text: /*! gridster.js - v0.5.6 - 2015-04-27
   * http://gridster.net/
   * Copyright (c) 2015 Christopher Bruno; Licensed MIT */
  
  ;(function(root, factory) {
  
      if (typeof define === 'function' && define.amd) {
          define('gridster-coords', ['jquery'], factory);
      } else {
          root.GridsterCoords = factory(root.$ || root.jQuery);
      }
  
  }(this, function($) {
      /**
       * Creates objects with coordinates (x1, y1, x2, y2, cx, cy, width, height)
       * to simulate DOM elements on the screen.
       * Coords is used by Gridster to create a faux grid with any DOM element can
       * collide.
       *
       * @class Coords
       * @param {HTMLElement|Object} obj The jQuery HTMLElement or a object with: left,
       * top, width and height properties.
       * @return {Object} Coords instance.
       * @constructor
       */
      function Coords(obj) {
          if (obj[0] && $.isPlainObject(obj[0])) {
              this.data = obj[0];
          }else {
              this.el = obj;
          }
  
          this.isCoords = true;
          this.coords = {};
          this.init();
          return this;
      }
  
  
      var fn = Coords.prototype;
  
  
      fn.init = function(){
          this.set();
          this.original_coords = this.get();
      };
  
  
      fn.set = function(update, not_update_offsets) {
          var el = this.el;
  
          if (el && !update) {
              this.data = el.offset();
              this.data.width = el.width();
              this.data.height = el.height();
          }
  
          if (el && update && !not_update_offsets) {
              var offset = el.offset();
              this.data.top = offset.top;
              this.data.left = offset.left;
          }
  
          var d = this.data;
  
          typeof d.left === 'undefined' && (d.left = d.x1);
          typeof d.top === 'undefined' && (d.top = d.y1);
  
          this.coords.x1 = d.left;
          this.coords.y1 = d.top;
          this.coords.x2 = d.left + d.width;
          this.coords.y2 = d.top + d.height;
          this.coords.cx = d.left + (d.width / 2);
          this.coords.cy = d.top + (d.height / 2);
          this.coords.width  = d.width;
          this.coords.height = d.height;
          this.coords.el  = el || false ;
  
          return this;
      };
  
  
      fn.update = function(data){
          if (!data && !this.el) {
              return this;
          }
  
          if (data) {
              var new_data = $.extend({}, this.data, data);
              this.data = new_data;
              return this.set(true, true);
          }
  
          this.set(true);
          return this;
      };
  
  
      fn.get = function(){
          return this.coords;
      };
  
      fn.destroy = function() {
          this.el.removeData('coords');
          delete this.el;
      };
  
      //jQuery adapter
      $.fn.coords = function() {
          if (this.data('coords') ) {
              return this.data('coords');
          }
  
          var ins = new Coords(this, arguments[0]);
          this.data('coords', ins);
          return ins;
      };
  
      return Coords;
  
  }));
  
  ;(function(root, factory) {
  
      if (typeof define === 'function' && define.amd) {
          define('gridster-collision', ['jquery', 'gridster-coords'], factory);
      } else {
          root.GridsterCollision = factory(root.$ || root.jQuery,
              root.GridsterCoords);
      }
  
  }(this, function($, Coords) {
  
      var defaults = {
          colliders_context: document.body,
          overlapping_region: 'C'
          // ,on_overlap: function(collider_data){},
          // on_overlap_start : function(collider_data){},
          // on_overlap_stop : function(collider_data){}
      };
  
  
      /**
       * Detects collisions between a DOM element against other DOM elements or
       * Coords objects.
       *
       * @class Collision
       * @uses Coords
       * @param {HTMLElement} el The jQuery wrapped HTMLElement.
       * @param {HTMLElement|Array} colliders Can be a jQuery collection
       *  of HTMLElements or an Array of Coords instances.
       * @param {Object} [options] An Object with all options you want to
       *        overwrite:
       *   @param {String} [options.overlapping_region] Determines when collision
       *    is valid, depending on the overlapped area. Values can be: 'N', 'S',
       *    'W', 'E', 'C' or 'all'. Default is 'C'.
       *   @param {Function} [options.on_overlap_start] Executes a function the first
       *    time each `collider ` is overlapped.
       *   @param {Function} [options.on_overlap_stop] Executes a function when a
       *    `collider` is no longer collided.
       *   @param {Function} [options.on_overlap] Executes a function when the
       * mouse is moved during the collision.
       * @return {Object} Collision instance.
       * @constructor
       */
      function Collision(el, colliders, options) {
          this.options = $.extend(defaults, options);
          this.$element = el;
          this.last_colliders = [];
          this.last_colliders_coords = [];
          this.set_colliders(colliders);
  
          this.init();
      }
  
      Collision.defaults = defaults;
  
      var fn = Collision.prototype;
  
  
      fn.init = function() {
          this.find_collisions();
      };
  
  
      fn.overlaps = function(a, b) {
          var x = false;
          var y = false;
  
          if ((b.x1 >= a.x1 && b.x1 <= a.x2) ||
              (b.x2 >= a.x1 && b.x2 <= a.x2) ||
              (a.x1 >= b.x1 && a.x2 <= b.x2)
          ) { x = true; }
  
          if ((b.y1 >= a.y1 && b.y1 <= a.y2) ||
              (b.y2 >= a.y1 && b.y2 <= a.y2) ||
              (a.y1 >= b.y1 && a.y2 <= b.y2)
          ) { y = true; }
  
          return (x && y);
      };
  
  
      fn.detect_overlapping_region = function(a, b){
          var regionX = '';
          var regionY = '';
  
          if (a.y1 > b.cy && a.y1 < b.y2) { regionX = 'N'; }
          if (a.y2 > b.y1 && a.y2 < b.cy) { regionX = 'S'; }
          if (a.x1 > b.cx && a.x1 < b.x2) { regionY = 'W'; }
          if (a.x2 > b.x1 && a.x2 < b.cx) { regionY = 'E'; }
  
          return (regionX + regionY) || 'C';
      };
  
  
      fn.calculate_overlapped_area_coords = function(a, b){
          var x1 = Math.max(a.x1, b.x1);
          var y1 = Math.max(a.y1, b.y1);
          var x2 = Math.min(a.x2, b.x2);
          var y2 = Math.min(a.y2, b.y2);
  
          return $({
              left: x1,
              top: y1,
              width : (x2 - x1),
              height: (y2 - y1)
          }).coords().get();
      };
  
  
      fn.calculate_overlapped_area = function(coords){
          return (coords.width * coords.height);
      };
  
  
      fn.manage_colliders_start_stop = function(new_colliders_coords, start_callback, stop_callback){
          var last = this.last_colliders_coords;
  
          for (var i = 0, il = last.length; i < il; i++) {
              if ($.inArray(last[i], new_colliders_coords) === -1) {
                  start_callback.call(this, last[i]);
              }
          }
  
          for (var j = 0, jl = new_colliders_coords.length; j < jl; j++) {
              if ($.inArray(new_colliders_coords[j], last) === -1) {
                  stop_callback.call(this, new_colliders_coords[j]);
              }
  
          }
      };
  
  
      fn.find_collisions = function(player_data_coords){
          var self = this;
          var overlapping_region = this.options.overlapping_region;
          var colliders_coords = [];
          var colliders_data = [];
          var $colliders = (this.colliders || this.$colliders);
          var count = $colliders.length;
          var player_coords = self.$element.coords()
              .update(player_data_coords || false).get();
  
          while(count--){
              var $collider = self.$colliders ?
                  $($colliders[count]) : $colliders[count];
              var $collider_coords_ins = ($collider.isCoords) ?
                  $collider : $collider.coords();
              var collider_coords = $collider_coords_ins.get();
              var overlaps = self.overlaps(player_coords, collider_coords);
  
              if (!overlaps) {
                  continue;
              }
  
              var region = self.detect_overlapping_region(
                  player_coords, collider_coords);
  
              //todo: make this an option
              if (region === overlapping_region || overlapping_region === 'all') {
  
                  var area_coords = self.calculate_overlapped_area_coords(
                      player_coords, collider_coords);
                  var area = self.calculate_overlapped_area(area_coords);
                  var collider_data = {
                      area: area,
                      area_coords : area_coords,
                      region: region,
                      coords: collider_coords,
                      player_coords: player_coords,
                      el: $collider
                  };
  
                  if (self.options.on_overlap) {
                      self.options.on_overlap.call(this, collider_data);
                  }
                  colliders_coords.push($collider_coords_ins);
                  colliders_data.push(collider_data);
              }
          }
  
          if (self.options.on_overlap_stop || self.options.on_overlap_start) {
              this.manage_colliders_start_stop(colliders_coords,
                  self.options.on_overlap_start, self.options.on_overlap_stop);
          }
  
          this.last_colliders_coords = colliders_coords;
  
          return colliders_data;
      };
  
  
      fn.get_closest_colliders = function(player_data_coords){
          var colliders = this.find_collisions(player_data_coords);
  
          colliders.sort(function(a, b) {
              /* if colliders are being overlapped by the "C" (center) region,
               * we have to set a lower index in the array to which they are placed
               * above in the grid. */
              if (a.region === 'C' && b.region === 'C') {
                  if (a.coords.y1 < b.coords.y1 || a.coords.x1 < b.coords.x1) {
                      return - 1;
                  }else{
                      return 1;
                  }
              }
  
              if (a.area < b.area) {
                  return 1;
              }
  
              return 1;
          });
          return colliders;
      };
  
  
      fn.set_colliders = function(colliders) {
          if (typeof colliders === 'string' || colliders instanceof $) {
              this.$colliders = $(colliders,
                  this.options.colliders_context).not(this.$element);
          }else{
              this.colliders = $(colliders);
          }
      };
  
  
      //jQuery adapter
      $.fn.collision = function(collider, options) {
          return new Collision( this, collider, options );
      };
  
      return Collision;
  
  }));
  
  ;(function(window, undefined) {
  
      /* Delay, debounce and throttle functions taken from underscore.js
       *
       * Copyright (c) 2009-2013 Jeremy Ashkenas, DocumentCloud and
       * Investigative Reporters & Editors
       *
       * Permission is hereby granted, free of charge, to any person
       * obtaining a copy of this software and associated documentation
       * files (the "Software"), to deal in the Software without
       * restriction, including without limitation the rights to use,
       * copy, modify, merge, publish, distribute, sublicense, and/or sell
       * copies of the Software, and to permit persons to whom the
       * Software is furnished to do so, subject to the following
       * conditions:
       *
       * The above copyright notice and this permission notice shall be
       * included in all copies or substantial portions of the Software.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
       * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
       * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
       * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
       * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
       * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
       * OTHER DEALINGS IN THE SOFTWARE.
       */
  
      window.delay = function(func, wait) {
          var args = Array.prototype.slice.call(arguments, 2);
          return setTimeout(function(){ return func.apply(null, args); }, wait);
      };
  
      window.debounce = function(func, wait, immediate) {
          var timeout;
          return function() {
              var context = this, args = arguments;
              var later = function() {
                  timeout = null;
                  if (!immediate) func.apply(context, args);
              };
              if (immediate && !timeout) func.apply(context, args);
              clearTimeout(timeout);
              timeout = setTimeout(later, wait);
          };
      };
  
      window.throttle = function(func, wait) {
          var context, args, timeout, throttling, more, result;
          var whenDone = debounce(
              function(){ more = throttling = false; }, wait);
          return function() {
              context = this; args = arguments;
              var later = function() {
                  timeout = null;
                  if (more) func.apply(context, args);
                  whenDone();
              };
              if (!timeout) timeout = setTimeout(later, wait);
              if (throttling) {
                  more = true;
              } else {
                  result = func.apply(context, args);
              }
              whenDone();
              throttling = true;
              return result;
          };
      };
  
  })(window);
  
  ;(function(root, factory) {
  
      if (typeof define === 'function' && define.amd) {
          define('gridster-draggable', ['jquery'], factory);
      } else {
          root.GridsterDraggable = factory(root.$ || root.jQuery);
      }
  
  }(this, function($) {
  
      var defaults = {
          items: 'li',
          distance: 1,
          limit: true,
          offset_left: 0,
          autoscroll: true,
          ignore_dragging: ['INPUT', 'TEXTAREA', 'SELECT', 'BUTTON'], // or function
          handle: null,
          container_width: 0,  // 0 == auto
          move_element: true,
          helper: false,  // or 'clone'
          remove_helper: true
          // drag: function(e) {},
          // start : function(e, ui) {},
          // stop : function(e) {}
      };
  
      var $window = $(window);
      var dir_map = { x : 'left', y : 'top' };
      var isTouch = !!('ontouchstart' in window);
  
      var capitalize = function(str) {
          return str.charAt(0).toUpperCase() + str.slice(1);
      };
  
      var idCounter = 0;
      var uniqId = function() {
          return ++idCounter + '';
      }
  
      /**
       * Basic drag implementation for DOM elements inside a container.
       * Provide start/stop/drag callbacks.
       *
       * @class Draggable
       * @param {HTMLElement} el The HTMLelement that contains all the widgets
       *  to be dragged.
       * @param {Object} [options] An Object with all options you want to
       *        overwrite:
       *    @param {HTMLElement|String} [options.items] Define who will
       *     be the draggable items. Can be a CSS Selector String or a
       *     collection of HTMLElements.
       *    @param {Number} [options.distance] Distance in pixels after mousedown
       *     the mouse must move before dragging should start.
       *    @param {Boolean} [options.limit] Constrains dragging to the width of
       *     the container
       *    @param {Object|Function} [options.ignore_dragging] Array of node names
       *      that sould not trigger dragging, by default is `['INPUT', 'TEXTAREA',
       *      'SELECT', 'BUTTON']`. If a function is used return true to ignore dragging.
       *    @param {offset_left} [options.offset_left] Offset added to the item
       *     that is being dragged.
       *    @param {Number} [options.drag] Executes a callback when the mouse is
       *     moved during the dragging.
       *    @param {Number} [options.start] Executes a callback when the drag
       *     starts.
       *    @param {Number} [options.stop] Executes a callback when the drag stops.
       * @return {Object} Returns `el`.
       * @constructor
       */
      function Draggable(el, options) {
          this.options = $.extend({}, defaults, options);
          this.$document = $(document);
          this.$container = $(el);
          this.$dragitems = $(this.options.items, this.$container);
          this.is_dragging = false;
          this.player_min_left = 0 + this.options.offset_left;
          this.id = uniqId();
          this.ns = '.gridster-draggable-' + this.id;
          this.init();
      }
  
      Draggable.defaults = defaults;
  
      var fn = Draggable.prototype;
  
      fn.init = function() {
          var pos = this.$container.css('position');
          this.calculate_dimensions();
          this.$container.css('position', pos === 'static' ? 'relative' : pos);
          this.disabled = false;
          this.events();
  
