index.js

/**
 * @name MarkerWithLabel for V3
 * @version 1.1.9 [June 30, 2013]
 * @author Gary Little (inspired by code from Marc Ridey of Google).
 * @copyright Copyright 2012 Gary Little [gary at luxcentral.com]
 * @fileoverview MarkerWithLabel extends the Google Maps JavaScript API V3
 *  <code>google.maps.Marker</code> class.
 *  <p>
 *  MarkerWithLabel allows you to define markers with associated labels. As you would expect,
 *  if the marker is draggable, so too will be the label. In addition, a marker with a label
 *  responds to all mouse events in the same manner as a regular marker. It also fires mouse
 *  events and "property changed" events just as a regular marker would. Version 1.1 adds
 *  support for the raiseOnDrag feature introduced in API V3.3.
 *  <p>
 *  If you drag a marker by its label, you can cancel the drag and return the marker to its
 *  original position by pressing the <code>Esc</code> key. This doesn't work if you drag the marker
 *  itself because this feature is not (yet) supported in the <code>google.maps.Marker</code> class.
 */

/*!
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/*jslint browser:true */
/*global document,google */

/**
 * @param {Function} childCtor Child class.
 * @param {Function} parentCtor Parent class.
 */
function inherits(childCtor, parentCtor) {
  /** @constructor */
  function tempCtor() {};
  tempCtor.prototype = parentCtor.prototype;
  childCtor.superClass_ = parentCtor.prototype;
  childCtor.prototype = new tempCtor();
  /** @override */
  childCtor.prototype.constructor = childCtor;
}

/**
 * @param {Object} gMapsApi The Google Maps API instance (usually `google.maps`)
 * @return {Function} The instantiable MarkerWithLabel class
 */
module.exports = function(gMapsApi) {

  /**
   * This constructor creates a label and associates it with a marker.
   * It is for the private use of the MarkerWithLabel class.
   * @constructor
   * @param {Marker} marker The marker with which the label is to be associated.
   * @param {string} crossURL The URL of the cross image =.
   * @param {string} handCursor The URL of the hand cursor.
   * @private
   */
  function MarkerLabel_(marker, crossURL, handCursorURL) {
    this.marker_ = marker;
    this.handCursorURL_ = marker.handCursorURL;

    this.labelDiv_ = document.createElement("div");
    this.labelDiv_.style.cssText = "position: absolute; overflow: hidden;";

    // Set up the DIV for handling mouse events in the label. This DIV forms a transparent veil
    // in the "overlayMouseTarget" pane, a veil that covers just the label. This is done so that
    // events can be captured even if the label is in the shadow of a google.maps.InfoWindow.
    // Code is included here to ensure the veil is always exactly the same size as the label.
    this.eventDiv_ = document.createElement("div");
    this.eventDiv_.style.cssText = this.labelDiv_.style.cssText;

    // This is needed for proper behavior on MSIE:
    this.eventDiv_.addEventListener('selectstart', function() { return false; });
    this.eventDiv_.addEventListener('dragstart', function() { return false; });

    // Get the DIV for the "X" to be displayed when the marker is raised.
    this.crossDiv_ = MarkerLabel_.getSharedCross(crossURL);
  }
  inherits(MarkerLabel_, gMapsApi.OverlayView);

  /**
   * Returns the DIV for the cross used when dragging a marker when the
   * raiseOnDrag parameter set to true. One cross is shared with all markers.
   * @param {string} crossURL The URL of the cross image =.
   * @private
   */
  MarkerLabel_.getSharedCross = function (crossURL) {
    var div;
    if (typeof MarkerLabel_.getSharedCross.crossDiv === "undefined") {
      div = document.createElement("img");
      div.style.cssText = "position: absolute; z-index: 1000002; display: none;";
      // Hopefully Google never changes the standard "X" attributes:
      div.style.marginLeft = "-8px";
      div.style.marginTop = "-9px";
      div.src = crossURL;
      MarkerLabel_.getSharedCross.crossDiv = div;
    }
    return MarkerLabel_.getSharedCross.crossDiv;
  };

