GMaps = function(options) {

    if (!(typeof window.google === 'object' && window.google.maps)) {
      if (typeof window.console === 'object' && window.console.error) {
        console.error('Google Maps API is required. Please register the following JavaScript library https://maps.googleapis.com/maps/api/js.');
      }

      return function() {};
    }

    if (!this) return new GMaps(options);

    options.zoom = options.zoom || 15;
    options.mapType = options.mapType || 'roadmap';

    var valueOrDefault = function(value, defaultValue) {
      return value === undefined ? defaultValue : value;
    };

    var self = this,
        i,
        events_that_hide_context_menu = [
          'bounds_changed', 'center_changed', 'click', 'dblclick', 'drag',
          'dragend', 'dragstart', 'idle', 'maptypeid_changed', 'projection_changed',
          'resize', 'tilesloaded', 'zoom_changed'
        ],
        events_that_doesnt_hide_context_menu = ['mousemove', 'mouseout', 'mouseover'],
        options_to_be_deleted = ['el', 'lat', 'lng', 'mapType', 'width', 'height', 'markerClusterer', 'enableNewStyle'],
        identifier = options.el || options.div,
        markerClustererFunction = options.markerClusterer,
        mapType = google.maps.MapTypeId[options.mapType.toUpperCase()],
        map_center = new google.maps.LatLng(options.lat, options.lng),
        zoomControl = valueOrDefault(options.zoomControl, true),
        zoomControlOpt = options.zoomControlOpt || {
          style: 'DEFAULT',
          position: 'TOP_LEFT'
        },
        zoomControlStyle = zoomControlOpt.style || 'DEFAULT',
        zoomControlPosition = zoomControlOpt.position || 'TOP_LEFT',
        panControl = valueOrDefault(options.panControl, true),
        mapTypeControl = valueOrDefault(options.mapTypeControl, true),
        scaleControl = valueOrDefault(options.scaleControl, true),
        streetViewControl = valueOrDefault(options.streetViewControl, true),
        overviewMapControl = valueOrDefault(overviewMapControl, true),
        map_options = {},
        map_base_options = {
          zoom: this.zoom,
          center: map_center,
          mapTypeId: mapType
        },
        map_controls_options = {
          panControl: panControl,
          zoomControl: zoomControl,
          zoomControlOptions: {
            style: google.maps.ZoomControlStyle[zoomControlStyle],
            position: google.maps.ControlPosition[zoomControlPosition]
          },
          mapTypeControl: mapTypeControl,
          scaleControl: scaleControl,
          streetViewControl: streetViewControl,
          overviewMapControl: overviewMapControl
        };

      if (typeof(options.el) === 'string' || typeof(options.div) === 'string') {
        if (identifier.indexOf("#") > -1) {
            /**
             * Container element
             *
             * @type {HTMLElement}
             */
            this.el = getElementById(identifier, options.context);
        } else {
            this.el = getElementsByClassName.apply(this, [identifier, options.context]);
        }
      } else {
          this.el = identifier;
      }

    if (typeof(this.el) === 'undefined' || this.el === null) {
      throw 'No element defined.';
    }

    window.context_menu = window.context_menu || {};
    window.context_menu[self.el.id] = {};

    /**
     * Collection of custom controls in the map UI
     *
     * @type {array}
     */
    this.controls = [];
    /**
     * Collection of map's overlays
     *
     * @type {array}
     */
    this.overlays = [];
    /**
     * Collection of KML/GeoRSS and FusionTable layers
     *
     * @type {array}
     */
    this.layers = [];
    /**
     * Collection of data layers (See {@link GMaps#addLayer})
     *
     * @type {object}
     */
    this.singleLayers = {};
    /**
     * Collection of map's markers
     *
     * @type {array}
     */
    this.markers = [];
    /**
     * Collection of map's lines
     *
     * @type {array}
     */
    this.polylines = [];
    /**
     * Collection of map's routes requested by {@link GMaps#getRoutes}, {@link GMaps#renderRoute}, {@link GMaps#drawRoute}, {@link GMaps#travelRoute} or {@link GMaps#drawSteppedRoute}
     *
     * @type {array}
     */
    this.routes = [];
    /**
     * Collection of map's polygons
     *
     * @type {array}
     */
    this.polygons = [];
    this.infoWindow = null;
    this.overlay_el = null;
    /**
     * Current map's zoom
     *
     * @type {number}
     */
    this.zoom = options.zoom;
    this.registered_events = {};

    this.el.style.width = options.width || this.el.scrollWidth || this.el.offsetWidth;
    this.el.style.height = options.height || this.el.scrollHeight || this.el.offsetHeight;

    google.maps.visualRefresh = options.enableNewStyle;

    for (i = 0; i < options_to_be_deleted.length; i++) {
      delete options[options_to_be_deleted[i]];
    }

    if(options.disableDefaultUI != true) {
      map_base_options = extend_object(map_base_options, map_controls_options);
    }

    map_options = extend_object(map_base_options, options);

    for (i = 0; i < events_that_hide_context_menu.length; i++) {
      delete map_options[events_that_hide_context_menu[i]];
    }

    for (i = 0; i < events_that_doesnt_hide_context_menu.length; i++) {
      delete map_options[events_that_doesnt_hide_context_menu[i]];
    }

