leafclusterer.js

/**
 * @name LeafClusterer
 * @version 1.0
 * @author Xiaoxi Wu
 * @author Imre Deak, ported for Leaflet
 * @copyright (c) 2009 Xiaoxi Wu
 * @fileoverview
 * This javascript library creates and manages per-zoom-level 
 * clusters for large amounts of markers (hundreds or thousands).
 * This library was inspired by the <a href="http://www.maptimize.com">
 * Maptimize</a> hosted clustering solution.
 * <br /><br/>
 * <b>How it works</b>:<br/>
 * The <code>LeafClusterer</code> will group markers into clusters according to
 * their distance from a cluster's center. When a marker is added,
 * the marker cluster will find a position in all the clusters, and 
 * if it fails to find one, it will create a new cluster with the marker.
 * The number of markers in a cluster will be displayed
 * on the cluster marker. When the map viewport changes,
 * <code>LeafClusterer</code> will destroy the clusters in the viewport 
 * and regroup them into new clusters.
 *
 */

/*
 * 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.
 */


/**
 * @name LeafClustererOptions
 * @class This class represents optional arguments to the {@link LeafClusterer}
 * constructor.
 * @property {Number} [maxZoom] The max zoom level monitored by a
 * marker cluster. If not given, the marker cluster assumes the maximum map
 * zoom level. When maxZoom is reached or exceeded all markers will be shown
 * without cluster.
 * @property {Number} [gridSize=60] The grid size of a cluster in pixel. Each
 * cluster will be a square. If you want the algorithm to run faster, you can set
 * this value larger.
 * @property {Array of MarkerStyleOptions} [styles]
 * Custom styles for the cluster markers.
 * The array should be ordered according to increasing cluster size,
 * with the style for the smallest clusters first, and the style for the
 * largest clusters last.
 */

/**
 * @name MarkerStyleOptions
 * @class An array of these is passed into the {@link LeafClustererOptions}
 * styles option.
 * @property {String} [url] Image url.
 * @property {Number} [height] Image height.
 * @property {Number} [height] Image width.
 * @property {Array of Number} [opt_anchor] Anchor for label text, like [24, 12]. 
 *    If not set, the text will align center and middle.
 * @property {String} [opt_textColor="black"] Text color.
 */

/**
 * Creates a new LeafClusterer to cluster markers on the map.
 *
 * @constructor
 * @param {GMap2} map The map that the markers should be added to.
 * @param {Array of GMarker} opt_markers Initial set of markers to be clustered.
 * @param {LeafClustererOptions} opt_opts A container for optional arguments.
 */
function LeafClusterer(map, opt_markers, opt_opts) {
  // private members
  var clusters_ = [];
  var map_ = map;
  var maxZoom_ = null;
  var me_ = this;
  var gridSize_ = 40;
  var sizes = [53, 56, 66, 78, 90];
  var styles_ = [];
  var leftMarkers_ = [];
  var mcfn_ = null;

  var i = 0;
  for (i = 1; i <= 5; ++i) {
    styles_.push({
      'url': "http://gmaps-utility-library.googlecode.com/svn/trunk/markerclusterer/images/m" + i + ".png",
      'height': sizes[i - 1],
      'width': sizes[i - 1]
    });
  }

  if (typeof opt_opts === "object" && opt_opts !== null) {
    if (typeof opt_opts.gridSize === "number" && opt_opts.gridSize > 0) {
      gridSize_ = opt_opts.gridSize;
    }
    if (typeof opt_opts.maxZoom === "number") {
      maxZoom_ = opt_opts.maxZoom;
    }
    if (typeof opt_opts.styles === "object" && opt_opts.styles !== null && opt_opts.styles.length !== 0) {
      styles_ = opt_opts.styles;
    }
  }

  /**
   * When we add a marker, the marker may not in the viewport of map, then we don't deal with it, instead
   * we add the marker into a array called leftMarkers_. When we reset LeafClusterer we should add the
   * leftMarkers_ into LeafClusterer.
   */
  function addLeftMarkers_() {
    if (leftMarkers_.length === 0) {
      return;
    }
    var leftMarkers = [];
    for (i = 0; i < leftMarkers_.length; ++i) {
      me_.addMarker(leftMarkers_[i], true, null, null, true);
    }
    leftMarkers_ = leftMarkers;
  }