          $(window).bind(this.nsEvent('resize'),
              throttle($.proxy(this.calculate_dimensions, this), 200));
      };
  
      fn.nsEvent = function(ev) {
          return (ev || '') + this.ns;
      };
  
      fn.events = function() {
          this.pointer_events = {
              start: this.nsEvent('touchstart') + ' ' + this.nsEvent('mousedown'),
              move: this.nsEvent('touchmove') + ' ' + this.nsEvent('mousemove'),
              end: this.nsEvent('touchend') + ' ' + this.nsEvent('mouseup'),
          };
  
          this.$container.on(this.nsEvent('selectstart'),
              $.proxy(this.on_select_start, this));
  
          this.$container.on(this.pointer_events.start, this.options.items,
              $.proxy(this.drag_handler, this));
  
          this.$document.on(this.pointer_events.end, $.proxy(function(e) {
              this.is_dragging = false;
              if (this.disabled) { return; }
              this.$document.off(this.pointer_events.move);
              if (this.drag_start) {
                  this.on_dragstop(e);
              }
          }, this));
      };
  
      fn.get_actual_pos = function($el) {
          var pos = $el.position();
          return pos;
      };
  
  
      fn.get_mouse_pos = function(e) {
          if (e.originalEvent && e.originalEvent.touches) {
              var oe = e.originalEvent;
              e = oe.touches.length ? oe.touches[0] : oe.changedTouches[0];
          }
  
          return {
              left: e.clientX,
              top: e.clientY
          };
      };
  
  
      fn.get_offset = function(e) {
          e.preventDefault();
          var mouse_actual_pos = this.get_mouse_pos(e);
          var diff_x = Math.round(
              mouse_actual_pos.left - this.mouse_init_pos.left);
          var diff_y = Math.round(mouse_actual_pos.top - this.mouse_init_pos.top);
  
          var left = Math.round(this.el_init_offset.left +
              diff_x - this.baseX + $(window).scrollLeft() - this.win_offset_x);
          var top = Math.round(this.el_init_offset.top +
              diff_y - this.baseY + $(window).scrollTop() - this.win_offset_y);
  
          if (this.options.limit) {
              if (left > this.player_max_left) {
                  left = this.player_max_left;
              } else if(left < this.player_min_left) {
                  left = this.player_min_left;
              }
          }
  
          return {
              position: {
                  left: left,
                  top: top
              },
              pointer: {
                  left: mouse_actual_pos.left,
                  top: mouse_actual_pos.top,
                  diff_left: diff_x + ($(window).scrollLeft() - this.win_offset_x),
                  diff_top: diff_y + ($(window).scrollTop() - this.win_offset_y)
              }
          };
      };
  
  
      fn.get_drag_data = function(e) {
          var offset = this.get_offset(e);
          offset.$player = this.$player;
          offset.$helper = this.helper ? this.$helper : this.$player;
  
          return offset;
      };
  
  
      fn.set_limits = function(container_width) {
          container_width || (container_width = this.$container.width());
          this.player_max_left = (container_width - this.player_width +
          - this.options.offset_left);
  
          this.options.container_width = container_width;
  
          return this;
      };
  
  
      fn.scroll_in = function(axis, data) {
          var dir_prop = dir_map[axis];
  
          var area_size = 50;
          var scroll_inc = 30;
  
          var is_x = axis === 'x';
          var window_size = is_x ? this.window_width : this.window_height;
          var doc_size = is_x ? $(document).width() : $(document).height();
          var player_size = is_x ? this.$player.width() : this.$player.height();
  
          var next_scroll;
          var scroll_offset = $window['scroll' + capitalize(dir_prop)]();
          var min_window_pos = scroll_offset;
          var max_window_pos = min_window_pos + window_size;
  
          var mouse_next_zone = max_window_pos - area_size;  // down/right
          var mouse_prev_zone = min_window_pos + area_size;  // up/left
  
          var abs_mouse_pos = min_window_pos + data.pointer[dir_prop];
  
          var max_player_pos = (doc_size - window_size + player_size);
  
          if (abs_mouse_pos >= mouse_next_zone) {
              next_scroll = scroll_offset + scroll_inc;
              if (next_scroll < max_player_pos) {
                  $window['scroll' + capitalize(dir_prop)](next_scroll);
                  this['scroll_offset_' + axis] += scroll_inc;
              }
          }
  
          if (abs_mouse_pos <= mouse_prev_zone) {
              next_scroll = scroll_offset - scroll_inc;
              if (next_scroll > 0) {
                  $window['scroll' + capitalize(dir_prop)](next_scroll);
                  this['scroll_offset_' + axis] -= scroll_inc;
              }
          }
  
          return this;
      };
  
  
      fn.manage_scroll = function(data) {
          this.scroll_in('x', data);
          this.scroll_in('y', data);
      };
  
  
      fn.calculate_dimensions = function(e) {
          this.window_height = $window.height();
          this.window_width = $window.width();
      };
  
  
      fn.drag_handler = function(e) {
          var node = e.target.nodeName;
          // skip if drag is disabled, or click was not done with the mouse primary button
          if (this.disabled || e.which !== 1 && !isTouch) {
              return;
          }
  
          if (this.ignore_drag(e)) {
              return;
          }
  
          var self = this;
          var first = true;
          this.$player = $(e.currentTarget);
  
          this.el_init_pos = this.get_actual_pos(this.$player);
          this.mouse_init_pos = this.get_mouse_pos(e);
          this.offsetY = this.mouse_init_pos.top - this.el_init_pos.top;
  
          this.$document.on(this.pointer_events.move, function(mme) {
              var mouse_actual_pos = self.get_mouse_pos(mme);
              var diff_x = Math.abs(
                  mouse_actual_pos.left - self.mouse_init_pos.left);
              var diff_y = Math.abs(
                  mouse_actual_pos.top - self.mouse_init_pos.top);
              if (!(diff_x > self.options.distance ||
                  diff_y > self.options.distance)
              ) {
                  return false;
              }
  
              if (first) {
                  first = false;
                  self.on_dragstart.call(self, mme);
                  return false;
              }
  
              if (self.is_dragging === true) {
                  self.on_dragmove.call(self, mme);
              }
  
              return false;
          });
  
          if (!isTouch) { return false; }
      };
  
  
      fn.on_dragstart = function(e) {
          e.preventDefault();
  
          if (this.is_dragging) { return this; }
  
          this.drag_start = this.is_dragging = true;
          var offset = this.$container.offset();
          this.baseX = Math.round(offset.left);
          this.baseY = Math.round(offset.top);
          this.initial_container_width = this.options.container_width || this.$container.width();
  
          if (this.options.helper === 'clone') {
              this.$helper = this.$player.clone()
                  .appendTo(this.$container).addClass('helper');
              this.helper = true;
          } else {
              this.helper = false;
          }
  
          this.win_offset_y = $(window).scrollTop();
          this.win_offset_x = $(window).scrollLeft();
          this.scroll_offset_y = 0;
          this.scroll_offset_x = 0;
          this.el_init_offset = this.$player.offset();
          this.player_width = this.$player.width();
          this.player_height = this.$player.height();
  
          this.set_limits(this.options.container_width);
  
          if (this.options.start) {
              this.options.start.call(this.$player, e, this.get_drag_data(e));
          }
          return false;
      };
  
  
      fn.on_dragmove = function(e) {
          var data = this.get_drag_data(e);
  
          this.options.autoscroll && this.manage_scroll(data);
  
          if (this.options.move_element) {
              (this.helper ? this.$helper : this.$player).css({
                  'position': 'absolute',
                  'left' : data.position.left,
                  'top' : data.position.top
              });
          }
  
          var last_position = this.last_position || data.position;
          data.prev_position = last_position;
  
          if (this.options.drag) {
              this.options.drag.call(this.$player, e, data);
          }
  
          this.last_position = data.position;
          return false;
      };
  
  
      fn.on_dragstop = function(e) {
          var data = this.get_drag_data(e);
          this.drag_start = false;
  
          if (this.options.stop) {
              this.options.stop.call(this.$player, e, data);
          }
  
          if (this.helper && this.options.remove_helper) {
              this.$helper.remove();
          }
  
          return false;
      };
  
      fn.on_select_start = function(e) {
          if (this.disabled) { return; }
  
          if (this.ignore_drag(e)) {
              return;
          }
  
          return false;
      };
  
      fn.enable = function() {
          this.disabled = false;
      };
  
      fn.disable = function() {
          this.disabled = true;
      };
  
      fn.destroy = function() {
          this.disable();
  
          this.$container.off(this.ns);
          this.$document.off(this.ns);
          $(window).off(this.ns);
  
          $.removeData(this.$container, 'drag');
      };
  
      fn.ignore_drag = function(event) {
          if (this.options.handle) {
              return !$(event.target).is(this.options.handle);
          }
  
          if ($.isFunction(this.options.ignore_dragging)) {
              return this.options.ignore_dragging(event);
          }
  
          return $(event.target).is(this.options.ignore_dragging.join(', '));
      };
  
      //jQuery adapter
      $.fn.drag = function ( options ) {
          return new Draggable(this, options);
      };
  
      return Draggable;
  
  }));
  
  ;(function(root, factory) {
  
      if (typeof define === 'function' && define.amd) {
          define(['jquery', 'gridster-draggable', 'gridster-collision'], factory);
      } else {
          root.Gridster = factory(root.$ || root.jQuery, root.GridsterDraggable,
              root.GridsterCollision);
      }
  
  }(this, function($, Draggable, Collision) {
  
      var defaults = {
          namespace: '',
          widget_selector: 'li',
          widget_margins: [10, 10],
          widget_base_dimensions: [400, 225],
          extra_rows: 0,
          extra_cols: 0,
          min_cols: 1,
          max_cols: Infinity,
          min_rows: 15,
          max_size_x: false,
          autogrow_cols: true,
          autogenerate_stylesheet: true,
          avoid_overlapped_widgets: true,
          auto_init: true,
          serialize_params: function($w, wgd) {
              return {
                  col: wgd.col,
                  row: wgd.row,
                  size_x: wgd.size_x,
                  size_y: wgd.size_y
              };
          },
          collision: {},
          draggable: {
              items: '.gs-w',
              distance: 4,
              ignore_dragging: Draggable.defaults.ignore_dragging.slice(0)
          },
          resize: {
              enabled: true,
              axes: ['both'],
              handle_append_to: '',
              handle_class: 'gs-resize-handle',
              max_size: [Infinity, Infinity],
              min_size: [1, 1]
          }
      };
  
      /**
       * @class Gridster
       * @uses Draggable
       * @uses Collision
       * @param {HTMLElement} el The HTMLelement that contains all the widgets.
       * @param {Object} [options] An Object with all options you want to
       *        overwrite:
       *    @param {HTMLElement|String} [options.widget_selector] Define who will
       *     be the draggable widgets. Can be a CSS Selector String or a
       *     collection of HTMLElements
       *    @param {Array} [options.widget_margins] Margin between widgets.
       *     The first index for the horizontal margin (left, right) and
       *     the second for the vertical margin (top, bottom).
       *    @param {Array} [options.widget_base_dimensions] Base widget dimensions
       *     in pixels. The first index for the width and the second for the
       *     height.
       *    @param {Number} [options.extra_cols] Add more columns in addition to
       *     those that have been calculated.
       *    @param {Number} [options.extra_rows] Add more rows in addition to
       *     those that have been calculated.
       *    @param {Number} [options.min_cols] The minimum required columns.
       *    @param {Number} [options.max_cols] The maximum columns possible (set to null
       *     for no maximum).
       *    @param {Number} [options.min_rows] The minimum required rows.
       *    @param {Number} [options.max_size_x] The maximum number of columns
       *     that a widget can span.
       *    @param {Boolean} [options.autogenerate_stylesheet] If true, all the
       *     CSS required to position all widgets in their respective columns
       *     and rows will be generated automatically and injected to the
       *     `<head>` of the document. You can set this to false, and write
       *     your own CSS targeting rows and cols via data-attributes like so:
       *     `[data-col="1"] { left: 10px; }`
       *    @param {Boolean} [options.avoid_overlapped_widgets] Avoid that widgets loaded
       *     from the DOM can be overlapped. It is helpful if the positions were
       *     bad stored in the database or if there was any conflict.
       *    @param {Boolean} [options.auto_init] Automatically call gridster init
       *     method or not when the plugin is instantiated.
       *    @param {Function} [options.serialize_params] Return the data you want
       *     for each widget in the serialization. Two arguments are passed:
       *     `$w`: the jQuery wrapped HTMLElement, and `wgd`: the grid
       *     coords object (`col`, `row`, `size_x`, `size_y`).
       *    @param {Object} [options.collision] An Object with all options for
       *     Collision class you want to overwrite. See Collision docs for
       *     more info.
       *    @param {Object} [options.draggable] An Object with all options for
       *     Draggable class you want to overwrite. See Draggable docs for more
       *     info.
       *       @param {Object|Function} [options.draggable.ignore_dragging] Note that
       *        if you use a Function, and resize is enabled, you should ignore the
       *        resize handlers manually (options.resize.handle_class).
       *    @param {Object} [options.resize] An Object with resize config options.
       *       @param {Boolean} [options.resize.enabled] Set to true to enable
       *        resizing.
       *       @param {Array} [options.resize.axes] Axes in which widgets can be
       *        resized. Possible values: ['x', 'y', 'both'].
       *       @param {String} [options.resize.handle_append_to] Set a valid CSS
       *        selector to append resize handles to.
       *       @param {String} [options.resize.handle_class] CSS class name used
       *        by resize handles.
       *       @param {Array} [options.resize.max_size] Limit widget dimensions
       *        when resizing. Array values should be integers:
       *        `[max_cols_occupied, max_rows_occupied]`
       *       @param {Array} [options.resize.min_size] Limit widget dimensions
       *        when resizing. Array values should be integers:
       *        `[min_cols_occupied, min_rows_occupied]`
       *       @param {Function} [options.resize.start] Function executed
       *        when resizing starts.
       *       @param {Function} [otions.resize.resize] Function executed
       *        during the resizing.
       *       @param {Function} [options.resize.stop] Function executed
       *        when resizing stops.
       *
       * @constructor
       */
      function Gridster(el, options) {
          this.options = $.extend(true, {}, defaults, options);
          this.$el = $(el);
          this.$wrapper = this.$el.parent();
          this.$widgets = this.$el.children(
              this.options.widget_selector).addClass('gs-w');
          this.widgets = [];
          this.$changed = $([]);
          this.wrapper_width = this.$wrapper.width();
          this.min_widget_width = (this.options.widget_margins[0] * 2) +
              this.options.widget_base_dimensions[0];
          this.min_widget_height = (this.options.widget_margins[1] * 2) +
              this.options.widget_base_dimensions[1];
  
          this.generated_stylesheets = [];
          this.$style_tags = $([]);
  
          this.options.auto_init && this.init();
      }
  
      Gridster.defaults = defaults;
      Gridster.generated_stylesheets = [];
  
  
      /**
       * Sorts an Array of grid coords objects (representing the grid coords of
       * each widget) in ascending way.
       *
       * @method sort_by_row_asc
       * @param {Array} widgets Array of grid coords objects
       * @return {Array} Returns the array sorted.
       */
      Gridster.sort_by_row_asc = function(widgets) {
          widgets = widgets.sort(function(a, b) {
              if (!a.row) {
                  a = $(a).coords().grid;
                  b = $(b).coords().grid;
              }
  
              if (a.row > b.row) {
                  return 1;
              }
              return -1;
          });
  
          return widgets;
      };
  
  
      /**
       * Sorts an Array of grid coords objects (representing the grid coords of
       * each widget) placing first the empty cells upper left.
       *
       * @method sort_by_row_and_col_asc
       * @param {Array} widgets Array of grid coords objects
       * @return {Array} Returns the array sorted.
       */
      Gridster.sort_by_row_and_col_asc = function(widgets) {
          widgets = widgets.sort(function(a, b) {
              if (a.row > b.row || a.row === b.row && a.col > b.col) {
                  return 1;
              }
              return -1;
          });
  
          return widgets;
      };
  
  
      /**
       * Sorts an Array of grid coords objects by column (representing the grid
       * coords of each widget) in ascending way.
       *
       * @method sort_by_col_asc
       * @param {Array} widgets Array of grid coords objects
       * @return {Array} Returns the array sorted.
       */
      Gridster.sort_by_col_asc = function(widgets) {
          widgets = widgets.sort(function(a, b) {
              if (a.col > b.col) {
                  return 1;
              }
              return -1;
          });
  
          return widgets;
      };
  
