Brackets indicating "Hauptstimme" and "Nebenstimme"

Brackets indicating "Hauptstimme" (main voice) and "Nebenstimme" (secondary voice) were first used by Arnold Schönberg, Alban Berg, and Anton Webern. If you want to print them, use the following code. The brackets, defined with postcript, will scale with customized staff-sizes, too.

\version "2.24"

%% http://lsr.di.unimi.it/LSR/Item?id=843

% contributed by harm6
% after an idea by Nathan
% see http://lists.gnu.org/archive/html/lilypond-user/2012-07/msg00036.html
% thanks to Mark Knoop

hauptStart = \markup {
  \path #0.25 #'((moveto 0 0)
                 (lineto 0 -2)
                 (moveto 0 -1)
                 (lineto 1 -1)
                 (moveto 1 0)
                 (lineto 1 -2)
                 (moveto 1 0)
                 (lineto 1.8 0))
}

nebenStart = \markup {
  \path #0.25 #'((moveto 0 -2)
                 (lineto 0 0)
                 (lineto 1 -2)
                 (lineto 1 0)
                 (lineto 1.8 0))
}

stimmeEnd = \markup {
  \path #0.25 #'((moveto 0 0)
                 (lineto 0.8 0)
                 (lineto 0.8 -0.8))
}

hauptstimmeStart =
#(define-music-function ()()
#{
          \once \override TextSpanner.before-line-breaking = 
              #(lambda (grob)
                  (let* ((sz (ly:grob-property grob 'font-size 0.0))
                         (mult (magstep sz)))
                  (begin
                     (ly:grob-set-property! grob 'style 'none)
                     (ly:grob-set-nested-property! grob 
                               '(bound-details left text) 
                                  (markup #:scale (cons mult mult) hauptStart))
                     (ly:grob-set-nested-property! grob 
                               '(bound-details right text) 
                                  (markup #:scale (cons mult mult) stimmeEnd))
                     ;;Perhaps you may want to uncomment the following lines
                     ;;and adjust the value (currently -0.5)
                     ;;(ly:grob-set-nested-property! grob 
                     ;;          '(bound-details right padding) -0.5)
                     (ly:grob-set-nested-property! grob 
                               '(bound-details left-broken text) #f)
                     (ly:grob-set-nested-property! grob 
                               '(bound-details right-broken text) #f))))
          $(make-music 'EventChord 'elements (list 
          		               (make-music
          		                 'TextSpanEvent
          		                 'span-direction -1)))
#})

nebenstimmeStart =
#(define-music-function ()()
#{
          \once \override TextSpanner.before-line-breaking = 
              #(lambda (grob)
                  (let* ((sz (ly:grob-property grob 'font-size 0.0))
                         (mult (magstep sz)))
                  (begin
                     (ly:grob-set-property! grob 'style 'none)
                     (ly:grob-set-nested-property! grob 
                               '(bound-details left text) 
                                  (markup #:scale (cons mult mult) nebenStart))
                     (ly:grob-set-nested-property! grob 
                               '(bound-details right text) 
                                  (markup #:scale (cons mult mult) stimmeEnd))
                     ;;Perhaps you may want to uncomment the following lines
                     ;;and adjust the value (currently -0.5)
                     ;;(ly:grob-set-nested-property! grob 
                     ;;          '(bound-details right padding) -0.5)
                     (ly:grob-set-nested-property! grob 
                               '(bound-details left-broken text) #f)
                     (ly:grob-set-nested-property! grob 
                               '(bound-details right-broken text) #f))))
          $(make-music 'EventChord 'elements (list 
          		               (make-music
          		                 'TextSpanEvent
          		                 'span-direction -1)))
#})

hauptstimmeEnd = \stopTextSpan
nebenStimmeEnd = \stopTextSpan

%------ test

mI = \relative c' {
        \hauptstimmeStart
        c4 cis d dis
        e f fis g\hauptstimmeEnd
        c2 c
        \nebenstimmeStart
        c,4 d e f
        g e c2\nebenStimmeEnd
}

mII = \relative c' { 
        \hauptstimmeStart
        c4 cis d dis
        e f fis g\hauptstimmeEnd
        c2 c
        \nebenstimmeStart
        c,4 d e f
        g e c2\nebenStimmeEnd
}

\new StaffGroup <<
   \new Staff \with { 
           	fontSize = #-5
           	\override StaffSymbol.staff-space = #(magstep -5)
           	\override StaffSymbol.thickness = #(magstep -5) 
             }
   \mI
   
   \new Staff 
   \mII
   >>