Re: How to tweak X-Y-offset of left Fingerings in a chord

[Thomas Morley]

Am Mi., 14. Apr. 2021 um 10:30 Uhr schrieb Jean Abou Samra <jean@abou-samra.fr>:
>
>
> Le 13/04/2021 à 23:18, Thomas Morley a écrit :
>
> Hi,
>
> let's say I've a chord with Fingerings left.
> Now I want to tweak a certain Fingering a little bit up/down and left/right.
>
> How to do so?
>
> Here a minimal to play with:
>
> {
>   \set fingeringOrientations = #'(left)
>   <c'-3 e'-2>
>
>   %% below does not work
>   \once \override Fingering.Y-offset = 10
>   \once \override Fingering.X-offset = 10
>   <c'-3 e'-2>
>
>   <c'-\tweak Y-offset #-10 -3 e'-\tweak Y-offset #10 -2>
> }
>
> Changing fingeringOrientations is not an option.
> Using extra-offset neither, because the Fingering will be the right
> bound of the FigerGlideSpanner, which would look misplaced then.
>
>
> Any hints?
>
>
> Thanks,
>   Harm
>
>
> Hi,
>
> Something very weird seems to be going
> on. Try:
>
> {
>   \set fingeringOrientations = #'(left)
>   \once \override Staff.FingeringColumn.positioning-done =
>     #(lambda (grob)
>        (let* ((fingering-array (ly:grob-object grob 'fingerings))
>               (fingerings (ly:grob-array->list fingering-array)))
>          (for-each
>            (lambda (fingering x)
>              (ly:message "Before: ~s" (ly:grob-property-data fingering 
> 'X-offset))
>              (ly:grob-set-property! fingering 'X-offset x)
>              (ly:message "After: ~s" (ly:grob-property-data fingering 
> 'X-offset)))
>            fingerings
>            '(0 -10))
>          #t))
>   <c'\tweak X-offset -4 -3 e'-2>
> }
>
> This displays
>
> Before: ()
>
> After: 0
>
> Before: ()
>
> After: -10
>
> No X-offset before seems somewhat odd, but why
> not. Maybe something that I haven't yet understood
> is setting it.
>
> However, the values 0 and -10 have no effect.
> Instead, the \tweak takes effect (try changing
> the -4), even though the value it gives to the
> property is supposed to be overwritten.
>
> This very much reminds me of
> https://lists.gnu.org/archive/html/bug-lilypond/2021-01/msg00014.html ...
>
> For X-offset, the following seems to do the trick
> as long as the values are negative:
>
> {
>   \set fingeringOrientations = #'(left)
>   \once \override Staff.FingeringColumn.positioning-done = ##t
>   <c'\tweak X-offset -4 -3 e'\tweak X-offset -2 -2>
> }
>
> For Y-offset, I haven't found a workaround yet.
>
>
> Cheers,
> Jean

I had a look at fingering-column.cc. While my C++-knowledge is aprox.
zero, It seems that X/Y-offset is simply ignored, and positioning is
done via the C++ version of ly:grob-translate-axis!, I could be wrong,
though.

Nevertheless, using it like below seems to work:

\version "2.23.2"

moveColumnedFinger =
#(define-music-function (finger x-y-move)(index? pair?)
#{
  \override Staff.FingeringColumn.positioning-done =
  #(lambda (grob)
    (let* ((fingers-array (ly:grob-object grob 'fingerings))
           (fingers
             (if (ly:grob-array? fingers-array)
                 (ly:grob-array->list fingers-array)
                 '()))
           (digit-grob-alist
             (map
               (lambda (finger)
                 (cons
                   (ly:event-property (event-cause finger) 'digit)
                   finger))
               fingers)))

    (ly:grob-set-property!
      (assoc-get finger digit-grob-alist) 'color red)
    (ly:grob-translate-axis!
      (assoc-get finger digit-grob-alist) (car x-y-move) X)
    (ly:grob-translate-axis!
      (assoc-get finger digit-grob-alist) (cdr x-y-move) Y)
    (ly:fingering-column::calc-positioning-done grob)))
#})


{
  \set fingeringOrientations = #'(right)
  < c'\glide-3 e'\glide-2 >2
  s1*2
  \set fingeringOrientations = #'(left)
  \once \moveColumnedFinger 2 #'(-1 . 1)
  < d'-3 fis'-2 >2
}

Ofcourse only one Fingering can be moved with this code.
While it is not too hard to extend this coding for moving multiple
Fingerings at once, it would be inconveniant calling it in a .ly-file.
Itw ould result in something at the lines of:

\moveColumnedFingers
  #(list
    '(1 . (x1 . y1))
    '(2 . (x2 . y2))
    '(3 ... )
    ...)

Not a nice user-interface, I'd say.

Additional, it would not work with only one Fingering present in chord
like <c'-3 e'>
Thus. I wonder, if it would be better toalways create a FingerigColumn.

Thanks,
  Harm