    /**
     * Google Maps map instance
     *
     * @type {google.maps.Map}
     */
    this.map = new google.maps.Map(this.el, map_options);

    if (markerClustererFunction) {
      /**
       * Marker Clusterer instance
       *
       * @type {object}
       */
      this.markerClusterer = markerClustererFunction.apply(this, [this.map]);
    }

    var buildContextMenuHTML = function(control, e) {
      var html = '',
          options = window.context_menu[self.el.id][control];

      for (var i in options){
        if (options.hasOwnProperty(i)) {
          var option = options[i];

          html += '<li><a id="' + control + '_' + i + '" href="#">' + option.title + '</a></li>';
        }
      }

      if (!getElementById('gmaps_context_menu')) return;

      var context_menu_element = getElementById('gmaps_context_menu');

      context_menu_element.innerHTML = html;

      var context_menu_items = context_menu_element.getElementsByTagName('a'),
          context_menu_items_count = context_menu_items.length,
          i;

      for (i = 0; i < context_menu_items_count; i++) {
        var context_menu_item = context_menu_items[i];

        var assign_menu_item_action = function(ev){
          ev.preventDefault();

          options[this.id.replace(control + '_', '')].action.apply(self, [e]);
          self.hideContextMenu();
        };

        google.maps.event.clearListeners(context_menu_item, 'click');
        google.maps.event.addDomListenerOnce(context_menu_item, 'click', assign_menu_item_action, false);
      }

      var position = findAbsolutePosition.apply(this, [self.el]),
          left = position[0] + e.pixel.x - 15,
          top = position[1] + e.pixel.y- 15;

      context_menu_element.style.left = left + "px";
      context_menu_element.style.top = top + "px";

      // context_menu_element.style.display = 'block';
    };

    this.buildContextMenu = function(control, e) {
      if (control === 'marker') {
        e.pixel = {};

        var overlay = new google.maps.OverlayView();
        overlay.setMap(self.map);

        overlay.draw = function() {
          var projection = overlay.getProjection(),
              position = e.marker.getPosition();

          e.pixel = projection.fromLatLngToContainerPixel(position);

          buildContextMenuHTML(control, e);
        };
      }
      else {
        buildContextMenuHTML(control, e);
      }

      var context_menu_element = getElementById('gmaps_context_menu');

      setTimeout(function() {
        context_menu_element.style.display = 'block';
      }, 0);
    };

    /**
     * Add a context menu for a map or a marker.
     *
     * @param {object} options - The `options` object should contain:
     * * `control` (string): Kind of control the context menu will be attached. Can be "map" or "marker".
     * * `options` (array): A collection of context menu items:
     *   * `title` (string): Item's title shown in the context menu.
     *   * `name` (string): Item's identifier.
     *   * `action` (function): Function triggered after selecting the context menu item.
     */
    this.setContextMenu = function(options) {
      window.context_menu[self.el.id][options.control] = {};

      var i,
          ul = doc.createElement('ul');

      for (i in options.options) {
        if (options.options.hasOwnProperty(i)) {
          var option = options.options[i];

          window.context_menu[self.el.id][options.control][option.name] = {
            title: option.title,
            action: option.action
          };
        }
      }

      ul.id = 'gmaps_context_menu';
      ul.style.display = 'none';
      ul.style.position = 'absolute';
      ul.style.minWidth = '100px';
      ul.style.background = 'white';
      ul.style.listStyle = 'none';
      ul.style.padding = '8px';
      ul.style.boxShadow = '2px 2px 6px #ccc';

      if (!getElementById('gmaps_context_menu')) {
        doc.body.appendChild(ul);
      }

      var context_menu_element = getElementById('gmaps_context_menu');

      google.maps.event.addDomListener(context_menu_element, 'mouseout', function(ev) {
        if (!ev.relatedTarget || !this.contains(ev.relatedTarget)) {
          window.setTimeout(function(){
            context_menu_element.style.display = 'none';
          }, 400);
        }
      }, false);
    };

