Example of two-pass vertical spacing tweaking

[Nicolas Sceaux]

Hi,

Here is an example showing how to use the two-pass vertical spacing
feature. (It cannot be added to LSR, which uses version 2.6).

nicolas


\version "2.7.36"
%{
 For the first pass, use the write-tweak option:
   $ lilypond -d write-tweaks file.ly
 This will write the file-page-layout.ly tweak file.
 Second pass:
   $ lilypond file.ly
 The file-page-layout.ly will be included, and tweaks
 used in the score. The file-page-layout.ly file will
 not be written.
%}
%%%
%%%  utility function for including tweaks depending
%%%  on the write-tweak option passed to lilypond
%%%
#(use-modules (srfi srfi-39) (ice-9 format))
#(define *write-tweaks* (make-parameter (ly:get-option 'write-tweaks)))

spacingTweaks = 
#(define-music-function (parser location props) (list?)
  "Tweak the system vertical stretching, if not asked to write
  the page-layout file."
  (if (*write-tweaks*)
      (make-music 'SequentialMusic)
      (let* ((space-left (cdr (assoc 'page-space-left props)))
             (music-size (apply + (cdr (assoc 'music-system-heights props))))
             (system-size (* -1 (cadr (assoc 'system-Y-extent props))))
             (extra-space (/ (* system-size space-left) music-size)))
        #{
          \overrideProperty #"Score.NonMusicalPaperColumn"
          #'line-break-system-details
          #$(list (cons 'alignment-extra-space extra-space))
        #})))

includePageLayout = 
#(define-music-function (parser location) ()
   "Include the page-layout file, if not asked to write it."
   (if (not (*write-tweaks*))
       (let ((tweak-filename (format #f "~a-page-layout.ly"
                                     (ly:parser-output-name parser))))
         (if (access? tweak-filename R_OK)
             (begin
              (format #t "Including tweak file ~a~%" tweak-filename)
              (ly:parser-parse-string 
                parser
                (format #f "\\include \"~a\"" tweak-filename))))))
   (make-music 'SequentialMusic 'void #t))

includeScoreTweak =
#(define-music-function (parser location name) (string?)
   "Include the score tweak, named by name (aa string), if not
  asked to write the page layout file."
   (if (not (*write-tweaks*))
       (let ((tweak-music (ly:parser-lookup parser (string->symbol name))))
         (if (ly:music? tweak-music)
             tweak-music
             (make-music 'SequentialMusic)))
       (make-music 'SequentialMusic)))

\paper {
  ragged-bottom = ##t
  ragged-last-bottom = ##t
  annotate-spacing = #(*write-tweaks*)
  #(define write-page-layout (ly:get-option 'write-tweaks))
}

%%%
%%% The scores
%%%

\includePageLayout

\score {
  \new StaffGroup <<
    \new Staff << \includeScoreTweak "A"
                  { \clef french c''1 \break c''1 } >>
    \new Staff { \clef soprano g'1 g'1 }
    \new Staff { \clef mezzosoprano e'1 e'1 }
    \new Staff { \clef alto g1 g1 }
    \new Staff { \clef bass c1 c1 }
  >>
  \header {
    title = "Score A"
  }
  \layout { #(define tweak-key "A") }
}