Re: MetronomeMark and break-visibility

[Jean Abou Samra]

Le 01/11/2022 à 12:55, Thomas Morley a écrit :
> Hi,
>
> the following code for _Rehearsal_Mark works as expected, i.e. the
> RehearsalMark is printed at end of line:
>
> {
>    b1
>    \override Score.RehearsalMark.break-visibility = ##(#t #f #f)
>    \mark \default
>    \break
>    b
> }
>
> Alas, the same for _Metronome_Mark fails, the MetronomeMark is not
> printed at all:
>
> {
>    b1
>    \override Score.MetronomeMark.break-visibility = ##(#t #f #f)
>    \tempo "Andante" 4 = 60
>    \break
>    b
> }
>
> although MetronomeMark has settings for break-visibility.
>
> Is this on purpose or a bug?
> How to make it work?


This looks weird. In this case at least, Metronome_engraver sets
non-musical = #t on the MetronomeMark, yet it also sets its X
parent to the current *musical* column, not the non-musical one.
That's contradictory. As a result, MetronomeMark is not a breakable
item, since its parent is PaperColumn and not NonMusicalPaperColumn.
But it has a break-visibility. This makes for a mess.

It works if you do

\version "2.23.80"

\new Score \with {
  \consists
    #(lambda (context)
       (let ((tempo #f))
         (make-engraver
          (acknowledgers
           ((metronome-mark-interface engraver grob source-engraver)
            (set! tempo grob)))
          ((stop-translation-timestep engraver)
           (when tempo
             (ly:grob-set-parent! tempo X (ly:context-property context 
'currentCommandColumn)))
           (set! tempo #f)))))
}
{
  b1
  \override Score.MetronomeMark.break-visibility = ##(#t #f #f)
  \override Score.MetronomeMark.self-alignment-X = #RIGHT
  \tempo "Andante" 4 = 60
  \break
  b
}



I suggest to open an issue.

It is probably related to
https://gitlab.com/lilypond/lilypond/-/issues/1276

Best,
Jean