Re: markup column with baseline-skip relative to font size

[Thomas Morley]

Hi Kieren,

Am Sa., 17. Nov. 2018 um 02:36 Uhr schrieb Kieren MacMillan
<address@hidden>:
>
> Hi all,
>
> In the snippet below, you’ll see that I’m attempting to override Fingering in 
> a custom context to add a caret (^) on top of the [formatted] finger number 
> to make it into a scale degree.
>
> The "padding" between the caret and the number isn’t relative, as I would 
> like it to be: it should always be some fraction of the font height (either 
> x-height or m-height or M-height or similar).

I don't think that's the way to go.

> Is there a way to accomplish this?

Default \center-column does not adjust baseline-skip according to the
grobs font-size.
Below I wrote 'center-column-fontsize-adjusted-baseline-skip' (you
should probably rename it, lol), which does so. Modeled after how
\fontsize deals with baseline-skip.

> Bonus points if the top of the caret and the baseline of the numbers remain 
> the same even when using lowercase numerals.

Not sure what you mean here, could you provide some example-code?

But here the code. I dropped all about 'UrlinieVoice', not needed for
a minimal, imho.
Is this what you aim at?

\version "2.19.82"


#(define-markup-command
  (center-column-fontsize-adjusted-baseline-skip layout props args)
  (markup-list?)
  #:category align
  #:properties ((font-size 0)
                (baseline-skip))

  ;; 'general-column' is not public, thus copied from define-markup.scm
  ;; and inserted here
  (define (general-column align-dir baseline mols)
    "Stack @var{mols} vertically, aligned to  @var{align-dir} horizontally."

    (let* ((aligned-mols
      (map (lambda (x) (ly:stencil-aligned-to x X align-dir)) mols))
           (stacked-stencil (stack-lines -1 0.0 baseline aligned-mols))
           (stacked-extent (ly:stencil-extent stacked-stencil X)))
      (ly:stencil-translate-axis stacked-stencil (- (car stacked-extent)) X)))

  (general-column CENTER (* baseline-skip (magstep font-size))
    (interpret-markup-list layout props args)))


%% Rewritten for easy exchanging procedures while testing
#(define (caret-finger proc)
  (lambda (grob)
    (let ((text (ly:grob-property grob 'text)))
      (grob-interpret-markup grob
        (make-text-markup
          (make-override-markup '(baseline-skip . 1.75)
            (proc (list "^" text))))))))

mus = { a'8-4 8-3 8-2 8-1 }

%% default
{
  \override Fingering.stencil =
    #(caret-finger make-center-column-markup)
  \mus
  \override Fingering.font-size = #4
  \mus
}

%% new code
{
  \override Fingering.stencil =
    #(caret-finger make-center-column-fontsize-adjusted-baseline-skip-markup)
  \mus
  \override Fingering.font-size = #4
  \mus
}


Cheers,
  Harm