function MarkerClusterer(map, opt_markers, opt_options) {
  this.extend(MarkerClusterer, google.maps.OverlayView);
  this.map_ = map;
  this.markers_ = [];
  this.clusters_ = [];
  this.sizes = [53, 56, 66, 78, 90];
  this.styles_ = [];
  this.ready_ = false;
  var options = opt_options || {};
  this.gridSize_ = options['gridSize'] || 60;
  this.maxZoom_ = options['maxZoom'] || null;
  this.styles_ = options['styles'] || [];
  this.imagePath_ = options['imagePath'] ||
      this.MARKER_CLUSTER_IMAGE_PATH_;
  this.imageExtension_ = options['imageExtension'] ||
      this.MARKER_CLUSTER_IMAGE_EXTENSION_;
  this.zoomOnClick_ = options['zoomOnClick'] || true;
  this.setupStyles_();
  this.setMap(map);
  this.prevZoom_ = this.map_.getZoom();
  var that = this;
  google.maps.event.addListener(this.map_, 'zoom_changed', function() {
  	var maxZoom = that.map_.mapTypes[that.map_.getMapTypeId()].maxZoom;
  	var zoom = that.map_.getZoom();
  	if (zoom < 0 || zoom > maxZoom) {
  	  return;
  	}
    if (that.prevZoom_ != zoom) {
      that.prevZoom_ = that.map_.getZoom();
      that.resetViewport();
    }
  });
  google.maps.event.addListener(this.map_, 'bounds_changed', function() {
    that.redraw();
  });
  if (opt_markers && opt_markers.length) {
    this.addMarkers(opt_markers, false);
  }
}
MarkerClusterer.prototype.MARKER_CLUSTER_IMAGE_PATH_ =
    'http://google-maps-utility-library-v3.googlecode.com/svn/trunk/markerclusterer/' +
    'images/m';
MarkerClusterer.prototype.MARKER_CLUSTER_IMAGE_EXTENSION_ = 'png';
MarkerClusterer.prototype.extend = function(obj1, obj2) {
  return (function(object) {
    for (property in object.prototype) {
      this.prototype[property] = object.prototype[property];
    }
    return this;
  }).apply(obj1, [obj2]);
};
MarkerClusterer.prototype.onAdd = function() {
  this.setReady_(true);
};
MarkerClusterer.prototype.idle = function() {};
MarkerClusterer.prototype.draw = function() {};
MarkerClusterer.prototype.setupStyles_ = function() {
  for (var i = 0, size; size = this.sizes[i]; i++) {
    this.styles_.push({
      url: this.imagePath_ + (i + 1) + '.' + this.imageExtension_,
      height: size,
      width: size
    });
  }
};
MarkerClusterer.prototype.setStyles = function(styles) {
  this.styles_ = styles;
};
MarkerClusterer.prototype.getStyles = function() {
  return this.styles_;
};
MarkerClusterer.prototype.isZoomOnClick = function() {
  return this.zoomOnClick_;
};
MarkerClusterer.prototype.getMarkers = function() {
  return this.markers_;
};
MarkerClusterer.prototype.getTotalMarkers = function() {
  return this.markers_;
};
MarkerClusterer.prototype.setMaxZoom = function(maxZoom) {
  this.maxZoom_ = maxZoom;
};
MarkerClusterer.prototype.getMaxZoom = function() {
  return this.maxZoom_ || this.map_.mapTypes[this.map_.getMapTypeId()].maxZoom;
};
MarkerClusterer.prototype.calculator_ = function(markers, numStyles) {
  var index = 0;
  var count = markers.length;
  var dv = count;
  while (dv !== 0) {
    dv = parseInt(dv / 10, 10);
    index++;
  }
  index = Math.min(index, numStyles);
  return {
    text: count,
    index: index
  };
};
MarkerClusterer.prototype.setCalculator = function(calculator) {
  this.calculator_ = calculator;
};
MarkerClusterer.prototype.getCalculator = function() {
  return this.calculator_;
};
MarkerClusterer.prototype.addMarkers = function(markers, opt_nodraw) {
  for (var i = 0, marker; marker = markers[i]; i++) {
    this.pushMarkerTo_(marker);
  }
  if (!opt_nodraw) {
    this.redraw();
  }
};
MarkerClusterer.prototype.pushMarkerTo_ = function(marker) {
  marker.setVisible(false);
  marker.setMap(null);
  marker.isAdded = false;
  if (marker['draggable']) {
    var that = this;
    google.maps.event.addListener(marker, 'dragend', function() {
      marker.isAdded = false;
      that.resetViewport();
      that.redraw();
    });
  }
  this.markers_.push(marker);
};
MarkerClusterer.prototype.addMarker = function(marker, opt_nodraw) {
