Removed MethodQueue.setStage(), use the same trick we use in

AnimationManager and that I saw in use in Tweener: just
listen for ENTER_FRAME on some random sprite.


git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@4926 542714f4-19e9-0310-aa3c-eee0fc999fb1

src/as/com/threerings/util/MethodQueue.as

@@ -21,7 +21,7 @@
 
 package com.threerings.util {
 
-import flash.display.Stage;
+import flash.display.Sprite;
 
 import flash.events.Event;
 
@@ -31,48 +31,14 @@ import flash.events.Event;
  */
 public class MethodQueue
 {
-    /**
-     * Set the stage which will be used for coordinating the use of the
-     * method queue. If no stage is set, functions will continue to pile up
-     * without being called.
-     */
-    public static function setStage (stage :Stage) :void
-    {
-        if (_listening) {
-            removeListener();
-        }
-        _stage = stage;
-        checkListen();
-    }
-
     /**
      * Call the specified method at the entry to the next frame.
      */
     public static function callLater (fn :Function, args :Array = null) :void
     {
         _methodQueue.push([fn, args]);
-        if (!_listening) {
-            checkListen();
-        }
-    }
-
-    /**
-     * Stop listening for the frame event.
-     */
-    protected static function removeListener () :void
-    {
-        _stage.removeEventListener(Event.ENTER_FRAME, handleEnterFrame);
-        _listening = false;
-    }
-
-    /**
-     * Check to see if we should be listening for the next frame event.
-     */
-    protected static function checkListen () :void
-    {
-        if (_stage != null && _methodQueue.length > 0) {
-            _stage.addEventListener(Event.ENTER_FRAME, handleEnterFrame);
-            _listening = true;
+        if (!_d.hasEventListener(Event.ENTER_FRAME)) {
+            _d.addEventListener(Event.ENTER_FRAME, handleEnterFrame);
         }
     }
 
@@ -101,17 +67,14 @@ public class MethodQueue
         // If no new functions were added while we were calling the current set,
         // then remove the listener.
         if (_methodQueue.length == 0) {
-            removeListener();
+            _d.removeEventListener(Event.ENTER_FRAME, handleEnterFrame);
         }
     }
 
-    /** The stage we're working with. */
-    protected static var _stage :Stage;
+    /** A display object on which we listen for ENTER_FRAME. */
+    protected static var _d :Sprite = new Sprite();
 
     /** The currently queued functions. */
     protected static var _methodQueue :Array = [];
-
-    /** Are we presently listening for the frame event? */
-    protected static var _listening :Boolean = false;
 }
 }