Making it so OpenLayers.Util.getResolutionFromScale returns undefined resolution when given a falsey scale. r=ahocevar (closes #2464, see #2462)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@10019 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Util.js

@@ -1182,18 +1182,19 @@ OpenLayers.Util.normalizeScale = function (scale) {
  * 
  * Returns:
  * {Float} The corresponding resolution given passed-in scale and unit 
- *         parameters.
+ *     parameters.  If the given scale is falsey, the returned resolution will
+ *     be undefined.
  */
 OpenLayers.Util.getResolutionFromScale = function (scale, units) {
-
+    var resolution;
-    if (units == null) {
+    if (scale) {
-        units = "degrees";
+        if (units == null) {
+            units = "degrees";
+        }
+        var normScale = OpenLayers.Util.normalizeScale(scale);
+        resolution = 1 / (normScale * OpenLayers.INCHES_PER_UNIT[units]
+                                        * OpenLayers.DOTS_PER_INCH);        
     }
-
-    var normScale = OpenLayers.Util.normalizeScale(scale);
-
-    var resolution = 1 / (normScale * OpenLayers.INCHES_PER_UNIT[units]
-                                    * OpenLayers.DOTS_PER_INCH);
     return resolution;
 };
 

tests/Util.html

@@ -670,7 +670,7 @@
     }
     
     function test_Util_getScaleResolutionTranslation(t) {
-        t.plan(4); 
+        t.plan(5); 
         
         var scale = 1/150000000; 
         var resolution = OpenLayers.Util.getResolutionFromScale(scale);
@@ -687,6 +687,11 @@
         scale = 150000000; 
         resolution = OpenLayers.Util.getResolutionFromScale(scale);
         t.eq(OpenLayers.Util.getScaleFromResolution(resolution), scale, "scale->resolution->scale works");
+        
+        scale = null;
+        resolution = OpenLayers.Util.getResolutionFromScale(scale);
+        t.eq(resolution, undefined, "falsey scale results in undefined resolution");
+        
     }
     
     function test_Util_getImgLocation(t) {