Re: Parenthesizing chord names

[Robin Bannister]

Tim McNamara wrote:
> Rather than writing a separate ending, I'd like to just parenthesize  
> the last three chords  over the final two bars so they would render:
> F    (    Ab7    Dbmaj7    C7    )


ChordName outputs via text-interface, so the easiest way should be 
 \once \override ChordNames.ChordName #'text = "(" 
 
But this has no effect. It probably acts too early, 
i.e. before the Chord_name_engraver has written its result to #'text. 

Trevor answered a similar question a year ago: 
http://lists.gnu.org/archive/html/lilypond-user/2008-03/msg00275.html 

His solution modified the stencil, letting it overwrite #'text 
just before printing. 
As "addBrackets" it wrapped only a single chord, but you could 
derive a left_only and a right_only version easily enough. 

But if you want the bracket standing alone, how about setting up 
a superfluous chord at the right place, and overwritung that? 

See the snippet below; overwriteCN could also do things like "N.C."


Cheers,
Robin

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\version "2.12.1"

overwriteCN = #(define-music-function (parser location text) (string?)
 #{\once \set ChordNames.chordChanges = ##f
   \once \override ChordNames.ChordName #'stencil = #(lambda (grob)
     (ly:grob-set-property! grob 'text (markup $text))
     (ly:text-interface::print grob)
    )
 #})

harmoniesA = \transpose f f {\chordmode {
 f2:maj7 d2:m7 |
 g2:m7 c2:7.9- |
 f2 aes2:7 |
 des2:maj7 c2:7 |
}}

harmoniesB = \transpose f f {\chordmode {
 f2:maj7 d2:m7 |
 g2:m7 c2:7.9- |
 f4 \overwriteCN "(" f4 aes2:7 |
 des2:maj7 c4:7 \overwriteCN ")" c4:7 |
}}
 
melody = \transpose f f' { \key f \major \time 4/4
 \times 2/3 {a4 g'4 f'4} a4. e'8 |
 d'4 bes8[ d8] a4 a8[ f8] ~ |
 f1 ~ |
 f1 |
}

\score {<< 
 \new ChordNames { \set chordChanges = ##t \harmoniesA }
 \new ChordNames { \set chordChanges = ##t \harmoniesB }
 \new Staff { \melody }
> > } 

\layout { 
 indent = 0 
 ragged-right = ##f
}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%