  this.pushMarkerTo_(marker);
  if (!opt_nodraw) {
    this.redraw();
  }
};
MarkerClusterer.prototype.removeMarker = function(marker) {
  var index = -1;
  if (this.markers_.indexOf) {
    index = this.markers_.indexOf(marker);
  } else {
    for (var i = 0, m; m = this.markers_[i]; i++) {
      if (m == marker) {
        index = i;
        continue;
      }
    }
  }
  if (index == -1) {
    return false;
  }
  this.markers_.splice(index, 1);
  marker.setVisible(false);
  marker.setMap(null);
  this.resetViewport();
  this.redraw();
  return true;
};
MarkerClusterer.prototype.setReady_ = function(ready) {
  if (!this.ready_) {
    this.ready_ = ready;
    this.createClusters_();
  }
};
MarkerClusterer.prototype.getTotalClusters = function() {
  return this.clusters_.length;
};
MarkerClusterer.prototype.getMap = function() {
  return this.map_;
};
MarkerClusterer.prototype.setMap = function(map) {
  this.map_ = map;
};
MarkerClusterer.prototype.getGridSize = function() {
  return this.gridSize_;
};
MarkerClusterer.prototype.setGridSize = function(size) {
  this.gridSize_ = size;
};
MarkerClusterer.prototype.getExtendedBounds = function(bounds) {
  var projection = this.getProjection();
  var tr = new google.maps.LatLng(bounds.getNorthEast().lat(),
      bounds.getNorthEast().lng());
  var bl = new google.maps.LatLng(bounds.getSouthWest().lat(),
      bounds.getSouthWest().lng());
  var trPix = projection.fromLatLngToDivPixel(tr);
  trPix.x += this.gridSize_;
  trPix.y -= this.gridSize_;
  var blPix = projection.fromLatLngToDivPixel(bl);
  blPix.x -= this.gridSize_;
  blPix.y += this.gridSize_;
  var ne = projection.fromDivPixelToLatLng(trPix);
  var sw = projection.fromDivPixelToLatLng(blPix);
  bounds.extend(ne);
  bounds.extend(sw);
  return bounds;
};
MarkerClusterer.prototype.isMarkerInBounds_ = function(marker, bounds) {
  return bounds.contains(marker.getPosition());
};
MarkerClusterer.prototype.clearMarkers = function() {
  this.resetViewport();
  this.markers_ = [];
};
MarkerClusterer.prototype.resetViewport = function() {
  for (var i = 0, cluster; cluster = this.clusters_[i]; i++) {
    cluster.remove();
  }
  for (var i = 0, marker; marker = this.markers_[i]; i++) {
    marker.isAdded = false;
    marker.setMap(null);
    marker.setVisible(false);
  }

  this.clusters_ = [];
};
MarkerClusterer.prototype.redraw = function() {
  this.createClusters_();
};
MarkerClusterer.prototype.createClusters_ = function() {
  if (!this.ready_) {
    return;
  }
  var mapBounds = new google.maps.LatLngBounds(this.map_.getBounds().getSouthWest(),
      this.map_.getBounds().getNorthEast());
  var bounds = this.getExtendedBounds(mapBounds);
  for (var i = 0, marker; marker = this.markers_[i]; i++) {
    var added = false;
    if (!marker.isAdded && this.isMarkerInBounds_(marker, bounds)) {
      for (var j = 0, cluster; cluster = this.clusters_[j]; j++) {
        if (!added && cluster.getCenter() &&
            cluster.isMarkerInClusterBounds(marker)) {
          added = true;
          cluster.addMarker(marker);
          break;
        }
      }
      if (!added) {
        var cluster = new Cluster(this);
        cluster.addMarker(marker);
        this.clusters_.push(cluster);
      }
    }
  }
};
function Cluster(markerClusterer) {
  this.markerClusterer_ = markerClusterer;
  this.map_ = markerClusterer.getMap();
  this.gridSize_ = markerClusterer.getGridSize();
  this.center_ = null;
  this.markers_ = [];
  this.bounds_ = null;
  this.clusterIcon_ = new ClusterIcon(this, markerClusterer.getStyles(),
      markerClusterer.getGridSize());
}
Cluster.prototype.isMarkerAlreadyAdded = function(marker) {
  if (this.markers_.indexOf) {
    return this.markers_.indexOf(marker) != -1;
  } else {
    for (var i = 0, m; m = this.markers_[i]; i++) {
      if (m == marker) {
        return true;
      }
    }
  }
  return false;
};
Cluster.prototype.addMarker = function(marker) {
  if (this.isMarkerAlreadyAdded(marker)) {
