Analysis brackets with labels

Text markup may be added to analysis brackets using the text property of the HorizontalBracketText grob. Adding different texts to brackets beginning at the same time requires the \tweak command.

Bracket text gets parenthesized after a line break.

\version "2.24"

\layout {
  \context {
    \Voice
    \consists "Horizontal_bracket_engraver"
    \override HorizontalBracket.direction = #UP
  }
}

{
  \once\override HorizontalBracketText.text = "a"
    c''\startGroup d''\stopGroup
    \once\override HorizontalBracketText.text = "a'"
    e''\startGroup d''\stopGroup |
  c''-\tweak HorizontalBracketText.text
        \markup \bold \huge "b" \startGroup
     -\tweak HorizontalBracketText.text "a" \startGroup
    d''\stopGroup
    e''-\tweak HorizontalBracketText.text "a'" \startGroup
    d''\stopGroup\stopGroup |
  c''-\tweak HorizontalBracketText.text foo \startGroup
    d'' e'' f'' | \break
  g'' a'' b'' c'''\stopGroup
}