Re: "merge" \layout definitions

[Thomas Morley]

2016-08-04 22:50 GMT+02:00 Urs Liska <address@hidden>:
> Hi again,
>
> I have the problem that I (seem to) have to "merge" an unknown number of
> \layout {} blocks.
>
> I create several such block independently in different included files (e.g.
> one for part generation and one global for the edition project as a whole).
> And as everthing is working within one Scheme function and the actual
> engraving is done with ly:book-process I can't write the \layout blocks as
> top-level expressions.
>
> I thought I'm clever and use the #@ construct to output them as a list but
> (of course) this results in *two* layout blocks being present in the \score
> block - and consequently the score being printed twice.
>
> I think the attached example is a correct reduction of my actual set-up to a
> MWE.
>
> AFAICS I need one out of two solutions:
>
> "merging" several \layout {} blocks so there is only one left in the \score
> block
> somehow apply \layout blocks independently as top-level expressions, but
> from within a Scheme function.
>
> Any ideas?
>
> Best
> Urs
>


Hi Urs,

maybe the code below. Though, it's more a proof of concept...

\version "2.19.45"

#(define (get-output-def-diff-alist output-def-1 output-def-2)
" Returns an alist of type:
  ((TabStaff . #<Context_def TabStaff merge-layouts-02.ly:47:5>)
   (Staff . #<Context_def Staff merge-layouts-02.ly:39:5>)
   (TabVoice . #<Context_def TabVoice merge-layouts-02.ly:43:5>))
"
  (lset-difference
    equal?
    (ly:output-find-context-def output-def-1)
    (ly:output-find-context-def output-def-2)))

engrave =
#(define-void-function (layouts music)(list? ly:music?)
"Takes a list of output-defs and some music.  The music becomes a score with the
merged output-defs.  Finally a book is returns."
  (let* ((my-layout (ly:output-def-clone $defaultlayout))
         ;; get the diffs of custom-layouts to default
         (diffs
           (append-map
             (lambda (output-def)
               (get-output-def-diff-alist output-def my-layout))
             layouts))
         ;; make a score from `music'
         (my-score (scorify-music music)))

    ;; apply `diff' to the default
    (for-each
      (lambda (x)
        (ly:output-def-set-variable! my-layout (car x) (cdr x)))
        diffs)

    ;; add `my-layout' to `my-score'
    (ly:score-add-output-def! my-score my-layout)

    (ly:book-process
      #{ \book { $my-score } #}
      #{ \paper {} #}  ; non-functional, placeholder
      #{ \layout {} #} ; non-functional, placeholder
      (ly:parser-output-name))))

layoutI =
  \layout {
    \context {
      \Staff
      \override TimeSignature.color = #blue
    }
    \context {
      \TabVoice
      \override TabNoteHead.color = #cyan
    }
    \context {
        \TabStaff
      \override Clef.color = #green
    }
  }

layoutII =
  \layout {
    \context {
      \Voice {
        \override NoteHead.color = #red
      }
    }
  }

\engrave
  #(list layoutI layoutII)
  <<
    \new Staff { c' }
    \new TabStaff { c' }
  >>


Cheers,
  Harm