  /**
   * Adds the DIV representing the label to the DOM. This method is called
   * automatically when the marker's <code>setMap</code> method is called.
   * @private
   */
  MarkerLabel_.prototype.onAdd = function () {
    var me = this;
    var cMouseIsDown = false;
    var cDraggingLabel = false;
    var cSavedZIndex;
    var cLatOffset, cLngOffset;
    var cIgnoreClick;
    var cRaiseEnabled;
    var cStartPosition;
    var cStartCenter;
    // Constants:
    var cRaiseOffset = 20;
    var cDraggingCursor = "url(" + this.handCursorURL_ + ")";

    // Stops all processing of an event.
    //
    var cAbortEvent = function (e) {
      if (e.preventDefault) {
        e.preventDefault();
      }
      e.cancelBubble = true;
      if (e.stopPropagation) {
        e.stopPropagation();
      }
    };

    var cStopBounce = function () {
      me.marker_.setAnimation(null);
    };

    this.getPanes().markerLayer.appendChild(this.labelDiv_);
    this.getPanes().overlayMouseTarget.appendChild(this.eventDiv_);
    // One cross is shared with all markers, so only add it once:
    if (typeof MarkerLabel_.getSharedCross.processed === "undefined") {
      this.getPanes().markerLayer.appendChild(this.crossDiv_);
      MarkerLabel_.getSharedCross.processed = true;
    }

