made metadata api parameters configurable. p="Jeff Maki",me r=me (closes #3013)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@11032 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Layer/Bing.js

@@ -42,6 +42,13 @@ OpenLayers.Layer.Bing = OpenLayers.Class(OpenLayers.Layer.XYZ, {
      *     used.  Default is "Road".
      */
     type: "Road",
+    
+    /**
+     * APIProperty: metadataParams
+     * {Object} Optional url parameters for the Get Imagery Metadata request
+     * as described here: http://msdn.microsoft.com/en-us/library/ff701716.aspx
+     */
+    metadataParams: null,
 
     /**
      * Constant: EVENT_TYPES
@@ -106,25 +113,26 @@ OpenLayers.Layer.Bing = OpenLayers.Class(OpenLayers.Layer.XYZ, {
         
         var newArgs = [name, null, options];
         OpenLayers.Layer.XYZ.prototype.initialize.apply(this, newArgs);
-        this.loadMetadata(this.type); 
+        this.loadMetadata(); 
     },
 
     /**
      * Method: loadMetadata
-     *
-     * Parameters:
-     * imageryType - {String}
      */
-    loadMetadata: function(imageryType) {
+    loadMetadata: function() {
         this._callbackId = "_callback_" + this.id.replace(/\./g, "_");
         // link the processMetadata method to the global scope and bind it
         // to this instance
         window[this._callbackId] = OpenLayers.Function.bind(
             OpenLayers.Layer.Bing.processMetadata, this
         );
+        var params = OpenLayers.Util.applyDefaults({
+            key: this.key,
+            jsonp: this._callbackId,
+            include: "ImageryProviders"
+        }, this.metadataParams);
         var url = "http://dev.virtualearth.net/REST/v1/Imagery/Metadata/" +
-            imageryType + "?key=" + this.key + "&jsonp=" + this._callbackId +
-            "&include=ImageryProviders";
+            this.type + "?" + OpenLayers.Util.getParameterString(params);
         var script = document.createElement("script");
         script.type = "text/javascript";
         script.src = url;