  
      /**
       * Sorts an Array of grid coords objects (representing the grid coords of
       * each widget) in descending way.
       *
       * @method sort_by_row_desc
       * @param {Array} widgets Array of grid coords objects
       * @return {Array} Returns the array sorted.
       */
      Gridster.sort_by_row_desc = function(widgets) {
          widgets = widgets.sort(function(a, b) {
              if (a.row + a.size_y < b.row + b.size_y) {
                  return 1;
              }
              return -1;
          });
          return widgets;
      };
  
  
  
      /** Instance Methods **/
  
      var fn = Gridster.prototype;
  
      fn.init = function() {
          this.options.resize.enabled && this.setup_resize();
          this.generate_grid_and_stylesheet();
          this.get_widgets_from_DOM();
          this.set_dom_grid_height();
          this.set_dom_grid_width();
          this.$wrapper.addClass('ready');
          this.draggable();
          this.options.resize.enabled && this.resizable();
  
          $(window).bind('resize.gridster', throttle(
              $.proxy(this.recalculate_faux_grid, this), 200));
      };
  
  
      /**
       * Disables dragging.
       *
       * @method disable
       * @return {Class} Returns the instance of the Gridster Class.
       */
      fn.disable = function() {
          this.$wrapper.find('.player-revert').removeClass('player-revert');
          this.drag_api.disable();
          return this;
      };
  
  
      /**
       * Enables dragging.
       *
       * @method enable
       * @return {Class} Returns the instance of the Gridster Class.
       */
      fn.enable = function() {
          this.drag_api.enable();
          return this;
      };
  
  
  
      /**
       * Disables drag-and-drop widget resizing.
       *
       * @method disable
       * @return {Class} Returns instance of gridster Class.
       */
      fn.disable_resize = function() {
          this.$el.addClass('gs-resize-disabled');
          this.resize_api.disable();
          return this;
      };
  
  
      /**
       * Enables drag-and-drop widget resizing.
       *
       * @method enable
       * @return {Class} Returns instance of gridster Class.
       */
      fn.enable_resize = function() {
          this.$el.removeClass('gs-resize-disabled');
          this.resize_api.enable();
          return this;
      };
  
  
      /**
       * Add a new widget to the grid.
       *
       * @method add_widget
       * @param {String|HTMLElement} html The string representing the HTML of the widget
       *  or the HTMLElement.
       * @param {Number} [size_x] The nº of rows the widget occupies horizontally.
       * @param {Number} [size_y] The nº of columns the widget occupies vertically.
       * @param {Number} [col] The column the widget should start in.
       * @param {Number} [row] The row the widget should start in.
       * @param {Array} [max_size] max_size Maximun size (in units) for width and height.
       * @param {Array} [min_size] min_size Minimum size (in units) for width and height.
       * @return {HTMLElement} Returns the jQuery wrapped HTMLElement representing.
       *  the widget that was just created.
       */
      fn.add_widget = function(html, size_x, size_y, col, row, max_size, min_size) {
          var pos;
          size_x || (size_x = 1);
          size_y || (size_y = 1);
  
          if (!col & !row) {
              pos = this.next_position(size_x, size_y);
          } else {
              pos = {
                  col: col,
                  row: row,
                  size_x: size_x,
                  size_y: size_y
              };
  
              this.empty_cells(col, row, size_x, size_y);
          }
  
          var $w = $(html).attr({
              'data-col': pos.col,
              'data-row': pos.row,
              'data-sizex' : size_x,
              'data-sizey' : size_y
          }).addClass('gs-w').appendTo(this.$el).hide();
  
          this.$widgets = this.$widgets.add($w);
  
          this.register_widget($w);
  
          this.add_faux_rows(pos.size_y);
          //this.add_faux_cols(pos.size_x);
  
          if (max_size) {
              this.set_widget_max_size($w, max_size);
          }
  
          if (min_size) {
              this.set_widget_min_size($w, min_size);
          }
  
          this.set_dom_grid_width();
          this.set_dom_grid_height();
  
          this.drag_api.set_limits(this.cols * this.min_widget_width);
  
          return $w.show();
      };
  
  
      /**
       * Change widget size limits.
       *
       * @method set_widget_min_size
       * @param {HTMLElement|Number} $widget The jQuery wrapped HTMLElement
       *  representing the widget or an index representing the desired widget.
       * @param {Array} min_size Minimum size (in units) for width and height.
       * @return {HTMLElement} Returns instance of gridster Class.
       */
      fn.set_widget_min_size = function($widget, min_size) {
          $widget = typeof $widget === 'number' ?
              this.$widgets.eq($widget) : $widget;
  
          if (!$widget.length) { return this; }
  
          var wgd = $widget.data('coords').grid;
          wgd.min_size_x = min_size[0];
          wgd.min_size_y = min_size[1];
  
          return this;
      };
  
  
      /**
       * Change widget size limits.
       *
       * @method set_widget_max_size
       * @param {HTMLElement|Number} $widget The jQuery wrapped HTMLElement
       *  representing the widget or an index representing the desired widget.
       * @param {Array} max_size Maximun size (in units) for width and height.
       * @return {HTMLElement} Returns instance of gridster Class.
       */
      fn.set_widget_max_size = function($widget, max_size) {
          $widget = typeof $widget === 'number' ?
              this.$widgets.eq($widget) : $widget;
  
          if (!$widget.length) { return this; }
  
          var wgd = $widget.data('coords').grid;
          wgd.max_size_x = max_size[0];
          wgd.max_size_y = max_size[1];
  
          return this;
      };
  
  
      /**
       * Append the resize handle into a widget.
       *
       * @method add_resize_handle
       * @param {HTMLElement} $widget The jQuery wrapped HTMLElement
       *  representing the widget.
       * @return {HTMLElement} Returns instance of gridster Class.
       */
      fn.add_resize_handle = function($w) {
          var append_to = this.options.resize.handle_append_to;
          var handle = $('.' + this.options.resize.handle_class, $w);
          if(handle.length == 0)
              $(this.resize_handle_tpl).appendTo( append_to ? $(append_to, $w) : $w);
  
          return this;
      };
  
  
      /**
       * Change the size of a widget. Width is limited to the current grid width.
       *
       * @method resize_widget
       * @param {HTMLElement} $widget The jQuery wrapped HTMLElement
       *  representing the widget.
       * @param {Number} size_x The number of columns that will occupy the widget.
       *  By default <code>size_x</code> is limited to the space available from
       *  the column where the widget begins, until the last column to the right.
       * @param {Number} size_y The number of rows that will occupy the widget.
       * @param {Function} [callback] Function executed when the widget is removed.
       * @return {HTMLElement} Returns $widget.
       */
      fn.resize_widget = function($widget, size_x, size_y, callback) {
          var wgd = $widget.coords().grid;
          var col = wgd.col;
          var max_cols = this.options.max_cols;
          var old_size_y = wgd.size_y;
          var old_col = wgd.col;
          var new_col = old_col;
  
          size_x || (size_x = wgd.size_x);
          size_y || (size_y = wgd.size_y);
  
          if (max_cols !== Infinity) {
              size_x = Math.min(size_x, max_cols - col + 1);
          }
  
          if (size_y > old_size_y) {
              this.add_faux_rows(Math.max(size_y - old_size_y, 0));
          }
  
          var player_rcol = (col + size_x - 1);
          if (player_rcol > this.cols) {
              this.add_faux_cols(player_rcol - this.cols);
          }
  
          var new_grid_data = {
              col: new_col,
              row: wgd.row,
              size_x: size_x,
              size_y: size_y
          };
  
          this.mutate_widget_in_gridmap($widget, wgd, new_grid_data);
  
          this.set_dom_grid_height();
          this.set_dom_grid_width();
  
          if (callback) {
              callback.call(this, new_grid_data.size_x, new_grid_data.size_y);
          }
  
          return $widget;
      };
  
  
      /**
       * Mutate widget dimensions and position in the grid map.
       *
       * @method mutate_widget_in_gridmap
       * @param {HTMLElement} $widget The jQuery wrapped HTMLElement
       *  representing the widget to mutate.
       * @param {Object} wgd Current widget grid data (col, row, size_x, size_y).
       * @param {Object} new_wgd New widget grid data.
       * @return {HTMLElement} Returns instance of gridster Class.
       */
      fn.mutate_widget_in_gridmap = function($widget, wgd, new_wgd) {
          var old_size_x = wgd.size_x;
          var old_size_y = wgd.size_y;
  
          var old_cells_occupied = this.get_cells_occupied(wgd);
          var new_cells_occupied = this.get_cells_occupied(new_wgd);
  
          var empty_cols = [];
          $.each(old_cells_occupied.cols, function(i, col) {
              if ($.inArray(col, new_cells_occupied.cols) === -1) {
                  empty_cols.push(col);
              }
          });
  
          var occupied_cols = [];
          $.each(new_cells_occupied.cols, function(i, col) {
              if ($.inArray(col, old_cells_occupied.cols) === -1) {
                  occupied_cols.push(col);
              }
          });
  
          var empty_rows = [];
          $.each(old_cells_occupied.rows, function(i, row) {
              if ($.inArray(row, new_cells_occupied.rows) === -1) {
                  empty_rows.push(row);
              }
          });
  
          var occupied_rows = [];
          $.each(new_cells_occupied.rows, function(i, row) {
              if ($.inArray(row, old_cells_occupied.rows) === -1) {
                  occupied_rows.push(row);
              }
          });
  
          this.remove_from_gridmap(wgd);
  
          if (occupied_cols.length) {
              var cols_to_empty = [
                  new_wgd.col, new_wgd.row, new_wgd.size_x, Math.min(old_size_y, new_wgd.size_y), $widget
              ];
              this.empty_cells.apply(this, cols_to_empty);
          }
  
          if (occupied_rows.length) {
              var rows_to_empty = [new_wgd.col, new_wgd.row, new_wgd.size_x, new_wgd.size_y, $widget];
              this.empty_cells.apply(this, rows_to_empty);
          }
  
          // not the same that wgd = new_wgd;
          wgd.col = new_wgd.col;
          wgd.row = new_wgd.row;
          wgd.size_x = new_wgd.size_x;
          wgd.size_y = new_wgd.size_y;
  
          this.add_to_gridmap(new_wgd, $widget);
  
          $widget.removeClass('player-revert');
  
          //update coords instance attributes
          $widget.data('coords').update({
              width: (new_wgd.size_x * this.options.widget_base_dimensions[0] +
              ((new_wgd.size_x - 1) * this.options.widget_margins[0]) * 2),
              height: (new_wgd.size_y * this.options.widget_base_dimensions[1] +
              ((new_wgd.size_y - 1) * this.options.widget_margins[1]) * 2)
          });
  
          $widget.attr({
              'data-col': new_wgd.col,
              'data-row': new_wgd.row,
              'data-sizex': new_wgd.size_x,
              'data-sizey': new_wgd.size_y
          });
  
          if (empty_cols.length) {
              var cols_to_remove_holes = [
                  empty_cols[0], new_wgd.row,
                  empty_cols.length,
                  Math.min(old_size_y, new_wgd.size_y),
                  $widget
              ];
  
              this.remove_empty_cells.apply(this, cols_to_remove_holes);
          }
  
          if (empty_rows.length) {
              var rows_to_remove_holes = [
                  new_wgd.col, new_wgd.row, new_wgd.size_x, new_wgd.size_y, $widget
              ];
              this.remove_empty_cells.apply(this, rows_to_remove_holes);
          }
  
          this.move_widget_up($widget);
  
          return this;
      };
  
  
      /**
       * Move down widgets in cells represented by the arguments col, row, size_x,
       * size_y
       *
       * @method empty_cells
       * @param {Number} col The column where the group of cells begin.
       * @param {Number} row The row where the group of cells begin.
       * @param {Number} size_x The number of columns that the group of cells
       * occupy.
       * @param {Number} size_y The number of rows that the group of cells
       * occupy.
       * @param {HTMLElement} $exclude Exclude widgets from being moved.
       * @return {Class} Returns the instance of the Gridster Class.
       */
      fn.empty_cells = function(col, row, size_x, size_y, $exclude) {
          var $nexts = this.widgets_below({
              col: col,
              row: row - size_y,
              size_x: size_x,
              size_y: size_y
          });
  
          $nexts.not($exclude).each($.proxy(function(i, w) {
              var wgd = $(w).coords().grid;
              if ( !(wgd.row <= (row + size_y - 1))) { return; }
              var diff =  (row + size_y) - wgd.row;
              this.move_widget_down($(w), diff);
          }, this));
  
          this.set_dom_grid_height();
  
          return this;
      };
  
  
      /**
       * Move up widgets below cells represented by the arguments col, row, size_x,
       * size_y.
       *
       * @method remove_empty_cells
       * @param {Number} col The column where the group of cells begin.
       * @param {Number} row The row where the group of cells begin.
       * @param {Number} size_x The number of columns that the group of cells
       * occupy.
       * @param {Number} size_y The number of rows that the group of cells
       * occupy.
       * @param {HTMLElement} exclude Exclude widgets from being moved.
       * @return {Class} Returns the instance of the Gridster Class.
       */
      fn.remove_empty_cells = function(col, row, size_x, size_y, exclude) {
          var $nexts = this.widgets_below({
              col: col,
              row: row,
              size_x: size_x,
              size_y: size_y
          });
  
          $nexts.not(exclude).each($.proxy(function(i, widget) {
              this.move_widget_up( $(widget), size_y );
          }, this));
  
          this.set_dom_grid_height();
  
          return this;
      };
  
  
      /**
       * Get the most left column below to add a new widget.
       *
       * @method next_position
       * @param {Number} size_x The nº of rows the widget occupies horizontally.
       * @param {Number} size_y The nº of columns the widget occupies vertically.
       * @return {Object} Returns a grid coords object representing the future
       *  widget coords.
       */
      fn.next_position = function(size_x, size_y) {
          size_x || (size_x = 1);
          size_y || (size_y = 1);
          var ga = this.gridmap;
          var cols_l = ga.length;
          var valid_pos = [];
          var rows_l;
  
          for (var c = 1; c < cols_l; c++) {
              rows_l = ga[c].length;
              for (var r = 1; r <= rows_l; r++) {
                  var can_move_to = this.can_move_to({
                      size_x: size_x,
                      size_y: size_y
                  }, c, r);
  
                  if (can_move_to) {
                      valid_pos.push({
                          col: c,
                          row: r,
                          size_y: size_y,
                          size_x: size_x
                      });
                  }
              }
          }
  
          if (valid_pos.length) {
              return Gridster.sort_by_row_and_col_asc(valid_pos)[0];
          }
          return false;
      };
  
  
      /**
       * Remove a widget from the grid.
       *
       * @method remove_widget
       * @param {HTMLElement} el The jQuery wrapped HTMLElement you want to remove.
       * @param {Boolean|Function} silent If true, widgets below the removed one
       * will not move up. If a Function is passed it will be used as callback.
       * @param {Function} callback Function executed when the widget is removed.
       * @return {Class} Returns the instance of the Gridster Class.
       */
      fn.remove_widget = function(el, silent, callback) {
          var $el = el instanceof $ ? el : $(el);
          var wgd = $el.coords().grid;
  
          // if silent is a function assume it's a callback
          if ($.isFunction(silent)) {
              callback = silent;
              silent = false;
          }
  
          this.cells_occupied_by_placeholder = {};
          this.$widgets = this.$widgets.not($el);
  
          var $nexts = this.widgets_below($el);
  
          this.remove_from_gridmap(wgd);
  
