add getLayer() function to Map

git-svn-id: http://svn.openlayers.org/trunk/openlayers@979 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Map.js

@@ -233,6 +233,24 @@ OpenLayers.Map.prototype = {
   /*                                                      */
   /********************************************************/         
 
+    /**
+     * @param {String} name
+     * 
+     * @returns The Layer with the corresponding id from the map's 
+     *           layer collection, or null if not found.
+     * @type OpenLayers.Layer
+     */
+    getLayer: function(id) {
+        var foundLayer = null;
+        for (var i = 0; i < this.layers.length; i++) {
+            var layer = this.layers[i];
+            if (layer.id == id) {
+                foundLayer = layer;
+            }
+        }
+        return foundLayer;
+    },
+
     /**
     * @param {OpenLayers.Layer} layer
     */    

tests/test_Map.html

@@ -205,6 +205,24 @@
         t.ok( !map.isValidLonLat(new OpenLayers.LonLat(10, 10)), "lonlat outside max extent is not valid" );
     }
 
+    function test_10_Map_getLayer(t) {
+        t.plan( 2 );    
+        map = new OpenLayers.Map($('map'));
+        layer = new OpenLayers.Layer.WMS('Test Layer', 
+                    "http://octo.metacarta.com/cgi-bin/mapserv", 
+                    {map: '/mapdata/vmap_wms.map', layers: 'basic', format: 'image/jpeg'}, 
+                    {maxExtent: new OpenLayers.Bounds(33861, 717605, 330846, 1019656), maxResolution: 296985/1024, projection:"EPSG:2805" } );
+
+        map.addLayer(layer);
+        var gotLayer = map.getLayer(layer.id);
+
+        t.ok( layer == gotLayer, "getLayer correctly returns layer" );
+
+        gotLayer = map.getLayer("chicken");
+
+        t.ok( gotLayer == null, "getLayer correctly returns null when layer not found");
+    }
+
     function test_99_Map_destroy (t) {
         t.plan( 2 );    
         map = new OpenLayers.Map($('map'));