\version "2.23.0"

% You can play around with these parameters.

line-count = 12
stem-end-position = 17
inter-line-gap = 2
min-grey = 0
max-grey = 0.7
min-thickness = 0.1
thickness-increment = 0.013
stem-thickness = 2
staff-line-blot = 0.2
light-blue = "CornflowerBlue"
note-head-base = \markup \filled-box #'(-0.6 . 0.6) #'(-0.5 . 0.5) #0.9

#(define-markup-command (whiteout-outline-with-color layout props thickness color arg)
                        (number? color? markup?)
   (stencil-whiteout-outline (interpret-markup layout props arg) thickness color))

note-head-part-one =
\markup
  % Strange that \whiteout-outline-with-color #0.1 #black \with-color #blue \note-head
  % doesn't work here. Let's work around.
  \combine
  \whiteout-outline-with-color
    #0.15
    #black
    \with-color #black \note-head-base
  \with-color #light-blue \note-head-base

note-head-part-two =
\markup
  \whiteout-outline-with-color
    #0.15
    #black
    \note-head-base
    
note-head-combined =
\markup \overlay {
    \note-head-part-one
    \translate #'(-0.5 . 0) \note-head-part-two
    \translate #'(-0.7 . -0.4) \rotate #-150 \fontsize #-9 \with-color #white \number "2"
}

#(define (calc-note-head-text grob)
   (if (ly:grob-property grob 'has-headphones)
       note-head-combined
       note-head-part-two))


% Not defined?
#(define pi (acos -1))

#(define (greyscale x)
   (let* ((value (+ (* (+ (/ (atan x) pi) 0.5) (- max-grey min-grey)) min-grey)))
     (rgb-color value value value)))

#(define (calc-thickness x)
   (+ min-thickness (* thickness-increment (abs x))))


#(define (calc-stem-position grob)
  (- stem-end-position (ly:grob-property grob 'stem-begin-position)))



% From lily/staff-symbol.cc
#(define (calc-staff-symbol-line-positions grob)
  (let* ((line-count (ly:grob-property grob 'line-count))
         (height (- line-count 1)))
    (map
      (lambda (i) (- height (* 2 i)))
      (iota line-count))))




#(define (calc-staff-symbol-stencil grob)
   (let ((x-extent (ly:stencil-extent (ly:staff-symbol::print grob) X)))
     (apply ly:stencil-add
       (map
         (lambda
          (x)
          (let ((thickness (calc-thickness x)))
            (ly:stencil-translate-axis
               (grob-interpret-markup grob
                #{
                  \markup
                    \with-color #(greyscale x)
                    \filled-box #x-extent #(cons (- thickness) thickness) #staff-line-blot
                #})
                (* (ly:grob-property grob 'staff-space 1) 0.5 x)
                Y)))
         (ly:grob-property grob 'line-positions)))))


% Borrowed from Pierre
% https://www.mail-archive.com/lilypond-user@gnu.org/msg140189.html
#(define (define-grob-property symbol type? description)
   "Define a new grob property.
`symbol': the property name
`type?': the type predicate for this property
`description': the type documentation"
  (set-object-property! symbol 'backend-type? type?)
  (set-object-property! symbol 'backend-doc description)
  symbol)


#(define-grob-property
  'has-headphones
  boolean?
  "Should this note be printed with headphones?")

\paper {
  page-breaking = #ly:one-line-auto-height-breaking
}

\layout {
  \context {
    \Score
    \remove System_start_delimiter_engraver
  }
  \context {
    \Staff
    \remove Bar_engraver
    \remove Clef_engraver
    \remove Time_signature_engraver
    \override Stem.thickness = #stem-thickness
    \override Stem.direction = #UP
    \override NoteHead.stencil = #ly:text-interface::print
    \override NoteHead.text = #calc-note-head-text
    \override Stem.length = #calc-stem-position
    \override Stem.X-offset = 0.63
    \override StaffSymbol.line-count = #line-count
    \override StaffSymbol.line-positions = #calc-staff-symbol-line-positions
    \override StaffSymbol.stencil = #calc-staff-symbol-stencil
    \override NoteHead.has-headphones = ##f
  }
}

headphones = \tweak has-headphones ##t \etc
move = \tweak NoteHead.extra-offset
  #(lambda (grob)
     (if (ly:grob-property grob 'has-headphones)
         '(1.78 . 0)
         '(1.30 . 0)))
  \etc

addSmallSpacing = {
  \once \override Score.SpacingSpanner.spacing-increment = 0.4
  s
  \newSpacingSection
}




\relative {
  \addSmallSpacing
  e'''
  <e \move \headphones f,>
  c
  <a \move c>
  a
  <a \move \headphones f>
  f
  \headphones f
  d
  <b \move c'>
  \headphones b
  b
  <b \move a,>
  <g \move a'>
  \headphones g
  g
  e
  e
  <c \move a>
  a
  <f \move \headphones f''>
  f
}