Re: Detect slurred notes in callback function

[Thomas Morley]

2016-02-07 14:30 GMT+01:00 Jakub Pavlík <address@hidden>:
> Hi,
>
> is it possible to detect slurred notes in a callback function? I would like
> to use a callback function to modify properties of all slurred notes.
>
> Below is my unsuccessful attempt.
> The callback function receives NoteHead grob as argument. The grob itself
> doesn't seem to contain information about slur attached, so I get it's
> event-cause. I know that slurs are stored in the NoteEvent's "articulations"
> property, but this property either isn't accessible this way (the object
> returned by event-cause doesn't seem to be a regular NoteEvent; what is it
> actually?), or I fail to find the correct way to access it.
>
> ---
>
> #(define (in-slur? notehead)
>    (begin
>     (display "grob")
>     (newline)
>     (display-scheme-music notehead)
>     (display "NoteEvent?")
>     (newline)
>     (display-scheme-music (event-cause notehead))
>     (display "try to dig slur")
>     (newline)
>     (display-scheme-music (ly:event-property (event-cause notehead)
> 'articulations))
>     #f))
>
> \score {
>   \relative c'' {
>     \override NoteHead #'color = #(lambda (grob)
>       (if (in-slur? grob)
>           red
>           blue))
>
>     a a
>     a( a)
>     a( a a)
>   }
> }
>
> ---
>
> Thanks for any help,
> Jakub



Hi Jakub,

if you look at the terminal output of
\displayMusic { a( a a) }
then you'll notice that the middle note has no info whether it is
under a slur or not.

Only chance I see, is to get start and stop of the slur, and knowing
this, get the NoteHeads between.

Nevertheless, below a draft of improving your initial code, you'll see
the midle note isn't catched.


#(define (in-slur? notehead)
   (let ((tst
           (if (null?
                 (map
                   (lambda (m)
                     (music-is-of-type? m 'slur-event))
                   (ly:music-property
                     (ly:prob-property
                       (event-cause notehead)
                       'music-cause)
                     'articulations)))
                #f
                #t)))
    (newline)
    (display-scheme-music tst)

    tst))

\score {
  \relative c'' {
    \override NoteHead #'color = #(lambda (grob)
      (if (in-slur? grob)
          red
          blue))

    %\displayMusic
    { a( a a) }
  }
}


HTH a bit,
  Harm