text: /**
   * This class provides a container DD instance that allows dropping on multiple child target nodes.
   *
   * By default, this class requires that child nodes accepting drop are registered with {@link Ext.dd.Registry}.
   * However a simpler way to allow a DropZone to manage any number of target elements is to configure the
   * DropZone with an implementation of {@link #getTargetFromEvent} which interrogates the passed
   * mouse event to see if it has taken place within an element, or class of elements. This is easily done
   * by using the event's {@link Ext.event.Event#getTarget getTarget} method to identify a node based on a
   * CSS selector.
   *
   * Once the DropZone has detected through calling getTargetFromEvent, that the mouse is over
   * a drop target, that target is passed as the first parameter to {@link #onNodeEnter}, {@link #onNodeOver},
   * {@link #onNodeOut}, {@link #onNodeDrop}. You may configure the instance of DropZone with implementations
   * of these methods to provide application-specific behaviour for these events to update both
   * application state, and UI state.
   *
   * For example to make a GridPanel a cooperating target with the example illustrated in
   * {@link Ext.dd.DragZone DragZone}, the following technique might be used:
   *
   *     myGridPanel.on('render', function() {
   *         myGridPanel.dropZone = new Ext.dd.DropZone(myGridPanel.getView().scroller, {
   *
   *             // If the mouse is over a grid row, return that node. This is
   *             // provided as the "target" parameter in all "onNodeXXXX" node event handling functions
   *             getTargetFromEvent: function(e) {
   *                 return e.getTarget(myGridPanel.getView().rowSelector);
   *             },
   *
   *             // On entry into a target node, highlight that node.
   *             onNodeEnter : function(target, dd, e, data){
   *                 Ext.fly(target).addCls('my-row-highlight-class');
   *             },
   *
   *             // On exit from a target node, unhighlight that node.
   *             onNodeOut : function(target, dd, e, data){
   *                 Ext.fly(target).removeCls('my-row-highlight-class');
   *             },
   *
   *             // While over a target node, return the default drop allowed class which
   *             // places a "tick" icon into the drag proxy.
   *             onNodeOver : function(target, dd, e, data){
   *                 return Ext.dd.DropZone.prototype.dropAllowed;
   *             },
   *
   *             // On node drop we can interrogate the target to find the underlying
   *             // application object that is the real target of the dragged data.
   *             // In this case, it is a Record in the GridPanel's Store.
   *             // We can use the data set up by the DragZone's getDragData method to read
   *             // any data we decided to attach in the DragZone's getDragData method.
   *             onNodeDrop : function(target, dd, e, data){
   *                 var rowIndex = myGridPanel.getView().findRowIndex(target);
   *                 var r = myGridPanel.getStore().getAt(rowIndex);
   *                 Ext.Msg.alert('Drop gesture', 'Dropped Record id ' + data.draggedRecord.id +
   *                     ' on Record id ' + r.id);
   *                 return true;
   *             }
   *         });
   *     }
   *
   * See the {@link Ext.dd.DragZone DragZone} documentation for details about building a DragZone which
   * cooperates with this DropZone.
   */
  Ext.define('Ext.dd.DropZone', {
      extend: 'Ext.dd.DropTarget',
      requires: ['Ext.dd.Registry'],
  
      /**
       * Returns a custom data object associated with the DOM node that is the target of the event.  By default
       * this looks up the event target in the {@link Ext.dd.Registry}, although you can override this method to
       * provide your own custom lookup.
       * @param {Event} e The event
       * @return {Object} data The custom data
       */
      getTargetFromEvent : function(e){
          return Ext.dd.Registry.getTargetFromEvent(e);
      },
  
      /**
       * Called when the DropZone determines that a {@link Ext.dd.DragSource} has entered a drop node
       * that has either been registered or detected by a configured implementation of {@link #getTargetFromEvent}.
       * This method has no default implementation and should be overridden to provide
       * node-specific processing if necessary.
       * @param {Object} nodeData The custom data associated with the drop node (this is the same value returned from 
       * {@link #getTargetFromEvent} for this node)
       * @param {Ext.dd.DragSource} source The drag source that was dragged over this drop zone
       * @param {Event} e The event
       * @param {Object} data An object containing arbitrary data supplied by the drag source
       */
      onNodeEnter : function(n, dd, e, data){
          
