Re: instrumentSwitch and addInstrumentDefinition use

[Jan-Peter Voigt]

Hi Keith,

thanks for that snippet! It should be possible to add KeySignatures to
the edition-engraver ... and to automatically create a KeySig on change
of instrument transposition ...

Cheers,
Jan-Peter

Am 12.01.2015 um 06:28 schrieb Keith OHara:
> ...
> 
> \version "2.19.15"
> transpositionUpdateKey =
> #(define-music-function (parser location new-transposition) (ly:pitch?)
>    (_i "Set instrument transposition and, based on the previous
> transposition and key, generate the key-change to keep the sounding key.")
>    (define (generate-key-change c)
>      (define (same-scale-step? a b) (= (car a) (car b)))
>      (let* ((old-alt (delete-duplicates!
>                         (append (ly:context-property c 'keyAlterations)
>                                 major)
>                         same-scale-step?))
>             (old-tonic (ly:context-property c 'tonic (ly:make-pitch 0 0
> 0)))
>             (old-transp (ly:context-property c 'instrumentTransposition
>                            (ly:make-pitch 0 0 0)))
>             (delta (ly:pitch-diff old-transp new-transposition))
>             (new-alt (ly:transpose-key-alist old-alt delta))
>             (new-tonic (ly:pitch-transpose old-tonic delta))
>             (sev (ly:make-stream-event `(key-change-event)
>                     `((pitch-alist . ,new-alt)
>                       (tonic . ,new-tonic)))))
>      (ly:broadcast (ly:context-event-source c) sev)))
>    #{
>      \applyContext #generate-key-change
>      \transposition $new-transposition
>    #} )
> 
> 
> prepClarinet = { \set Staff.shortInstrumentName="Clar"
>                 <>^\markup\italic\center-align "pick up clarinet" }
> clarinet = { <>^\markup\bold"Clarinet"
>              \once\set Staff.whichBar = "||"
>              \transpositionUpdateKey bes }
> 
> concertBandEdition = {
>   s1*3 \tag#'Sue \prepClarinet
>   s1 \mark"All Reeds" \tag#'Sue \clarinet}
> 
> tune =  { \key c\major \repeat unfold 4 {c'4 e' g' b' R1} }
> backup = { \key c\major \repeat unfold 8 {c'4 e' g' b' } }
> \addQuote "tune" \tune
> 
> << \new Staff \with { instrumentName="horn in F" }
>    \keepWithTag#'Sue <<
>       \concertBandEdition \transposition f
>       \quoteDuring "tune" #(skip-of-length tune) >>
>    \new Staff \with { instrumentName="alto clarinet" }
>    \keepWithTag#'Joe <<
>       \concertBandEdition \transposition es
>       \transpose es c' \backup >>>>
>