+'Count'] = Draggables.observers.select(
        function(o) { return o[eventName]; }
      ).length;
    });
  }
}

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

var Draggable = Class.create();
Draggable.prototype = {
  initialize: function(element) {
    var options = Object.extend({
      handle: false,
      starteffect: function(element) { 
        new Effect.Opacity(element, {duration:0.2, from:1.0, to:0.7}); 
      },
      reverteffect: function(element, top_offset, left_offset) {
        var dur = Math.sqrt(Math.abs(top_offset^2)+Math.abs(left_offset^2))*0.02;
        element._revert = new Effect.Move(element, { x: -left_offset, y: -top_offset, duration: dur});
      },
      endeffect: function(element) { 
        new Effect.Opacity(element, {duration:0.2, from:0.7, to:1.0}); 
      },
      zindex: 1000,
      revert: false,
      scroll: false,
      scrollSensitivity: 20,
      scrollSpeed: 15,
      snap: false   // false, or xy or [x,y] or function(x,y){ return [x,y] }
    }, arguments[1] || {});

    this.element = $(element);
    
    if(options.handle && (typeof options.handle == 'string'))
      this.handle = Element.childrenWithClassName(this.element, options.handle)[0];  
    if(!this.handle) this.handle = $(options.handle);
    if(!this.handle) this.handle = this.element;
    
    if(options.scroll) options.scroll = $(options.scroll);

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

    this.delta    = this.currentDelta();
    this.options  = options;
    this.dragging = false;   

    this.eventMouseDown = this.initDrag.bindAsEventListener(this);
    Event.observe(this.handle, "mousedown", this.eventMouseDown);
    
    Draggables.register(this);
  },
  
  destroy: function() {
    Event.stopObserving(this.handle, "mousedown", this.eventMouseDown);
    Draggables.unregister(this);
  },
  
  currentDelta: function() {
    return([
      parseInt(Element.getStyle(this.element,'left') || '0'),
      parseInt(Element.getStyle(this.element,'top') || '0')]);
  },
  
  initDrag: function(event) {
    if(Event.isLeftClick(event)) {    
      // abort on form elements, fixes a Firefox issue
      var src = Event.element(event);
      if(src.tagName && (
        src.tagName=='INPUT' ||
        src.tagName=='SELECT' ||
        src.tagName=='OPTION' ||
        src.tagName=='BUTTON' ||
        src.tagName=='TEXTAREA')) return;
        
      if(this.element._revert) {
        this.element._revert.cancel();
        this.element._revert = null;
      }
      
      var pointer = [Event.pointerX(event), Event.pointerY(event)];
      var pos     = Position.cumulativeOffset(this.element);
      this.offset = [0,1].map( function(i) { return (pointer[i] - pos[i]) });
      
      Draggables.activate(this);
      Event.stop(event);
    }
  },
  
  startDrag: function(event) {
    this.dragging = true;
    
    if(this.options.zindex) {
      this.originalZ = parseInt(Element.getStyle(this.element,'z-index') || 0);
      this.element.style.zIndex = this.options.zindex;
    }
    
    if(this.options.ghosting) {
      this._clone = this.element.cloneNode(true);
      Position.absolutize(this.element);
      this.element.parentNode.insertBefore(this._clone, this.element);
    }
    
    if(this.options.scroll) {
      this.originalScrollLeft = this.options.scroll.scrollLeft;
      this.originalScrollTop = this.options.scroll.scrollTop;
    }
    
    Draggables.notify('onStart', this, event);
    if(this.options.starteffect) this.options.starteffect(this.element);
  },
  
  updateDrag: function(event, pointer) {
    if(!this.dragging) this.startDrag(event);
    Position.prepare();
    Droppables.show(pointer, this.element);
    Draggables.notify('onDrag', this, event);
    this.draw(pointer);
    if(this.options.change) this.options.change(this);
    
    if(this.options.scroll) {
      //if(this.scrollInterval) this.scroll();
      this.stopScrolling();
      var p = Position.page(this.options.scroll);
      p[0] += this.options.scroll.scrollLeft;
      p[1] += this.options.scroll.scrollTop;
      p.push(p[0]+this.options.scroll.offsetWidth);
      p.push(p[1]+this.options.scroll.offsetHeight);
      var speed = [0,0];
      if(pointer[0] < (p[0]+this.options.scrollSensitivity)) speed[0] = pointer[0]-(p[0]+this.options.scrollSensitivity);
      if(pointer[1] < (p[1]+this.options.scrollSensitivity)) speed[1] = pointer[1]-(p[1]+this.options.scrollSensitivity);
      if(pointer[0] > (p[2]-this.options.scrollSensitivity)) speed[0] = pointer[0]-(p[2]-this.options.scrollSensitivity);
      if(pointer[1] > (p[3]-this.options.scrollSensitivity)) speed[1] = pointer[1]-(p[3]-this.options.scrollSensitivity);
      this.startScrolling(speed);
    }
    
    // fix AppleWebKit rendering
    if(navigator.appVersion.indexOf('AppleWebKit')>0) window.scrollBy(0,0);
    
    Event.stop(event);
  },
  
  finishDrag: function(event, success) {
    this.dragging = false;

    if(this.options.ghosting) {
      Position.relativize(this.element);
      Element.remove(this._clone);
      this._clone = null;
    }

    if(success) Droppables.fire(event, this.element);
    Draggables.notify('onEnd', this, event);

    var revert = this.options.revert;
    if(revert && typeof revert == 'function') revert = revert(this.element);
    
    var d = this.currentDelta();
    if(revert && this.options.reverteffect) {
      this.options.reverteffect(this.element, 
        d[1]-this.delta[1], d[0]-this.delta[0]);
    } else {
      this.delta = d;