fix for #168 - getScale() thanks for great patch from Tim Schaub

git-svn-id: http://svn.openlayers.org/trunk/openlayers@1227 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Map.js

@@ -810,6 +810,24 @@ OpenLayers.Map.prototype = {
         return resolution;
     },
 
+     /**
+      * @returns The current scale denominator of the map. 
+      *          If no baselayer is set, returns null.
+      * @type float
+      */
+    getScale: function () {
+        var scale = null;
+
+        if (this.baseLayer != null) {
+            var res = this.baseLayer.getResolution();
+            var units = this.baseLayer.units;
+            scale = res * OpenLayers.INCHES_PER_UNIT[units] *
+                    OpenLayers.DOTS_PER_INCH;
+        }
+        return scale;
+    },
+
+
     /**
     * @param {OpenLayers.Bounds} bounds
     *