How to center text above a bar in Lilypond

Question

In my (MuseScore) sheets have a lot of custom bar number indicators, like this:

which help me quickly glance over the length of the sections. The bar count can also be above a bar containing notes:

Unfortunately, I'm having a hard time figuring out how to do this in Lilypond. I'm pretty sure this is possible but figuring out how-exactly is a bit of a pain.

When an empty-chord mark is used in a bar with notes, then the markup is displayed above the next note and not in the middle. So, as a workaround I could just use that but this is more of a challenge to understand how to use Lilypond to get what is needed.

Currently I'm trying to achieve this with Text Spanners, as I would like the number in parentheses to be centered above a bar. All the examples override the text at the left and right edges of a spanner. I've also seen the span-type and span-text in some functions but am not sure how to use them.

I've also seen \textSpannerUp commands but have no idea how they are to be used.

Edit: The automatic bar numbers are positioned correctly when \set Score.centerBarNumbers = ##t is used. Meaning it is certainly doable.

The code is here but I don't know Scheme that well. :(

Answer 1

Quick and dirty way to do it:

markAtCenterAboveMeasure =
#(define-music-function (m music)
   (markup? ly:music?)
   #{
     \once\override
     Staff.MeasureCounter.text = #m
     <>\startMeasureCount
     #music
     <>\stopMeasureCount
   #})

\new DrumStaff \with {
  \consists Measure_counter_engraver
}{
  s1*7
  \markAtCenterAboveMeasure \markup\dynamic"(8)" s1
}

Answer 2

Since you are indicating bar numbers, perhaps it makes sense to try something like a modification of Measure-centered bar numbers, however this won't work for LilyPond versions earlier than v2.23.

Answer 3

Empty-Chord Marks

A simple solution for the blank bars can be the empty chord mark:

s1 <>^\markup {(2)} or simply s1 <>^"(4)".

This is not centered above the bar, unfortunately.

The good thing with a markup is that it can be customized in detail and extracted into a function which can be included in multiple score sheets.

Text Spanners

Using spanners, I've managed to do

    \override TextSpanner.text = "blah"
    \override TextSpanner.stencil = #ly:text-interface::print
    \override TextSpanner.font-shape = #'upright
    \override TextSpanner.side-axis = 0
    \override TextSpanner.direction = #'CENTER

    bd4 \startTextSpan sn bd sn \stopTextSpan

which produces

but is not centered, although it does span the whole bar.