Bold tenuto

A tenuto with more thick lines, e.g. for better readability in poor lighting conditions.
Internally a new stencil function is defined for the articulation scripts, which checks the type of articulation. If it's tenuto or portato, the alternate graphic is returned, in all other conditions the basic function ly:script-interface::print is called.

\version "2.24.0"

%% http://lsr.di.unimi.it/LSR/Item?id=858

% by: ArnoldTheresius, supplemented by 'Harm'

\paper { tagline = ##f }

#(define (bold-tenuto-script-stencil grob)
   (let*
     ((scale (magstep (ly:grob-property grob 'font-size 0)))
      (dir (ly:grob-property grob 'direction 0))
      (script-stencil (ly:grob-property grob 'script-stencil))
      (tenuto-width 0.25) ;;; alter this value to modify the line width of the tenuto
      (tenuto-length 1.5) ;;; alter this value to modify the line length of the tenuto
      (tl (* -0.5 tenuto-length))
      (tr (* 0.5 tenuto-length))
      (ten-sil (make-line-stencil (* scale tenuto-width) (* scale tl) 0.0 (* scale tr) 0.0))
      (dot-sil (make-circle-stencil (* scale 0.15) (* scale 0.1) #t))
      (por-sil (ly:stencil-combine-at-edge 
                  ten-sil 
                  Y
                  (if (= dir 0)
                    -1
                    (* -1 dir))
                  dot-sil 
                  (* scale 0.4))))
   (if (and (pair? script-stencil) (pair? (cdr script-stencil)))
     (let* ((rv (cdr script-stencil))
            (script-type (if (<= dir 0) (car rv) (cdr rv))))
        (cond ((equal? script-type "tenuto")
               ten-sil)
              ((or (equal? script-type "uportato") (equal? script-type "dportato"))
               por-sil)
              (else (ly:script-interface::print grob))))
     (ly:script-interface::print grob))))

% define globally
\layout {
  \context {
    \Voice
    \override Script.stencil = #bold-tenuto-script-stencil
  }
}

{
  % alternatively: override locally (in voice)
  % \override Script.stencil = #bold-tenuto-script-stencil
  c'--^"bold tenuto / portato:" d'-- f'-- c''--
  c'-_ d'-_ f'-_ c''-_ \bar "||"
  \revert Script.stencil
  c'--^"original design:" d'-- f'-- c''--
  c'-_ d'-_ f'-_ c''-_ \bar "||"
}