Re: Add dead-is-alive boolean property to Hara_kiri_group_spanner (issue 6948058)

[k-ohara5a5a]

On 2012/12/16 08:09:38, dak wrote:
> Well, the idea was to use this in pairs of contexts with otherwise
> identical harakiri conditions, and give only one of them the
> dead-is-alive flag.  So one context pops up only when the other
> doesn't.

> I had the idea of using this with the Keep_alive_together engraver >
in order to make the conditions identical by force (and that is
> mentioned in the doc strings), but [...]

That works fine.  The input below will show a single staff, except for
the one line containing the voice-crossing section, regardless of where
the line-breaks fall. (We can do this with current LilyPond using two
Staff contexts; the new feature enables the measure that could be
printed either as chords or divided staves, depending on linebreaks.)

The problems with 'dead-is-alive' are the difficulty of keeping track of
the reversed logic, and loss of the usual action of removeEmptyStaves
when all affected staves are truly empty.

\paper {
  #(set-paper-size "a6")
  indent = 1.0\cm
  short-indent = 1.2\cm
}

violinII = \relative c' {
  c4 d e f g f e d
  <c e>-"divisi" <d f> <e g> <f a>
  s1  % this measure is too complex to show on a single staff
  c4-"unison" d e f g f e d
  c d e f c1
  \bar "|."}

letStaffVanish = \set Staff.keepAliveInterfaces = #'()
showStaff = \unset Staff.keepAliveInterfaces

violinIIa = \relative c' {
  \letStaffVanish \quoteDuring "violinII" s1*2
  e4 f g a
  \showStaff b4 g d g
  \letStaffVanish \quoteDuring "violinII" s1*4
}

violinIIb = \relative c' {
  \letStaffVanish \quoteDuring #"violinII" s1*2
  c4 d e f
  \showStaff g4 b d b
  \letStaffVanish \quoteDuring #"violinII" s1*4 }

\addQuote "violinII" \violinII

\new StaffGroup <<
  \new Staff \with {
    instrumentName = "Vn 1"
    shortInstrumentName = "Vn1"
  } \repeat unfold 8 c''1
  \new GrandStaff \with {
    \consists Keep_alive_together_engraver
    instrumentName = "Vn 2"
    shortInstrumentName = "Vn2"
  } <<
    \new Staff \with {
      \override VerticalAxisGroup #'remove-first = ##t
      shortInstrumentName="outer"
    } \new Voice \violinIIa
    \new Staff \with {
      \override VerticalAxisGroup #'dead-is-alive = ##t
      \override VerticalAxisGroup #'remove-first = ##t
      keepAliveInterfaces = #'()
    } \violinII
    \new Staff \with {
      \override VerticalAxisGroup #'remove-first = ##t
      shortInstrumentName="inner"
    } \new Voice \violinIIb >> >>
\layout { \context {
        \Staff \RemoveEmptyStaves }}

https://codereview.appspot.com/6948058/