    /**
     * Hide the current context menu
     */
    this.hideContextMenu = function() {
      var context_menu_element = getElementById('gmaps_context_menu');

      if (context_menu_element) {
        context_menu_element.style.display = 'none';
      }
    };

    var setupListener = function(object, name) {
      google.maps.event.addListener(object, name, function(e){
        if (e == undefined) {
          e = this;
        }

        options[name].apply(this, [e]);

        self.hideContextMenu();
      });
    };

    //google.maps.event.addListener(this.map, 'idle', this.hideContextMenu);
    google.maps.event.addListener(this.map, 'zoom_changed', this.hideContextMenu);

    for (var ev = 0; ev < events_that_hide_context_menu.length; ev++) {
      var name = events_that_hide_context_menu[ev];

      if (name in options) {
        setupListener(this.map, name);
      }
    }

    for (var ev = 0; ev < events_that_doesnt_hide_context_menu.length; ev++) {
      var name = events_that_doesnt_hide_context_menu[ev];

      if (name in options) {
        setupListener(this.map, name);
      }
    }

    google.maps.event.addListener(this.map, 'rightclick', function(e) {
      if (options.rightclick) {
        options.rightclick.apply(this, [e]);
      }

      if(window.context_menu[self.el.id]['map'] != undefined) {
        self.buildContextMenu('map', e);
      }
    });

    /**
     * Trigger a `resize` event, useful if you need to repaint the current map (for changes in the viewport or display / hide actions).
     */
    this.refresh = function() {
      google.maps.event.trigger(this.map, 'resize');
    };

    /**
     * Adjust the map zoom to include all the markers added in the map.
     */
    this.fitZoom = function() {
      var latLngs = [],
          markers_length = this.markers.length,
          i;

      for (i = 0; i < markers_length; i++) {
        if(typeof(this.markers[i].visible) === 'boolean' && this.markers[i].visible) {
          latLngs.push(this.markers[i].getPosition());
        }
      }

      this.fitLatLngBounds(latLngs);
    };

    /**
     * Adjust the map zoom to include all the coordinates in the `latLngs` array.
     *
     * @param {array} latLngs - Collection of `google.maps.LatLng` objects.
     */
    this.fitLatLngBounds = function(latLngs) {
      var total = latLngs.length,
          bounds = new google.maps.LatLngBounds(),
          i;

      for(i = 0; i < total; i++) {
        bounds.extend(latLngs[i]);
      }

      this.map.fitBounds(bounds);
    };

    /**
     * Center the map using the `lat` and `lng` coordinates.
     *
     * @param {number} lat - Latitude of the coordinate.
     * @param {number} lng - Longitude of the coordinate.
     * @param {function} [callback] - Callback that will be executed after the map is centered.
     */
    this.setCenter = function(lat, lng, callback) {
      this.map.panTo(new google.maps.LatLng(lat, lng));

      if (callback) {
        callback();
      }
    };

    /**
     * Return the HTML element container of the map.
     *
     * @returns {HTMLElement} the element container.
     */
    this.getElement = function() {
      return this.el;
    };

    /**
     * Increase the map's zoom.
     *
     * @param {number} [magnitude] - The number of times the map will be zoomed in.
     */
    this.zoomIn = function(value) {
      value = value || 1;

      this.zoom = this.map.getZoom() + value;
      this.map.setZoom(this.zoom);
    };

    /**
     * Decrease the map's zoom.
     *
     * @param {number} [magnitude] - The number of times the map will be zoomed out.
     */
    this.zoomOut = function(value) {
      value = value || 1;

      this.zoom = this.map.getZoom() - value;
      this.map.setZoom(this.zoom);
    };

    var native_methods = [],
        method;

    for (method in this.map) {
      if (typeof(this.map[method]) == 'function' && !this[method]) {
        native_methods.push(method);
      }
    }

    for (i = 0; i < native_methods.length; i++) {
      (function(gmaps, scope, method_name) {
        gmaps[method_name] = function(){
          return scope[method_name].apply(scope, arguments);
        };
      })(this, this.map, native_methods[i]);
    }
  }
Creates a new GMaps instance, including a Google Maps map.
@class GMaps
@constructs
@param {object} options - `options` accepts all the [MapOptions](https://developers.google.com/maps/documentation/javascript/reference#MapOptions) and [events](https://developers.google.com/maps/documentation/javascript/reference#Map) listed in the Google Maps API. Also accepts:
* `lat` (number): Latitude of the map's center
* `lng` (number): Longitude of the map's center
* `el` (string or HTMLElement): container where the map will be rendered
* `markerClusterer` (function): A function to create a marker cluster. You can use MarkerClusterer or MarkerClustererPlus.