lilypond-common-includes/auto_rest_merging.ly

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%% http://lsr.dsi.unimi.it/LSR/Item?id=336
%% see also http://code.google.com/p/lilypond/issues/detail?id=1228
%% Usage:
%% \new Staff \with {
%% \override RestCollision.positioning-done = #merge-rests-on-positioning
%% } << \somevoice \\ \othervoice >>
%% or (globally):
%% \layout {
%% \context {
%% \Staff
%% \override RestCollision.positioning-done = #merge-rests-on-positioning
%% }
%% }
%%
%% Limitations:
%% - only handles two voices
%% - does not handle multi-measure/whole-measure rests
#(define (rest-score r)
(let ((score 0)
(yoff (ly:grob-property-data r 'Y-offset))
(sp (ly:grob-property-data r 'staff-position)))
(if (number? yoff)
(set! score (+ score 2))
(if (eq? yoff 'calculation-in-progress)
(set! score (- score 3))))
(and (number? sp)
(<= 0 2 sp)
(set! score (+ score 2))
(set! score (- score (abs (- 1 sp)))))
score))
#(define (merge-rests-on-positioning grob)
(let* ((can-merge #f)
(elts (ly:grob-object grob 'elements))
(num-elts (and (ly:grob-array? elts)
(ly:grob-array-length elts)))
(two-voice? (= num-elts 2)))
(if two-voice?
(let* ((v1-grob (ly:grob-array-ref elts 0))
(v2-grob (ly:grob-array-ref elts 1))
(v1-rest (ly:grob-object v1-grob 'rest))
(v2-rest (ly:grob-object v2-grob 'rest)))
(and
(ly:grob? v1-rest)
(ly:grob? v2-rest)
(let* ((v1-duration-log (ly:grob-property v1-rest 'duration-log))
(v2-duration-log (ly:grob-property v2-rest 'duration-log))
(v1-dot (ly:grob-object v1-rest 'dot))
(v2-dot (ly:grob-object v2-rest 'dot))
(v1-dot-count (and (ly:grob? v1-dot)
(ly:grob-property v1-dot 'dot-count -1)))
(v2-dot-count (and (ly:grob? v2-dot)
(ly:grob-property v2-dot 'dot-count -1))))
(set! can-merge
(and
(number? v1-duration-log)
(number? v2-duration-log)
(= v1-duration-log v2-duration-log)
(eq? v1-dot-count v2-dot-count)))
(if can-merge
;; keep the rest that looks best:
(let* ((keep-v1? (>= (rest-score v1-rest)
(rest-score v2-rest)))
(rest-to-keep (if keep-v1? v1-rest v2-rest))
(dot-to-kill (if keep-v1? v2-dot v1-dot)))
;; uncomment if you're curious of which rest was chosen:
;;(ly:grob-set-property! v1-rest 'color green)
;;(ly:grob-set-property! v2-rest 'color blue)
(ly:grob-suicide! (if keep-v1? v2-rest v1-rest))
(if (ly:grob? dot-to-kill)
(ly:grob-suicide! dot-to-kill))
(ly:grob-set-property! rest-to-keep 'direction 0)
(ly:rest::y-offset-callback rest-to-keep)))))))
(if can-merge
#t
(ly:rest-collision::calc-positioning-done grob))))
generalLayout = \layout {
\generalLayout
\context {
\Staff
\override RestCollision.positioning-done = #merge-rests-on-positioning
}
}