Cluster strategy should register for moveend on the layer instead of zoomend on the map. p=elemoine,me r=me (closes #1834)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@8460 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Strategy/Cluster.js

@@ -70,9 +70,9 @@ OpenLayers.Strategy.Cluster = OpenLayers.Class(OpenLayers.Strategy, {
         if(activated) {
             this.layer.events.on({
                 "beforefeaturesadded": this.cacheFeatures,
+                "moveend": this.cluster,
                 scope: this
             });
-            this.layer.map.events.on({"zoomend": this.cluster, scope: this});
         }
         return activated;
     },
@@ -91,9 +91,9 @@ OpenLayers.Strategy.Cluster = OpenLayers.Class(OpenLayers.Strategy, {
             this.clearCache();
             this.layer.events.un({
                 "beforefeaturesadded": this.cacheFeatures,
+                "moveend": this.cluster,
                 scope: this
             });
-            this.layer.map.events.un({"zoomend": this.cluster, scope: this});
         }
         return deactivated;
     },
@@ -137,9 +137,13 @@ OpenLayers.Strategy.Cluster = OpenLayers.Class(OpenLayers.Strategy, {
     /**
      * Method: cluster
      * Cluster features based on some threshold distance.
+     *
+     * Parameters:
+     * event - {Object} The event received when cluster is called as a
+     *     result of a moveend event.
      */
-    cluster: function() {
-        if(this.features) {
+    cluster: function(event) {
+        if((!event || event.zoomChanged) && this.features) {
             var resolution = this.layer.map.getResolution();
             if(resolution != this.resolution || !this.clustersExist()) {
                 this.resolution = resolution;

tests/Strategy/Cluster.html

@@ -59,8 +59,8 @@
         // add one additional feature, with no geometry - just to confirm it doesn't break things
         features.push(new OpenLayers.Feature.Vector());
         
-        map.setCenter(new OpenLayers.LonLat(0, 0), 0);
         layer.addFeatures(features);
+        map.setCenter(new OpenLayers.LonLat(0, 0), 0);
         
         // resolution 4
         // threshold: 4 * 20 = 80 units