View source for Dashed individual staff lines

You can customize a staff so that some (or all) of its lines are dashed instead of solid. This snippet defines a command called <code>\dashedStaffSymbolLines</code> that replaces specified lines of a <code>StaffSymbol</code> grob with dashed lines. For example, the following replaces the center line of the staff with a dashed line.

 \dashedStaffSymbolLines #'(#f #f #t #f #f)

A list containing booleans (<code>#t</code> and <code>#f</code>) indicates which lines are to be dashed. (<code>#t</code> means dashed, <code>#f</code> means normal and unchanged)

The width of the dashes and the spacing between them can optionally be customized by adding a pair of values as the first argument when calling the function. The first number of the pair is the width, the second is the spacing. (The default is 0.5 for both.) The following creates wider dashes (1.5) with more space between them (1.2).

 \dashedStaffSymbolLines #'(1.5 . 1.2) #'(#f #f #t #f #f)

The function also works with staves that have different numbers of lines and/or different line positions.

<lilypond version="2.24">
% original code (for zig-zag lines) by Thomas Morley (Harm)
% -> http://lists.gnu.org/archive/html/lilypond-user/2012-12/msg00715.html
% slightly modified to create dashed lines by Paul Morris

dashedStaffSymbolLines =
#(define-music-function (dash-space bool-list)
 ((number-pair? '(0.5 . 0.5)) list?)
"
Replaces specified lines of a StaffSymbol with dashed lines.

The lines to be changed should be given as a list containing booleans, with
the meaning:
  #f - no dashes, print a normal line
  #t - print a dashed line
The order of the bool-list corresponds with the order of the given list of
'line-positions or if not specified, with the default.
If the length of the bool-list and the 'line-positions doesn't match a warning
is printed.

The width of the dashes and the spacing between them can be altered by adding a pair
as first argument while calling the function:
\\dashedStaffSymbolLines #'(1 . 1) #'(#f #f #t #f #f)
the first number of the pair is the width, the second the spacing
"
#{
 \override Staff.StaffSymbol.after-line-breaking =
   #(lambda (grob)
     (let* ((staff-stencil (ly:grob-property grob 'stencil))
            (staff-line-positions 
              (if (equal? (ly:grob-property grob 'line-positions) '() )
                '(-4 -2 0 2 4)
                (ly:grob-property grob 'line-positions)))
            (staff-width
              (interval-length
                (ly:stencil-extent staff-stencil X)))
            (staff-space (ly:staff-symbol-staff-space grob))
            (staff-line-thickness (ly:staff-symbol-line-thickness grob))
            ;; width of the dash
            (dash-width (car dash-space))
            ;; space between dashes
            (space-width (cdr dash-space))
            ;; Construct the first dash
            (sample-path `((moveto 0 0)
                           (lineto ,dash-width 0)
                           ))
            ;; Make a stencil of the first dash
            (dash-stencil
              (grob-interpret-markup
                grob
                (markup
                  #:path staff-line-thickness sample-path)))
           ;; width of both dash and space
           (dash-space-width (+ dash-width space-width))
           
           ;; another way: get width of dash from the dash stencil
           ;; (stil-width
           ;;   (interval-length
           ;;     (ly:stencil-extent dash-stencil X)))
           ;; (dash-space-width (+ stil-width space-width))
           
            ;; Make a guess how many dashes are needed.
            (count-dashes
              (inexact->exact
                (round
                  (/ staff-width
                     (- dash-space-width
                        staff-line-thickness)))))
            ;; Construct a stencil of dashes with the guessed count
            (dashed-stil
                (ly:stencil-aligned-to
                  (apply ly:stencil-add
                    (map
                      (lambda (x)
                        (ly:stencil-translate-axis
                          dash-stencil
                          (* (- dash-space-width staff-line-thickness) x)
                          X))
                      (iota count-dashes)))
                  Y
                  CENTER))
            ;; Get the the length of that dashed stencil
            (stil-x-length
              (interval-length
                (ly:stencil-extent dashed-stil  X)))
            ;; Construct a line-stencil to replace the staff-lines.
            (line-stil
              (make-line-stencil staff-line-thickness 0 0 staff-width 0))
            ;; Calculate the factor to scale the dashed-stil to fit
            ;; the width of the original staff-symbol-stencil
            (corr-factor
              (/ staff-width (- stil-x-length staff-line-thickness)))
            ;; Construct the new staff-symbol
            (new-stil
              (apply
                ly:stencil-add
                  (map
                    (lambda (x y)
                      (ly:stencil-translate
                          (if (eq? y #f)
                            line-stil
                            (ly:stencil-scale
                              dashed-stil
                              corr-factor 1))
                          (cons (/ staff-line-thickness 2)
                                (* (/ x 2) staff-space))))
                    staff-line-positions bool-list))))
       
      (if (= (length bool-list)(length staff-line-positions))
        (ly:grob-set-property! grob 'stencil new-stil)
        (ly:warning
          "length of dashed line bool-list doesn't match the line-positions - ignoring"))))
#})


%%%%%%%%%%%%%%%%%%%%%%%%%%
% EXAMPLE
%%%%%%%%%%%%%%%%%%%%%%%%%%

music =
\relative f' {
  c2 d e f g a b
}

<<
 \new Staff \with {
           \dashedStaffSymbolLines #'(#f #f #t #f #f)
 }
 \music
 
 
 \new Staff \with {
           \dashedStaffSymbolLines #'(0.2 . 0.3) #'(#f #t #f #t #f)
 }
 \music

 \new Staff \with {
           \override StaffSymbol.line-positions = #'(-4  0  4)
           \dashedStaffSymbolLines #'(#f #t #f)
           % make staff smaller:
           fontSize = #-3
           \override StaffSymbol.staff-space = #(magstep -3)
           \override StaffSymbol.thickness = #(magstep -3)
 }
 \music
>>
</lilypond>

[[Category:Staff notation]]
[[Category:Tweaks and overrides]]
[[Category:Scheme]]
[[Category:Contemporary notation]]
[[Category:Snippet]]