fix: calling viewer.destroy() multiple times throw an error. And a simple destroy to mousetracker

src/eventhandler.js

@@ -91,26 +91,20 @@ $.EventHandler.prototype = {
 
 
     /**
-     * Remove all event handler for a given event type.
+     * Remove all event handler for a given event type. If no type is given all event handlers for every event type is removed
      * @function
      * @param {String} eventName - Name of event for which all handlers are to be removed.
      */
     removeAllHandlers: function( eventName ) {
+        if (eventName){
             this.events[ eventName ] = [];
-    },
-
-
-    /**
-     * Remove every event handler for all event types
-     * @function
-     */
-     removeAllHandlersForAllEvents: function( ) {
+        } else{
             for (var eventType in this.events) {
                 this.events[eventType] = [];
             }
+        }
     },
 
-
     /**
      * Retrive the list of all handlers registered for a given event.
      * @function

src/mousetracker.js

@@ -171,6 +171,15 @@
 
     $.MouseTracker.prototype = {
 
+        /**
+         * Clean up any events or objects created the mouse tracker
+         * @function
+         */
+        destroy: function() {
+            stopTracking( this );
+            this.element = null;
+        },
+
         /**
          * Are we currently tracking events on this element.
          * @deprecated Just use this.tracking

src/viewer.js

@@ -499,7 +499,9 @@ $.extend( $.Viewer.prototype, $.EventHandler.prototype, $.ControlDock.prototype,
 
         this.viewport   = this.preserveViewport ? this.viewport : null;
         //this.profiler   = null;
+        if (this.canvas){
             this.canvas.innerHTML = "";
+        }
 
         VIEWERS[ this.hash ] = null;
         delete VIEWERS[ this.hash ];
@@ -518,19 +520,27 @@ $.extend( $.Viewer.prototype, $.EventHandler.prototype, $.ControlDock.prototype,
     destroy: function( ) {
         this.close();
 
-        this.removeAllHandlersForAllEvents();
+        this.removeAllHandlers();
 
         // Go through top element (passed to us) and remove all children
         // Use removeChild to make sure it handles SVG or any non-html
         // also it performs better - http://jsperf.com/innerhtml-vs-removechild/15
+        if (this.element){
             while (this.element.firstChild) {
                 this.element.removeChild(this.element.firstChild);
             }
+        }
 
-        // remove the mouse trackers - should we be cleaning up their callbacks?
-        delete this.keyboardCommandArea.innerTracker;
-        delete this.innerTracker;
-        delete this.outerTracker;
+        // destroy the mouse trackers
+        if (this.keyboardCommandArea){
+            this.keyboardCommandArea.innerTracker.destroy();
+        }
+        if (this.innerTracker){
+            this.innerTracker.destroy();
+        }
+        if (this.outerTracker){
+            this.outerTracker.destroy();
+        }
 
         // clear all our references to dom objects
         this.canvas = null;