code: function(type, pointerEvent) {
        if(type == ionic.Gestures.EVENT_END) {
          this.pointers = {};
        }
        else {
          pointerEvent.identifier = pointerEvent.pointerId;
          this.pointers[pointerEvent.pointerId] = pointerEvent;
        }
  
        return Object.keys(this.pointers).length;
      }
docs: update the position of a pointer
  @param   {String}   type             ionic.Gestures.EVENT_END
  @param   {Object}   pointerEvent