Re: Distance of grob to barlines

[David Nalesnik]

Hi Andrew,

On Fri, Aug 21, 2015 at 6:51 PM, Andrew Bernard <address@hidden> wrote:

Can anybody kindly point me to code examples showing how to find the distance of a grob to its nearest enclosing barlines, in Scheme?

I don't know of any examples out there, be this will do it.

This uses the horizontal coordinate of the grob and barline as a simple demonstration.  Depending on what precisely you mean by "distance" (right edge to left edge, left edge to right edge, etc.) you may want to use ly:grob-extent.

HTH,

David

%%%%%%%%%%%%%%

 \version "2.19.23"

#(define (distance-to-nearest-barline dir)

   (lambda (grob)

     (let* ((refp (ly:grob-system grob))

            (all-elts (ly:grob-array->list (ly:grob-object refp 'all-elements)))

            (barlines (filter (lambda (elt)

                                (grob::has-interface elt 'bar-line-interface))

                              all-elts))

            (me-pos (grob::rhythmic-location grob))

            (pred? (if (= LEFT dir) rhythmic-location>=? rhythmic-location<?))

            (closest (filter (lambda (b)

                               (pred? me-pos (grob::rhythmic-location b)))

                             barlines))

            (closest (reduce

                      (lambda (elem prev)

                        (if (pred?

                             (grob::rhythmic-location prev) (grob::rhythmic-location elem))

                            prev

                            elem))

                      #f

                      closest)))

       

       (if closest

           (let* ((me-X (ly:grob-relative-coordinate grob refp X))

                  (closest-X (ly:grob-relative-coordinate closest refp X))

                  (dist (- closest-X me-X)))

             (ly:grob-set-property! grob 'color darkgreen) ; for testing

             (ly:grob-set-property! closest 'color red) ; for testing

             (format #t "distance between ~a and ~a: ~a~%"

               grob closest dist))

           (ly:message "No closest barline!")))))

{

  

  c'4 d' e' 

  \once \override NoteHead.after-line-breaking = #(distance-to-nearest-barline RIGHT)

  f'

  d'1

  c'4 d' e'

  \once \override Stem.after-line-breaking = #(distance-to-nearest-barline LEFT)

  f'

  d'1

}