    return false;
  }
  if (!this.center_) {
    this.center_ = marker.getPosition();
    this.calculateBounds_();
  }
  if (this.markers_.length == 0) {
    marker.setMap(this.map_);
    marker.setVisible(true);
  } else if (this.markers_.length == 1) {
    this.markers_[0].setMap(null);
    this.markers_[0].setVisible(false);
  }
  marker.isAdded = true;
  this.markers_.push(marker);

  this.updateIcon();
  return true;
};
Cluster.prototype.getMarkerClusterer = function() {
  return this.markerClusterer_;
};
Cluster.prototype.getBounds = function() {
  this.calculateBounds_();
  return this.bounds_;
};
Cluster.prototype.remove = function() {
  this.clusterIcon_.remove();
  delete this.markers_;
};
Cluster.prototype.getCenter = function() {
  return this.center_;
};
Cluster.prototype.calculateBounds_ = function() {
  var bounds = new google.maps.LatLngBounds(this.center_, this.center_);
  this.bounds_ = this.markerClusterer_.getExtendedBounds(bounds);
};
Cluster.prototype.isMarkerInClusterBounds = function(marker) {
  return this.bounds_.contains(marker.getPosition());
};
Cluster.prototype.getMap = function() {
  return this.map_;
};
Cluster.prototype.updateIcon = function() {
  var zoom = this.map_.getZoom();
  var mz = this.markerClusterer_.getMaxZoom();
  if (zoom > mz) {
    for (var i = 0, marker; marker = this.markers_[i]; i++) {
      marker.setMap(this.map_);
      marker.setVisible(true);
    }
    return;
  }
  if (this.markers_.length < 2) {
    this.clusterIcon_.hide();
    return;
  }
  var numStyles = this.markerClusterer_.getStyles().length;
  var sums = this.markerClusterer_.getCalculator()(this.markers_, numStyles);
  this.clusterIcon_.setCenter(this.center_);
  this.clusterIcon_.setSums(sums);
  this.clusterIcon_.show();
};
function ClusterIcon(cluster, styles, opt_padding) {
  cluster.getMarkerClusterer().extend(ClusterIcon, google.maps.OverlayView);
  this.styles_ = styles;
  this.padding_ = opt_padding || 0;
  this.cluster_ = cluster;
  this.center_ = null;
  this.map_ = cluster.getMap();
  this.div_ = null;
  this.sums_ = null;
  this.visible_ = false;

  this.setMap(this.map_);
}
ClusterIcon.prototype.triggerClusterClick = function() {
  var markerClusterer = this.cluster_.getMarkerClusterer();
  google.maps.event.trigger(markerClusterer, 'clusterclick', [this.cluster_]);
  if (markerClusterer.isZoomOnClick()) {
    this.map_.panTo(this.cluster_.getCenter());
    this.map_.fitBounds(this.cluster_.getBounds());
  }
};
ClusterIcon.prototype.onAdd = function() {
  this.div_ = document.createElement('DIV');
  if (this.visible_) {
    var pos = this.getPosFromLatLng_(this.center_);
    this.div_.style.cssText = this.createCss(pos);
    this.div_.innerHTML = this.sums_.text;
  }
  var panes = this.getPanes();
  panes.overlayImage.appendChild(this.div_);
  var that = this;
  google.maps.event.addDomListener(this.div_, 'click', function() {
    that.triggerClusterClick();
  });
};
ClusterIcon.prototype.getPosFromLatLng_ = function(latlng) {
  var pos = this.getProjection().fromLatLngToDivPixel(latlng);
  pos.x -= parseInt(this.width_ / 2, 10);
  pos.y -= parseInt(this.height_ / 2, 10);
  return pos;
};
ClusterIcon.prototype.draw = function() {
  if (this.visible_) {
    var pos = this.getPosFromLatLng_(this.center_);
    this.div_.style.top = pos.y + 'px';
    this.div_.style.left = pos.x + 'px';
  }
};
ClusterIcon.prototype.hide = function() {
  if (this.div_) {
    this.div_.style.display = 'none';
  }
  this.visible_ = false;
};
ClusterIcon.prototype.show = function() {
  if (this.div_) {
    var pos = this.getPosFromLatLng_(this.center_);
    this.div_.style.cssText = this.createCss(pos);
    this.div_.style.display = '';
  }
  this.visible_ = true;
};
ClusterIcon.prototype.remove = function() {
  this.setMap(null);
};
ClusterIcon.prototype.onRemove = function() {
  if (this.div_ && this.div_.parentNode) {
    this.hide();
    this.div_.parentNode.removeChild(this.div_);
