Map.addLayer() will return false when adding duplicate layers. Fixes #248.

git-svn-id: http://svn.openlayers.org/trunk/openlayers@2539 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Map.js

@@ -299,6 +299,12 @@ OpenLayers.Map.prototype = {
     * @param {OpenLayers.Layer} layer
     */    
     addLayer: function (layer) {
+        for(var i=0; i < this.layers.length; i++) {
+            if (this.layers[i] == layer) {
+                return false;
+            }
+        }    
+        
         layer.div.style.overflow = "";
         this.setLayerZIndex(layer, this.layers.length);
 

tests/test_Map.html

@@ -220,6 +220,20 @@
         t.ok( gotLayer == null, "getLayer correctly returns null when layer not found");
     }
     
+    function test_11_Map_double_addLayer(t) {
+        t.plan( 1 );    
+        map = new OpenLayers.Map($('map'));
+        layer = new OpenLayers.Layer.WMS('Test Layer', 
+                    "http://octo.metacarta.com/cgi-bin/mapserv", 
+                    {map: '/mapdata/vmap_wms.map', layers: 'basic', format: 'image/jpeg'} 
+                    );
+
+        map.addLayers([layer,layer]);
+        
+        t.eq( map.layers.length, 1, "Map does not allow double adding of layers." );
+    
+    }
+
     function test_10_Map_setBaseLayer(t) {
         t.plan( 4 );