Printing bar numbers inside boxes or circles

Bar numbers can also be printed inside boxes or circles.

\version "2.24"

\relative c' {
  % Center bar numbers except at the beginning of a staff.
  \override Score.BarNumber.self-alignment-X =
    #(break-alignment-list CENTER CENTER 0.3)

  % Prevent bar numbers at the end of a line and permit them elsewhere.
  \override Score.BarNumber.break-visibility = #end-of-line-invisible

  \set Score.barNumberVisibility = #(every-nth-bar-number-visible 4)

  % Increase the size of the bar number by 2.
  \override Score.BarNumber.font-size = 2

  % Draw a circle round the following bar number(s).
  \override Score.BarNumber.stencil
    = #(make-stencil-circler 0.1 0.25 ly:text-interface::print)
  \repeat unfold 7 { c1 } \break

  % Draw a box round the following bar number(s).
  \override Score.BarNumber.stencil
    = #(make-stencil-boxer 0.1 0.25 ly:text-interface::print)
  \repeat unfold 7 { c1 } \bar "|."
}