Re: Misplaced dashed barlines in vertically compressed score

[Thomas Morley]

Am Mo., 13. Juni 2022 um 19:39 Uhr schrieb William Rehwinkel via
bug-lilypond <bug-lilypond@gnu.org>:
>
> Dear Lilypond,
>
> After not being able to find any bugs discussing this in the tracker, I
> would like to share the following miniature example which I believe
> shows that dashed bar-lines are misplaced in vertically compressed
> scores (using default lilypond spacing settings). After testing in
> 2.22.2 and 2.23.9, the same behavior persists. The dashed lines should
> have rendered in the same way as the double bar and dotted bar did, but
> it does not connect between the two Piano Staves and extends above the
> top staff. Note that if the spacing of systems is manually expanded, via
> "\paper{ systems-per-page = 4 }", for example, the dashed bar-lines are
> rendered properly.
>
> Thank you,
>
> -William
>
> ---
>
> \version "2.23.9" % "2.22.2"
> \score {
>      <<
>          \new PianoStaff <<
>              \new Staff \repeat unfold 32 { 8 8 8 8 \bar "!" 8 8 8 8
> \bar "||" 8 8 8 8 \bar ";" 8 8 8 8 }
>              \new Staff \repeat unfold 32 { 8 8 8 8 8 8 8 8 8 8 8 8 8 8
> 8 8 }
>          >>
>          \new Staff \repeat unfold 32 { 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 }
>      >>
> }

Confirmed.

Here a more tiny example:

mus = {
  \override Staff.BarLine.bar-extent =
    #(lambda (grob) (interval-widen (ly:bar-line::calc-bar-extent grob) 0.5))

  f'4 \bar "!" f''4
}

\new PianoStaff
  <<
      \new Staff \mus
      \new Staff \mus
  >>

Actually a dashed bar line uses dashed-line _or_ a line constructed
from filled boxes, depending on certain conditions.
Iirc, this is due to wished different behaviour if BarLine.color is
different from StaffSymbol.color. I may be wrong here though...

If a _SpanBar_ is dashed with filled boxes the result needs to be
moved between the staves.Though, this is a very rare case and not
covered by any regtest afaict, thus it was undetected so far.

Many thanks for your report.
On it ...

Cheers,
  Harm