Hello, Le 30/03/2021 à 03:33, Kieren MacMillan a écrit :
Hi Craig,That worked for my over-simplified MWE. But here's my real-world problem with multiple key changes. There are only some that need to be over-ridden enharmonically. See bar 2 of the Alto Sax where I'd like to override this key signature without changing the whole global setup. Is this possible?
I have to say that in 99.99% of cases, "Is this possible?" is a rhetorical question in LilyPond.
If it is, I can’t wait to see the solution… As the composer and arranger of musical theatre and other multi-instrumentalist music, Lilypond’s awkward handling of key signatures and transposition is a long-time thorn in my side. David K once devised a rather brilliant almost-solution (cf. <http://lilypond.1069038.n5.nabble.com/quot-smart-quot-transposition-of-key-signatures-td151940.html>), but it wasn’t able to handle the high abstraction of my Lilypond code. There was a suggestion that an “enharmonize-engraver” might solve the problem, but I don’t think anyone tackled that.
Something like the attached? While admittedly ugly and in need for more testing, it should provide a start. I would be curious of better approaches others may think of. There is a big drawback: \relative changes behavior in the naturalized version. I haven't investigated how to fix it yet. Regards, Jean
\version "2.22.0"
#(use-modules (ice-9 receive))
#(define possible-naturalizations
(list
#{ deses #}
#{ bis #}))
#(define no-naturalization
#{ c #})
#(define (key-alterations context pitch-alist)
"Compute alterations in the key, based on the pitch-alist.
This replicates the action of Key_engraver::read_event in lily/key-engraver.cc."
(let loop ((alist (list-copy pitch-alist))
(order (ly:context-property context 'keyAlterationOrder))
(accidentals '()))
(if (or (null? alist)
(null? order))
(append
(filter-map
(lambda (entry)
(and (not (zero? (cdr entry)))
; No, don't warn, because we may get very
; weird accidentals in the process of finding
; the best key.
entry))
alist)
(reverse! accidentals))
(let* ((entry (car order))
(head (member entry alist))
(found (and head (car head)))
(remaining-order (cdr order)))
(if found
(loop (delete! found alist)
remaining-order
(cons found accidentals))
(loop alist
remaining-order
accidentals))))))
#(define (alteration-number accidentals)
"Compute the number of accidentals in this key, taking double accidentals into account."
(* 2 (apply + (map abs (map cdr accidentals)))))
#(define (best-naturalization context tonic pitch-alist alterations)
"Determine best tonic to minimize the number of alterations.
Receives pre-computed alterations for the base tonic, to avoid calculating
them again. Returns the best alterations found, for the same reason.
This applies a very simple-minded algorithm: try two possible ways to
naturalize, changing flats to sharps or sharps to flats, and return the
best one among the default and these two."
(let loop ((best-naturalization-found tonic)
(best-alterations-found alterations)
(changed #f)
(naturalizations-to-try possible-naturalizations))
(if (null? naturalizations-to-try)
(values best-naturalization-found best-alterations-found changed)
(let* ((naturalization (car naturalizations-to-try))
(remaining-naturalizations (cdr naturalizations-to-try))
(new-pitch (ly:pitch-transpose tonic naturalization))
(new-pitch-alist (ly:transpose-key-alist pitch-alist naturalization))
(new-alterations (key-alterations context new-pitch-alist)))
(if (< (alteration-number new-alterations)
(alteration-number best-alterations-found))
(loop naturalization
new-alterations
#t
remaining-naturalizations)
(loop best-naturalization-found
best-alterations-found
changed
remaining-naturalizations))))))
#(define (naturalize-note! event naturalization)
(ly:event-set-property!
event
'pitch
(ly:pitch-transpose (ly:event-property event 'pitch)
naturalization)))
#(define (reset-naturalization! context)
(ly:context-set-property! context 'currentNaturalization no-naturalization))
#(set-object-property! 'currentNaturalization 'translation-type? ly:pitch?)
#(define (Naturalize_engraver context)
(let ((notes-with-original-pitches '()))
(make-engraver
(listeners
((note-event engraver event)
(set! notes-with-original-pitches
(cons
(cons event
(ly:event-property event 'pitch))
notes-with-original-pitches))
(naturalize-note! event
(ly:context-property context 'currentNaturalization)))
((key-change-event engraver event)
(let* ((tonic (ly:event-property event 'tonic))
(pitch-alist (ly:event-property event 'pitch-alist))
(default-alterations
(key-alterations context pitch-alist)))
; Find the best key to minimize accidentals. If it
; is different from what we had (that is, we managed
; to find a better enharmony), then use it.
(receive (new-naturalization new-alterations changed)
(best-naturalization context
tonic
pitch-alist
default-alterations)
(if changed
(begin
(ly:context-set-property!
context
'tonic
(ly:pitch-transpose tonic new-naturalization))
(ly:context-set-property!
context
'keyAlterations
new-alterations)
(ly:context-set-property!
context
'currentNaturalization
new-naturalization)
; Strictly speaking, the order of events is
; unspecified. Who knows: we may get a note
; before the key. In this case, we have to
; re-transpose the previously transposed notes.
(for-each
(lambda (entry)
(let ((note-event (car entry))
(original-pitch (cdr entry)))
(ly:event-set-property! note-event
'pitch
original-pitch)
(naturalize-note! note-event new-tonic)))
notes-with-original-pitches))
; Nothing better could be found.
(reset-naturalization! context))))))
((stop-translation-timestep engraver)
(set! notes-with-original-pitches '())))))
#(ly:register-translator
Naturalize_engraver 'Naturalize_engraver
'((grobs-created . ())
(events-accepted . (key-change-event note-event))
(properties-read . ())
(properties-written . (currentNaturalization keyAlterations tonic))
(description . "Try to naturalize key signatures.")))
\layout {
\context {
\Staff
% Start with a no-op, for the case when there is no \key involved.
currentNaturalization = #no-naturalization
}
}
%% Example
\layout {
\context {
\Staff
% Just for visibility in this snippet
printKeyCancellation = ##f
}
}
notes = \relative {
\key aeses \major
aeses'8 beses ces deses eeses fes ges aeses
\key cis \minor
cis, dis e fis gis a bis cis
\break
}
music = <<
\notes
\transpose ees c \notes
>>
\score {
\new StaffGroup \with {
instrumentName = "Default"
} \music
}
\score {
\layout {
\context {
\Staff
\consists Naturalize_engraver
}
}
\new StaffGroup \with {
instrumentName = "Naturalized"
} \music
}
naturalize-engraver.pdf
Description: Adobe PDF document
