Re: Displaying typesetting information at compile time

[Jean Abou Samra]

Le 20/03/2022 à 17:43, Richard Shann a écrit :
> I wonder if someone could suggest how to get LilyPond to emit various
> bits of information about the score it is typesetting. Specifically can
> it be persuaded to display the number of pages in the output PDF and
> the total number of systems?
> The idea would be to guide the user as to suitable values for
>
> \paper {
>    system-count = xx
>    page-count = yy
> }
>
> without having to count up the number of systems (pages is not really a
> problem of course).
>
> Richard Shann

Not sure if there's a more elegant way, but you could try

\version "2.22.2"

markWithPageInfo =
  %% Must not get called before line breaking
  \tweak X-extent #'(0 . 0)
  \tweak Y-extent #'(0 . 0)
  \tweak horizontal-skylines
    #(ly:make-unpure-pure-container 
ly:grob::simple-horizontal-skylines-from-extents)
  \tweak vertical-skylines
    #(ly:make-unpure-pure-container 
ly:grob::simple-vertical-skylines-from-extents)
  \tweak stencil
    #(lambda (grob)
       (let* ((sys (ly:grob-system grob))
              ;; No broken pieces for systems ...
              (alignment (ly:grob-object sys 'vertical-alignment))
              (all-alignments (ly:spanner-broken-into (ly:grob-original 
alignment)))
              (all-systems (map ly:grob-system all-alignments))
              (n-systems (length all-systems))
              (all-pages (map (lambda (s) (ly:grob-property s 'page-number))
                              all-systems))
              (n-pages (1+ (- (apply max all-pages)
                              (apply min all-pages))))
              (layout (ly:grob-layout grob))
              (defs (append `((n-systems . ,(number->string n-systems))
                              (n-pages . ,(number->string n-pages)))
                            (ly:output-def-lookup layout 'text-font-defaults)))
              (props (ly:grob-alist-chain grob defs))
              (text (ly:grob-property grob 'text)))
         (interpret-markup layout props text)))
  \mark \etc

{
  \markWithPageInfo \markup { Have \fromproperty #'n-systems systems on 
\fromproperty #'n-pages pages }
  \repeat unfold 20 { 1 1 \break }
}
       

Jean