          $el.hide(0, $.proxy(function() {
              $el.remove();
  
              if (!silent) {
                  $nexts.each($.proxy(function(i, widget) {
                      this.move_widget_up( $(widget), wgd.size_y );
                  }, this));
              }
  
              this.set_dom_grid_height();
  
              if (callback) {
                  callback.call(this, el);
              }
          }, this));
  
          return this;
      };
  
  
      /**
       * Remove all widgets from the grid.
       *
       * @method remove_all_widgets
       * @param {Function} callback Function executed for each widget removed.
       * @return {Class} Returns the instance of the Gridster Class.
       */
      fn.remove_all_widgets = function(callback) {
          this.$widgets.each($.proxy(function(i, el){
              this.remove_widget(el, true, callback);
          }, this));
  
          return this;
      };
  
  
      /**
       * Returns a serialized array of the widgets in the grid.
       *
       * @method serialize
       * @param {HTMLElement} [$widgets] The collection of jQuery wrapped
       *  HTMLElements you want to serialize. If no argument is passed all widgets
       *  will be serialized.
       * @return {Array} Returns an Array of Objects with the data specified in
       *  the serialize_params option.
       */
      fn.serialize = function($widgets) {
          $widgets || ($widgets = this.$widgets);
  
          return $widgets.map($.proxy(function(i, widget) {
              var $w = $(widget);
              return this.options.serialize_params($w, $w.coords().grid);
          }, this)).get();
      };
  
  
      /**
       * Returns a serialized array of the widgets that have changed their
       *  position.
       *
       * @method serialize_changed
       * @return {Array} Returns an Array of Objects with the data specified in
       *  the serialize_params option.
       */
      fn.serialize_changed = function() {
          return this.serialize(this.$changed);
      };
  
  
      /**
       * Convert widgets from DOM elements to "widget grid data" Objects.
       *
       * @method dom_to_coords
       * @param {HTMLElement} $widget The widget to be converted.
       */
      fn.dom_to_coords = function($widget) {
          return {
              'col': parseInt($widget.attr('data-col'), 10),
              'row': parseInt($widget.attr('data-row'), 10),
              'size_x': parseInt($widget.attr('data-sizex'), 10) || 1,
              'size_y': parseInt($widget.attr('data-sizey'), 10) || 1,
              'max_size_x': parseInt($widget.attr('data-max-sizex'), 10) || false,
              'max_size_y': parseInt($widget.attr('data-max-sizey'), 10) || false,
              'min_size_x': parseInt($widget.attr('data-min-sizex'), 10) || false,
              'min_size_y': parseInt($widget.attr('data-min-sizey'), 10) || false,
              'el': $widget
          };
      };
  
  
      /**
       * * converts (column,row, sizex, sizey) space into pixel (x,y, width, height) space
       * @param grid_data grid data
       * @returns {{x: *, y: *, width: number, height: number}}
       */
  
      fn.coords_to_dom = function(grid_data)
      {
          var dimensions = this.options.widget_base_dimensions,
              margins = this.options.widget_margins;
  
          return {
              x: (grid_data.col - 1) * (dimensions[0] + 2*margins[0]) + margins[0],
              y: (grid_data.row - 1) * (dimensions[1] + 2*margins[1]) + margins[1],
              width : grid_data.size_x*dimensions[0] + (grid_data.size_x-1)*2*margins[0],
              height : grid_data.size_y*dimensions[1] + (grid_data.size_y-1)*2*margins[1]
          };
  
      };
  
      /**
       * arranges the widgets to remove vertical clipping
       * @param widgets to check*
       */
  
      fn.arrange_widgets_no_vertical_clipping = function ($check_widgets) {
  
          var count = $check_widgets.length,
              i = 0;
  
          for (; i < count; i++) {
              var $w = $($check_widgets[i]);
              if (this.is_clipped_vertically($w.coords().grid)) {
                  this.move_widget_to_closest_available_cell($w);
              }
          }
  
      };
  
      /**
       * Is the widget vertically clipped ?
       * @param grid_data
       * @returns {boolean} true of clipped, false otherwise
       */
  
      fn.is_clipped_vertically = function(grid_data)
      {
          var frame = this.coords_to_dom(grid_data);
          return (frame.y+frame.height + this.options.widget_margins[1]+16.0 > this.$wrapper.height());
  
      };
  
      /**
       * moves the widget to the closest available not clipped cell. If this cannot be
       * done, the widget is not moved
       * @param $widget
       * @returns false if not moved, Gridster object if moved
       */
  
      fn.move_widget_to_closest_available_cell = function($widget){
  
          var widget_grid_data = $widget.coords().grid;
          var start_col = widget_grid_data.col;
  
          var new_data = $.extend({}, widget_grid_data);
          var placed = false;
  
          //check in this column
          var row = this.get_highest_occupied_row_for_col(new_data.col)+2;
  
          while(row > 1 && !placed){
              row--;
              placed = this.move_widget_to_row_in_col($widget, row, new_data.col);
          }
  
          if(placed){
              return this;
          }
  
          var shift_idx = 1;
  
          while(start_col - shift_idx > 0 && !placed){
              //check column to left
              new_data.col = start_col - shift_idx;
              var row = this.get_highest_occupied_row_for_col(new_data.col)+2;
              while(row > 1 && !placed){
                  row--;
                  placed = this.move_widget_to_row_in_col($widget, row, new_data.col);
  
              }
  
              if(placed){
                  return this;
              }
  
              new_data.col = start_col + shift_idx;
              row = this.get_highest_occupied_row_for_col(new_data.col)+2;
  
              while(row > 1 && !placed){
                  row--;
                  placed = this.move_widget_to_row_in_col($widget, row, new_data.col);
  
              }
  
              if(placed){
                  return this;
              }
  
              shift_idx++;
          }
  
          //keep checking to the right
          while(!placed && new_data.col < 100){
  
              new_data.col = start_col + shift_idx;
              var row = this.get_highest_occupied_row_for_col(new_data.col)+2;
              while(row > 1 && !placed){
                  row--;
                  placed = this.move_widget_to_row_in_col($widget, row, new_data.col);
  
              }
  
              if(placed){
                  return this;
              }
  
              shift_idx++;
          }
  
          return false;
      };
  
  
      /**
       * Creates the grid coords object representing the widget an add it to the
       * mapped array of positions.
       *
       * @method register_widget
       * @param {HTMLElement|Object} $el jQuery wrapped HTMLElement representing
       *  the widget, or an "widget grid data" Object with (col, row, el ...).
       * @return {Boolean} Returns true if the widget final position is different
       *  than the original.
       */
      fn.register_widget = function($el) {
          var isDOM = $el instanceof jQuery;
          var wgd = isDOM ? this.dom_to_coords($el) : $el;
          var posChanged = false;
          isDOM || ($el = wgd.el);
  
          var empty_upper_row = this.can_go_widget_up(wgd);
          if (empty_upper_row) {
              wgd.row = empty_upper_row;
              $el.attr('data-row', empty_upper_row);
              this.$el.trigger('gridster:positionchanged', [wgd]);
              posChanged = true;
          }
  
          if (this.options.avoid_overlapped_widgets &&
              !this.can_move_to(
                  {size_x: wgd.size_x, size_y: wgd.size_y}, wgd.col, wgd.row)
          ) {
              $.extend(wgd, this.next_position(wgd.size_x, wgd.size_y));
              $el.attr({
                  'data-col': wgd.col,
                  'data-row': wgd.row,
                  'data-sizex': wgd.size_x,
                  'data-sizey': wgd.size_y
              });
              posChanged = true;
          }
  
          // attach Coord object to player data-coord attribute
          $el.data('coords', $el.coords());
          // Extend Coord object with grid position info
          $el.data('coords').grid = wgd;
  
          this.add_to_gridmap(wgd, $el);
  
          this.options.resize.enabled && this.add_resize_handle($el);
  
          return posChanged;
      };
  
  
      /**
       * Update in the mapped array of positions the value of cells represented by
       * the grid coords object passed in the `grid_data` param.
       *
       * @param {Object} grid_data The grid coords object representing the cells
       *  to update in the mapped array.
       * @param {HTMLElement|Boolean} value Pass `false` or the jQuery wrapped
       *  HTMLElement, depends if you want to delete an existing position or add
       *  a new one.
       * @method update_widget_position
       * @return {Class} Returns the instance of the Gridster Class.
       */
      fn.update_widget_position = function(grid_data, value) {
          this.for_each_cell_occupied(grid_data, function(col, row) {
              if (!this.gridmap[col]) { return this; }
              this.gridmap[col][row] = value;
          });
          return this;
      };
  
  
      /**
       * Remove a widget from the mapped array of positions.
       *
       * @method remove_from_gridmap
       * @param {Object} grid_data The grid coords object representing the cells
       *  to update in the mapped array.
       * @return {Class} Returns the instance of the Gridster Class.
       */
      fn.remove_from_gridmap = function(grid_data) {
          return this.update_widget_position(grid_data, false);
      };
  
  
      /**
       * Add a widget to the mapped array of positions.
       *
       * @method add_to_gridmap
       * @param {Object} grid_data The grid coords object representing the cells
       *  to update in the mapped array.
       * @param {HTMLElement|Boolean} value The value to set in the specified
       *  position .
       * @return {Class} Returns the instance of the Gridster Class.
       */
      fn.add_to_gridmap = function(grid_data, value) {
          this.update_widget_position(grid_data, value || grid_data.el);
  
          if (grid_data.el) {
              var $widgets = this.widgets_below(grid_data.el);
              $widgets.each($.proxy(function(i, widget) {
                  this.move_widget_up( $(widget));
              }, this));
          }
      };
  
  
      /**
       * Make widgets draggable.
       *
       * @uses Draggable
       * @method draggable
       * @return {Class} Returns the instance of the Gridster Class.
       */
      fn.draggable = function() {
          var self = this;
          var draggable_options = $.extend(true, {}, this.options.draggable, {
              offset_left: this.options.widget_margins[0],
              offset_top: this.options.widget_margins[1],
              container_width: this.cols * this.min_widget_width,
              limit: true,
              start: function(event, ui) {
                  self.$widgets.filter('.player-revert')
                      .removeClass('player-revert');
  
                  self.$player = $(this);
                  self.$helper = $(ui.$helper);
  
                  self.helper = !self.$helper.is(self.$player);
  
                  self.on_start_drag.call(self, event, ui);
                  self.$el.trigger('gridster:dragstart');
              },
              stop: function(event, ui) {
                  self.on_stop_drag.call(self, event, ui);
                  self.$el.trigger('gridster:dragstop');
              },
              drag: throttle(function(event, ui) {
                  self.on_drag.call(self, event, ui);
                  self.$el.trigger('gridster:drag');
              }, 60)
          });
  
          this.drag_api = this.$el.drag(draggable_options);
          return this;
      };
  
  
      /**
       * Bind resize events to get resize working.
       *
       * @method resizable
       * @return {Class} Returns instance of gridster Class.
       */
      fn.resizable = function() {
          this.resize_api = this.$el.drag({
              items: '.' + this.options.resize.handle_class,
              offset_left: this.options.widget_margins[0],
              container_width: this.container_width,
              move_element: false,
              resize: true,
              limit: this.options.autogrow_cols ? false : true,
              start: $.proxy(this.on_start_resize, this),
              stop: $.proxy(function(event, ui) {
                  delay($.proxy(function() {
                      this.on_stop_resize(event, ui);
                  }, this), 120);
              }, this),
              drag: throttle($.proxy(this.on_resize, this), 60)
          });
  
          return this;
      };
  
  
      /**
       * Setup things required for resizing. Like build templates for drag handles.
       *
       * @method setup_resize
       * @return {Class} Returns instance of gridster Class.
       */
      fn.setup_resize = function() {
          this.resize_handle_class = this.options.resize.handle_class;
          var axes = this.options.resize.axes;
          var handle_tpl = '<span class="' + this.resize_handle_class + ' ' +
              this.resize_handle_class + '-{type}" />';
  
          this.resize_handle_tpl = $.map(axes, function(type) {
              return handle_tpl.replace('{type}', type);
          }).join('');
  
          if ($.isArray(this.options.draggable.ignore_dragging)) {
              this.options.draggable.ignore_dragging.push(
                  '.' + this.resize_handle_class);
          }
  
          return this;
      };
  
  
      /**
       * This function is executed when the player begins to be dragged.
       *
       * @method on_start_drag
       * @param {Event} event The original browser event
       * @param {Object} ui A prepared ui object with useful drag-related data
       */
      fn.on_start_drag = function(event, ui) {
          this.$helper.add(this.$player).add(this.$wrapper).addClass('dragging');
  
          this.highest_col = this.get_highest_occupied_cell().col;
  
          this.$player.addClass('player');
          this.player_grid_data = this.$player.coords().grid;
          this.placeholder_grid_data = $.extend({}, this.player_grid_data);
  
          this.$vertically_clipped_widgets = [];
  
          this.set_dom_grid_height(this.$el.height() +
              (this.player_grid_data.size_y * this.min_widget_height));
  
          this.set_dom_grid_width(this.cols);
  
          var pgd_sizex = this.player_grid_data.size_x;
          var cols_diff = this.cols - this.highest_col;
  
          if (this.options.autogrow_cols && cols_diff <= pgd_sizex) {
              this.add_faux_cols(Math.min(pgd_sizex - cols_diff, 1));
          }
  
          var colliders = this.faux_grid;
          var coords = this.$player.data('coords').coords;
  
          this.cells_occupied_by_player = this.get_cells_occupied(
              this.player_grid_data);
          this.cells_occupied_by_placeholder = this.get_cells_occupied(
              this.placeholder_grid_data);
  
          this.last_cols = [];
          this.last_rows = [];
  
          // see jquery.collision.js
          this.collision_api = this.$helper.collision(
              colliders, this.options.collision);
  
          this.$preview_holder = $('<' + this.$player.get(0).tagName + ' />', {
              'class': 'preview-holder',
              'data-row': this.$player.attr('data-row'),
              'data-col': this.$player.attr('data-col'),
              css: {
                  width: coords.width,
                  height: coords.height
              }
          }).appendTo(this.$el);
  
          if (this.options.draggable.start) {
              this.options.draggable.start.call(this, event, ui);
          }
      };
  
  
      /**
       * This function is executed when the player is being dragged.
       *
       * @method on_drag
       * @param {Event} event The original browser event
       * @param {Object} ui A prepared ui object with useful drag-related data
       */
      fn.on_drag = function(event, ui) {
          //break if dragstop has been fired
          if (this.$player === null) {
              return false;
          }
  
          var abs_offset = {
              left: ui.position.left + this.baseX,
              top: ui.position.top + this.baseY
          };
  
          // auto grow cols
          if (this.options.autogrow_cols) {
              var prcol = this.placeholder_grid_data.col +
                  this.placeholder_grid_data.size_x - 1;
  
              // "- 1" due to adding at least 1 column in on_start_drag
              if (prcol >= this.cols - 1 && this.options.max_cols >= this.cols + 1) {
                  this.add_faux_cols(1);
                  this.set_dom_grid_width(this.cols + 1);
                  this.drag_api.set_limits(this.container_width);
              }
  
              this.collision_api.set_colliders(this.faux_grid);
          }
  
          this.colliders_data = this.collision_api.get_closest_colliders(
              abs_offset);
  
          this.on_overlapped_column_change(
              this.on_start_overlapping_column, this.on_stop_overlapping_column);
  
          this.on_overlapped_row_change(
              this.on_start_overlapping_row, this.on_stop_overlapping_row);
  
  
          if (this.helper && this.$player) {
              this.$player.css({
                  'left': ui.position.left,
                  'top': ui.position.top
              });
          }
  
          if (this.options.draggable.drag) {
              this.options.draggable.drag.call(this, event, ui);
          }
      };
  
