Re: Do not display chord name after line break

[Ernie Braganza]

I am not sure where to place this new engraver code so I can use it. I tried researching this in the manual, but was still unclear. Where should it appear? Again, thanks for your help 

On Mon, Jul 13, 2020 at 8:15 PM Thomas Morley <thomasmorley65@gmail.com> wrote:

Am Mo., 13. Juli 2020 um 19:40 Uhr schrieb Carl Sorensen
<carl.d.sorensen@gmail.com>:
>
> Hi Ernie,
>
> On Mon, Jul 13, 2020 at 7:03 AM Ernie Braganza <ernie.braganza@gmail.com> wrote:
>>
>> Hello,
>>
>> How can I stop the repeated chord name after the line break?
>> I thought the break-visibility settings for ChordName would work, for example setting the beginning-of-line-invisible value to false:
>>  \override Score.ChordName.break-visibility = ##(#t #t #f)
>> but that does not have any effect at all.
>
>
> The reason this does not have any effect is that the code executed when chordChanges is set to ##t changes the break-visiblity of the specific chord name (sets it to beginning-of-line-visible).  And that code is in C++, not Scheme, so I don't know how to override it.
>
> I guess one could write a Scheme engraver for ChordName to replace the built-in one.
>
> You should also raise an issue on the issues list asking for an enhancement.  The enhancement would need to add some additional property (or change the existing property from a simple boolean), because we'd need to separately control hiding of repeated chord names only when not at the beginning of the line, and always hiding repeated chord names.
>
> I actually think the best way to do it would be to change the chordChanges property from a boolean to a break-visibility.  I can see that being quite easy to do.
>
> In the meantime, as a workaround, you might just wish to fill up your chordmode with a bunch of s chords, and only put the chords in where you want them displayed:
>
> \version "2.20.0"
> harmonies = \chordmode {
>   d2  c
>  \break
>   % I don't want the repeated c chord name to display after the line break
>   s d
> }
> \new ChordNames {
>   \harmonies
> }
>
> HTH,
>
> Carl
>

Here an engraver which transforms the default stencil to an empty
stencil under certain conditions (it's not a rewrite of
Chord_name_engraver)

\new ChordNames
  \with {
    chordChanges = ##t
      \consists
      #(lambda (ctx)
        (let* ((chord #f)
               (last-chord #f))

       (define (at-line-beginning? grob)
         (let* ((col (ly:item-get-column grob))
                (ln (ly:grob-object col 'left-neighbor))
                (col-to-check (if (ly:grob? ln) ln col)))
           (and (eq? #t (ly:grob-property col-to-check 'non-musical))
                (= 1 (ly:item-break-dir col-to-check)))))

         (make-engraver
          (acknowledgers
           ((chord-name-interface this-engraver grob source-engraver)

             (if chord
                 (begin
                   (set! last-chord chord)
                   (set! chord #f)))

             (set! chord (ly:grob-property grob 'text))

             ;; If two subsequent chords are equal and chordChanges is enabled,
             ;; set 'after-line-breaking to a procedure which sets the stencil
             ;; to an empty-stencil if the new chord is at line-start.
             (if (and (equal? chord last-chord)
                      (ly:context-property ctx 'chordChanges #f))
                 (ly:grob-set-property! grob 'after-line-breaking
                   (lambda (grob)
                     (if (at-line-beginning? grob)
                         (ly:grob-set-property! grob 'stencil empty-stencil))
                     ;; keep default
                     (ly:chord-name::after-line-breaking grob))))))
          ((finalize this-engraver)
            ;; house keeping
            (set! chord #f)
            (set! last-chord #f)))))
  }
  \chordmode { d2 c~ \break c d }

HTH,
  Harm