    this.listeners_ = [
      gMapsApi.event.addDomListener(this.eventDiv_, "mouseover", function (e) {
        if (me.marker_.getDraggable() || me.marker_.getClickable()) {
          this.style.cursor = "pointer";
          gMapsApi.event.trigger(me.marker_, "mouseover", e);
        }
      }),
      gMapsApi.event.addDomListener(this.eventDiv_, "mouseout", function (e) {
        if ((me.marker_.getDraggable() || me.marker_.getClickable()) && !cDraggingLabel) {
          this.style.cursor = me.marker_.getCursor();
          gMapsApi.event.trigger(me.marker_, "mouseout", e);
        }
      }),
      gMapsApi.event.addDomListener(this.eventDiv_, "mousedown", function (e) {
        cDraggingLabel = false;
        if (me.marker_.getDraggable()) {
          cMouseIsDown = true;
          this.style.cursor = cDraggingCursor;
        }
        if (me.marker_.getDraggable() || me.marker_.getClickable()) {
          gMapsApi.event.trigger(me.marker_, "mousedown", e);
          cAbortEvent(e); // Prevent map pan when starting a drag on a label
        }
      }),
      gMapsApi.event.addDomListener(document, "mouseup", function (mEvent) {
        var position;
        if (cMouseIsDown) {
          cMouseIsDown = false;
          me.eventDiv_.style.cursor = "pointer";
          gMapsApi.event.trigger(me.marker_, "mouseup", mEvent);
        }
        if (cDraggingLabel) {
          if (cRaiseEnabled) { // Lower the marker & label
            position = me.getProjection().fromLatLngToDivPixel(me.marker_.getPosition());
            position.y += cRaiseOffset;
            me.marker_.setPosition(me.getProjection().fromDivPixelToLatLng(position));
            // This is not the same bouncing style as when the marker portion is dragged,
            // but it will have to do:
            try { // Will fail if running Google Maps API earlier than V3.3
              me.marker_.setAnimation(gMapsApi.Animation.BOUNCE);
              setTimeout(cStopBounce, 1406);
            } catch (e) {}
          }
          me.crossDiv_.style.display = "none";
          me.marker_.setZIndex(cSavedZIndex);
          cIgnoreClick = true; // Set flag to ignore the click event reported after a label drag
          cDraggingLabel = false;
          mEvent.latLng = me.marker_.getPosition();
          gMapsApi.event.trigger(me.marker_, "dragend", mEvent);
        }
      }),
      gMapsApi.event.addListener(me.marker_.getMap(), "mousemove", function (mEvent) {
        var position;
        if (cMouseIsDown) {
          if (cDraggingLabel) {
            // Change the reported location from the mouse position to the marker position:
            mEvent.latLng = new gMapsApi.LatLng(mEvent.latLng.lat() - cLatOffset, mEvent.latLng.lng() - cLngOffset);
            position = me.getProjection().fromLatLngToDivPixel(mEvent.latLng);
            if (cRaiseEnabled) {
              me.crossDiv_.style.left = position.x + "px";
              me.crossDiv_.style.top = position.y + "px";
              me.crossDiv_.style.display = "";
              position.y -= cRaiseOffset;
            }
            me.marker_.setPosition(me.getProjection().fromDivPixelToLatLng(position));
            if (cRaiseEnabled) { // Don't raise the veil; this hack needed to make MSIE act properly
              me.eventDiv_.style.top = (position.y + cRaiseOffset) + "px";
            }
            gMapsApi.event.trigger(me.marker_, "drag", mEvent);
          } else {
            // Calculate offsets from the click point to the marker position:
            cLatOffset = mEvent.latLng.lat() - me.marker_.getPosition().lat();
            cLngOffset = mEvent.latLng.lng() - me.marker_.getPosition().lng();
            cSavedZIndex = me.marker_.getZIndex();
            cStartPosition = me.marker_.getPosition();
            cStartCenter = me.marker_.getMap().getCenter();
            cRaiseEnabled = me.marker_.get("raiseOnDrag");
            cDraggingLabel = true;
            me.marker_.setZIndex(1000000); // Moves the marker & label to the foreground during a drag
            mEvent.latLng = me.marker_.getPosition();
            gMapsApi.event.trigger(me.marker_, "dragstart", mEvent);
          }
        }
      }),
      gMapsApi.event.addDomListener(document, "keydown", function (e) {
        if (cDraggingLabel) {
          if (e.keyCode === 27) { // Esc key
            cRaiseEnabled = false;
            me.marker_.setPosition(cStartPosition);
            me.marker_.getMap().setCenter(cStartCenter);
            gMapsApi.event.trigger(document, "mouseup", e);
          }
        }
      }),
      gMapsApi.event.addDomListener(this.eventDiv_, "click", function (e) {
        if (me.marker_.getDraggable() || me.marker_.getClickable()) {
          if (cIgnoreClick) { // Ignore the click reported when a label drag ends
            cIgnoreClick = false;
          } else {
            gMapsApi.event.trigger(me.marker_, "click", e);
            cAbortEvent(e); // Prevent click from being passed on to map
          }
        }
      }),
      gMapsApi.event.addDomListener(this.eventDiv_, "dblclick", function (e) {
        if (me.marker_.getDraggable() || me.marker_.getClickable()) {
          gMapsApi.event.trigger(me.marker_, "dblclick", e);
          cAbortEvent(e); // Prevent map zoom when double-clicking on a label
        }
      }),
      gMapsApi.event.addListener(this.marker_, "dragstart", function (mEvent) {
        if (!cDraggingLabel) {
          cRaiseEnabled = this.get("raiseOnDrag");
        }
      }),
      gMapsApi.event.addListener(this.marker_, "drag", function (mEvent) {
        if (!cDraggingLabel) {
          if (cRaiseEnabled) {
            me.setPosition(cRaiseOffset);
            // During a drag, the marker's z-index is temporarily set to 1000000 to
            // ensure it appears above all other markers. Also set the label's z-index
            // to 1000000 (plus or minus 1 depending on whether the label is supposed
            // to be above or below the marker).
            me.labelDiv_.style.zIndex = 1000000 + (this.get("labelInBackground") ? -1 : +1);
          }
        }
      }),
      gMapsApi.event.addListener(this.marker_, "dragend", function (mEvent) {
        if (!cDraggingLabel) {
          if (cRaiseEnabled) {
            me.setPosition(0); // Also restores z-index of label
          }
        }
      }),
      gMapsApi.event.addListener(this.marker_, "position_changed", function () {
        me.setPosition();
      }),
      gMapsApi.event.addListener(this.marker_, "zindex_changed", function () {
        me.setZIndex();
      }),
      gMapsApi.event.addListener(this.marker_, "visible_changed", function () {
        me.setVisible();
      }),
      gMapsApi.event.addListener(this.marker_, "labelvisible_changed", function () {
        me.setVisible();
      }),
      gMapsApi.event.addListener(this.marker_, "title_changed", function () {
        me.setTitle();
      }),
      gMapsApi.event.addListener(this.marker_, "labelcontent_changed", function () {
        me.setContent();
      }),
      gMapsApi.event.addListener(this.marker_, "labelanchor_changed", function () {
        me.setAnchor();
      }),
      gMapsApi.event.addListener(this.marker_, "labelclass_changed", function () {
        me.setStyles();
      }),
      gMapsApi.event.addListener(this.marker_, "labelstyle_changed", function () {
        me.setStyles();
      })
    ];
  };