    this.div_ = null;
  }
};
ClusterIcon.prototype.setSums = function(sums) {
  this.sums_ = sums;
  this.text_ = sums.text;
  this.index_ = sums.index;
  if (this.div_) {
    this.div_.innerHTML = sums.text;
  }
  this.useStyle();
};
ClusterIcon.prototype.useStyle = function() {
  var index = Math.max(0, this.sums_.index - 1);
  index = Math.min(this.styles_.length - 1, index);
  var style = this.styles_[index];
  this.url_ = style.url;
  this.height_ = style.height;
  this.width_ = style.width;
  this.textColor_ = style.opt_textColor;
  this.anchor = style.opt_anchor;
  this.textSize_ = style.opt_textSize;
};
ClusterIcon.prototype.setCenter = function(center) {
  this.center_ = center;
};
ClusterIcon.prototype.createCss = function(pos) {
  var style = [];
  if (document.all) {
    style.push('filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(' +
        'sizingMethod=scale,src="' + this.url_ + '");');
  } else {
    style.push('background:url(' + this.url_ + ');');
  }
  if (typeof this.anchor_ === 'object') {
    if (typeof this.anchor_[0] === 'number' && this.anchor_[0] > 0 &&
        this.anchor_[0] < this.height_) {
      style.push('height:' + (this.height_ - this.anchor_[0]) +
          'px; padding-top:' + this.anchor_[0] + 'px;');
    } else {
      style.push('height:' + this.height_ + 'px; line-height:' + this.height_ +
          'px;');
    }
    if (typeof this.anchor_[1] === 'number' && this.anchor_[1] > 0 &&
        this.anchor_[1] < this.width_) {
      style.push('width:' + (this.width_ - this.anchor_[1]) +
          'px; padding-left:' + this.anchor_[1] + 'px;');
    } else {
      style.push('width:' + this.width_ + 'px; text-align:center;');
    }
  } else {
    style.push('height:' + this.height_ + 'px; line-height:' +
        this.height_ + 'px; width:' + this.width_ + 'px; text-align:center;');
  }
  var txtColor = this.textColor_ ? this.textColor_ : 'black';
  var txtSize = this.textSize_ ? this.textSize_ : 11;

  style.push('cursor:pointer; top:' + pos.y + 'px; left:' +
      pos.x + 'px; color:' + txtColor + '; position:absolute; font-size:' +
      txtSize + 'px; font-family:Arial,sans-serif; font-weight:bold');
  return style.join('');
};
window['MarkerClusterer'] = MarkerClusterer;
MarkerClusterer.prototype['addMarker'] = MarkerClusterer.prototype.addMarker;
MarkerClusterer.prototype['addMarkers'] = MarkerClusterer.prototype.addMarkers;
MarkerClusterer.prototype['clearMarkers'] = MarkerClusterer.prototype.clearMarkers;
MarkerClusterer.prototype['getCalculator'] = MarkerClusterer.prototype.getCalculator;
MarkerClusterer.prototype['getGridSize'] = MarkerClusterer.prototype.getGridSize;
MarkerClusterer.prototype['getMap'] = MarkerClusterer.prototype.getMap;
MarkerClusterer.prototype['getMarkers'] = MarkerClusterer.prototype.getMarkers;
MarkerClusterer.prototype['getMaxZoom'] = MarkerClusterer.prototype.getMaxZoom;
MarkerClusterer.prototype['getStyles'] = MarkerClusterer.prototype.getStyles;
MarkerClusterer.prototype['getTotalClusters'] = MarkerClusterer.prototype.getTotalClusters;
MarkerClusterer.prototype['getTotalMarkers'] = MarkerClusterer.prototype.getTotalMarkers;
MarkerClusterer.prototype['redraw'] = MarkerClusterer.prototype.redraw;
MarkerClusterer.prototype['removeMarker'] = MarkerClusterer.prototype.removeMarker;
MarkerClusterer.prototype['resetViewport'] = MarkerClusterer.prototype.resetViewport;
MarkerClusterer.prototype['setCalculator'] = MarkerClusterer.prototype.setCalculator;
MarkerClusterer.prototype['setGridSize'] = MarkerClusterer.prototype.setGridSize;
MarkerClusterer.prototype['onAdd'] = MarkerClusterer.prototype.onAdd;
MarkerClusterer.prototype['draw'] = MarkerClusterer.prototype.draw;
MarkerClusterer.prototype['idle'] = MarkerClusterer.prototype.idle;
ClusterIcon.prototype['onAdd'] = ClusterIcon.prototype.onAdd;
ClusterIcon.prototype['draw'] = ClusterIcon.prototype.draw;
ClusterIcon.prototype['onRemove'] = ClusterIcon.prototype.onRemove;