Repeat-bar-lines with angle-wings for whole StaffGroup (automatic and semi-automatic) (obsolete in 2.25.26)

The here-defined CertainBracketTipsBarLines automatically adds angle wings to certain bar lines of an entire StaffGroup, relying on the new-defined property tip. To activate it, say

\override Staff.BarLine.tip = #'auto

Using values up and down instead of auto, the settings can be made explicit, offering the possibility to limit those angle wings to certain StaffGroups among others of the same score. An example for this is commented in the code below.

CertainBracketTipsBarLines is currently limited to the default repeat bars, i.e., ":..:", ":|.", ".|:-|" ".|:"

\version "2.24"

#(define (define-grob-property symbol type? description)
  (if (not (equal? (object-property symbol 'backend-doc) #f))
      (ly:error (_ "symbol ~S redefined") symbol))

  (set-object-property! symbol 'backend-type? type?)
  (set-object-property! symbol 'backend-doc description)
  symbol)

#(for-each
  (lambda (x)
    (apply define-grob-property x))
    `((tip 
      ,symbol? 
      "Which bracket tip should be printed for certain BarLines?")))

%% If other symbols than 'up or 'down are used for `BarLine.tip' an
%% automatic procedure takes over trying to choose the correct BarLine, which 
%% may work. If not, use 'up and 'down at appropriate place.
%% Limitation:
%% `CertainBracketTipsBarLines' will only work for the default repet-bar-lines,
%% i.e. ":..:", ":|.", ".|:-|" ".|:"
CertainBracketTipsBarLines =
\override Score.BreakAlignGroup.after-line-breaking =
  #(lambda (grob)
    (let* ((elts (ly:grob-object grob 'elements))
           (bar-lines
             (if (null? elts)
                 '()
                 (filter 
                   (lambda (g) 
                     (and
                       (grob::has-interface g 'bar-line-interface)
                       (not (grob::has-interface g 'span-bar-interface))))
                   (ly:grob-array->list elts))))
           (possible-relevant-bar-lines
             (filter 
               (lambda (b) (not (null? (ly:grob-property b 'tip))))
               bar-lines)))
      (if (and (>= (length bar-lines) 2)
               (not (null? possible-relevant-bar-lines))
               (member 
                 (ly:grob-property (car bar-lines) 'glyph-name)
                 '(":..:" ":|." ".|:-|" ".|:")))
          (let* ((possible-top-bar-lines 
                   (filter 
                     (lambda (b) (eq? (ly:grob-property b 'tip) 'up))
                     bar-lines))
                 (top-bar-lines
                   (if (null? possible-top-bar-lines)
                       (list (car bar-lines))
                       possible-top-bar-lines))
                 (bar-lines-list-length (length top-bar-lines))
                 (possible-bottom-bar-lines 
                   (filter 
                     (lambda (b) (eq? (ly:grob-property b 'tip) 'down))
                     bar-lines))
                 (bottom-bar-lines
                   (if (null? possible-bottom-bar-lines)
                       (list (last bar-lines))
                       possible-bottom-bar-lines))
                 (top-stil 
                   (ly:grob-property (car top-bar-lines) 'stencil))
                 (bottom-stil 
                   (ly:grob-property (car bottom-bar-lines) 'stencil))
                 (font
                   (ly:grob-default-font grob))
                 (tip (ly:font-get-glyph font "brackettips.up"))
                 (top-glyph-name 
                   (ly:grob-property (car top-bar-lines) 'glyph-name))
                 (up-tip
                   (cond ((or (string=? top-glyph-name ":|.")
                              (string=? top-glyph-name ":|.-|"))
                           (ly:stencil-translate-axis
                             (ly:stencil-scale tip -1 1)
                             (cdr (ly:stencil-extent top-stil X))
                             X))
                         ((string=? top-glyph-name  ":..:")
                           (let ((kern 
                                    (/ (ly:grob-property (car top-bar-lines) 
                                                         'kern) 
                                       10))
                                 (top-stil-ext (ly:stencil-extent top-stil X)))
                             (ly:stencil-translate-axis
                               (ly:stencil-combine-at-edge
                                 (ly:stencil-scale tip -1 1)
                                 X RIGHT
                                 tip
                                 kern)
                               (- (interval-center top-stil-ext) (/ kern 2))
                               X)))
                         (else tip)))
                 (down-tip (ly:stencil-scale up-tip 1 -1)))
            (for-each
              (lambda (grobb bar-stil dir tip-style)
                      (ly:grob-set-property! grobb 'stencil
                        (ly:stencil-combine-at-edge
                          bar-stil
                          Y
                          dir
                          tip-style
                          0)))
               (append top-bar-lines bottom-bar-lines)
               (append
                 (make-list bar-lines-list-length top-stil)
                 (make-list bar-lines-list-length bottom-stil))
               (append
                 (make-list bar-lines-list-length 1)
                 (make-list bar-lines-list-length -1))
               (append
                 (make-list bar-lines-list-length up-tip)
                 (make-list bar-lines-list-length down-tip)))))))
                 
%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% EXAMPLES
%%%%%%%%%%%%%%%%%%%%%%%%%%%

\paper {
  indent = 0
  tagline = ##f
}
                   
mus =
#(make-sequential-music
  (map
    (lambda (s) 
      #{ 
      	 s1  \bar $s s1 \break \bar $s 
      #})
    '(":..:" ".|:-|" ":|.")))

\markup
  \fill-line {
    \pad-around #4
    \column {
      "Tips created automatic, using "
      "\\override BarLine.tip = #'auto"
    }
  }
    
\score {
  \new StaffGroup
  <<
    \new Staff 
      \with { \override BarLine.tip = #'auto } 
      { \mus \break s1 \bar "|." }
    \new Staff 
      { \mus \break s1 \bar "|." }
    \new Staff 
      { \mus \break s1 \bar "|." }
  >>
  \layout {
    \context {
      \Score 
      \CertainBracketTipsBarLines
    }
  }
}


%% A semi-automatic method making different at the same time are possible:
%{
\markup
  \rounded-box
  \fill-line {
    \pad-around #4
    \column {
      "Tips set by user, using "
      "\\override BarLine.tip = #'up"
      "or"
      "\\override BarLine.tip = #'down"
      "Every BarLine will get a tip according to the override"
      "Different styles at the same time are possible"
    }
  }

\score {
  <<
    \new StaffGroup
    <<
      \new Staff 
        \with { \override BarLine.tip = #'up }
        \mus
      \new Staff 
        \mus
      \new Staff 
        \with { \override BarLine.tip = #'down }
        \mus
    >>
    
    \new StaffGroup
    <<
      \new Staff 
        \mus
      \new Staff 
        \mus
      \new Staff 
        \mus
    >>
  >>
  \layout {
    \context {
      \Score 
      \CertainBracketTipsBarLines
    }
  }
}
%}