  /**
   * Removes the DIV for the label from the DOM. It also removes all event handlers.
   * This method is called automatically when the marker's <code>setMap(null)</code>
   * method is called.
   * @private
   */
  MarkerLabel_.prototype.onRemove = function () {
    var i;
    if (this.labelDiv_.parentNode) {
      this.labelDiv_.parentNode.removeChild(this.labelDiv_);
      this.eventDiv_.parentNode.removeChild(this.eventDiv_);
    }
    
    // Remove event listeners:
    if (this.listeners_) {
      for (i = 0; i < this.listeners_.length; i++) {
        gMapsApi.event.removeListener(this.listeners_[i]);
      }
    }
  };

  /**
   * Draws the label on the map.
   * @private
   */
  MarkerLabel_.prototype.draw = function () {
    this.setContent();
    this.setTitle();
    this.setStyles();
  };

  /**
   * Sets the content of the label.
   * The content can be plain text or an HTML DOM node.
   * @private
   */
  MarkerLabel_.prototype.setContent = function () {
    var content = this.marker_.get("labelContent");
    if (typeof content.nodeType === "undefined") {
      this.labelDiv_.innerHTML = content;
      this.eventDiv_.innerHTML = this.labelDiv_.innerHTML;
    } else {
      // Remove current content
      while (this.labelDiv_.lastChild) {
        this.labelDiv_.removeChild(this.labelDiv_.lastChild);
      }

      while (this.eventDiv_.lastChild) {
        this.eventDiv_.removeChild(this.eventDiv_.lastChild);
      }

      this.labelDiv_.appendChild(content);
      content = content.cloneNode(true);
      this.eventDiv_.appendChild(content);
    }
  };

  /**
   * Sets the content of the tool tip for the label. It is
   * always set to be the same as for the marker itself.
   * @private
   */
  MarkerLabel_.prototype.setTitle = function () {
    this.eventDiv_.title = this.marker_.getTitle() || "";
  };

  /**
   * Sets the style of the label by setting the style sheet and applying
   * other specific styles requested.
   * @private
   */
  MarkerLabel_.prototype.setStyles = function () {
    var i, labelStyle;

    // Apply style values from the style sheet defined in the labelClass parameter:
    this.labelDiv_.className = this.marker_.get("labelClass");
    this.eventDiv_.className = this.labelDiv_.className;

    // Clear existing inline style values:
    this.labelDiv_.style.cssText = "";
    this.eventDiv_.style.cssText = "";
    // Apply style values defined in the labelStyle parameter:
    labelStyle = this.marker_.get("labelStyle");
    for (i in labelStyle) {
      if (labelStyle.hasOwnProperty(i)) {
        this.labelDiv_.style[i] = labelStyle[i];
        this.eventDiv_.style[i] = labelStyle[i];
      }
    }
    this.setMandatoryStyles();
  };

  /**
   * Sets the mandatory styles to the DIV representing the label as well as to the
   * associated event DIV. This includes setting the DIV position, z-index, and visibility.
   * @private
   */
  MarkerLabel_.prototype.setMandatoryStyles = function () {
    this.labelDiv_.style.position = "absolute";
    this.labelDiv_.style.overflow = "hidden";
    // Make sure the opacity setting causes the desired effect on MSIE:
    if (typeof this.labelDiv_.style.opacity !== "undefined" && this.labelDiv_.style.opacity !== "") {
      this.labelDiv_.style.MsFilter = "\"progid:DXImageTransform.Microsoft.Alpha(opacity=" + (this.labelDiv_.style.opacity * 100) + ")\"";
      this.labelDiv_.style.filter = "alpha(opacity=" + (this.labelDiv_.style.opacity * 100) + ")";
    }

    this.eventDiv_.style.position = this.labelDiv_.style.position;
    this.eventDiv_.style.overflow = this.labelDiv_.style.overflow;
    this.eventDiv_.style.opacity = 0.01; // Don't use 0; DIV won't be clickable on MSIE
    this.eventDiv_.style.MsFilter = "\"progid:DXImageTransform.Microsoft.Alpha(opacity=1)\"";
    this.eventDiv_.style.filter = "alpha(opacity=1)"; // For MSIE

    this.setAnchor();
    this.setPosition(); // This also updates z-index, if necessary.
    this.setVisible();
  };

