input/regression/flags-in-scheme.ly

   1 \version "2.12.0"
   2
   3 \header {
   4   texidoc = "The 'flag property of the Stem grob can be set to a custom
   5 scheme function to generate the glyph for the flag."
   6 }
   7
   8
   9 % test notes, which will be shown in different style:
  10 testnotes = { \autoBeamOff c'8 d'16 c'32 d'64 \acciaccatura {c'8} d'64 c''8 d''16 c''32 d''64 \acciaccatura {c''8} d''64  }
  11
  12 #(define-public (weight-flag stem-grob)
  13   (let* ((log (- (ly:grob-property stem-grob 'duration-log) 2))
  14          (is-up (eqv? (ly:grob-property stem-grob 'direction) UP))
  15          (yext (if is-up (cons (* log -0.8) 0) (cons 0 (* log 0.8))))
  16          (flag-stencil (make-filled-box-stencil '(-0.4 . 0.4) yext))
  17          (stroke-style (ly:grob-property stem-grob 'stroke-style))
  18          (stroke-stencil (if (equal? stroke-style "grace") (make-line-stencil 0.2 -0.9 -0.4 0.9 -0.4) empty-stencil)))
  19     (ly:stencil-add flag-stencil stroke-stencil)))
  20
  21
  22 % Create a flag stencil by looking up the glyph from the font
  23 #(define (inverted-flag stem-grob)
  24   (let* ((dir (if (eqv? (ly:grob-property stem-grob 'direction) UP) "d" "u"))
  25          (flag (retrieve-glyph-flag "" dir "" stem-grob))
  26          (line-thickness (ly:staff-symbol-line-thickness stem-grob))
  27          (stem-thickness (ly:grob-property stem-grob 'thickness))
  28          (stem-width (* line-thickness stem-thickness))
  29          (stroke-style (ly:grob-property stem-grob 'stroke-style))
  30          (stencil (if (null? stroke-style) flag
  31                          (add-stroke-glyph flag stem-grob dir stroke-style "")))
  32          (rotated-flag (ly:stencil-rotate-absolute stencil 180 0 0)))
  33     (ly:stencil-translate rotated-flag (cons (- (/ stem-width 2))  0))))
  34
  35 {
  36   \override Score.RehearsalMark #'self-alignment-X = #LEFT
  37   \time 2/4
  38   \mark "Function: weight-flag (custom)"
  39   \override Stem #'flag = #weight-flag
  40   \testnotes
  41
  42   \mark "Function: inverted-flag (custom)"
  43   \override Stem #'flag = #inverted-flag
  44   \testnotes
  45
  46 }