  /**
   * Get cluster marker images of this marker cluster. Mostly used by {@link Cluster}
   * @private
   * @return {Array of String}
   */
  this.getStyles_ = function () {
    return styles_;
  };

  /**
   * Remove all markers from LeafClusterer.
   */
  this.clearMarkers = function () {
    for (var i = 0; i < clusters_.length; ++i) {
      if (typeof clusters_[i] !== "undefined" && clusters_[i] !== null) {
        clusters_[i].clearMarkers();
      }
    }
    clusters_ = [];
    leftMarkers_ = [];
    map.off(mcfn_);
  };

  /**
   * Check a marker, whether it is in current map viewport.
   * @private
   * @return {Boolean} if it is in current map viewport
   */
  function isMarkerInViewport_(marker) {
    return map_.getBounds().contains(marker.getLatLng());
  }

  /**
   * When reset LeafClusterer, there will be some markers get out of its cluster.
   * These markers should be add to new clusters.
   * @param {Array of GMarker} markers Markers to add.
   */
  function reAddMarkers_(markers) {
    var len = markers.length;
    var clusters = [];
    for (var i = len - 1; i >= 0; --i) {
      me_.addMarker(markers[i].marker, true, markers[i].isAdded, clusters, true);
    }
    addLeftMarkers_();
  }

  /**
   * Add a marker.
   * @private
   * @param {GMarker} marker Marker you want to add
   * @param {Boolean} opt_isNodraw Whether redraw the cluster contained the marker
   * @param {Boolean} opt_isAdded Whether the marker is added to map. Never use it.
   * @param {Array of Cluster} opt_clusters Provide a list of clusters, the marker
   *     cluster will only check these cluster where the marker should join.
   */
  this.addMarker = function (marker, opt_isNodraw, opt_isAdded, opt_clusters, opt_isNoCheck) {
    if (opt_isNoCheck !== true) {
      if (!isMarkerInViewport_(marker)) {
        leftMarkers_.push(marker);
        return;
      }
    }

    var isAdded = opt_isAdded;
    var clusters = opt_clusters;
    var pos = map_.latLngToLayerPoint(marker.getLatLng());

    if (typeof isAdded !== "boolean") {
      isAdded = false;
    }
    if (typeof clusters !== "object" || clusters === null) {
      clusters = clusters_;
    }

    var length = clusters.length;
    var cluster = null;
    for (var i = length - 1; i >= 0; i--) {
      cluster = clusters[i];
      var center = cluster.getCenter();
      if (center === null) {
        continue;
      }
      center = map_.latLngToLayerPoint(center);

      // Found a cluster which contains the marker.
      if (pos.x >= center.x - gridSize_ && pos.x <= center.x + gridSize_ &&
          pos.y >= center.y - gridSize_ && pos.y <= center.y + gridSize_) {
        cluster.addMarker({
          'isAdded': isAdded,
          'marker': marker
        });
        if (!opt_isNodraw) {
          cluster.redraw_();
        }
        return;
      }
    }

    // No cluster contain the marker, create a new cluster.
    cluster = new Cluster(this, map);
    cluster.addMarker({
      'isAdded': isAdded,
      'marker': marker
    });
    if (!opt_isNodraw) {
      cluster.redraw_();
    }

    // Add this cluster both in clusters provided and clusters_
    clusters.push(cluster);
    if (clusters !== clusters_) {
      clusters_.push(cluster);
    }
  };

  /**
   * Remove a marker.
   *
   * @param {GMarker} marker The marker you want to remove.
   */

  this.removeMarker = function (marker) {
    for (var i = 0; i < clusters_.length; ++i) {
      if (clusters_[i].remove(marker)) {
        clusters_[i].redraw_();
        return;
      }
    }
  };

  /**
   * Redraw all clusters in viewport.
   */
  this.redraw_ = function () {
    var clusters = this.getClustersInViewport_();
    for (var i = 0; i < clusters.length; ++i) {
      clusters[i].redraw_(true);
    }
  };

  /**
   * Get all clusters in viewport.
   * @return {Array of Cluster}
   */
  this.getClustersInViewport_ = function () {
    var clusters = [];
    var curBounds = map_.getBounds();
    for (var i = 0; i < clusters_.length; i ++) {
      if (clusters_[i].isInBounds(curBounds)) {
        clusters.push(clusters_[i]);
      }
    }
    return clusters;
  };

  /**
   * Get max zoom level.
   * @private
   * @return {Number}
   */
  this.getMaxZoom_ = function () {
    return maxZoom_;
  };