  /**
   * Sets the anchor point of the label.
   * @private
   */
  MarkerLabel_.prototype.setAnchor = function () {
    var anchor = this.marker_.get("labelAnchor");
    this.labelDiv_.style.marginLeft = -anchor.x + "px";
    this.labelDiv_.style.marginTop = -anchor.y + "px";
    this.eventDiv_.style.marginLeft = -anchor.x + "px";
    this.eventDiv_.style.marginTop = -anchor.y + "px";
  };

  /**
   * Sets the position of the label. The z-index is also updated, if necessary.
   * @private
   */
  MarkerLabel_.prototype.setPosition = function (yOffset) {
    var position = this.getProjection().fromLatLngToDivPixel(this.marker_.getPosition());
    if (typeof yOffset === "undefined") {
      yOffset = 0;
    }
    this.labelDiv_.style.left = Math.round(position.x) + "px";
    this.labelDiv_.style.top = Math.round(position.y - yOffset) + "px";
    this.eventDiv_.style.left = this.labelDiv_.style.left;
    this.eventDiv_.style.top = this.labelDiv_.style.top;

    this.setZIndex();
  };

  /**
   * Sets the z-index of the label. If the marker's z-index property has not been defined, the z-index
   * of the label is set to the vertical coordinate of the label. This is in keeping with the default
   * stacking order for Google Maps: markers to the south are in front of markers to the north.
   * @private
   */
  MarkerLabel_.prototype.setZIndex = function () {
    var zAdjust = (this.marker_.get("labelInBackground") ? -1 : +1);
    if (typeof this.marker_.getZIndex() === "undefined") {
      this.labelDiv_.style.zIndex = parseInt(this.labelDiv_.style.top, 10) + zAdjust;
      this.eventDiv_.style.zIndex = this.labelDiv_.style.zIndex;
    } else {
      this.labelDiv_.style.zIndex = this.marker_.getZIndex() + zAdjust;
      this.eventDiv_.style.zIndex = this.labelDiv_.style.zIndex;
    }
  };

  /**
   * Sets the visibility of the label. The label is visible only if the marker itself is
   * visible (i.e., its visible property is true) and the labelVisible property is true.
   * @private
   */
  MarkerLabel_.prototype.setVisible = function () {
    if (this.marker_.get("labelVisible")) {
      this.labelDiv_.style.display = this.marker_.getVisible() ? "block" : "none";
    } else {
      this.labelDiv_.style.display = "none";
    }
    this.eventDiv_.style.display = this.labelDiv_.style.display;
  };