      },
  
      /**
       * Called while the DropZone determines that a {@link Ext.dd.DragSource} is over a drop node
       * that has either been registered or detected by a configured implementation of {@link #getTargetFromEvent}.
       * The default implementation returns this.dropAllowed, so it should be
       * overridden to provide the proper feedback.
       * @param {Object} nodeData The custom data associated with the drop node (this is the same value returned from
       * {@link #getTargetFromEvent} for this node)
       * @param {Ext.dd.DragSource} source The drag source that was dragged over this drop zone
       * @param {Event} e The event
       * @param {Object} data An object containing arbitrary data supplied by the drag source
       * @return {String} status The CSS class that communicates the drop status back to the source so that the
       * underlying {@link Ext.dd.StatusProxy} can be updated
       * @template
       */
      onNodeOver : function(n, dd, e, data){
          return this.dropAllowed;
      },
  
      /**
       * Called when the DropZone determines that a {@link Ext.dd.DragSource} has been dragged out of
       * the drop node without dropping.  This method has no default implementation and should be overridden to provide
       * node-specific processing if necessary.
       * @param {Object} nodeData The custom data associated with the drop node (this is the same value returned from
       * {@link #getTargetFromEvent} for this node)
       * @param {Ext.dd.DragSource} source The drag source that was dragged over this drop zone
       * @param {Event} e The event
       * @param {Object} data An object containing arbitrary data supplied by the drag source
       * @template
       */
      onNodeOut : function(n, dd, e, data){
          
      },
  
      /**
       * Called when the DropZone determines that a {@link Ext.dd.DragSource} has been dropped onto
       * the drop node.  The default implementation returns false, so it should be overridden to provide the
       * appropriate processing of the drop event and return true so that the drag source's repair action does not run.
       * @param {Object} nodeData The custom data associated with the drop node (this is the same value returned from
       * {@link #getTargetFromEvent} for this node)
       * @param {Ext.dd.DragSource} source The drag source that was dragged over this drop zone
       * @param {Event} e The event
       * @param {Object} data An object containing arbitrary data supplied by the drag source
       * @return {Boolean} True if the drop was valid, else false
       * @template
       */
      onNodeDrop : function(n, dd, e, data){
          return false;
      },
  
      /**
       * Called while the DropZone determines that a {@link Ext.dd.DragSource} is being dragged over it,
       * but not over any of its registered drop nodes.  The default implementation returns this.dropNotAllowed, so
       * it should be overridden to provide the proper feedback if necessary.
       * @param {Ext.dd.DragSource} source The drag source that was dragged over this drop zone
       * @param {Event} e The event
       * @param {Object} data An object containing arbitrary data supplied by the drag source
       * @return {String} status The CSS class that communicates the drop status back to the source so that the
       * underlying {@link Ext.dd.StatusProxy} can be updated
       * @template
       */
      onContainerOver : function(dd, e, data){
          return this.dropNotAllowed;
      },
  
      /**
       * Called when the DropZone determines that a {@link Ext.dd.DragSource} has been dropped on it,
       * but not on any of its registered drop nodes.  The default implementation returns false, so it should be
       * overridden to provide the appropriate processing of the drop event if you need the drop zone itself to
       * be able to accept drops.  It should return true when valid so that the drag source's repair action does not run.
       * @param {Ext.dd.DragSource} source The drag source that was dragged over this drop zone
       * @param {Event} e The event
       * @param {Object} data An object containing arbitrary data supplied by the drag source
       * @return {Boolean} True if the drop was valid, else false
       * @template
       */
      onContainerDrop : function(dd, e, data){
          return false;
      },
  