  /**
   * Get map object.
   * @private
   * @return {GMap2}
   */
  this.getMap_ = function () {
    return map_;
  };

  /**
   * Get grid size
   * @private
   * @return {Number}
   */
  this.getGridSize_ = function () {
    return gridSize_;
  };

  /**
   * Get total number of markers.
   * @return {Number}
   */
  this.getTotalMarkers = function () {
    var result = 0;
    for (var i = 0; i < clusters_.length; ++i) {
      result += clusters_[i].getTotalMarkers();
    }
    return result;
  };

  /**
   * Get total number of clusters.
   * @return {int}
   */
  this.getTotalClusters = function () {
    return clusters_.length;
  };

  /**
   * Collect all markers of clusters in viewport and regroup them.
   */
  this.resetViewport = function () {
    var clusters = this.getClustersInViewport_();
    var tmpMarkers = [];
    var removed = 0;

    for (var i = 0; i < clusters.length; ++i) {
      var cluster = clusters[i];
      var oldZoom = cluster.getCurrentZoom();
      if (oldZoom === null) {
        continue;
      }
      var curZoom = map_.getZoom();
      if (curZoom !== oldZoom) {

        // If the cluster zoom level changed then destroy the cluster
        // and collect its markers.
        var mks = cluster.getMarkers();
        for (var j = 0; j < mks.length; ++j) {
          var newMarker = {
            'isAdded': false,
            'marker': mks[j].marker
          };
          tmpMarkers.push(newMarker);
        }
        cluster.clearMarkers();
        removed++;
        for (j = 0; j < clusters_.length; ++j) {
          if (cluster === clusters_[j]) {
            clusters_.splice(j, 1);
          }
        }
      }
    }

    // Add the markers collected into marker cluster to reset
    reAddMarkers_(tmpMarkers);
    this.redraw_();
  };


  /**
   * Add a set of markers.
   *
   * @param {Array of GMarker} markers The markers you want to add.
   */
  this.addMarkers = function (markers) {
    for (var i = 0; i < markers.length; ++i) {
      this.addMarker(markers[i], true);
    }
    this.redraw_();
  };

  // initialize
  if (typeof opt_markers === "object" && opt_markers !== null) {
    this.addMarkers(opt_markers);
  }

  // when map move end, regroup.
  mcfn_ = map_.on("moveend", function () {
    me_.resetViewport();
  });
}

/**
 * Create a cluster to collect markers.
 * A cluster includes some markers which are in a block of area.
 * If there are more than one markers in cluster, the cluster
 * will create a {@link ClusterMarker_} and show the total number
 * of markers in cluster.
 *
 * @constructor
 * @private
 * @param {LeafClusterer} leafClusterer The marker cluster object
 */
function Cluster(leafClusterer) {
  var center_ = null;
  var markers_ = [];
  var leafClusterer_ = leafClusterer;
  var map_ = leafClusterer.getMap_();
  var clusterMarker_ = null;
  var zoom_ = map_.getZoom();

  /**
   * Get markers of this cluster.
   *
   * @return {Array of GMarker}
   */
  this.getMarkers = function () {
    return markers_;
  };

  /**
   * If this cluster intersects certain bounds.
   *
   * @param {GLatLngBounds} bounds A bounds to test
   * @return {Boolean} Is this cluster intersects the bounds
   */
  this.isInBounds = function (bounds) {
    if (center_ === null) {
      return false;
    }

    if (!bounds) {
      bounds = map_.getBounds();
    }
    var sw = map_.latLngToLayerPoint(bounds.getSouthWest());
    var ne = map_.latLngToLayerPoint(bounds.getNorthEast());

    var centerxy = map_.latLngToLayerPoint(center_);
    var inViewport = true;
    var gridSize = leafClusterer.getGridSize_();
    if (zoom_ !== map_.getZoom()) {
      var dl = map_.getZoom() - zoom_;
      gridSize = Math.pow(2, dl) * gridSize;
    }
    if (ne.x !== sw.x && (centerxy.x + gridSize < sw.x || centerxy.x - gridSize > ne.x)) {
      inViewport = false;
    }
    if (inViewport && (centerxy.y + gridSize < ne.y || centerxy.y - gridSize > sw.y)) {
      inViewport = false;
    }
    return inViewport;
  };

  /**
   * Get cluster center.
   *
   * @return {GLatLng}
   */
  this.getCenter = function () {
    return center_;
  };