  /**
   * @name MarkerWithLabelOptions
   * @class This class represents the optional parameter passed to the {@link MarkerWithLabel} constructor.
   *  The properties available are the same as for <code>google.maps.Marker</code> with the addition
   *  of the properties listed below. To change any of these additional properties after the labeled
   *  marker has been created, call <code>google.maps.Marker.set(propertyName, propertyValue)</code>.
   *  <p>
   *  When any of these properties changes, a property changed event is fired. The names of these
   *  events are derived from the name of the property and are of the form <code>propertyname_changed</code>.
   *  For example, if the content of the label changes, a <code>labelcontent_changed</code> event
   *  is fired.
   *  <p>
   * @property {string|Node} [labelContent] The content of the label (plain text or an HTML DOM node).
   * @property {Point} [labelAnchor] By default, a label is drawn with its anchor point at (0,0) so
   *  that its top left corner is positioned at the anchor point of the associated marker. Use this
   *  property to change the anchor point of the label. For example, to center a 50px-wide label
   *  beneath a marker, specify a <code>labelAnchor</code> of <code>google.maps.Point(25, 0)</code>.
   *  (Note: x-values increase to the right and y-values increase to the top.)
   * @property {string} [labelClass] The name of the CSS class defining the styles for the label.
   *  Note that style values for <code>position</code>, <code>overflow</code>, <code>top</code>,
   *  <code>left</code>, <code>zIndex</code>, <code>display</code>, <code>marginLeft</code>, and
   *  <code>marginTop</code> are ignored; these styles are for internal use only.
   * @property {Object} [labelStyle] An object literal whose properties define specific CSS
   *  style values to be applied to the label. Style values defined here override those that may
   *  be defined in the <code>labelClass</code> style sheet. If this property is changed after the
   *  label has been created, all previously set styles (except those defined in the style sheet)
   *  are removed from the label before the new style values are applied.
   *  Note that style values for <code>position</code>, <code>overflow</code>, <code>top</code>,
   *  <code>left</code>, <code>zIndex</code>, <code>display</code>, <code>marginLeft</code>, and
   *  <code>marginTop</code> are ignored; these styles are for internal use only.
   * @property {boolean} [labelInBackground] A flag indicating whether a label that overlaps its
   *  associated marker should appear in the background (i.e., in a plane below the marker).
   *  The default is <code>false</code>, which causes the label to appear in the foreground.
   * @property {boolean} [labelVisible] A flag indicating whether the label is to be visible.
   *  The default is <code>true</code>. Note that even if <code>labelVisible</code> is
   *  <code>true</code>, the label will <i>not</i> be visible unless the associated marker is also
   *  visible (i.e., unless the marker's <code>visible</code> property is <code>true</code>).
   * @property {boolean} [raiseOnDrag] A flag indicating whether the label and marker are to be
   *  raised when the marker is dragged. The default is <code>true</code>. If a draggable marker is
   *  being created and a version of Google Maps API earlier than V3.3 is being used, this property
   *  must be set to <code>false</code>.
   * @property {boolean} [optimized] A flag indicating whether rendering is to be optimized for the
   *  marker. <b>Important: The optimized rendering technique is not supported by MarkerWithLabel,
   *  so the value of this parameter is always forced to <code>false</code>.
   * @property {string} [crossImage="http://maps.gstatic.com/intl/en_us/mapfiles/drag_cross_67_16.png"]
   *  The URL of the cross image to be displayed while dragging a marker.
   * @property {string} [handCursor="http://maps.gstatic.com/intl/en_us/mapfiles/closedhand_8_8.cur"]
   *  The URL of the cursor to be displayed while dragging a marker.
   */
  /**
   * Creates a MarkerWithLabel with the options specified in {@link MarkerWithLabelOptions}.
   * @constructor
   * @param {MarkerWithLabelOptions} [opt_options] The optional parameters.
   */
  function MarkerWithLabel(opt_options) {
    opt_options = opt_options || {};
    opt_options.labelContent = opt_options.labelContent || "";
    opt_options.labelAnchor = opt_options.labelAnchor || new gMapsApi.Point(0, 0);
    opt_options.labelClass = opt_options.labelClass || "markerLabels";
    opt_options.labelStyle = opt_options.labelStyle || {};
    opt_options.labelInBackground = opt_options.labelInBackground || false;
    if (typeof opt_options.labelVisible === "undefined") {
      opt_options.labelVisible = true;
    }
    if (typeof opt_options.raiseOnDrag === "undefined") {
      opt_options.raiseOnDrag = true;
    }
    if (typeof opt_options.clickable === "undefined") {
      opt_options.clickable = true;
    }
    if (typeof opt_options.draggable === "undefined") {
      opt_options.draggable = false;
    }
    if (typeof opt_options.optimized === "undefined") {
      opt_options.optimized = false;
    }
    opt_options.crossImage = opt_options.crossImage || "http" + (document.location.protocol === "https:" ? "s" : "") + "://maps.gstatic.com/intl/en_us/mapfiles/drag_cross_67_16.png";
    opt_options.handCursor = opt_options.handCursor || "http" + (document.location.protocol === "https:" ? "s" : "") + "://maps.gstatic.com/intl/en_us/mapfiles/closedhand_8_8.cur";
    opt_options.optimized = false; // Optimized rendering is not supported

    this.label = new MarkerLabel_(this, opt_options.crossImage, opt_options.handCursor); // Bind the label to the marker

    // Call the parent constructor. It calls Marker.setValues to initialize, so all
    // the new parameters are conveniently saved and can be accessed with get/set.
    // Marker.set triggers a property changed event (called "propertyname_changed")
    // that the marker label listens for in order to react to state changes.
    gMapsApi.Marker.apply(this, arguments);
  }
  inherits(MarkerWithLabel, gMapsApi.Marker);

  /**
   * Overrides the standard Marker setMap function.
   * @param {Map} theMap The map to which the marker is to be added.
   * @private
   */
  MarkerWithLabel.prototype.setMap = function (theMap) {

    // Call the inherited function...
    gMapsApi.Marker.prototype.setMap.apply(this, arguments);

    // ... then deal with the label:
    this.label.setMap(theMap);
  };

  return MarkerWithLabel;
}