dragdrop.js

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// Copyright (c) 2005 Thomas Fuchs (http://script.aculo.us, http://mir.aculo.us)
// 
// Element.Class part Copyright (c) 2005 by Rick Olson
// 
// 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));
      }
    }

    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(pX, pY, element, drop) {
    return (
      (drop.element!=element) &&
      ((!drop._containers) ||
        this.isContained(element, drop)) &&
      ((!drop.accept) ||
        (Element.Class.has_any(element, drop.accept))) &&
      Position.within(drop.element, pX, pY) );
  },

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

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

  show: function(event, element) {
    if(!this.drops.length) return;
    var pX = Event.pointerX(event);
    var pY = Event.pointerY(event);
    Position.prepare();

    var i = this.drops.length-1; do {
      var drop = this.drops[i];
      if(this.isAffected(pX, pY, element, drop)) {
        if(drop.onHover)
           drop.onHover(element, drop.element, Position.overlap(drop.overlap, drop.element));
        if(drop.greedy) { 
          this.activate(drop);
          return;
        }
      }
    } while (i--);
    
    if(this.last_active) this.deactivate(this.last_active);
  },

  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 = {
  observers: [],
  addObserver: function(observer) {
    this.observers.push(observer);    
  },
  removeObserver: function(element) {  // element instead of obsever fixes mem leaks
    this.observers = this.observers.reject( function(o) { return o.element==element });
  },
  notify: function(eventName, draggable) {  // 'onStart', 'onEnd'
    this.observers.invoke(eventName, draggable);
  }
}

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

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;
        new Effect.MoveBy(element, -top_offset, -left_offset, {duration:dur});
      },
      endeffect: function(element) { 
         new Effect.Opacity(element, {duration:0.2, from:0.7, to:1.0}); 
      },
      zindex: 1000,
      revert: false
    }, arguments[1] || {});

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

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

    this.offsetX      = 0;
    this.offsetY      = 0;
    this.originalLeft = this.currentLeft();
    this.originalTop  = this.currentTop();
    this.originalX    = this.element.offsetLeft;
    this.originalY    = this.element.offsetTop;

    this.options      = options;

    this.active       = false;
    this.dragging     = false;   

    this.eventMouseDown = this.startDrag.bindAsEventListener(this);
    this.eventMouseUp   = this.endDrag.bindAsEventListener(this);
    this.eventMouseMove = this.update.bindAsEventListener(this);
    this.eventKeypress  = this.keyPress.bindAsEventListener(this);
    
    this.registerEvents();
  },
  destroy: function() {
    Event.stopObserving(this.handle, "mousedown", this.eventMouseDown);
    this.unregisterEvents();
  },
  registerEvents: function() {
    Event.observe(document, "mouseup", this.eventMouseUp);
    Event.observe(document, "mousemove", this.eventMouseMove);
    Event.observe(document, "keypress", this.eventKeypress);
    Event.observe(this.handle, "mousedown", this.eventMouseDown);
  },
  unregisterEvents: function() {
    //if(!this.active) return;
    //Event.stopObserving(document, "mouseup", this.eventMouseUp);
    //Event.stopObserving(document, "mousemove", this.eventMouseMove);
    //Event.stopObserving(document, "keypress", this.eventKeypress);
  },
  currentLeft: function() {
    return parseInt(this.element.style.left || '0');
  },
  currentTop: function() {
    return parseInt(this.element.style.top || '0')
  },
  startDrag: 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=='BUTTON' ||
        src.tagName=='TEXTAREA')) return;
      
      // this.registerEvents();
      this.active = true;
      var pointer = [Event.pointerX(event), Event.pointerY(event)];
      var offsets = Position.cumulativeOffset(this.element);
      this.offsetX =  (pointer[0] - offsets[0]);
      this.offsetY =  (pointer[1] - offsets[1]);
      Event.stop(event);
    }
  },
  finishDrag: function(event, success) {
    // this.unregisterEvents();

    this.active = false;
    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);

    var revert = this.options.revert;
    if(revert && typeof revert == 'function') revert = revert(this.element);

    if(revert && this.options.reverteffect) {
      this.options.reverteffect(this.element, 
      this.currentTop()-this.originalTop,
      this.currentLeft()-this.originalLeft);
    } else {
      this.originalLeft = this.currentLeft();
      this.originalTop  = this.currentTop();
    }

    if(this.options.zindex)
      this.element.style.zIndex = this.originalZ;

    if(this.options.endeffect) 
      this.options.endeffect(this.element);


    Droppables.reset();
  },
  keyPress: function(event) {
    if(this.active) {
      if(event.keyCode==Event.KEY_ESC) {
        this.finishDrag(event, false);
        Event.stop(event);
      }
    }
  },
  endDrag: function(event) {
    if(this.active && this.dragging) {
      this.finishDrag(event, true);
      Event.stop(event);
    }
    this.active = false;
    this.dragging = false;
  },