code: private void obtainNavigationWidth() {
          int navigationWidth;
  
          try {
              navigationWidth = ThemeUtil.getDimensionPixelSize(this, R.attr.navigationWidth);
          } catch (NotFoundException e) {
              navigationWidth = getResources().getDimensionPixelSize(R.dimen.navigation_width);
          }
  
          setNavigationWidth(navigationWidth);
      }
docs: Obtains the width of the navigation from the activity's theme.