Re: footnote marks not included in skylines

[Jean Abou Samra]

Le 27/04/2021 à 07:28, Werner LEMBERG a écrit :

> Right now, the NR section on footnotes looks very ugly.  Reason is
> that footnote marks are not included in skylines; as a consequence,
> they are cut off, see attached images.  (BTW, it seems that this fact
> is not mentioned in the documentation.)
>
> Do you have suggestions how the samples in the NR can be improved to
> avoid this cut-off?


Hi Werner,

I think this is more-or-less expected: we don't want footnotes to
influence the spacing of the music in general, especially horizontal
spacing.  As to vertical spacing, I don't really know. Maybe they
ought to be part of the system's skylines, but should we let them
reserve space between systems?

Cross-staff objects suffer from a similar problem:

<<
  \new Staff = "up" { s4 }
  \new Staff = "down" {
    \stemUp
    \override Beam.positions = #'(17 . 17)
    a16 b
    \change Staff = "up"
    c' d'
  }
>>

Maybe we should introduce a property for skylines used by
the system and let it default to the value of vertical-skylines?
This does mean letting footnotes reserve space between systems,
which may be desired or not.

Notice how in the case of footnotes, if you move the engraver to
Voice, and you use the override-like form of \footnote (the
\tweak-like form doesn't work the way the engraver is written),
and you set vertical-skylines to the appropriate unpure-pure
container ... then you do get the right skylines.

\version "2.23.3"

#(ly:set-option 'debug-skylines)

\layout {
  \context {
    \Score
    \remove "Footnote_engraver"
  }
  \context {
    \Voice
    \consists "Footnote_engraver"
    \override FootnoteItem.vertical-skylines = 
#grob::always-vertical-skylines-from-stencil
  }
}

\book {
  \header { tagline = ##f }
  \relative c'' {
    \footnote #'(-1 . 9) "A note" NoteHead a4
    a4
    \footnote #'(2 . 2) "A rest" Rest r4
    a4
  }
}

This seems to warrant more investigation and thought. I suggest
creating a tracker issue.

Best,
Jean