/** 默认的Screen主线程中(非ShotLoop线程)事件 */
 public final void alter(LTimerContext context) {
   long elapsedTime = context.getTimeSinceLastUpdate();
   if (touch != null) {
     touch.update(elapsedTime);
   }
   if (scrollDelay.action(elapsedTime)) {
     switch (backgroundMode) {
       case BACK_STAR_MODE:
         this.dot[this.count] = (int) (MathUtils.random() * this.getWidth());
         ++this.count;
         this.count %= dot_size;
         break;
       case BACK_SCROLL_MODE:
         if (scroll != null) {
           scroll.update(context.getTimeSinceLastUpdate());
         }
         break;
       case BACK_EMPTY_MODE:
         emptyBackground();
         break;
     }
   }
   update(elapsedTime);
 }
  public final void alter(LTimerContext timer) {
    for (int i = 0; i < keySize; i++) {
      ActionKey act = (ActionKey) keyActions.get(i);
      if (act.isPressed()) {
        act.act(elapsedTime);
        if (act.isReturn) {
          return;
        }
      }
    }
    if (content.isVisible()) {
      processEvents();
      content.updateNode(timer.getMilliseconds());
    }
    if (follow != null) {
      for (TileMap tile : tiles) {
        float offsetX = getHalfWidth() - follow.getX();
        offsetX = MathUtils.min(offsetX, 0);
        offsetX = MathUtils.max(offsetX, getWidth() - tile.getWidth());

        float offsetY = getHalfHeight() - follow.getY();
        offsetY = MathUtils.min(offsetY, 0);
        offsetY = MathUtils.max(offsetY, getHeight() - tile.getHeight());

        setOffset(tile, offsetX, offsetY);
        tile.update(elapsedTime);
      }
    }
    for (SpriteBatchObject o : objects) {
      o.update(elapsedTime);
      if (updateListener != null) {
        updateListener.act(o, elapsedTime);
      }
    }
    update(elapsedTime);
    commits();
  }