Big Time Signatures

[Tina Petzel]

Hello all,

fyi, for a music SE question I have implemented big in-staff time signatures, 
as 
used in some modern scores.

It is also sitting in the snippet wiki under
https://wiki.lilypond.community/wiki/Big_Time_Signatures[1]

Regards,
Tina

--------
[1] https://wiki.lilypond.community/wiki/Big_Time_Signatures

%%% Define a new `BigTimeSignature` spanner
#(define (big-time-signature::print grob)
   (let*
    ((elts (ly:grob-object grob 'elements)) ; time-sig grobs
     (ref (ly:grob-common-refpoint-of-array grob elts Y)) ; common refpoint
     (exts (map (lambda (x) (ly:grob-extent x ref Y)) (ly:grob-array->list elts))) ; extents of all ts-grobs
     (full-ext (cons (apply min (map car exts)) (apply max (map cdr exts)))) ; full extent of ts column
     (stc (ly:grob-property (ly:grob-array-ref elts 0) 'stencil)) ; the stencil of one time signature
     (stc-ext-y (car exts)) ; the Y-extent of the time sig stencil
     (f (/ (interval-length full-ext) (interval-length stc-ext-y)))) ; scaling factor for the stencil
    (ly:grob-set-parent! grob Y ref) ; Y-parent should be System = ref already, but just in case make sure
    (ly:stencil-translate-axis ; shift resulting stencil to begin of time sig column
     (ly:stencil-aligned-to (ly:stencil-scale stc 1 f) Y DOWN) ; scale stencil and make sure it is not shifted
     (car full-ext) Y)))

#(set! all-grob-descriptions
  (sort
   (cons
    ((@@ (lily) completize-grob-entry)
     `(BigTimeSignature
       . ((stencil . ,big-time-signature::print)
          (meta
           . ((class . Spanner)
              (interfaces . (spanner-interface))
              (description . "A big time signature"))))))
    all-grob-descriptions)
   alist<?))

\layout {
  \context {
    \Global
    \grobdescriptions #all-grob-descriptions
  }
}


%%% Create engraver for big time signatures
#(define (big-time-signature-engraver context)
   (let ((time-sig '()))
     (make-engraver
      (acknowledgers
       ((time-signature-interface engraver grob source-engraver) ; collect time signature grobs
        (set! time-sig (cons grob time-sig))))
      ((process-acknowledged engraver)
       (if (not (null? time-sig)) ; if any time-signatures
           (let ; create BigTimeSignature spanner with time sigs at parents
            ((spanner (ly:engraver-make-spanner engraver 'BigTimeSignature '())))
            (ly:spanner-set-bound! spanner UP (first time-sig))
            (ly:spanner-set-bound! spanner DOWN (first time-sig))
            (ly:grob-set-parent! spanner X (first time-sig)) ; set one time signature as X-parent for proper alignment
            (ly:grob-set-object! spanner 'elements (ly:grob-list->grob-array time-sig))))
       (set! time-sig '())))))


%%% Example (score level)
\score {
  \layout {
    \context {
      \Score
      \consists #big-time-signature-engraver
      \override TimeSignature.transparent = ##t
    }
  }

  <<
    \new Staff {
      \numericTimeSignature
      c''1 \time 3/4 d''2.
    }
    \new Staff {
      c''1 \time 3/4 d''2.
    }
    \new Staff {
      c''1 \time 3/4 d''2.
    }
  >>
}


%%% Example (staff group level)
\score {
  \layout {
    \context {
      \StaffGroup
      \consists #big-time-signature-engraver
      \override TimeSignature.transparent = ##t
    }
  }

  <<
    \new Staff {
      \numericTimeSignature
      c''1 \time 3/4 d''2.
    }
    <<
      \new StaffGroup <<
        \new Staff {
          c''1 \time 3/4 d''2.
        }
        \new Staff {
          c''1 \time 3/4 d''2.
        }
      >>
    >>
    <<
      \new StaffGroup <<
        \new Staff {
          c''1 \time 3/4 d''2.
        }
        \new Staff {
          c''1 \time 3/4 d''2.
        }
        \new Staff {
          c''1 \time 3/4 d''2.
        }
      >>
    >>
  >>
}

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