  
      /**
       * This function is executed when the player stops being dragged.
       *
       * @method on_stop_drag
       * @param {Event} event The original browser event
       * @param {Object} ui A prepared ui object with useful drag-related data
       */
      fn.on_stop_drag = function(event, ui) {
          this.$helper.add(this.$player).add(this.$wrapper)
              .removeClass('dragging');
  
          ui.position.left = ui.position.left + this.baseX;
          ui.position.top = ui.position.top + this.baseY;
          this.colliders_data = this.collision_api.get_closest_colliders(
              ui.position);
  
          this.on_overlapped_column_change(
              this.on_start_overlapping_column,
              this.on_stop_overlapping_column
          );
  
          this.on_overlapped_row_change(
              this.on_start_overlapping_row,
              this.on_stop_overlapping_row
          );
  
          this.$player.addClass('player-revert').removeClass('player')
              .attr({
                  'data-col': this.placeholder_grid_data.col,
                  'data-row': this.placeholder_grid_data.row
              }).css({
                  'left': '',
                  'top': ''
              });
  
          this.$changed = this.$changed.add(this.$player);
  
          this.cells_occupied_by_player = this.get_cells_occupied(
              this.placeholder_grid_data);
          this.set_cells_player_occupies(
              this.placeholder_grid_data.col, this.placeholder_grid_data.row);
  
          this.$player.coords().grid.row = this.placeholder_grid_data.row;
          this.$player.coords().grid.col = this.placeholder_grid_data.col;
  
          if (this.options.draggable.stop) {
              this.options.draggable.stop.call(this, event, ui);
          }
  
          this.$preview_holder.remove();
  
          if (!this.$vertically_clipped_widgets) {
              this.$vertically_clipped_widgets = [];
          }
  
          this.$vertically_clipped_widgets.push(this.$player);
  
          this.arrange_widgets_no_vertical_clipping(this.$widgets);
  
          this.$vertically_clipped_widgets = [];
  
          this.$player = null;
          this.$helper = null;
          this.placeholder_grid_data = {};
          this.player_grid_data = {};
          this.cells_occupied_by_placeholder = {};
          this.cells_occupied_by_player = {};
  
          this.set_dom_grid_height();
          this.set_dom_grid_width();
  
          if (this.options.autogrow_cols) {
              this.drag_api.set_limits(this.cols * this.min_widget_width);
          }
  
  
      };
  
  
      /**
       * This function is executed every time a widget starts to be resized.
       *
       * @method on_start_resize
       * @param {Event} event The original browser event
       * @param {Object} ui A prepared ui object with useful drag-related data
       */
      fn.on_start_resize = function(event, ui) {
          this.$resized_widget = ui.$player.closest('.gs-w');
          this.resize_coords = this.$resized_widget.coords();
          this.resize_wgd = this.resize_coords.grid;
          this.resize_initial_width = this.resize_coords.coords.width;
          this.resize_initial_height = this.resize_coords.coords.height;
          this.resize_initial_sizex = this.resize_coords.grid.size_x;
          this.resize_initial_sizey = this.resize_coords.grid.size_y;
          this.resize_initial_col = this.resize_coords.grid.col;
          this.resize_last_sizex = this.resize_initial_sizex;
          this.resize_last_sizey = this.resize_initial_sizey;
  
          this.resize_max_size_x = Math.min(this.resize_wgd.max_size_x ||
              this.options.resize.max_size[0],
              this.options.max_cols - this.resize_initial_col + 1);
          this.resize_max_size_y = this.resize_wgd.max_size_y ||
              this.options.resize.max_size[1];
  
          this.resize_min_size_x = (this.resize_wgd.min_size_x ||
          this.options.resize.min_size[0] || 1);
          this.resize_min_size_y = (this.resize_wgd.min_size_y ||
          this.options.resize.min_size[1] || 1);
  
          this.resize_initial_last_col = this.get_highest_occupied_cell().col;
  
          this.set_dom_grid_width(this.cols);
  
          this.resize_dir = {
              right: ui.$player.is('.' + this.resize_handle_class + '-x'),
              bottom: ui.$player.is('.' + this.resize_handle_class + '-y')
          };
  
          this.$resized_widget.css({
              'min-width': this.options.widget_base_dimensions[0],
              'min-height': this.options.widget_base_dimensions[1]
          });
  
          var nodeName = this.$resized_widget.get(0).tagName;
          this.$resize_preview_holder = $('<' + nodeName + ' />', {
              'class': 'preview-holder resize-preview-holder',
              'data-row': this.$resized_widget.attr('data-row'),
              'data-col': this.$resized_widget.attr('data-col'),
              'css': {
                  'width': this.resize_initial_width,
                  'height': this.resize_initial_height
              }
          }).appendTo(this.$el);
  
          this.$resized_widget.addClass('resizing');
  
          this.$vertically_clipped_widgets = [];
  
          if (this.options.resize.start) {
              this.options.resize.start.call(this, event, ui, this.$resized_widget);
          }
  
          this.$el.trigger('gridster:resizestart');
      };
  
  
      /**
       * This function is executed every time a widget stops being resized.
       *
       * @method on_stop_resize
       * @param {Event} event The original browser event
       * @param {Object} ui A prepared ui object with useful drag-related data
       */
      fn.on_stop_resize = function(event, ui) {
          this.$resized_widget
              .removeClass('resizing');
  
          delay($.proxy(function() {
              this.$resize_preview_holder
                  .remove()
                  .css({
                      'min-width': '',
                      'min-height': ''
                  });
  
              if (this.options.resize.stop) {
                  this.options.resize.stop.call(this, event, ui, this.$resized_widget);
              }
  
              this.$el.trigger('gridster:resizestop');
          }, this), 300);
  
          this.set_dom_grid_width();
  
          if (this.options.autogrow_cols) {
              this.drag_api.set_limits(this.cols * this.min_widget_width);
          }
  
          if (!this.$vertically_clipped_widgets) {
              this.$vertically_clipped_widgets = [];
          }
  
          this.$vertically_clipped_widgets.push(this.$resized_widget);
          this.arrange_widgets_no_vertical_clipping(this.$vertically_clipped_widgets);
          this.$vertically_clipped_widgets = [];
      };
  
  
      /**
       * This function is executed when a widget is being resized.
       *
       * @method on_resize
       * @param {Event} event The original browser event
       * @param {Object} ui A prepared ui object with useful drag-related data
       */
      fn.on_resize = function(event, ui) {
          var rel_x = (ui.pointer.diff_left);
          var rel_y = (ui.pointer.diff_top);
          var wbd_x = this.options.widget_base_dimensions[0];
          var wbd_y = this.options.widget_base_dimensions[1];
          var margin_x = this.options.widget_margins[0];
          var margin_y = this.options.widget_margins[1];
          var max_size_x = this.resize_max_size_x;
          var min_size_x = this.resize_min_size_x;
          var max_size_y = this.resize_max_size_y;
          var min_size_y = this.resize_min_size_y;
          var autogrow = this.options.autogrow_cols;
          var width;
          var max_width = Infinity;
          var max_height = Infinity;
  
          var inc_units_x = Math.ceil((rel_x / (wbd_x + margin_x * 2)) - 0.2);
          var inc_units_y = Math.ceil((rel_y / (wbd_y + margin_y * 2)) - 0.2);
  
          var size_x = Math.max(1, this.resize_initial_sizex + inc_units_x);
          var size_y = Math.max(1, this.resize_initial_sizey + inc_units_y);
  
          var max_cols = (this.container_width / this.min_widget_width) -
              this.resize_initial_col + 1;
          var limit_width = ((max_cols * this.min_widget_width) - margin_x * 2);
  
          size_x = Math.max(Math.min(size_x, max_size_x), min_size_x);
          size_x = Math.min(max_cols, size_x);
          width = (max_size_x * wbd_x) + ((size_x - 1) * margin_x * 2);
          max_width = Math.min(width, limit_width);
          min_width = (min_size_x * wbd_x) + ((size_x - 1) * margin_x * 2);
  
          size_y = Math.max(Math.min(size_y, max_size_y), min_size_y);
          max_height = (max_size_y * wbd_y) + ((size_y - 1) * margin_y * 2);
          min_height = (min_size_y * wbd_y) + ((size_y - 1) * margin_y * 2);
  
          if (this.resize_dir.right) {
              size_y = this.resize_initial_sizey;
          } else if (this.resize_dir.bottom) {
              size_x = this.resize_initial_sizex;
          }
  
          if (autogrow) {
              var last_widget_col = this.resize_initial_col + size_x - 1;
              if (autogrow && this.resize_initial_last_col <= last_widget_col) {
                  this.set_dom_grid_width(Math.max(last_widget_col + 1, this.cols));
  
                  if (this.cols < last_widget_col) {
                      this.add_faux_cols(last_widget_col - this.cols);
                  }
              }
          }
  
          var css_props = {};
          !this.resize_dir.bottom && (css_props.width = Math.max(Math.min(
              this.resize_initial_width + rel_x, max_width), min_width));
          !this.resize_dir.right && (css_props.height = Math.max(Math.min(
              this.resize_initial_height + rel_y, max_height), min_height));
  
          this.$resized_widget.css(css_props);
  
          if (size_x !== this.resize_last_sizex ||
              size_y !== this.resize_last_sizey) {
  
              if (size_x % 2 === 1) size_x++;  // snap widgets to even number column sizes
  
              this.resize_widget(this.$resized_widget, size_x, size_y);
              this.set_dom_grid_width(this.cols);
  
  
              this.$resize_preview_holder.css({
                  'width': '',
                  'height': ''
              }).attr({
                  'data-row': this.$resized_widget.attr('data-row'),
                  'data-sizex': size_x,
                  'data-sizey': size_y
              });
          }
  
          if (this.options.resize.resize) {
              this.options.resize.resize.call(this, event, ui, this.$resized_widget);
          }
  
          this.$el.trigger('gridster:resize');
  
          this.resize_last_sizex = size_x;
          this.resize_last_sizey = size_y;
      };
  
  
      /**
       * Executes the callbacks passed as arguments when a column begins to be
       * overlapped or stops being overlapped.
       *
       * @param {Function} start_callback Function executed when a new column
       *  begins to be overlapped. The column is passed as first argument.
       * @param {Function} stop_callback Function executed when a column stops
       *  being overlapped. The column is passed as first argument.
       * @method on_overlapped_column_change
       * @return {Class} Returns the instance of the Gridster Class.
       */
      fn.on_overlapped_column_change = function(start_callback, stop_callback) {
          if (!this.colliders_data.length) {
              return this;
          }
          var cols = this.get_targeted_columns(
              this.colliders_data[0].el.data.col);
  
          var last_n_cols = this.last_cols.length;
          var n_cols = cols.length;
          var i;
  
          for (i = 0; i < n_cols; i++) {
              if ($.inArray(cols[i], this.last_cols) === -1) {
                  (start_callback || $.noop).call(this, cols[i]);
              }
          }
  
          for (i = 0; i< last_n_cols; i++) {
              if ($.inArray(this.last_cols[i], cols) === -1) {
                  (stop_callback || $.noop).call(this, this.last_cols[i]);
              }
          }
  
          this.last_cols = cols;
  
          return this;
      };
  
  
      /**
       * Executes the callbacks passed as arguments when a row starts to be
       * overlapped or stops being overlapped.
       *
       * @param {Function} start_callback Function executed when a new row begins
       *  to be overlapped. The row is passed as first argument.
       * @param {Function} end_callback Function executed when a row stops being
       *  overlapped. The row is passed as first argument.
       * @method on_overlapped_row_change
       * @return {Class} Returns the instance of the Gridster Class.
       */
      fn.on_overlapped_row_change = function(start_callback, end_callback) {
          if (!this.colliders_data.length) {
              return this;
          }
          var rows = this.get_targeted_rows(this.colliders_data[0].el.data.row);
          var last_n_rows = this.last_rows.length;
          var n_rows = rows.length;
          var i;
  
          for (i = 0; i < n_rows; i++) {
              if ($.inArray(rows[i], this.last_rows) === -1) {
                  (start_callback || $.noop).call(this, rows[i]);
              }
          }
  
          for (i = 0; i < last_n_rows; i++) {
              if ($.inArray(this.last_rows[i], rows) === -1) {
                  (end_callback || $.noop).call(this, this.last_rows[i]);
              }
          }
  
          this.last_rows = rows;
      };
  
  
      /**
       * Sets the current position of the player
       *
       * @param {Number} col
       * @param {Number} row
       * @param {Boolean} no_player
       * @method set_player
       * @return {object}
       */
      fn.set_player = function(col, row, no_player) {
          var self = this;
          if (!no_player) {
              this.empty_cells_player_occupies();
          }
          var cell = !no_player ? self.colliders_data[0].el.data : {col: col};
          var to_col = cell.col;
          var to_row = row || cell.row;
  
          this.player_grid_data = {
              col: to_col,
              row: to_row,
              size_y : this.player_grid_data.size_y,
              size_x : this.player_grid_data.size_x
          };
  
          this.cells_occupied_by_player = this.get_cells_occupied(
              this.player_grid_data);
  
          var $overlapped_widgets = this.get_widgets_overlapped(
              this.player_grid_data);
  
          var constraints = this.widgets_constraints($overlapped_widgets);
  
          this.manage_movements(constraints.can_go_up, to_col, to_row);
          this.manage_movements(constraints.can_not_go_up, to_col, to_row);
  
          /* if there is not widgets overlapping in the new player position,
           * update the new placeholder position. */
          if (!$overlapped_widgets.length) {
              var pp = this.can_go_player_up(this.player_grid_data);
              if (pp !== false) {
                  to_row = pp;
              }
              this.set_placeholder(to_col, to_row);
          }
  
          return {
              col: to_col,
              row: to_row
          };
      };
  
  
      /**
       * See which of the widgets in the $widgets param collection can go to
       * a upper row and which not.
       *
       * @method widgets_contraints
       * @param {jQuery} $widgets A jQuery wrapped collection of
       * HTMLElements.
       * @return {object} Returns a literal Object with two keys: `can_go_up` &
       * `can_not_go_up`. Each contains a set of HTMLElements.
       */
      fn.widgets_constraints = function($widgets) {
          var $widgets_can_go_up = $([]);
          var $widgets_can_not_go_up;
          var wgd_can_go_up = [];
          var wgd_can_not_go_up = [];
  
          $widgets.each($.proxy(function(i, w) {
              var $w = $(w);
              var wgd = $w.coords().grid;
              if (this.can_go_widget_up(wgd)) {
                  $widgets_can_go_up = $widgets_can_go_up.add($w);
                  wgd_can_go_up.push(wgd);
              } else {
                  wgd_can_not_go_up.push(wgd);
              }
          }, this));
  
          $widgets_can_not_go_up = $widgets.not($widgets_can_go_up);
  
          return {
              can_go_up: Gridster.sort_by_row_asc(wgd_can_go_up),
              can_not_go_up: Gridster.sort_by_row_desc(wgd_can_not_go_up)
          };
      };
  
  
      /**
       * Sorts an Array of grid coords objects (representing the grid coords of
       * each widget) in descending way.
       *
       * @method manage_movements
       * @param {jQuery} $widgets A jQuery collection of HTMLElements
       *  representing the widgets you want to move.
       * @param {Number} to_col The column to which we want to move the widgets.
       * @param {Number} to_row The row to which we want to move the widgets.
       * @return {Class} Returns the instance of the Gridster Class.
       */
      fn.manage_movements = function($widgets, to_col, to_row) {
          $.each($widgets, $.proxy(function(i, w) {
              var wgd = w;
              var $w = wgd.el;
  
              var can_go_widget_up = this.can_go_widget_up(wgd);
  
              if (can_go_widget_up) {
                  //target CAN go up
                  //so move widget up
                  this.move_widget_to($w, can_go_widget_up);
                  this.set_placeholder(to_col, can_go_widget_up + wgd.size_y);
  
