Re: Centering Systems

[Jean Abou Samra]

Le 15/08/2022 à 18:28, josh a écrit :
> Thanks for helping me out. I've attached some examples of what I am 
> working with so far.
>
> The ANSIAsuccessful files have the code that works correctly (minus 
> all of the vertical collision, which I can deal with). What it shows 
> best is that there is one system per page and the systems vertically 
> fill the pages.
>
> The ANSICunccessful files show that there are multiple systems per 
> page with and the systems are all bunched together.
>
> The finishedexample pdf shows what I have been able to achieve in the 
> past using the ANSI A page size. I am moving to ANSI C page size for 
> better spacing in general.
>
> I hope all of this makes sense.



OK, I've opened a bug report about this:

https://gitlab.com/lilypond/lilypond/-/issues/6407

And I suggest a completely different solution to center the systems,
sidestepping the issue:


\version "2.22.2"

\paper {
  ragged-right = ##t
  indent = 0
  short-indent = 0
}


\layout {
  \context {
    \Score
    %% Can't use a callback for line-break-system-details because it is 
sometimes
    %% read before line breaking, for alignment-distances. Even 
after-line-breaking
    %% can be too early for the System's X-extent due to things like 
system start
    %% delimiters which trigger page layout prematurely.
    \override NonMusicalPaperColumn.stencil =
      #(lambda (grob)
         (let* ((sys (ly:grob-system grob))
                (ext (ly:grob-extent sys sys X))
                (len (interval-length ext))
                (layout (ly:grob-layout grob))
                (width (ly:output-def-lookup layout 'paper-width))
                (left-margin (ly:output-def-lookup layout 'left-margin))
                (off (- (* 1/2 (- width len))
                        left-margin))
                (det (ly:grob-property grob 'line-break-system-details)))
           (ly:grob-set-property! grob
                                  'line-break-system-details
                                  (acons 'extra-offset
                                         (cons off 0)
                                         det)))
         #f)
  }
}

{
  #@(map (lambda (i)
           #{ \repeat unfold #i { c'1 \noBreak } \break #})
         (cdr (iota 15)))
}



I tested it on the score you sent me privately and it seems to work.

Best,
Jean