Re: Finding the objects at the start of the current measure

[Urs Liska]

Hi Thomas,

thank you for the consideration!

Am 26.02.19 um 12:02 schrieb Thomas Morley:
> Am Mo., 25. Feb. 2019 um 13:14 Uhr schrieb Urs Liska <address@hidden>:
> > ...
> >
> > \version "2.19.82"
> >
> > \include "oll-core/package.ily"
> Hi Urs,
>
> because of my limited time I can't keep track what's going on oll.
>
> Thus all your example code is limited to oll-users, I'd recommend to
> break it doing to core-lilypond-functionality while asking here,
> otherwise only those oll-users have a chance to compile your surely
> nice code.


Well, I must admit I found this too complicated in this case, especially 
given that in the end I'll make it available somewhere in openLilyLib 
anyway.


> That said, I probably can imagine what the not-core-functions do ;)
>
> Why not going for bound-padding instead of minimum-length.


I wasn't aware that multimeasure rests are spanners and that I could use 
bound-padding.


> Here a sketch:
>
> foo =
>      \override MultiMeasureRest.before-line-breaking =
>      #(lambda (grob)
>         (let* ((vag (ly:grob-parent grob Y)) ;; VerticalAxisGroup
>                (vag-elts-array (ly:grob-object vag 'elements))
>                (vag-elts-ls
>                  (if (ly:grob-array? vag-elts-array)
>                      (ly:grob-array->list vag-elts-array)
>                      '()))
>                (mm-grobs
>                  (filter
>                    (lambda (elt)
>                      (and
>                        (equal? (ly:grob-parent elt X) grob)
>                        (grob::has-interface elt 'multi-measure-interface)))
>                    vag-elts-ls)))
>
>           (if (pair? mm-grobs)
>               (let* ((mmr-stil-x-length
>                        (interval-length
>                          (ly:stencil-extent
>                            (ly:multi-measure-rest::print grob) X)))
>                      (mm-text-stil-x-lengths
>                        (map
>                          (lambda (mm)
>                            (ly:stencil-extent
>                              (grob-interpret-markup
>                                mm
>                                (ly:grob-property mm 'text))
>                              X))
>                          mm-grobs))
>                      (max-text-x-length
>                        (apply max (map cdr mm-text-stil-x-lengths)))
>                      (half-x-diff
>                        (/ (abs (- mmr-stil-x-length max-text-x-length)) 2)))
>                 (ly:grob-set-property! grob 'bound-padding half-x-diff)))))
>
> {
>      \foo
>      R1
>      \key bes \major
>      R1
>
>      \key b \major
>      \time 16/16
>
>      R1^"very very long"_"not short either"
>      R^"very very very long"_"not really short either"
> }


I must admit that this doesn't seem to properly work when applied to my 
code.

Do I understand correctly that bound-padding ensures padding to the 
right and left of the given (spanner) grob. So when the rest (or my 
in-place replacement with arbitrary markup) has a width of, say, 4 staff 
spaces, and bound-padding is set to, say, 10, then my measure is 
guaranteed to be (at least) 24 staff spaces wide?

I can successfully map your code to mine, determining a bound-padding 
value of half the difference between the wider markup and the stencil 
within the staff. However, without any additional padding I notice that 
the measures are usually *wider* than necessary, even forcing the music 
to run off the staff to the right.

The attached images show that the effective padding is very different in 
different measures. And when I subtract some manual offset I end up some 
measures still having generous padding while others already have the 
markup overlap the barlines.

So I have the impresstion that - while solving the original issue of 
measure-start elements - bound-padding is still not sufficiently 
reliable/manageable for my issue.

Urs

1756_034_1.png
Description: PNG image

1756_034_1.png
Description: PNG image