Layer: add getter method for maxExtent, p=regli_dominik, r=me

git-svn-id: http://svn.openlayers.org/trunk/openlayers@10681 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Layer/Grid.js

@@ -354,7 +354,7 @@ OpenLayers.Layer.Grid = OpenLayers.Class(OpenLayers.Layer.HTTPRequest, {
         var minCols = Math.ceil(viewSize.w/this.tileSize.w) +
                       Math.max(1, 2 * this.buffer);
         
-        var extent = this.maxExtent;
+        var extent = this.getMaxExtent();
         var resolution = this.map.getResolution();
         
         var tileLayout = this.calculateGridLayout(bounds, extent, resolution);
@@ -429,6 +429,18 @@ OpenLayers.Layer.Grid = OpenLayers.Class(OpenLayers.Layer.HTTPRequest, {
         //now actually draw the tiles
         this.spiralTileLoad();
     },
+
+    /**
+     * Method: getMaxExtent
+     * Get this layer's maximum extent. (Implemented as a getter for
+     *     potential specific implementations in sub-classes.)
+     *
+     * Returns:
+     * {OpenLayers.Bounds}
+     */
+    getMaxExtent: function() {
+        return this.maxExtent;
+    },
     
     /**
      * Method: spiralTileLoad