Editing Recitation tone

A reciting note is sustained for several syllables.

Normally only the initial reciting tone is printed (and it is printed as a 
half-note, whole-note, or breve) and the rest of the syllables are printed 
without notes above them. However, if the number of syllables to be recited is 
long enough that a line break needs to occur within the recitation, then the 
reciting tone is repeated at the beginning of the new line. These definitions 
enable this formatting.

Usage:

 \recite 8 g'

The number is the number of syllables to be said on the reciting tone. These syllables are entered as normal in <code>\lyricmode</code>. The note is the pitch for the reciting tone.

 \recite g'

When there are no lyrics associated with the recitation tone (as, for example, when printing a psalm tone) then only the pitch of the reciting tone is specified. This usage is for ensuring consistent appearance.

<lilypond version="2.24">
#(define (line-position grob)
   "Return position of @var{grob} in current system:
@code{'start}, if at first time-step;
@code{'end}, if at last time-step;
@code{'middle} otherwise."
   (let* ((col (ly:item-get-column grob))
          (ln (ly:grob-object col 'left-neighbor))
          (rn (ly:grob-object col 'right-neighbor))
          (col-to-check-left (if (ly:grob? ln) ln col))
          (col-to-check-right (if (ly:grob? rn) rn col))
          (break-dir-left
           (and
            (ly:grob-property col-to-check-left 'non-musical #f)
            (ly:item-break-dir col-to-check-left)))
          (break-dir-right
           (and
            (ly:grob-property col-to-check-right 'non-musical #f)
            (ly:item-break-dir col-to-check-right))))
     (cond ((eqv? 1 break-dir-left) 'start)
           ((eqv? -1 break-dir-right) 'end)
           (else 'middle))))

#(define (tranparent-at-line-position vctor)
   (lambda (grob)
     "Relying on @code{line-position} select the relevant entry from
@var{vctor}.  Used to determine transparency."
     (case (line-position grob)
       ((end) (not (vector-ref vctor 0)))
       ((middle) (not (vector-ref vctor 1)))
       ((start) (not (vector-ref vctor 2))))))

noteHeadBreakVisibility =
  #(define-music-function (break-visibility)(vector?)
     "Makes notes transparent relying on @var{break-visibility}.
The list of objects to make transparent is taken from @code{hideNotes}."
     #{
       \override NoteHead.transparent =
	 #(tranparent-at-line-position break-visibility)
       \override Dots.transparent =
	 #(tranparent-at-line-position break-visibility)
       \override Accidental.transparent =
	 #(tranparent-at-line-position break-visibility)
       \override Rest.transparent =
	 #(tranparent-at-line-position break-visibility)
       % Stems are always hidden in chant.
       % We assume chants are not in a TabStaff and so don't need to hide
       % TabNoteHeads.
       % Ledger lines have to be taken care of in the layout block using
       % delete-ledgers-for-transparent-note-heads.
     #})

#(define delete-ledgers-for-transparent-note-heads
   (lambda (grob)
     "Reads whether a @code{NoteHead} is transparent.
If so this @code{NoteHead} is removed from @code{'note-heads} from
@var{grob}, which is supposed to be @code{LedgerLineSpanner}.
As a result ledgers are not printed for this @code{NoteHead}"
     (let* ((nhds-array (ly:grob-object grob 'note-heads))
            (nhds-list
             (if (ly:grob-array? nhds-array)
                 (ly:grob-array->list nhds-array)
                 '()))
            ;; Relies on the transparent-property being done before
            ;; Staff.LedgerLineSpanner.after-line-breaking is executed.
            ;; This is fragile ...
            (to-keep
             (remove
              (lambda (nhd)
                (ly:grob-property nhd 'transparent #f))
              nhds-list)))
       ;; TODO find a better method to iterate over grob-arrays, similar
       ;; to filter/remove etc for lists.
       ;; For now rebuilt from scratch.
       (set! (ly:grob-object grob 'note-heads)  '())
       (for-each
        (lambda (nhd)
          (ly:pointer-group-interface::add-grob grob 'note-heads nhd))
        to-keep))))


\layout {
  \context {
    \Staff
    \override LedgerLineSpanner.after-line-breaking =
      #delete-ledgers-for-transparent-note-heads
  }
}

recite =
  #(define-music-function (times note) ((index? 1) ly:music?)
     "Causes @code{note} to be set as a reciting note for @code{times}
syllables.  The value of @code{recite-duration} determines
how the recitation note looks: 1 is a half-note, 0 is a
whole note, and -1 is a breve.  Only the first occurance
of the recitation note and those which appear at the
beginning of a line are visible."
     (let* ((note2 (ly:music-deep-copy note))
	    (recite-duration 0)
	    (recite-multiplier (/ (expt 2 recite-duration) 4)))
       (if (eqv? times 1)
           (withMusicProperty
	    'duration (ly:make-duration recite-duration) note)
           #{ #(withMusicProperty
		'duration (ly:make-duration
			   recite-duration 0 recite-multiplier) note)
             \noteHeadBreakVisibility #begin-of-line-visible
             \repeat unfold #(1- times) {
	       #(withMusicProperty
		 'duration (ly:make-duration
			    recite-duration 0 recite-multiplier) note2)
	       \bar "" }
             \noteHeadBreakVisibility #all-visible
           #})))


% Examples starts here.
\language "english"

global = { \key c \major }

music = {
  \recite 6 g' d' f' g' \bar "|"
}

doxology_words = \lyricmode {
  Glory be to the Father and to the Son
}

\new Staff
<<
  \new Voice = "mel" {
    \cadenzaOn \global \music \bar "||"
    \music \bar "||"
    \music \bar "|."
  }
  \new Lyrics \lyricsto "mel" {
    \doxology_words
    \doxology_words
    \doxology_words
  }
>>
</lilypond>

[[Category:Scheme]]
[[Category:Specific notation]]
[[Category:Vocal music]]
[[Category:Snippet]]