Re: "merge" \layout definitions

[Urs Liska]

Am 05.08.2016 um 18:23 schrieb 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...

Hi Harm,

thank you for the "proof-of-concept".
I think I roughly understand what you do and try figuring out how to
integrate it in my real-world use case.

Best
Urs

>
> \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