Re: Broken slurs won't overlap end-of-measure clef change

[Thomas Morley]

2016-10-19 3:02 GMT+02:00 David Nalesnik <address@hidden>:
> On Tue, Oct 18, 2016 at 4:56 PM, Javier Ruiz-Alma <address@hidden> wrote:
>> The first segment of a slur that spans to the next system is typeset short 
>> if a clef change is present at the end of the originating measure.  The 
>> first segment won't overlap the space above the changed clef.
>>
>> Javier Ruiz-Alma
>>
>> \version "2.18.2"
>> \score {
>>   <<
>>    { c''2 c''4\( c''  \break
>>      c''1\)
>>      c''4 c'' c'' c''(      \break
>>      c''1)
>>    }
>>    { c''1 \clef bass
>>      c'  c' \clef treble
>>      c'
>>    }
>>   >>
>>   \layout { ragged-right = ##t indent = 0 }
>> }
>>
>
> The problem you're seeing is that the right-bound of the slur is set
> to the *left* extent of the NonMusicalPaperColumn that encompasses the
> end materials of the line: Ordinarily, this means that a slur will end
> slightly before a barline, which looks fine.  Unfortunately, the
> cautionary clef belongs to the NonMusicalPaperColumn at the end of the
> line, hence the distortion you're seeing.
>
> (The endpoint seems to be created in
> Slur_score_state::get_base_attachments in lily/slur-scoring.cc.)
>
> What's needed is the ability to align the endpoint of a slur to
> specific elements within the 'elements array of the paper column
> bound.  Something like the 'break-alignable-interface which allows
> flexible alignments to grobs like BarNumber.
>
> David



Hi David,

thanks for your analysis, which reminded me, how I dealed with the
problem in the bend-engraver.
There I mimiced the default behaviour, but you can do it different, at
least manually. (Although reading a property is surely the way to go.)

As a proof of concept, setting all but last broken curve's right-bound
to BarLine:

\version "2.19.48"

#(define (set-broken-curve-right-bound grob)
  (let* ((orig (ly:grob-original grob))
         (siblings (if (ly:grob? orig)
                       (ly:spanner-broken-into orig)
                       '())))
    (if (and (pair? siblings) (not (equal? grob (last siblings))))
        (let* ((right-bound
                 (ly:spanner-bound grob RIGHT))
               (right-bound-elts
                   (ly:grob-array->list (ly:grob-object right-bound 'elements)))
               (bar-lines
                 (filter
                   (lambda (g) (grob::has-interface g 'bar-line-interface))
                   right-bound-elts)))
          (if (pair? bar-lines)
              (ly:spanner-set-bound! grob RIGHT (car bar-lines)))))))

resetRightBound = {
  \override Slur.after-line-breaking = #set-broken-curve-right-bound
  \override PhrasingSlur.after-line-breaking = #set-broken-curve-right-bound
}

\score {
  <<
   { c''2 \resetRightBound c''4\( c''  \break
     c''1\)
     c''4 c'' c'' c''(    \break
     c''1)
   }
   { c''1 \clef bass
     c'  c' \clef treble
     c'
   }
  >>
  \layout { ragged-right = ##t indent = 0 }
}

Cheers,
  Harm