              } else {
                  //target can't go up
                  var can_go_player_up = this.can_go_player_up(
                      this.player_grid_data);
  
                  if (!can_go_player_up) {
                      // target can't go up
                      // player cant't go up
                      // so we need to move widget down to a position that dont
                      // overlaps player
                      var y = (to_row + this.player_grid_data.size_y) - wgd.row;
  
                      this.move_widget_down($w, y);
                      this.set_placeholder(to_col, to_row);
                  }
              }
          }, this));
  
          return this;
      };
  
      /**
       * Determines if there is a widget in the row and col given. Or if the
       * HTMLElement passed as first argument is the player.
       *
       * @method is_player
       * @param {Number|HTMLElement} col_or_el A jQuery wrapped collection of
       * HTMLElements.
       * @param {Number} [row] The column to which we want to move the widgets.
       * @return {Boolean} Returns true or false.
       */
      fn.is_player = function(col_or_el, row) {
          if (row && !this.gridmap[col_or_el]) { return false; }
          var $w = row ? this.gridmap[col_or_el][row] : col_or_el;
          return $w && ($w.is(this.$player) || $w.is(this.$helper));
      };
  
  
      /**
       * Determines if the widget that is being dragged is currently over the row
       * and col given.
       *
       * @method is_player_in
       * @param {Number} col The column to check.
       * @param {Number} row The row to check.
       * @return {Boolean} Returns true or false.
       */
      fn.is_player_in = function(col, row) {
          var c = this.cells_occupied_by_player || {};
          return $.inArray(col, c.cols) >= 0 && $.inArray(row, c.rows) >= 0;
      };
  
  
      /**
       * Determines if the placeholder is currently over the row and col given.
       *
       * @method is_placeholder_in
       * @param {Number} col The column to check.
       * @param {Number} row The row to check.
       * @return {Boolean} Returns true or false.
       */
      fn.is_placeholder_in = function(col, row) {
          var c = this.cells_occupied_by_placeholder || {};
          return this.is_placeholder_in_col(col) && $.inArray(row, c.rows) >= 0;
      };
  
  
      /**
       * Determines if the placeholder is currently over the column given.
       *
       * @method is_placeholder_in_col
       * @param {Number} col The column to check.
       * @return {Boolean} Returns true or false.
       */
      fn.is_placeholder_in_col = function(col) {
          var c = this.cells_occupied_by_placeholder || [];
          return $.inArray(col, c.cols) >= 0;
      };
  
  
      /**
       * Determines if the cell represented by col and row params is empty.
       *
       * @method is_empty
       * @param {Number} col The column to check.
       * @param {Number} row The row to check.
       * @return {Boolean} Returns true or false.
       */
      fn.is_empty = function(col, row) {
          if (typeof this.gridmap[col] !== 'undefined') {
              if(typeof this.gridmap[col][row] !== 'undefined' &&
                  this.gridmap[col][row] === false
              ) {
                  return true;
              }
              return false;
          }
          return true;
      };
  
  
      /**
       * Determines if the cells represented by the grid_data region param is occupied.
       *
       * @method is_cells_occupied
       * @param grid_data region to check
       * @return {Boolean} Returns true or false.
       */
  
      fn.is_cells_occupied = function(grid_data)
      {
          var startCol = grid_data.col,
              startRow = grid_data.row,
              endCol = startCol+grid_data.size_x,
              endRow = startRow+grid_data.size_y;
  
          var col = startCol;
          for(; col < endCol; col++){
              var row = startRow;
              for(; row < endRow; row++){
                  if(this.is_occupied(col, row)){
                      return true;
                  }
              }
          }
  
          return false;
      };
  
      /**
       * Determines if the cell represented by col and row params is occupied.
       *
       * @method is_occupied
       * @param {Number} col The column to check.
       * @param {Number} row The row to check.
       * @return {Boolean} Returns true or false.
       */
      fn.is_occupied = function(col, row) {
          if (!this.gridmap[col]) {
              return false;
          }
  
          if (this.gridmap[col][row]) {
              return true;
          }
          return false;
      };
  
  
      /**
       * Determines if there is a widget in the cell represented by col/row params.
       *
       * @method is_widget
       * @param {Number} col The column to check.
       * @param {Number} row The row to check.
       * @return {Boolean|HTMLElement} Returns false if there is no widget,
       * else returns the jQuery HTMLElement
       */
      fn.is_widget = function(col, row) {
          var cell = this.gridmap[col];
          if (!cell) {
              return false;
          }
  
          cell = cell[row];
  
          if (cell) {
              return cell;
          }
  
          return false;
      };
  
  
      /**
       * Determines if there is a widget in the cell represented by col/row
       * params and if this is under the widget that is being dragged.
       *
       * @method is_widget_under_player
       * @param {Number} col The column to check.
       * @param {Number} row The row to check.
       * @return {Boolean} Returns true or false.
       */
      fn.is_widget_under_player = function(col, row) {
          if (this.is_widget(col, row)) {
              return this.is_player_in(col, row);
          }
          return false;
      };
  
  
      /**
       * Get widgets overlapping with the player or with the object passed
       * representing the grid cells.
       *
       * @method get_widgets_under_player
       * @return {HTMLElement} Returns a jQuery collection of HTMLElements
       */
      fn.get_widgets_under_player = function(cells) {
          cells || (cells = this.cells_occupied_by_player || {cols: [], rows: []});
          var $widgets = $([]);
  
          $.each(cells.cols, $.proxy(function(i, col) {
              $.each(cells.rows, $.proxy(function(i, row) {
                  if(this.is_widget(col, row)) {
                      $widgets = $widgets.add(this.gridmap[col][row]);
                  }
              }, this));
          }, this));
  
          return $widgets;
      };
  
  
      /**
       * Put placeholder at the row and column specified.
       *
       * @method set_placeholder
       * @param {Number} col The column to which we want to move the
       *  placeholder.
       * @param {Number} row The row to which we want to move the
       *  placeholder.
       * @return {Class} Returns the instance of the Gridster Class.
       */
      fn.set_placeholder = function(col, row) {
          var phgd = $.extend({}, this.placeholder_grid_data);
          var $nexts = this.widgets_below({
              col: phgd.col,
              row: phgd.row,
              size_y: phgd.size_y,
              size_x: phgd.size_x
          });
  
          // Prevents widgets go out of the grid
          var right_col = (col + phgd.size_x - 1);
          if (right_col > this.cols) {
              col = col - (right_col - col);
          }
  
          var moved_down = this.placeholder_grid_data.row < row;
          var changed_column = this.placeholder_grid_data.col !== col;
  
          this.placeholder_grid_data.col = col;
          this.placeholder_grid_data.row = row;
  
          this.cells_occupied_by_placeholder = this.get_cells_occupied(
              this.placeholder_grid_data);
  
          this.$preview_holder.attr({
              'data-row' : row,
              'data-col' : col
          });
  
          if (moved_down || changed_column) {
              $nexts.each($.proxy(function(i, widget) {
                  this.move_widget_up(
                      $(widget), this.placeholder_grid_data.col - col + phgd.size_y);
              }, this));
          }
  
          var $widgets_under_ph = this.get_widgets_under_player(
              this.cells_occupied_by_placeholder);
  
          if ($widgets_under_ph.length) {
              $widgets_under_ph.each($.proxy(function(i, widget) {
                  var $w = $(widget);
                  this.move_widget_down(
                      $w, row + phgd.size_y - $w.data('coords').grid.row);
              }, this));
          }
  
      };
  
  
      /**
       * Determines whether the player can move to a position above.
       *
       * @method can_go_player_up
       * @param {Object} widget_grid_data The actual grid coords object of the
       *  player.
       * @return {Number|Boolean} If the player can be moved to an upper row
       *  returns the row number, else returns false.
       */
      fn.can_go_player_up = function(widget_grid_data) {
          var p_bottom_row = widget_grid_data.row + widget_grid_data.size_y - 1;
          var result = true;
          var upper_rows = [];
          var min_row = 10000;
          var $widgets_under_player = this.get_widgets_under_player();
  
          /* generate an array with columns as index and array with upper rows
           * empty as value */
          this.for_each_column_occupied(widget_grid_data, function(tcol) {
              var grid_col = this.gridmap[tcol];
              var r = p_bottom_row + 1;
              upper_rows[tcol] = [];
  
              while (--r > 0) {
                  if (this.is_empty(tcol, r) || this.is_player(tcol, r) ||
                      this.is_widget(tcol, r) &&
                      grid_col[r].is($widgets_under_player)
                  ) {
                      upper_rows[tcol].push(r);
                      min_row = r < min_row ? r : min_row;
                  } else {
                      break;
                  }
              }
  
              if (upper_rows[tcol].length === 0) {
                  result = false;
                  return true; //break
              }
  
              upper_rows[tcol].sort(function(a, b) {
                  return a - b;
              });
          });
  
          if (!result) { return false; }
  
          return this.get_valid_rows(widget_grid_data, upper_rows, min_row);
      };
  
  
      /**
       * Determines whether a widget can move to a position above.
       *
       * @method can_go_widget_up
       * @param {Object} widget_grid_data The actual grid coords object of the
       *  widget we want to check.
       * @return {Number|Boolean} If the widget can be moved to an upper row
       *  returns the row number, else returns false.
       */
      fn.can_go_widget_up = function(widget_grid_data) {
          var p_bottom_row = widget_grid_data.row + widget_grid_data.size_y - 1;
          var result = true;
          var upper_rows = [];
          var min_row = 10000;
  
          /* generate an array with columns as index and array with topmost rows
           * empty as value */
          this.for_each_column_occupied(widget_grid_data, function(tcol) {
              var grid_col = this.gridmap[tcol];
              upper_rows[tcol] = [];
  
              var r = p_bottom_row + 1;
              // iterate over each row
              while (--r > 0) {
                  if (this.is_widget(tcol, r) && !this.is_player_in(tcol, r)) {
                      if (!grid_col[r].is(widget_grid_data.el)) {
                          break;
                      }
                  }
  
                  if (!this.is_player(tcol, r) &&
                      !this.is_placeholder_in(tcol, r) &&
                      !this.is_player_in(tcol, r)) {
                      upper_rows[tcol].push(r);
                  }
  
                  if (r < min_row) {
                      min_row = r;
                  }
              }
  
              if (upper_rows[tcol].length === 0) {
                  result = false;
                  return true; //break
              }
  
              upper_rows[tcol].sort(function(a, b) {
                  return a - b;
              });
          });
  
          if (!result) { return false; }
  
          return this.get_valid_rows(widget_grid_data, upper_rows, min_row);
      };
  
  
      /**
       * Search a valid row for the widget represented by `widget_grid_data' in
       * the `upper_rows` array. Iteration starts from row specified in `min_row`.
       *
       * @method get_valid_rows
       * @param {Object} widget_grid_data The actual grid coords object of the
       *  player.
       * @param {Array} upper_rows An array with columns as index and arrays
       *  of valid rows as values.
       * @param {Number} min_row The upper row from which the iteration will start.
       * @return {Number|Boolean} Returns the upper row valid from the `upper_rows`
       *  for the widget in question.
       */
      fn.get_valid_rows = function(widget_grid_data, upper_rows, min_row) {
          var p_top_row = widget_grid_data.row;
          var p_bottom_row = widget_grid_data.row + widget_grid_data.size_y - 1;
          var size_y = widget_grid_data.size_y;
          var r = min_row - 1;
          var valid_rows = [];
  
          while (++r <= p_bottom_row ) {
              var common = true;
              $.each(upper_rows, function(col, rows) {
                  if ($.isArray(rows) && $.inArray(r, rows) === -1) {
                      common = false;
                  }
              });
  
              if (common === true) {
                  valid_rows.push(r);
                  if (valid_rows.length === size_y) {
                      break;
                  }
              }
          }
  
          var new_row = false;
          if (size_y === 1) {
              if (valid_rows[0] !== p_top_row) {
                  new_row = valid_rows[0] || false;
              }
          } else {
              if (valid_rows[0] !== p_top_row) {
                  new_row = this.get_consecutive_numbers_index(
                      valid_rows, size_y);
              }
          }
  
          return new_row;
      };
  
  
      fn.get_consecutive_numbers_index = function(arr, size_y) {
          var max = arr.length;
          var result = [];
          var first = true;
          var prev = -1; // or null?
  
          for (var i=0; i < max; i++) {
              if (first || arr[i] === prev + 1) {
                  result.push(i);
                  if (result.length === size_y) {
                      break;
                  }
                  first = false;
              } else {
                  result = [];
                  first = true;
              }
  
              prev = arr[i];
          }
  
          return result.length >= size_y ? arr[result[0]] : false;
      };
  
  
      /**
       * Get widgets overlapping with the player.
       *
       * @method get_widgets_overlapped
       * @return {jQuery} Returns a jQuery collection of HTMLElements.
       */
      fn.get_widgets_overlapped = function() {
          var $w;
          var $widgets = $([]);
          var used = [];
          var rows_from_bottom = this.cells_occupied_by_player.rows.slice(0);
          rows_from_bottom.reverse();
  
          $.each(this.cells_occupied_by_player.cols, $.proxy(function(i, col) {
              $.each(rows_from_bottom, $.proxy(function(i, row) {
                  // if there is a widget in the player position
                  if (!this.gridmap[col]) { return true; } //next iteration
                  var $w = this.gridmap[col][row];
                  if (this.is_occupied(col, row) && !this.is_player($w) &&
                      $.inArray($w, used) === -1
                  ) {
                      $widgets = $widgets.add($w);
                      used.push($w);
                  }
  
              }, this));
          }, this));
  
          return $widgets;
      };
  
  
      /**
       * This callback is executed when the player begins to collide with a column.
       *
       * @method on_start_overlapping_column
       * @param {Number} col The collided column.
       * @return {jQuery} Returns a jQuery collection of HTMLElements.
       */
      fn.on_start_overlapping_column = function(col) {
          this.set_player(col, false);
      };
  
  
      /**
       * A callback executed when the player begins to collide with a row.
       *
       * @method on_start_overlapping_row
       * @param {Number} row The collided row.
       * @return {jQuery} Returns a jQuery collection of HTMLElements.
       */
      fn.on_start_overlapping_row = function(row) {
          this.set_player(false, row);
      };
  
  
      /**
       * A callback executed when the the player ends to collide with a column.
       *
       * @method on_stop_overlapping_column
       * @param {Number} col The collided row.
       * @return {jQuery} Returns a jQuery collection of HTMLElements.
       */
      fn.on_stop_overlapping_column = function(col) {
          this.set_player(col, false);
  
          var self = this;
          this.for_each_widget_below(col, this.cells_occupied_by_player.rows[0],
              function(tcol, trow) {
                  self.move_widget_up(this, self.player_grid_data.size_y);
              });
      };
  
  
      /**
       * This callback is executed when the player ends to collide with a row.
       *
       * @method on_stop_overlapping_row
       * @param {Number} row The collided row.
       * @return {jQuery} Returns a jQuery collection of HTMLElements.
       */
      fn.on_stop_overlapping_row = function(row) {
          this.set_player(false, row);
  
          var self = this;
          var cols = this.cells_occupied_by_player.cols;
          for (var c = 0, cl = cols.length; c < cl; c++) {
              this.for_each_widget_below(cols[c], row, function(tcol, trow) {
                  self.move_widget_up(this, self.player_grid_data.size_y);
              });
          }
      };
  
