Re: Access Clef during after-line-breaking of ClefModifier

[Aaron Hill]

On 2020-04-16 4:47 pm, Noeck wrote:
> Hi,
>
> I have redefined the \clef command to sneak in an override to the
> ClefModifier. That works but I can't use it as a layout as it is "baked
> in" the music expression.
>
> I guess there is some "after-line-breaking" solution with a lambda
> function operating on the grob (ClefModifier). But I could not find it.
> I would need access to the kind of clef, the ClefModifier is attached 
> to.

While you can get to the Clef grob from the ClefModifier, the original 
string "treble_8" is not accessible near as I can tell.  You are however 
able to reverse engineer it given the glyph, direction, and text:

%%%%
\version "2.20.0"

{
  \override Staff.ClefModifier.color = #red
  \override Staff.ClefModifier.extra-offset =
  #(lambda (grob)
    (let* ((clef (ly:grob-parent grob X))
           (glyph (ly:grob-property clef 'glyph))
           (dir (ly:grob-property grob 'direction))
           (text (markup->string (ly:grob-property grob 'text))))
      (cond
        ;; treble_8
        ((equal? (list glyph dir text) (list "clefs.G" DOWN "8"))
          '(1.5 . 0.5))
        ;; bass^15
        ((equal? (list glyph dir text) (list "clefs.F" UP "15"))
          '(-1.5 . 0.5))
        (else '(0 . 0)))))

  \clef "treble^15" R1
  \clef "treble_8" R1
  \clef "bass^15" R1
  \clef "bass_8" R1
}
%%%%


-- Aaron Hill

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