Re: Display Question Mark at center of a measure

[Jean Abou Samra]

Le 14/01/2022 à 10:39, Lukas-Fabian Moser a écrit :
> Hi Rajesh,
>
> Am 14.01.22 um 01:44 schrieb Rajesh Baskar:
> > I'm tying to display a question mark at the center of the 1st measure 
> > in a 2 measure score.
> >
> > I have got this working with hard-coding the offset (3 . 4.5) but 
> > this will not work when the number of notes in a measure is larger 
> > than 3. Is there a way to get this to work dynamically where the 
> > question mark moves to the center of the measure irrespective of the 
> > length of a measure.
>
> Please try to remove everything in your examples not actually related 
> to the problem at hand (here, for example, everything having to do 
> with MIDI, proportional notation, boxed measure counters etc.).
>
> What comes to mind is that your question mark is exactly in the 
> position where you would normally expect a whole bar rest. So how about:
>
> \version "2.22.0"
>
> #(define (center-stencil stil)
>    (ly:stencil-aligned-to
>     (ly:stencil-aligned-to stil X CENTER)
>     Y CENTER))



This is predefined under the name
'centered-stencil' :-)


> questionMarkMultiMeasureRest = {
>   \override MultiMeasureRest.stencil =
>   #(grob-transformer
>     'stencil
>     (lambda (grob default)
>       (ly:stencil-translate-axis
>        (center-stencil (ly:text-interface::print grob))
>        (interval-center (ly:stencil-extent default X))
>        X)))
>   \override MultiMeasureRest.text = "?"
>   \override MultiMeasureRest.font-size = 7
>   \override MultiMeasureRest.color = "#6A00F4"
> }
>
> \new Staff {
>   \clef bass
>   <<
>     { \hideNotes b2 c }
>     \new Voice {
>       \questionMarkMultiMeasureRest
>       R1
>     }
>   >>
>   \unHideNotes a2 c'4 g
> }
>
> One could of course wrap the simultaenous addition of the tweaked full 
> bar rest in a music function.
>
> The reason I'm using such a comparatively complex stencil override is 
> that the default positioning of the MultiMeasureRest (which is what we 
> want here) is handled in the default stencil; if we overwrite that 
> function completely, we don't get the nice centered alignment we want.


To add another solution, in current development versions,
you can do this:

\version "2.23.5"

questionMarkMultiMeasureRest = \once {
  \override MultiMeasureRest.stencil = #centered-text-interface::print
  \override MultiMeasureRest.text = \markup \vcenter "?"
  \override MultiMeasureRest.self-alignment-X = #CENTER
  \override MultiMeasureRest.font-size = 7
  \override MultiMeasureRest.color = "#6A00F4"
}

\new Staff {
  \clef bass
  <<
    { \hideNotes b2 c }
    \new Voice {
      \questionMarkMultiMeasureRest
      R1
    }
  >>
  \unHideNotes a2 c'4 g
}

I'm not sure if it's much simpler to find, but
it doesn't require Scheme at all.

Cheers,
Jean