  /**
   * Add a marker.
   *
   * @param {Object} marker An object of marker you want to add:
   *   {Boolean} isAdded If the marker is added on map.
   *   {GMarker} marker The marker you want to add.
   */
  this.addMarker = function (marker) {
    if (center_ === null) {
      center_ = marker.marker.getLatLng();
    }
    markers_.push(marker);
  };

  /**
   * Remove a marker from cluster.
   *
   * @param {GMarker} marker The marker you want to remove.
   * @return {Boolean} Whether find the marker to be removed.
   */
  this.removeMarker = function (marker) {
    for (var i = 0; i < markers_.length; ++i) {
      if (marker === markers_[i].marker) {
        if (markers_[i].isAdded) {
          map_.removeLayer(markers_[i].marker);
        }
        markers_.splice(i, 1);
        return true;
      }
    }
    return false;
  };

  /**
   * Get current zoom level of this cluster.
   * Note: the cluster zoom level and map zoom level not always the same.
   *
   * @return {Number}
   */
  this.getCurrentZoom = function () {
    return zoom_;
  };

  /**
   * Redraw a cluster.
   * @private
   * @param {Boolean} isForce If redraw by force, no matter if the cluster is
   *     in viewport.
   */
  this.redraw_ = function (isForce) {
    if (!isForce && !this.isInBounds()) {
      return;
    }

    // Set cluster zoom level.
    zoom_ = map_.getZoom();
    var i = 0;
    var mz = leafClusterer.getMaxZoom_();
    if (mz === null) {
      mz = map_.getMaxZoom();
    }
    if (zoom_ >= mz || this.getTotalMarkers() === 1) {
      // If current zoom level is beyond the max zoom level or the cluster
      // have only one marker, the marker(s) in cluster will be showed on map.
      for (i = 0; i < markers_.length; ++i) {
        map_.addLayer(markers_[i].marker);
        markers_[i].isAdded = true;
      }
      if (clusterMarker_ !== null)
        clusterMarker_.hide();
    } else {
      // Else add a cluster marker on map to show the number of markers in
      // this cluster.
      for (i = 0; i < markers_.length; ++i) {
        if (markers_[i].isAdded) {
          map_.removeLayer(markers_[i].marker);
        }
      }
      if (clusterMarker_ === null) {
        clusterMarker_ = new ClusterMarker_(center_, this.getTotalMarkers(), leafClusterer_.getStyles_(), leafClusterer_.getGridSize_() / 2);
        map_.addLayer(clusterMarker_);
      } else {
        clusterMarker_.reset({count: this.getTotalMarkers()});
        clusterMarker_.redraw();
        if (clusterMarker_.isHidden()) {
          clusterMarker_.show();
        }
      }
    }
  };

  /**
   * Remove all the markers from this cluster.
   */
  this.clearMarkers = function () {
    if (clusterMarker_ !== null) {
      map_.removeLayer(clusterMarker_);
    }
    for (var i = 0; i < markers_.length; ++i) {
      if (markers_[i].isAdded) {
        map_.removeLayer(markers_[i].marker);
      }
    }
    markers_ = [];
  };

  /**
   * Get number of markers.
   * @return {Number}
   */
  this.getTotalMarkers = function () {
    return markers_.length;
  };
}

ClusterMarker_ = L.Class.extend({
  initialize: function(latLng_, count_, styles_, padding_) {
    this.reset({latLng:latLng_, count: count_, styles: styles_, padding: padding_});
  },
               
  reset: function(opts) {
    if (!opts || typeof opts !== "object")
      return;

    var updated = 0;
    if (typeof opts.latLng === "object" && opts.latLng != this.latlng_) {
      this.latlng_ = opts.latLng;
      updated = 1;
    }

    var styles_updated = 0;
    if (typeof opts.styles === "object" && opts.styles != this.styles_) {
      this.styles_ = opts.styles;
      updated = 1;
      styles_updated = 1;
    }

    if (typeof opts.count === "number" && opts.count != this.count_ || styles_updated) {
      this.count_ = opts.count;

      var index = 0;
      var dv = this.count_;
      while (dv !== 0) {
          dv = parseInt(dv / 10, 10);
          index ++;
      }

      var styles = this.styles_;

