%
% Thanks to Alexander Kobel for http://lsr.dsi.unimi.it/LSR/Item?id=651
%

% i want breve MMRs appear as whole ones always:
#(define mmr-breve-as-whole #t)

% i've never seen MMRs on the middle line,
% so, put them on fourth if 'staff-position=0 :
#(define mmr-escape-from-zero #t)

% this will return markup for MMRNubmer's 'text property:
#(define (normalize-mmrs-callback grob)
  (let* ((mmr (ly:grob-parent grob Y))
         (evt (ly:grob-property grob 'cause))
         (mus (ly:event-property evt 'music-cause))
         (len (ly:music-duration-length mus))
         (pos (ly:grob-property mmr 'staff-position))
         (restglyph
            (if (and (equal? len (ly:make-moment 2 1))
                     (eq? #f mmr-breve-as-whole))
                (if (> (abs pos) 4)
                    ;; stub. need to draw a ledger line?.. *DONT_KNOW*
                    "rests.M1"
                    "rests.M1")
                (if (> (abs pos) 4)
                    ;; this one already has ledger line:
                    "rests.0o"
                    "rests.0"))))
      ;; "adjust" 'staff-position if needed:
      (if (and (eq? #t mmr-escape-from-zero)
               (eq? 0 pos)
               (or (not (equal? len (ly:make-moment 2 1)))
                   (eq? #t mmr-breve-as-whole)))
          (ly:grob-set-property! mmr 'staff-position 2))
      ;; and return markup:
      (markup #:line (#:musicglyph restglyph))))


rests = \relative c'' {
  %
  \oneVoice
  \time 3/4
  R2. |
  \time 4/4
  R1 |
  \time 4/2
  R1*2 |
  \time 5/2
  \once \override MultiMeasureRest #'staff-position = #6
  R1*5/2 |
  %
  \voiceTwo
  \time 6/2
  R1*3 |
  \once \override MultiMeasureRest #'staff-position = #-6
  R1*3 |
}

normalizeMMRs = {
  % these overrides would go into \layout for \Score context,
  % if you need these changes globally:
  \override MultiMeasureRest #'transparent = ##t
  % place MultiMeasureRestNumber to MultiMeasureRest's position:
  \override MultiMeasureRestNumber #'Y-offset = #0
  \override MultiMeasureRestNumber #'text = #normalize-mmrs-callback
}

revertMMRs = {
  \revert MultiMeasureRest #'transparent
  \revert MultiMeasureRestNumber #'Y-offset
  \revert MultiMeasureRestNumber #'text
}


\score {
  \new Staff {
    \new Voice {
      \rests
      \break
      \normalizeMMRs
      \rests
      \break
      \revertMMRs
      \rests
    }
  }
}

%{
\layout {
  \context {
    \Score
      % to make this by default:
      \override MultiMeasureRest #'transparent = ##t
      \override MultiMeasureRestNumber #'Y-offset = #0
      \override MultiMeasureRestNumber #'text = #normalize-mmrs-callback
  }
}
%}

\paper {
  indent = 0
}