Re: Letters as note heads

[Aaron Hill]

On 2019-01-08 12:24 am, Gloops wrote:
> Indeed it's what I wanted "ly: pitch-semitones" but there is a mistake 
> at
> the change of octave …
>
> [ . . . ]
>
> %No good
> \relative c' {
>    \override NoteHead.stencil = #(lambda (grob)
>      (let* ((cause (ly:grob-property grob 'cause))
>             (pitch (ly:event-property cause 'pitch))
>             (notenames '("C" "C+" "D" "D+" "E" "F" "F+" "G" "G+" "A" 
> "A+"
> "B"))
>             (notename (list-ref notenames (ly:pitch-semitones pitch))))
>        (grob-interpret-markup grob #{ \markup
>          \halign #0 \vcenter \fontsize #-2 \sans \bold $notename #})))
>    \hide Stem
>    c4 cis d dis e f fis g gis a ais b c
> }

The output from LilyPond exactly explains the issue:

> In procedure list-ref in expression
>   (list-ref notenames (ly:pitch-semitones pitch)):
> Argument 2 out of range: 12

ly:pitch-semitones is returning 12 as opposed to 0.  I'm not sure why 
this is expected behavior, but a simple modulus operation would be good 
enough to patch it:

    (modulo (ly:pitch-semitones pitch) 12)

By the way, you should remove the "\halign #0" as it overly compresses 
the spacing on the left side of a note, resulting in uneven spacing of 
notes within the measure.


-- Aaron Hill