      if (styles.length < index) {
          index = styles.length;
      }
      this.url_ = styles[index - 1].url;
      this.height_ = styles[index - 1].height;
      this.width_ = styles[index - 1].width;
      this.textColor_ = styles[index - 1].opt_textColor;
      this.anchor_ = styles[index - 1].opt_anchor;
      this.index_ = index;
    }

    if (typeof opts.padding === "number" && this.padding_ != opts.padding) {
      this.padding_ = opts.padding;
      updated = 1;
    }

    this.updated |= updated;
  },

  onAdd: function(map) {
    this.map_ = map;
    this.container_ = L.DomUtil.create('div', 'cluster-marker-container');
    map.getPanes().overlayPane.appendChild(this.container_);
    var cluster = this;

    if (this.container_.addEventListener) {
      this.container_.addEventListener("click",
        function() {
          cluster.onClick_(cluster);
        }, false); 
    } else if (this.container_.attachEvent) {
      this.container_.attachEvent("onclick",
        function() {
          cluster.onClick_(cluster);
        });     
    }   
    map.on('viewreset', this.redraw, this);
    this.redraw();
  },
    
  onClick_: function(cluster) {
    var padding = cluster.padding_;
    var map = cluster.map_;

    var pos = cluster.map_.latLngToLayerPoint(cluster.latlng_);
    var sw = new L.Point(pos.x - padding, pos.y + padding);
    sw = map.layerPointToLatLng(sw);
    var ne = new L.Point(pos.x + padding, pos.y - padding);
    ne = map.layerPointToLatLng(ne);
    var zoom = map.getBoundsZoom(new L.LatLngBounds(sw, ne));
    map.setView(cluster.latlng_, zoom);
  },

  onRemove: function(map) {
    map.getPanes().overlayPane.removeChild(this.container_);
    map.off('viewreset', this.redraw, this);
  },

  redraw: function() {
    if (this.div_ && this.updated) {
        this.container_.removeChild(this.div_);
        this.div_ = null;
    }
    if (!this.div_) {
      this.div_ = this.initLayout_();
      this.container_.appendChild(this.div_);
    }

    var pos = this.map_.latLngToLayerPoint(this.latlng_);
    pos.x -= parseInt(this.width_ / 2, 10);
    pos.y -= parseInt(this.height_ / 2, 10);
    this.container_.style.top =  pos.y + "px";
    this.container_.style.left = pos.x + "px";
  },

  hide: function() {
    this.div_.style.display = "none";
  },

  show: function() {
    this.div_.style.display = "";
  },

  isHidden: function () {
    return this.div_.style.display === "none";
  },

  initLayout_: function() {
    var div = L.DomUtil.create('div', 'cluster-marker');
    var latlng = this.latlng_;
    var pos = this.map_.latLngToLayerPoint(latlng);
    pos.x -= parseInt(this.width_ / 2, 10);
    pos.y -= parseInt(this.height_ / 2, 10);
    var mstyle = "";

    if (document.all) {
      mstyle = 'filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale,src="' + this.url_ + '");';
    } else {
      mstyle = "background:url(" + this.url_ + ");";
    }
    if (typeof this.anchor_ === "object") {
      if (typeof this.anchor_[0] === "number" && this.anchor_[0] > 0 && this.anchor_[0] < this.height_) {
        mstyle += 'height:' + (this.height_ - this.anchor_[0]) + 'px;padding-top:' + this.anchor_[0] + 'px;';
      } else {
        mstyle += 'height:' + this.height_ + 'px;line-height:' + this.height_ + 'px;';
      }
      if (typeof this.anchor_[1] === "number" && this.anchor_[1] > 0 && this.anchor_[1] < this.width_) {
        mstyle += 'width:' + (this.width_ - this.anchor_[1]) + 'px;padding-left:' + this.anchor_[1] + 'px;';
      } else {
        mstyle += 'width:' + this.width_ + 'px;text-align:center;';
      }
    } else {
      mstyle += 'height:' + this.height_ + 'px;line-height:' + this.height_ + 'px;';
      mstyle += 'width:' + this.width_ + 'px;text-align:center;';
    }
    var txtColor = this.textColor_ ? this.textColor_ : 'black';
  
    div.style.cssText = mstyle + 'cursor:pointer;top:' + pos.y + "px;left:" +
        pos.x + "px;color:" + txtColor +  ";position:absolute;font-size:11px;" +
        'font-family:Arial,sans-serif;font-weight:bold';
    div.innerHTML = this.count_;

    return div;
  }
});