getDataExtent should return null when there are no features with a geometry, r=ahocevar (closes #3435)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@12187 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Layer/Vector.js

@@ -597,7 +597,7 @@ OpenLayers.Layer.Vector = OpenLayers.Class(OpenLayers.Layer, {
                 if(this.events.triggerEvent("beforefeatureadded",
                                             {feature: feature}) === false) {
                     continue;
-                };
+                }
                 this.preFeatureInsert(feature);
             }
 
@@ -816,7 +816,7 @@ OpenLayers.Layer.Vector = OpenLayers.Class(OpenLayers.Layer, {
             this.unrenderedFeatures[feature.id] = feature;
         } else {
             delete this.unrenderedFeatures[feature.id];
-        };
+        }
     },
     
     /**
@@ -988,17 +988,20 @@ OpenLayers.Layer.Vector = OpenLayers.Class(OpenLayers.Layer, {
      * Calculates the max extent which includes all of the features.
      * 
      * Returns:
-     * {<OpenLayers.Bounds>}
+     * {<OpenLayers.Bounds>} or null if the layer has no features with
+     * geometries.
      */
     getDataExtent: function () {
         var maxExtent = null;
         var features = this.features;
         if(features && (features.length > 0)) {
-            maxExtent = new OpenLayers.Bounds();
             var geometry = null;
             for(var i=0, len=features.length; i<len; i++) {
                 geometry = features[i].geometry;
                 if (geometry) {
+                    if (maxExtent === null) {
+                        maxExtent = new OpenLayers.Bounds();
+                    }
                     maxExtent.extend(geometry.getBounds());
                 }
             }

tests/Layer/Vector.html

@@ -286,6 +286,14 @@
         t.ok(extent.toBBOX() != layer.features[0].geometry.getBounds().toBBOX(), "extent from getDataExtent doesn't clobber first feature");
     }
 
+    function test_Layer_Vector_getDataExtentEmpty(t) {
+        t.plan(1);
+        var layer = new OpenLayers.Layer.Vector(name);
+        layer.addFeatures([new OpenLayers.Feature.Vector(null), new OpenLayers.Feature.Vector(null)]);
+        var extent = layer.getDataExtent();
+        t.eq(extent, null, "We expect null to be returned if there are no features with a geometry");
+    }
+
     function test_Layer_Vector_removeFeatures(t) {
         t.plan(17);