      /**
       * The function a {@link Ext.dd.DragSource} calls once to notify this drop zone that the source is now over
       * the zone.  The default implementation returns this.dropNotAllowed and expects that only registered drop
       * nodes can process drag drop operations, so if you need the drop zone itself to be able to process drops
       * you should override this method and provide a custom implementation.
       * @param {Ext.dd.DragSource} source The drag source that was dragged over this drop zone
       * @param {Event} e The event
       * @param {Object} data An object containing arbitrary data supplied by the drag source
       * @return {String} status The CSS class that communicates the drop status back to the source so that the
       * underlying {@link Ext.dd.StatusProxy} can be updated
       * @template
       */
      notifyEnter : function(dd, e, data){
          return this.dropNotAllowed;
      },
  
      /**
       * The function a {@link Ext.dd.DragSource} calls continuously while it is being dragged over the drop zone.
       * This method will be called on every mouse movement while the drag source is over the drop zone.
       * It will call {@link #onNodeOver} while the drag source is over a registered node, and will also automatically
       * delegate to the appropriate node-specific methods as necessary when the drag source enters and exits
       * registered nodes ({@link #onNodeEnter}, {@link #onNodeOut}). If the drag source is not currently over a
       * registered node, it will call {@link #onContainerOver}.
       * @param {Ext.dd.DragSource} source The drag source that was dragged over this drop zone
       * @param {Event} e The event
       * @param {Object} data An object containing arbitrary data supplied by the drag source
       * @return {String} status The CSS class that communicates the drop status back to the source so that the
       * underlying {@link Ext.dd.StatusProxy} can be updated
       * @template
       */
      notifyOver : function(dd, e, data){
          var me = this,
              n = me.getTargetFromEvent(e);
  
          if (!n) { // not over valid drop target
              if (me.lastOverNode) {
                  me.onNodeOut(me.lastOverNode, dd, e, data);
                  me.lastOverNode = null;
              }
              return me.onContainerOver(dd, e, data);
          }
  
          if (me.lastOverNode !== n) {
              if (me.lastOverNode) {
                  me.onNodeOut(me.lastOverNode, dd, e, data);
              }
              me.onNodeEnter(n, dd, e, data);
              me.lastOverNode = n;
          }
  
          return me.onNodeOver(n, dd, e, data);
      },
  
      /**
       * The function a {@link Ext.dd.DragSource} calls once to notify this drop zone that the source has been dragged
       * out of the zone without dropping.  If the drag source is currently over a registered node, the notification
       * will be delegated to {@link #onNodeOut} for node-specific handling, otherwise it will be ignored.
       * @param {Ext.dd.DragSource} source The drag source that was dragged over this drop target
       * @param {Event} e The event
       * @param {Object} data An object containing arbitrary data supplied by the drag zone
       * @template
       */
      notifyOut : function(dd, e, data){
          if(this.lastOverNode){
              this.onNodeOut(this.lastOverNode, dd, e, data);
              this.lastOverNode = null;
          }
      },
  
      /**
       * The function a {@link Ext.dd.DragSource} calls once to notify this drop zone that the dragged item has
       * been dropped on it.  The drag zone will look up the target node based on the event passed in, and if there
       * is a node registered for that event, it will delegate to {@link #onNodeDrop} for node-specific handling,
       * otherwise it will call {@link #onContainerDrop}.
       * @param {Ext.dd.DragSource} source The drag source that was dragged over this drop zone
       * @param {Event} e The event
       * @param {Object} data An object containing arbitrary data supplied by the drag source
       * @return {Boolean} False if the drop was invalid.
       * @template
       */
      notifyDrop : function(dd, e, data){
          var me = this,
              n = me.getTargetFromEvent(e),
              result = n ?
                  me.onNodeDrop(n, dd, e, data) :
                  me.onContainerDrop(dd, e, data);
  
          // Exit the overNode upon drop.
          // Must do this after dropping because exiting a node may perform actions which invalidate a drop.
          if (me.lastOverNode) {
              me.onNodeOut(me.lastOverNode, dd, e, data);
              me.lastOverNode = null;
          }
          return result;
      },
  
      // private
      triggerCacheRefresh : function() {
          Ext.dd.DDM.refreshCache(this.groups);
      }
  });