  
      /**
       * Move a widget to a specific row in specified column. The cell or cells must be empty.
       * If the widget has widgets below, all of these widgets will be moved also
       * if they can.
       *
       * @method move_widget_to
       * @param {HTMLElement} $widget The jQuery wrapped HTMLElement of the
       * widget is going to be moved.
       * @return {Class} Returns the instance of the Gridster Class.
       */
      fn.move_widget_to_row_in_col = function($widget, row, col) {
          var self = this;
          var widget_grid_data = $widget.coords().grid;
          var diff = row - widget_grid_data.row;
  
          var new_data = $.extend({}, widget_grid_data);
          new_data.col = col;
          new_data.row = row;
  
          var can_move_to_new_cell =
              !(this.is_cells_occupied(new_data) || this.is_clipped_vertically(new_data));
  
          if (can_move_to_new_cell === false) {
              return false;
          }
  
          this.remove_from_gridmap(widget_grid_data);
          widget_grid_data.row = row;
          widget_grid_data.col = col;
          this.add_to_gridmap(widget_grid_data);
          $widget.attr('data-row', row);
          $widget.attr('data-col', col);
  
          this.$changed = this.$changed.add($widget);
  
  
          return this;
      };
  
      /**
       * Move a widget to a specific row. The cell or cells must be empty.
       * If the widget has widgets below, all of these widgets will be moved also
       * if they can.
       *
       * @method move_widget_to
       * @param {HTMLElement} $widget The jQuery wrapped HTMLElement of the
       * widget is going to be moved.
       * @return {Class} Returns the instance of the Gridster Class.
       */
      fn.move_widget_to = function($widget, row) {
          var self = this;
          var widget_grid_data = $widget.coords().grid;
          var diff = row - widget_grid_data.row;
          var $next_widgets = this.widgets_below($widget);
  
          var can_move_to_new_cell = this.can_move_to(
              widget_grid_data, widget_grid_data.col, row, $widget);
  
          if (can_move_to_new_cell === false) {
              return false;
          }
  
          this.remove_from_gridmap(widget_grid_data);
          widget_grid_data.row = row;
          this.add_to_gridmap(widget_grid_data);
          $widget.attr('data-row', row);
          this.$changed = this.$changed.add($widget);
  
  
          $next_widgets.each(function(i, widget) {
              var $w = $(widget);
              var wgd = $w.coords().grid;
              var can_go_up = self.can_go_widget_up(wgd);
              if (can_go_up && can_go_up !== wgd.row) {
                  self.move_widget_to($w, can_go_up);
              }
          });
  
          return this;
      };
  
  
      /**
       * Move up the specified widget and all below it.
       *
       * @method move_widget_up
       * @param {HTMLElement} $widget The widget you want to move.
       * @param {Number} [y_units] The number of cells that the widget has to move.
       * @return {Class} Returns the instance of the Gridster Class.
       */
      fn.move_widget_up = function($widget, y_units) {
          var el_grid_data = $widget.coords().grid;
          var actual_row = el_grid_data.row;
          var moved = [];
          var can_go_up = true;
          y_units || (y_units = 1);
  
          if (!this.can_go_up($widget)) { return false; } //break;
  
          this.for_each_column_occupied(el_grid_data, function(col) {
              // can_go_up
              if ($.inArray($widget, moved) === -1) {
                  var widget_grid_data = $widget.coords().grid;
                  var next_row = actual_row - y_units;
                  next_row = this.can_go_up_to_row(
                      widget_grid_data, col, next_row);
  
                  if (!next_row) {
                      return true;
                  }
  
                  var $next_widgets = this.widgets_below($widget);
  
                  this.remove_from_gridmap(widget_grid_data);
                  widget_grid_data.row = next_row;
                  this.add_to_gridmap(widget_grid_data);
                  $widget.attr('data-row', widget_grid_data.row);
                  this.$changed = this.$changed.add($widget);
  
                  moved.push($widget);
  
                  $next_widgets.each($.proxy(function(i, widget) {
                      this.move_widget_up($(widget), y_units);
                  }, this));
              }
          });
  
      };
  
  
      /**
       * Move down the specified widget and all below it.
       *
       * @method move_widget_down
       * @param {jQuery} $widget The jQuery object representing the widget
       *  you want to move.
       * @param {Number} y_units The number of cells that the widget has to move.
       * @return {Class} Returns the instance of the Gridster Class.
       */
      fn.move_widget_down = function($widget, y_units) {
          var el_grid_data, actual_row, moved, y_diff;
  
          if (y_units <= 0) { return false; }
  
          el_grid_data = $widget.coords().grid;
          actual_row = el_grid_data.row;
          moved = [];
          y_diff = y_units;
  
          if (!$widget) { return false; }
  
          if ($.inArray($widget, moved) === -1) {
  
              var widget_grid_data = $widget.coords().grid;
              var next_row = actual_row + y_units;
              var $next_widgets = this.widgets_below($widget);
  
              this.remove_from_gridmap(widget_grid_data);
  
              $next_widgets.each($.proxy(function(i, widget) {
                  var $w = $(widget);
                  var wd = $w.coords().grid;
                  var tmp_y = this.displacement_diff(
                      wd, widget_grid_data, y_diff);
  
                  if (tmp_y > 0) {
                      this.move_widget_down($w, tmp_y);
                  }
              }, this));
  
              widget_grid_data.row = next_row;
              this.update_widget_position(widget_grid_data, $widget);
              $widget.attr('data-row', widget_grid_data.row);
              this.$changed = this.$changed.add($widget);
  
              moved.push($widget);
  
              //clipped widgets
              if(this.is_clipped_vertically(widget_grid_data)){
                  if (this.$vertically_clipped_widgets) {
                      if ($.inArray($widget, this.$vertically_clipped_widgets) === -1) {
                          this.$vertically_clipped_widgets.push($widget);
                      }
  
                  }
              }
  
  
          }
      };
  
  
      /**
       * Check if the widget can move to the specified row, else returns the
       * upper row possible.
       *
       * @method can_go_up_to_row
       * @param {Number} widget_grid_data The current grid coords object of the
       *  widget.
       * @param {Number} col The target column.
       * @param {Number} row The target row.
       * @return {Boolean|Number} Returns the row number if the widget can move
       *  to the target position, else returns false.
       */
      fn.can_go_up_to_row = function(widget_grid_data, col, row) {
          var ga = this.gridmap;
          var result = true;
          var urc = []; // upper_rows_in_columns
          var actual_row = widget_grid_data.row;
          var r;
  
          /* generate an array with columns as index and array with
           * upper rows empty in the column */
          this.for_each_column_occupied(widget_grid_data, function(tcol) {
              var grid_col = ga[tcol];
              urc[tcol] = [];
  
              r = actual_row;
              while (r--) {
                  if (this.is_empty(tcol, r) &&
                      !this.is_placeholder_in(tcol, r)
                  ) {
                      urc[tcol].push(r);
                  } else {
                      break;
                  }
              }
  
              if (!urc[tcol].length) {
                  result = false;
                  return true;
              }
  
          });
  
          if (!result) { return false; }
  
          /* get common rows starting from upper position in all the columns
           * that widget occupies */
          r = row;
          for (r = 1; r < actual_row; r++) {
              var common = true;
  
              for (var uc = 0, ucl = urc.length; uc < ucl; uc++) {
                  if (urc[uc] && $.inArray(r, urc[uc]) === -1) {
                      common = false;
                  }
              }
  
              if (common === true) {
                  result = r;
                  break;
              }
          }
  
          return result;
      };
  
  
      fn.displacement_diff = function(widget_grid_data, parent_bgd, y_units) {
          var actual_row = widget_grid_data.row;
          var diffs = [];
          var parent_max_y = parent_bgd.row + parent_bgd.size_y;
  
          this.for_each_column_occupied(widget_grid_data, function(col) {
              var temp_y_units = 0;
  
              for (var r = parent_max_y; r < actual_row; r++) {
                  if (this.is_empty(col, r)) {
                      temp_y_units = temp_y_units + 1;
                  }
              }
  
              diffs.push(temp_y_units);
          });
  
          var max_diff = Math.max.apply(Math, diffs);
          y_units = (y_units - max_diff);
  
          return y_units > 0 ? y_units : 0;
      };
  
  
      /**
       * Get widgets below a widget.
       *
       * @method widgets_below
       * @param {HTMLElement} $el The jQuery wrapped HTMLElement.
       * @return {jQuery} A jQuery collection of HTMLElements.
       */
      fn.widgets_below = function($el) {
          var el_grid_data = $.isPlainObject($el) ? $el : $el.coords().grid;
          var self = this;
          var ga = this.gridmap;
          var next_row = el_grid_data.row + el_grid_data.size_y - 1;
          var $nexts = $([]);
  
          this.for_each_column_occupied(el_grid_data, function(col) {
              self.for_each_widget_below(col, next_row, function(tcol, trow) {
                  if (!self.is_player(this) && $.inArray(this, $nexts) === -1) {
                      $nexts = $nexts.add(this);
                      return true; // break
                  }
              });
          });
  
          return Gridster.sort_by_row_asc($nexts);
      };
  
  
      /**
       * Update the array of mapped positions with the new player position.
       *
       * @method set_cells_player_occupies
       * @param {Number} col The new player col.
       * @param {Number} col The new player row.
       * @return {Class} Returns the instance of the Gridster Class.
       */
      fn.set_cells_player_occupies = function(col, row) {
          this.remove_from_gridmap(this.placeholder_grid_data);
          this.placeholder_grid_data.col = col;
          this.placeholder_grid_data.row = row;
          this.add_to_gridmap(this.placeholder_grid_data, this.$player);
          return this;
      };
  
  
      /**
       * Remove from the array of mapped positions the reference to the player.
       *
       * @method empty_cells_player_occupies
       * @return {Class} Returns the instance of the Gridster Class.
       */
      fn.empty_cells_player_occupies = function() {
          this.remove_from_gridmap(this.placeholder_grid_data);
          return this;
      };
  
  
      fn.can_go_up = function($el) {
          var el_grid_data = $el.coords().grid;
          var initial_row = el_grid_data.row;
          var prev_row = initial_row - 1;
          var ga = this.gridmap;
          var upper_rows_by_column = [];
  
          var result = true;
          if (initial_row === 1) { return false; }
  
          this.for_each_column_occupied(el_grid_data, function(col) {
              var $w = this.is_widget(col, prev_row);
  
              if (this.is_occupied(col, prev_row) ||
                  this.is_player(col, prev_row) ||
                  this.is_placeholder_in(col, prev_row) ||
                  this.is_player_in(col, prev_row)
              ) {
                  result = false;
                  return true; //break
              }
          });
  
          return result;
      };
  
  
      /**
       * Check if it's possible to move a widget to a specific col/row. It takes
       * into account the dimensions (`size_y` and `size_x` attrs. of the grid
       *  coords object) the widget occupies.
       *
       * @method can_move_to
       * @param {Object} widget_grid_data The grid coords object that represents
       *  the widget.
       * @param {Object} col The col to check.
       * @param {Object} row The row to check.
       * @param {Number} [max_row] The max row allowed.
       * @return {Boolean} Returns true if all cells are empty, else return false.
       */
      fn.can_move_to = function(widget_grid_data, col, row, max_row) {
          var ga = this.gridmap;
          var $w = widget_grid_data.el;
          var future_wd = {
              size_y: widget_grid_data.size_y,
              size_x: widget_grid_data.size_x,
              col: col,
              row: row
          };
          var result = true;
  
          //Prevents widgets go out of the grid
          var right_col = col + widget_grid_data.size_x - 1;
          if (right_col > this.cols) {
              return false;
          }
  
          if (max_row && max_row < row + widget_grid_data.size_y - 1) {
              return false;
          }
  
          this.for_each_cell_occupied(future_wd, function(tcol, trow) {
              var $tw = this.is_widget(tcol, trow);
              if ($tw && (!widget_grid_data.el || $tw.is($w))) {
                  result = false;
              }
          });
  
          return result;
      };
  
  
      /**
       * Given the leftmost column returns all columns that are overlapping
       *  with the player.
       *
       * @method get_targeted_columns
       * @param {Number} [from_col] The leftmost column.
       * @return {Array} Returns an array with column numbers.
       */
      fn.get_targeted_columns = function(from_col) {
          var max = (from_col || this.player_grid_data.col) +
              (this.player_grid_data.size_x - 1);
          var cols = [];
          for (var col = from_col; col <= max; col++) {
              cols.push(col);
          }
          return cols;
      };
  
  
      /**
       * Given the upper row returns all rows that are overlapping with the player.
       *
       * @method get_targeted_rows
       * @param {Number} [from_row] The upper row.
       * @return {Array} Returns an array with row numbers.
       */
      fn.get_targeted_rows = function(from_row) {
          var max = (from_row || this.player_grid_data.row) +
              (this.player_grid_data.size_y - 1);
          var rows = [];
          for (var row = from_row; row <= max; row++) {
              rows.push(row);
          }
          return rows;
      };
  
      /**
       * Get all columns and rows that a widget occupies.
       *
       * @method get_cells_occupied
       * @param {Object} el_grid_data The grid coords object of the widget.
       * @return {Object} Returns an object like `{ cols: [], rows: []}`.
       */
      fn.get_cells_occupied = function(el_grid_data) {
          var cells = { cols: [], rows: []};
          var i;
          if (arguments[1] instanceof $) {
              el_grid_data = arguments[1].coords().grid;
          }
  
          for (i = 0; i < el_grid_data.size_x; i++) {
              var col = el_grid_data.col + i;
              cells.cols.push(col);
          }
  
          for (i = 0; i < el_grid_data.size_y; i++) {
              var row = el_grid_data.row + i;
              cells.rows.push(row);
          }
  
          return cells;
      };
  
  
      /**
       * Iterate over the cells occupied by a widget executing a function for
       * each one.
       *
       * @method for_each_cell_occupied
       * @param {Object} el_grid_data The grid coords object that represents the
       *  widget.
       * @param {Function} callback The function to execute on each column
       *  iteration. Column and row are passed as arguments.
       * @return {Class} Returns the instance of the Gridster Class.
       */
      fn.for_each_cell_occupied = function(grid_data, callback) {
          this.for_each_column_occupied(grid_data, function(col) {
              this.for_each_row_occupied(grid_data, function(row) {
                  callback.call(this, col, row);
              });
          });
          return this;
      };
  
  
      /**
       * Iterate over the columns occupied by a widget executing a function for
       * each one.
       *
       * @method for_each_column_occupied
       * @param {Object} el_grid_data The grid coords object that represents
       *  the widget.
       * @param {Function} callback The function to execute on each column
       *  iteration. The column number is passed as first argument.
       * @return {Class} Returns the instance of the Gridster Class.
       */
      fn.for_each_column_occupied = function(el_grid_data, callback) {
          for (var i = 0; i < el_grid_data.size_x; i++) {
              var col = el_grid_data.col + i;
              callback.call(this, col, el_grid_data);
          }
      };
  
  
      /**
       * Iterate over the rows occupied by a widget executing a function for
       * each one.
       *
       * @method for_each_row_occupied
       * @param {Object} el_grid_data The grid coords object that represents
       *  the widget.
       * @param {Function} callback The function to execute on each column
       *  iteration. The row number is passed as first argument.
       * @return {Class} Returns the instance of the Gridster Class.
       */
      fn.for_each_row_occupied = function(el_grid_data, callback) {
          for (var i = 0; i < el_grid_data.size_y; i++) {
              var row = el_grid_data.row + i;
              callback.call(this, row, el_grid_data);
          }
      };
  
