Option for loading utfgrid via jsonp

lib/OpenLayers/Layer/UTFGrid.js

@@ -82,6 +82,20 @@ OpenLayers.Layer.UTFGrid = OpenLayers.Class(OpenLayers.Layer.Grid, {
      */
     serverResolutions: null,
 
+    /**
+     * APIProperty: useJSONP
+     * Should we use a JSONP script approach instead of a standard AJAX call?
+     *
+     * Set to true for using utfgrids from another server. 
+     * Avoids same-domain policy restrictions. 
+     * Note that this only works if the server accepts 
+     * the callback GET parameter and dynamically 
+     * wraps the returned json in a function call.
+     * 
+     * {Boolean} Default is false
+     */
+    useJSONP: false,
+
     /**
      * Constructor: OpenLayers.Layer.UTFGrid
      *

lib/OpenLayers/Tile/UTFGrid.js

@@ -107,28 +107,27 @@ OpenLayers.Tile.UTFGrid = OpenLayers.Class(OpenLayers.Tile, {
             }
             this.url = this.layer.getURL(this.bounds);
 
-            var resp = new OpenLayers.Protocol.Response({requestType: "read"});
-            resp.priv = OpenLayers.Request.GET({
-                url: this.url,
-                callback: this.parseData,
-                scope: this
-            });
-
-            /*
-             * MP TODO Investigate JSONP method to avoid xbrowser polucy
-             *
-            grid = function(e) { 
-                console.log(e);
-            };
-
-            var ols = new OpenLayers.Protocol.Script({
-                url: "http://tiles/world_utfgrid/2/2/1.json", 
-                callback: grid,
-                scope: this
-            });
-            var res = ols.read();
-            console.log(res.priv);
-            */
+            if (this.layer.useJSONP) {
+                // Use JSONP method to avoid xbrowser polucy
+                var that = this;
+                var cback = function(resp) {
+                    that.json = resp.data;
+                };
+                var ols = new OpenLayers.Protocol.Script({
+                    url: this.url, 
+                    callback: cback,
+                    scope: this
+                });
+                var res = ols.read();
+            } else {
+                // Use standard AJAX call
+                var resp = new OpenLayers.Protocol.Response({requestType: "read"});
+                resp.priv = OpenLayers.Request.GET({
+                    url: this.url,
+                    callback: this.parseData,
+                    scope: this
+                });
+            }
 
             this.positionTile();
         } else {