From 3c416a4d6070a4fd0e6b5546401a76bfe6bf8e41 Mon Sep 17 00:00:00 2001
From: Xavier Mamano <xavier.mamano@gmail.com>
Date: Tue, 16 Oct 2012 18:43:53 +0200
Subject: [PATCH 1/2] Clear the cache on `Strategy.Cluster` when features are
 removed.

This prevents reappearing the removed features after zooming.
---
 lib/OpenLayers/Strategy/Cluster.js | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/lib/OpenLayers/Strategy/Cluster.js b/lib/OpenLayers/Strategy/Cluster.js
index 50a14b7859..026a0c63af 100644
--- a/lib/OpenLayers/Strategy/Cluster.js
+++ b/lib/OpenLayers/Strategy/Cluster.js
@@ -79,6 +79,7 @@ OpenLayers.Strategy.Cluster = OpenLayers.Class(OpenLayers.Strategy, {
         if(activated) {
             this.layer.events.on({
                 "beforefeaturesadded": this.cacheFeatures,
+                "featuresremoved": this.clearCache,
                 "moveend": this.cluster,
                 scope: this
             });
@@ -100,6 +101,7 @@ OpenLayers.Strategy.Cluster = OpenLayers.Class(OpenLayers.Strategy, {
             this.clearCache();
             this.layer.events.un({
                 "beforefeaturesadded": this.cacheFeatures,
+                "featuresremoved": this.clearCache,
                 "moveend": this.cluster,
                 scope: this
             });
@@ -134,7 +136,9 @@ OpenLayers.Strategy.Cluster = OpenLayers.Class(OpenLayers.Strategy, {
      * Clear out the cached features.
      */
     clearCache: function() {
-        this.features = null;
+        if(!this.clustering) {
+            this.features = null;
+        }
     },
     
     /**
@@ -169,7 +173,9 @@ OpenLayers.Strategy.Cluster = OpenLayers.Class(OpenLayers.Strategy, {
                         }
                     }
                 }
+                this.clustering = true;
                 this.layer.removeAllFeatures();
+                this.clustering = false;
                 if(clusters.length > 0) {
                     if(this.threshold > 1) {
                         var clone = clusters.slice();

From ee3444884408497c50f6a64c883eb6b37353673b Mon Sep 17 00:00:00 2001
From: Xavier Mamano <xavier.mamano@gmail.com>
Date: Wed, 17 Oct 2012 19:06:53 +0200
Subject: [PATCH 2/2] Add test remove features and zoom on
 Strategy/Cluster.html

---
 tests/Strategy/Cluster.html | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/tests/Strategy/Cluster.html b/tests/Strategy/Cluster.html
index 38cc116ba7..05130bbfb7 100644
--- a/tests/Strategy/Cluster.html
+++ b/tests/Strategy/Cluster.html
@@ -19,7 +19,7 @@
     }
 
     function test_clusters(t) {
-        t.plan(17);
+        t.plan(22);
 
         function featuresEq(got, exp) {
             var eq = false;
@@ -103,7 +103,24 @@
         // the one feature with no geometry is not added to the layer
         t.eq(layer.features.length, features.length-1, "[1-threshold 100] layer has " + (features.length-1) + " clusters");
         t.ok(featuresEq(layer.features, features.slice(0, 80)), "[1-threshold 100] layer has all features with geometry");
-        
+
+        // remove features and zoom
+        strategy.threshold = 1;
+        map.setCenter(new OpenLayers.LonLat(0, 0), 0);
+        t.eq(strategy.features.length, 81,
+                    "[remove features] cluster has cache");
+        layer.removeAllFeatures();
+        t.eq(layer.features.length, 0,
+                    "[remove features] layer has no features after remove");
+        t.ok(!strategy.features,
+                    "[remove features] cluster has no cache after remove");
+        map.zoomIn();
+        t.eq(layer.features.length, 0,
+                    "[remove features] layer has no features after zoom");
+        t.ok(!strategy.features,
+                    "[remove features] cluster has no cache after zoom");
+
+        map.destroy();
     }
 
     function test_deactivate(t) {