  
  
      fn._traversing_widgets = function(type, direction, col, row, callback) {
          var ga = this.gridmap;
          if (!ga[col]) { return; }
  
          var cr, max;
          var action = type + '/' + direction;
          if (arguments[2] instanceof $) {
              var el_grid_data = arguments[2].coords().grid;
              col = el_grid_data.col;
              row = el_grid_data.row;
              callback = arguments[3];
          }
          var matched = [];
          var trow = row;
  
  
          var methods = {
              'for_each/above': function() {
                  while (trow--) {
                      if (trow > 0 && this.is_widget(col, trow) &&
                          $.inArray(ga[col][trow], matched) === -1
                      ) {
                          cr = callback.call(ga[col][trow], col, trow);
                          matched.push(ga[col][trow]);
                          if (cr) { break; }
                      }
                  }
              },
              'for_each/below': function() {
                  for (trow = row + 1, max = ga[col].length; trow < max; trow++) {
                      if (this.is_widget(col, trow) &&
                          $.inArray(ga[col][trow], matched) === -1
                      ) {
                          cr = callback.call(ga[col][trow], col, trow);
                          matched.push(ga[col][trow]);
                          if (cr) { break; }
                      }
                  }
              }
          };
  
          if (methods[action]) {
              methods[action].call(this);
          }
      };
  
  
      /**
       * Iterate over each widget above the column and row specified.
       *
       * @method for_each_widget_above
       * @param {Number} col The column to start iterating.
       * @param {Number} row The row to start iterating.
       * @param {Function} callback The function to execute on each widget
       *  iteration. The value of `this` inside the function is the jQuery
       *  wrapped HTMLElement.
       * @return {Class} Returns the instance of the Gridster Class.
       */
      fn.for_each_widget_above = function(col, row, callback) {
          this._traversing_widgets('for_each', 'above', col, row, callback);
          return this;
      };
  
  
      /**
       * Iterate over each widget below the column and row specified.
       *
       * @method for_each_widget_below
       * @param {Number} col The column to start iterating.
       * @param {Number} row The row to start iterating.
       * @param {Function} callback The function to execute on each widget
       *  iteration. The value of `this` inside the function is the jQuery wrapped
       *  HTMLElement.
       * @return {Class} Returns the instance of the Gridster Class.
       */
      fn.for_each_widget_below = function(col, row, callback) {
          this._traversing_widgets('for_each', 'below', col, row, callback);
          return this;
      };
  
  
      /**
       * Returns the highest occupied row in the grid for specified column.
       *
       * @method get_highest_occupied_cell
       * @return {Number} Returns an row number.
       */
  
      fn.get_highest_occupied_row_for_col = function(col){
  
          var r;
          var gm = this.gridmap;
          var rl = gm[1].length;
          var rows = [0];
          for (r = rl - 1; r >= 1; r--) {
              if (this.is_widget(col, r)) {
                  rows.push(r);
                  break;
              }
          }
  
          return Math.max.apply(Math, rows);
  
      };
  
  
      /**
       * Returns the highest occupied cell in the grid.
       *
       * @method get_highest_occupied_cell
       * @return {Object} Returns an object with `col` and `row` numbers.
       */
      fn.get_highest_occupied_cell = function() {
          var r;
          var gm = this.gridmap;
          var rl = gm[1].length;
          var rows = [], cols = [];
          var row_in_col = [];
          for (var c = gm.length - 1; c >= 1; c--) {
              for (r = rl - 1; r >= 1; r--) {
                  if (this.is_widget(c, r)) {
                      rows.push(r);
                      cols.push(c);
                      break;
                  }
              }
          }
  
          return {
              col: Math.max.apply(Math, cols),
              row: Math.max.apply(Math, rows)
          };
      };
  
  
      fn.get_widgets_from = function(col, row) {
          var ga = this.gridmap;
          var $widgets = $();
  
          if (col) {
              $widgets = $widgets.add(
                  this.$widgets.filter(function() {
                      var tcol = $(this).attr('data-col');
                      return (tcol === col || tcol > col);
                  })
              );
          }
  
          if (row) {
              $widgets = $widgets.add(
                  this.$widgets.filter(function() {
                      var trow = $(this).attr('data-row');
                      return (trow === row || trow > row);
                  })
              );
          }
  
          return $widgets;
      };
  
  
      /**
       * Set the current height of the parent grid.
       *
       * @method set_dom_grid_height
       * @return {Object} Returns the instance of the Gridster class.
       */
      fn.set_dom_grid_height = function(height) {
          /*if (typeof height === 'undefined') {
           var r = this.get_highest_occupied_cell().row;
           height = r * this.min_widget_height;
           }*/
  
          this.container_height = this.$wrapper.height();
          this.$el.css('height', this.wrapper_height);
          return this;
      };
  
      /**
       * Set the current width of the parent grid.
       *
       * @method set_dom_grid_width
       * @return {Object} Returns the instance of the Gridster class.
       */
      fn.set_dom_grid_width = function(cols) {
          if (typeof cols === 'undefined') {
              cols = this.get_highest_occupied_cell().col;
          }
  
          var max_cols = (this.options.autogrow_cols ? this.options.max_cols :
              this.cols);
  
          cols = Math.min(max_cols, Math.max(cols, this.options.min_cols));
          this.container_width = cols * this.min_widget_width;
          this.$el.css('width', this.container_width);
          return this;
      };
  
  
      /**
       * It generates the neccessary styles to position the widgets.
       *
       * @method generate_stylesheet
       * @param {Number} rows Number of columns.
       * @param {Number} cols Number of rows.
       * @return {Object} Returns the instance of the Gridster class.
       */
      fn.generate_stylesheet = function(opts) {
          var styles = '';
          var max_size_x = this.options.max_size_x || this.cols;
          var max_rows = 0;
          var max_cols = 0;
          var i;
          var rules;
  
          opts || (opts = {});
          opts.cols || (opts.cols = this.cols);
          opts.rows || (opts.rows = this.rows);
          opts.namespace || (opts.namespace = this.options.namespace);
          opts.widget_base_dimensions ||
          (opts.widget_base_dimensions = this.options.widget_base_dimensions);
          opts.widget_margins ||
          (opts.widget_margins = this.options.widget_margins);
          opts.min_widget_width = (opts.widget_margins[0] * 2) +
              opts.widget_base_dimensions[0];
          opts.min_widget_height = (opts.widget_margins[1] * 2) +
              opts.widget_base_dimensions[1];
  
          // don't duplicate stylesheets for the same configuration
          var serialized_opts = $.param(opts);
          if ($.inArray(serialized_opts, Gridster.generated_stylesheets) >= 0) {
              return false;
          }
  
          this.generated_stylesheets.push(serialized_opts);
          Gridster.generated_stylesheets.push(serialized_opts);
  
          /* generate CSS styles for cols */
          for (i = opts.cols; i >= 0; i--) {
              styles += (opts.namespace + ' [data-col="'+ (i + 1) + '"] { left:' +
              ((i * opts.widget_base_dimensions[0]) +
              (i * opts.widget_margins[0]) +
              ((i + 1) * opts.widget_margins[0])) + 'px; }\n');
          }
  
          /* generate CSS styles for rows */
          for (i = opts.rows; i >= 0; i--) {
              styles += (opts.namespace + ' [data-row="' + (i + 1) + '"] { top:' +
              ((i * opts.widget_base_dimensions[1]) +
              (i * opts.widget_margins[1]) +
              ((i + 1) * opts.widget_margins[1]) ) + 'px; }\n');
          }
  
          for (var y = 1; y <= opts.rows; y++) {
              styles += (opts.namespace + ' [data-sizey="' + y + '"] { height:' +
              (y * opts.widget_base_dimensions[1] +
              (y - 1) * (opts.widget_margins[1] * 2)) + 'px; }\n');
          }
  
          for (var x = 1; x <= max_size_x; x++) {
              styles += (opts.namespace + ' [data-sizex="' + x + '"] { width:' +
              (x * opts.widget_base_dimensions[0] +
              (x - 1) * (opts.widget_margins[0] * 2)) + 'px; }\n');
          }
  
          this.remove_style_tags();
  
          return this.add_style_tag(styles);
      };
  
  
      /**
       * Injects the given CSS as string to the head of the document.
       *
       * @method add_style_tag
       * @param {String} css The styles to apply.
       * @return {Object} Returns the instance of the Gridster class.
       */
      fn.add_style_tag = function(css) {
          var d = document;
          var tag = d.createElement('style');
  
          d.getElementsByTagName('head')[0].appendChild(tag);
          tag.setAttribute('type', 'text/css');
  
          if (tag.styleSheet) {
              tag.styleSheet.cssText = css;
          } else {
              tag.appendChild(document.createTextNode(css));
          }
  
          this.$style_tags = this.$style_tags.add(tag);
  
          return this;
      };
  
  
      /**
       * Remove the style tag with the associated id from the head of the document
       *
       * @method  remove_style_tag
       * @return {Object} Returns the instance of the Gridster class.
       */
      fn.remove_style_tags = function() {
          var all_styles = Gridster.generated_stylesheets;
          var ins_styles = this.generated_stylesheets;
  
          this.$style_tags.remove();
  
          Gridster.generated_stylesheets = $.map(all_styles, function(s) {
              if ($.inArray(s, ins_styles) === -1) { return s; }
          });
      };
  
  
      /**
       * Generates a faux grid to collide with it when a widget is dragged and
       * detect row or column that we want to go.
       *
       * @method generate_faux_grid
       * @param {Number} rows Number of columns.
       * @param {Number} cols Number of rows.
       * @return {Object} Returns the instance of the Gridster class.
       */
      fn.generate_faux_grid = function(rows, cols) {
          this.faux_grid = [];
          this.gridmap = [];
          var col;
          var row;
          for (col = cols; col > 0; col--) {
              this.gridmap[col] = [];
              for (row = rows; row > 0; row--) {
                  this.add_faux_cell(row, col);
              }
          }
          return this;
      };
  
  
      /**
       * Add cell to the faux grid.
       *
       * @method add_faux_cell
       * @param {Number} row The row for the new faux cell.
       * @param {Number} col The col for the new faux cell.
       * @return {Object} Returns the instance of the Gridster class.
       */
      fn.add_faux_cell = function(row, col) {
          var coords = $({
              left: this.baseX + ((col - 1) * this.min_widget_width),
              top: this.baseY + (row -1) * this.min_widget_height,
              width: this.min_widget_width,
              height: this.min_widget_height,
              col: col,
              row: row,
              original_col: col,
              original_row: row
          }).coords();
  
          if (!$.isArray(this.gridmap[col])) {
              this.gridmap[col] = [];
          }
  
          this.gridmap[col][row] = false;
          this.faux_grid.push(coords);
  
          return this;
      };
  
  
      /**
       * Add rows to the faux grid.
       *
       * @method add_faux_rows
       * @param {Number} rows The number of rows you want to add to the faux grid.
       * @return {Object} Returns the instance of the Gridster class.
       */
      fn.add_faux_rows = function(rows) {
          var actual_rows = this.rows;
          var max_rows = actual_rows + (rows || 1);
  
          for (var r = max_rows; r > actual_rows; r--) {
              for (var c = this.cols; c >= 1; c--) {
                  this.add_faux_cell(r, c);
              }
          }
  
          this.rows = max_rows;
  
          if (this.options.autogenerate_stylesheet) {
              this.generate_stylesheet();
          }
  
          return this;
      };
  
      /**
       * Add cols to the faux grid.
       *
       * @method add_faux_cols
       * @param {Number} cols The number of cols you want to add to the faux grid.
       * @return {Object} Returns the instance of the Gridster class.
       */
      fn.add_faux_cols = function(cols) {
          var actual_cols = this.cols;
          var max_cols = actual_cols + (cols || 1);
          max_cols = Math.min(max_cols, this.options.max_cols);
  
          for (var c = actual_cols + 1; c <= max_cols; c++) {
              for (var r = this.rows; r >= 1; r--) {
                  this.add_faux_cell(r, c);
              }
          }
  
          this.cols = max_cols;
  
          if (this.options.autogenerate_stylesheet) {
              this.generate_stylesheet();
          }
  
          return this;
      };
  
  
      /**
       * Recalculates the offsets for the faux grid. You need to use it when
       * the browser is resized.
       *
       * @method recalculate_faux_grid
       * @return {Object} Returns the instance of the Gridster class.
       */
      fn.recalculate_faux_grid = function() {
          var aw = this.$wrapper.width();
          this.baseX = ($(window).width() - aw) / 2;
          this.baseY = this.$wrapper.offset().top;
  
          $.each(this.faux_grid, $.proxy(function(i, coords) {
              this.faux_grid[i] = coords.update({
                  left: this.baseX + (coords.data.col -1) * this.min_widget_width,
                  top: this.baseY + (coords.data.row -1) * this.min_widget_height
              });
          }, this));
  
          return this;
      };
  
  
      /**
       * Get all widgets in the DOM and register them.
       *
       * @method get_widgets_from_DOM
       * @return {Object} Returns the instance of the Gridster class.
       */
      fn.get_widgets_from_DOM = function() {
          var widgets_coords = this.$widgets.map($.proxy(function(i, widget) {
              var $w = $(widget);
              return this.dom_to_coords($w);
          }, this));
  
          widgets_coords = Gridster.sort_by_row_and_col_asc(widgets_coords);
  
          var changes = $(widgets_coords).map($.proxy(function(i, wgd) {
              return this.register_widget(wgd) || null;
          }, this));
  
          if (changes.length) {
              this.$el.trigger('gridster:positionschanged');
          }
  
          return this;
      };
  
  
      /**
       * Calculate columns and rows to be set based on the configuration
       *  parameters, grid dimensions, etc ...
       *
       * @method generate_grid_and_stylesheet
       * @return {Object} Returns the instance of the Gridster class.
       */
      fn.generate_grid_and_stylesheet = function() {
          var aw = this.$wrapper.width();
          var max_cols = this.options.max_cols;
  
          var cols = Math.floor(aw / this.min_widget_width) +
              this.options.extra_cols;
  
          var actual_cols = this.$widgets.map(function() {
              return $(this).attr('data-col');
          }).get();
  
          //needed to pass tests with phantomjs
          actual_cols.length || (actual_cols = [0]);
  
          var min_cols = Math.max.apply(Math, actual_cols);
  
          this.cols = Math.max(min_cols, cols, this.options.min_cols);
  
          if (max_cols !== Infinity && max_cols >= min_cols && max_cols < this.cols) {
              this.cols = max_cols;
          }
  
          // get all rows that could be occupied by the current widgets
          var max_rows = this.options.extra_rows;
          this.$widgets.each(function(i, w) {
              max_rows += (+$(w).attr('data-sizey'));
          });
  
          this.rows = Math.max(max_rows, this.options.min_rows);
  
          this.baseX = ($(window).width() - aw) / 2;
          this.baseY = this.$wrapper.offset().top;
  
          if (this.options.autogenerate_stylesheet) {
              this.generate_stylesheet();
          }
  
          return this.generate_faux_grid(this.rows, this.cols);
      };
  
      /**
       * Destroy this gridster by removing any sign of its presence, making it easy to avoid memory leaks
       *
       * @method destroy
       * @param {Boolean} remove If true, remove gridster from DOM.
       * @return {Object} Returns the instance of the Gridster class.
       */
      fn.destroy = function(remove) {
          this.$el.removeData('gridster');
  
          // remove bound callback on window resize
          $(window).unbind('.gridster');
  
          if (this.drag_api) {
              this.drag_api.destroy();
          }
  
          if (this.resize_api) {
              this.resize_api.destroy();
          }
  
          this.remove_style_tags();
  
          remove && this.$el.remove();
  
          return this;
      };
  
  
      //jQuery adapter
      $.fn.gridster = function(options) {
          return this.each(function() {
              if (! $(this).data('gridster')) {
                  $(this).data('gridster', new Gridster( this, options ));
              }
          });
      };
  
      return Gridster;
  
  }));