Using circles in \tabFullNotation

[Jean Abou Samra]

> Hello,
>
>       I'm trying to have an output similar to the attached images
>         when using \tabFullNotation: half-notes and chords
>         circled with a single stem and whole notes and chords
>         circled with no stem. Reading the source code for
>         \tabFullNotation, I think I need to \override
>         TabStaff.Stem.stencil with a custom Scheme function, but I'm note
>         sure how to do that. Can someone point me in the right
>         direction?

Hi,

Your hunch is correct. Try this somewhat experimental
code (note that I am not sure how you are positioning the
TabNoteHead grobs horizontally, I used an X-offset).

Regards,
Jean

\version "2.23.0"

% Define new grob properties used for Stem

#(set-object-property! 'oval-thickness 'backend-type? number?)
#(set-object-property! 'oval-x-padding 'backend-type? number?)
#(set-object-property! 'oval-y-padding 'backend-type? number?)

% Amended from scm/stencil.scm, to use #t for filling

#(define (filled-oval-stencil stencil thickness x-padding y-padding)
  (let* ((x-ext (ly:stencil-extent stencil X))
         (y-ext (ly:stencil-extent stencil Y))
         (x-length (+ (interval-length x-ext) x-padding thickness))
         (y-length (+ (interval-length y-ext) y-padding thickness))
         (x-radius (* 0.707 x-length) )
         (y-radius (* 0.707 y-length) )
         (oval (make-oval-stencil x-radius y-radius thickness #! #f !# #t)))
    (ly:stencil-add
     stencil
     (ly:stencil-translate oval
                           (cons
                            (interval-center x-ext)
                            (interval-center y-ext))))))

#(define (custom-stem-stencil stem)
   "Draw a stem and an oval around all note heads found."
   (define (coords-for-axis note-head-array note-heads axis)
     "Compute relative coordinates of note heads
      relative to the stem along given axis."
     (let* ((refpoint(ly:grob-common-refpoint-of-array stem note-head-array axis))
            (note-head-coords (map (lambda (note-head)
                                 (ly:grob-relative-coordinate
                                   note-head
                                   refpoint
                                   axis))
                         note-heads))
            (stem-coord (ly:grob-relative-coordinate
                          stem
                          refpoint
                          axis))
            (scaled-coords (map (lambda (coord)
                                  (- coord stem-coord))
                                note-head-coords)))
       scaled-coords))
           
   (let* ((stem-stencil (ly:stem::print stem))
          (oval-thickness (ly:grob-property stem 'oval-thickness))
          (oval-x-padding (ly:grob-property stem 'oval-x-padding))
          (oval-y-padding (ly:grob-property stem 'oval-y-padding))
          (note-head-array (ly:grob-object stem 'note-heads))
          (note-heads (ly:grob-array->list note-head-array))
          (scaled-x-coords (coords-for-axis note-head-array note-heads X))
          (scaled-y-coords (coords-for-axis note-head-array note-heads Y))
          (stencils (map (lambda (note-head)
                           (tab-note-head::print note-head))
                         note-heads))
          (translated-stencils (map (lambda (stencil x y)
                                      (ly:stencil-translate
                                        stencil
                                        (cons x y)))
                                    stencils
                                    scaled-x-coords
                                    scaled-y-coords))
          (combo-stencil (apply ly:stencil-add translated-stencils)))
     (ly:stencil-add
       stem-stencil
       (stencil-with-color
         (filled-oval-stencil combo-stencil oval-thickness oval-x-padding oval-y-padding)
         white)
       (oval-stencil combo-stencil oval-thickness oval-x-padding oval-y-padding))))

\layout {
  \context {
    \TabVoice
    \override Stem.stencil = #custom-stem-stencil
   
    % You can set these.
    \override Stem.oval-thickness = 0.1
    \override Stem.oval-x-padding = 0.75
    \override Stem.oval-y-padding = 0.75
   
    % The oval is drawn over the stem. Lower the layer to prevent
    % it from going over the staff symbol too.
    \override Stem.layer = -1
   
    % Override default extent calculations, because those do not
    % actually use the stencil.
    \override Stem.X-extent = #'(0 . 0)
    \override Stem.Y-extent = #(ly:make-unpure-pure-container grob::always-Y-extent-from-stencil)
   
    % Add a bit of padding on the right of TabNoteHead to
    % account for the right side of the oval. This is required
    % for proper alignment of dots.
    \override TabNoteHead.X-extent = #'(-1 . 2)
  }
}


symbols = {
  \time 3/4
  <a \tweak X-offset 0.7 e'>2.
}

\score {
  \new TabStaff {
    \tabFullNotation
    \symbols
  }
}