code: private void setBackground(boolean filled) {
          if (filled) {
              final int background = styledAttributes
                      .getResourceId(R.styleable.PinLock_statusFilledBackground, R.drawable.dot_filled);
              setBackgroundResource(background);
          } else {
              final int background = styledAttributes
                      .getResourceId(R.styleable.PinLock_statusEmptyBackground, R.drawable.dot_empty);
              setBackgroundResource(background);
          }
      }
docs: Setting up background for the view. Should pass shapes for both filled and empty dots.
  Otherwise will use the default backgrounds