code: public void showBackground(SwipeDirection direction, boolean dimBackground){
          if(SwipeDirection.DIRECTION_NEUTRAL != direction && mBackgroundMap.get(direction) == null) return;
  
          if(SwipeDirection.DIRECTION_NEUTRAL != visibleView)
              mBackgroundMap.get(visibleView).setVisibility(View.INVISIBLE);
          if(SwipeDirection.DIRECTION_NEUTRAL != direction) {
              mBackgroundMap.get(direction).setVisibility(View.VISIBLE);
              mBackgroundMap.get(direction).setAlpha(dimBackground ? 0.4f : 1);
          }
  
          visibleView = direction;
      }
docs: Show the View linked to a key. Don't do anything if the key is not found
  
  @param direction The key of the View to be shown
  @param dimBackground Indicates whether the background should be dimmed