Re: accessing accidentals with \tweak

[Mark Polesky]

Carl Sorensen wrote:
> What if a property like tweak-callback were added, whose job is
> just to trigger the grob callback necessary for what you want to
> do?
>
> Then you could have
> \relative {
>   <c! \tweak #'tweak-callback #color-accidental e! g!>
> }
>
> I think you could have multiple calls to #'tweak-callback,
> because all of the tweaks are stored in a list, and would all be
> executed.
>
> \displayMusic
> \relative {
>   <c 
>     \tweak #'color #red
>     \tweak #'color #yellow
>   d> 
> }

Unfortunately this doesn't seem to work. See attached PNG and
console output below. When using this "indirect" tweaking method,
only the *last* tweak affects the typeset output. The desired
output in the example below is to have both E-naturals colored red
and reduced in size. The first one is reduced but not colored; the
second one is colored, but not reduced.

It seems to me that a satisfactory resolution of this issue will
have significant implications for my LilyPond projects, so
hopefully someone can help me find the answer!

Thanks so much.
- Mark

____________________

\version "2.13.2"

#(define (color-accidental note-grob color)
  ;; notehead before-line-breaking callback
  (let ((accidental (ly:grob-object note-grob 'accidental-grob)))
    (if (not (null? accidental))
        (ly:grob-set-property! accidental 'color color))))

#(define (resize-accidental note-grob fontsize)
  ;; notehead before-line-breaking callback
  (let ((accidental (ly:grob-object note-grob 'accidental-grob)))
    (if (not (null? accidental))
        (ly:grob-set-property! accidental 'font-size fontsize))))

\relative { 
  <c!
    \tweak #'before-line-breaking
      #(lambda (grob) (color-accidental grob red))
    \tweak #'before-line-breaking
      #(lambda (grob) (resize-accidental grob -3)) e!>

  \displayMusic
  <c!
    \tweak #'before-line-breaking
      #(lambda (grob) (resize-accidental grob -3))
    \tweak #'before-line-breaking
      #(lambda (grob) (color-accidental grob red)) e!>
}

____________________

(make-music
  'EventChord
  'elements
  (list (make-music
          'NoteEvent
          'duration
          (ly:make-duration 2 0 1 1)
          'force-accidental
          #t
          'pitch
          (ly:make-pitch -1 0 0))
        (make-music
          'NoteEvent
          'duration
          (ly:make-duration 2 0 1 1)
          'tweaks
          (list (cons 'before-line-breaking
                      #<procedure #f (grob)>)
                (cons 'before-line-breaking
                      #<procedure #f (grob)>))
          'force-accidental
          #t
          'pitch
          (ly:make-pitch -1 2 0))))

accidental-tweaks.png
Description: PNG image