Google Maps API v3 add shadow on clicked marker

Question

I am aware that officially google removed shadows on markers in v3 of the google maps API. With this is in mind i have a project where marker shadows are required. I would like to place a shadow on a marker when the marker is clicked. Its essentially add an event listener to a marker and when its clicked add a shadow to the marker as a way to show that the clicked marker is the active marker.

I read through some pages e.g. marker shadows in google maps v3 which put shadows on all markers but I would like to borrow on such an example and have the shadows added when a marker is clicked and have the shadows removed when the marker loses focus i.e. when another marker is clicked.

My jsfiddle with two markers to play with is here and code is below: jsfiddle is here

var marker;
var locations = [["6","43.683","9.58","3002: Location 1",1],["7","45.149","9.44","3003: Location",2]];
function initialize() {
    var mapProp = {
    center: new google.maps.LatLng(43.683, 9.44),
    zoom: 5,
    mapTypeId: google.maps.MapTypeId.ROADMAP};

    var map = new google.maps.Map(document.getElementById("googleMap"), mapProp);
        for (i = 0; i < locations.length; i++) {
        marker = new google.maps.Marker({
        position:new google.maps.LatLng(locations[i][1], locations[i][2]),
        icon:'https://maps.gstatic.com/mapfiles/ms2/micons/purple.png',
    });

    google.maps.event.addListener(marker, 'click', (function(marker, i) {
        return function() {
            alert(locations[i][3] + " was clicked");
        }
    })(marker, i));

    marker.setMap(map);
    }
}

google.maps.event.addDomListener(window, 'load', initialize);

If anyone can help with coming up with a strategy or even a code snippet to place shadows on a marker when its clicked I would be very happy. Please feel free to fork the jsfiddle and add to it and post the link back here.

Answer 1

Another option, create the marker shadow object (from my answer to the question you reference) the first time a marker is clicked, move it to a newly clicked marker when that is clicked (add a .setPosition method to the MarkerShadow class).

var marker;
var locations = [
  ["6", "43.683", "9.58", "3002: Location 1", 1, true],
  ["7", "45.149", "9.44", "3003: Location", 2, false]
];
var markerShadow;
var infowindow = new google.maps.InfoWindow();

function initialize() {
  var mapProp = {
    center: new google.maps.LatLng(43.683, 9.44),
    zoom: 5,
    mapTypeId: google.maps.MapTypeId.ROADMAP
  };

  var map = new google.maps.Map(document.getElementById("googleMap"), mapProp);
  var iconShadow = {
    url: 'http://www.geocodezip.com/mapIcons/marker_shadow.png',
    // The shadow image is larger in the horizontal dimension
    // while the position and offset are the same as for the main image.
    size: new google.maps.Size(37, 34),
    origin: new google.maps.Point(0, 0),
    anchor: new google.maps.Point(10, 34)
  };


  for (i = 0; i < locations.length; i++) {
    marker = new google.maps.Marker({
      position: new google.maps.LatLng(locations[i][1], locations[i][2]),
      icon: 'https://maps.gstatic.com/mapfiles/ms2/micons/purple.png',
      title: locations[i][3]
    });
    google.maps.event.addListener(marker, 'click', (function(marker, i) {
      return function() {
        if (markerShadow && markerShadow.setPosition) {
          markerShadow.setPosition(this.getPosition());
        } else if (!markerShadow) {
          markerShadow = new MarkerShadow(marker.getPosition(), iconShadow, map);
        }
      }
    })(marker, i));

    marker.setMap(map);
  }
}

google.maps.event.addDomListener(window, 'load', initialize);

// marker shadow code
MarkerShadow.prototype = new google.maps.OverlayView();
MarkerShadow.prototype.setPosition = function(latlng) {
    this.posn_ = latlng;
    this.draw();
  }
  /** @constructor */

function MarkerShadow(position, options, map) {

    // Initialize all properties.
    this.posn_ = position;
    this.map_ = map;
    if (typeof(options) == "string") {
      this.image = options;
    } else {
      this.options_ = options;
      if (!!options.size) this.size_ = options.size;
      if (!!options.url) this.image_ = options.url;
    }

    // Define a property to hold the image's div. We'll
    // actually create this div upon receipt of the onAdd()
    // method so we'll leave it null for now.
    this.div_ = null;

    // Explicitly call setMap on this overlay.
    this.setMap(map);
  }
  /**
   * onAdd is called when the map's panes are ready and the overlay has been
   * added to the map.
   */
MarkerShadow.prototype.onAdd = function() {
  // if no url, return, nothing to do.
  if (!this.image_) return;
  var div = document.createElement('div');
  div.style.borderStyle = 'none';
  div.style.borderWidth = '0px';
  div.style.position = 'absolute';

  // Create the img element and attach it to the div.
  var img = document.createElement('img');
  img.src = this.image_;
  img.style.width = this.options_.size.x + 'px';
  img.style.height = this.options_.size.y + 'px';
  img.style.position = 'absolute';
  div.appendChild(img);

  this.div_ = div;

  // Add the element to the "overlayLayer" pane.
  var panes = this.getPanes();
  panes.overlayShadow.appendChild(div);
};

MarkerShadow.prototype.draw = function() {
  // if no url, return, nothing to do.
  if (!this.image_) return;
  // We use the coordinates of the overlay to peg it to the correct position 
  // To do this, we need to retrieve the projection from the overlay.
  var overlayProjection = this.getProjection();

  var posn = overlayProjection.fromLatLngToDivPixel(this.posn_);

  // Resize the image's div to fit the indicated dimensions.
  if (!this.div_) return;
  var div = this.div_;
  if (!!this.options_.anchor) {
    div.style.left = Math.floor(posn.x - this.options_.anchor.x) + 'px';
    div.style.top = Math.floor(posn.y - this.options_.anchor.y) + 'px';
  }
  if (!!this.options_.size) {
    div.style.width = this.size_.x + 'px';
    div.style.height = this.size_.y + 'px';
  }
};

// The onRemove() method will be called automatically from the API if
// we ever set the overlay's map property to 'null'.
MarkerShadow.prototype.onRemove = function() {
  if (!this.div_) return;
  this.div_.parentNode.removeChild(this.div_);
  this.div_ = null;
};

html,
body,
#googleMap {
  height: 100%;
  width: 100%;
  margin: 0px;
  padding: 0px
}

<script src="https://maps.googleapis.com/maps/api/js"></script>
<div id="googleMap"></div>

fiddle showing result