Lilypond finger placement brackets

Question

In music sheets intended for beginner harpists it's very common that the fingering includes not only the numbers but also brackets that indicate which fingers are positioned at the same time, replacements, etc. Here is one example:

I'd like to know what would be the best way to achieve a similar effect in Lilypond.

Ref. for image: http://elizabethlouiseharpist.com/harp-fingerings-brackets-marking-harp-music/

Answer 1

\version "2.19.52"
variable = {
 \once \override TextSpanner.style = #'line
 \once \override TextSpanner.to-barline = ##f
 \once \override TextSpanner.bound-details =
  #`(
   (left
    (text . ,#{ \markup { \draw-line #'( 0 . -.5) } #})
    (Y . 0)
    (padding . 0.25)
    (attach-dir . -3)
   )
   (right
    (text . ,#{ \markup { \draw-line #'( 0 . -.5) } #})
    (Y . 0)
    (padding . 0.25)
    (attach-dir . 3)
    )
   )
}

\relative c' {
 \key c \major
 \time 3/4
 \partial 4
 \override Fingering.staff-padding = #'()
 \variable
 \once \override TextSpanner.rotation = #'(4 1.9 0)
 a'8_3\startTextSpan b_2 \variable \once \override TextSpanner.rotation = #'(-4.5 -4.5 0)
 c4-1\stopTextSpan\startTextSpan b-2 a_3 \variable \once \override TextSpanner.rotation = #'(3 -0.2 0)
 g_4\stopTextSpan\startTextSpan a_3 b-2 \variable \once \override TextSpanner.rotation = #'(-7 -2.5 0)
 c-1\stopTextSpan\startTextSpan g_2 f_3
 e2_4\stopTextSpan
}

It's a bit hacky, but it gets the job done.

As always, manual fiddling required to get it the way you want to look. ;)

Answer 2

One possibility is to include LilyPond's fingering capabilities (-4, for instance, after a pitch) and the analysis bracket capability found at the LilyPond Snippet Repository.

\version "2.19.47"

\layout {
  \context {
    \Voice
    \consists "Horizontal_bracket_engraver"
  }
}
\relative c'' {
  c4-1\startGroup b4-2 a4-3 g4-4\stopGroup |
}