Fix hash tile generation by checking the validity of URL input parameter and fallback to level, x, y variables.

src/tilesource.js

@@ -688,11 +688,14 @@ $.TileSource.prototype = {
      * @param {*} postData data the tile was fetched with (type depends on getTilePostData(..) return type)
      */
     getTileHashKey: function(level, x, y, url, ajaxHeaders, postData) {
-        if (ajaxHeaders) {
+        function withHeaders(hash) {
-            return url + "+" + JSON.stringify(ajaxHeaders);
+            return ajaxHeaders ? hash + "+" + JSON.stringify(ajaxHeaders) : hash;
-        } else {
-            return url;
         }
+
+        if (typeof url !== "string") {
+            return withHeaders(level + "/" + x + "_" + y);
+        }
+        return withHeaders(url);
     },
 
     /**

src/viewer.js

@@ -1398,11 +1398,6 @@ $.extend( $.Viewer.prototype, $.EventSource.prototype, $.ControlDock.prototype,
             options.ajaxHeaders = $.extend({}, this.ajaxHeaders, options.ajaxHeaders);
         }
 
-        if (!$.isFunction(options.tileSource.getTileHashKey)) {
-            //silently add custom implementation
-            options.tileSource.getTileHashKey = $.TileSource.prototype.getTileHashKey;
-        }
-
         var myQueueItem = {
             options: options
         };