Re: How to check if script belongs to first note

[Jean Abou Samra]

Le 30/10/2022 à 20:55, Martín Rincón Botero a écrit :
>       Hi all,
>
>    
> I hope this can be answered with pseudo- C++ code. I've been working on something but I'm stuck with this. Say I have a list of scripts produced by extract_grob_set. They all make part of a spanner. How can I generally check if a certain script is attached to the first note of the spanner? I tried getting the x parent of the script (which I imagine is a note),



Depends on what kind of script we are talking about. It
could also be a FingeringColumn, for example.

\version "2.23.80"

{
  \override Fingering.after-line-breaking =
    #(lambda (grob)
       (ly:message "~s" (ly:grob-parent grob X)))
  \set fingeringOrientations = #'(left left)
  <c'-1 c''-5>
}




> getting the column of this x parent (with get_column ()),


There is no need to get the X parent for that. Just do
script->get_column (), not script->get_x_parent ()->get_column ().
get_column () works on any Item (vs. Spanner).



> and then comparing that column with the first note-column of the spanner 
> without success. Can someone point me in the right direction?



My guess from your message is that you did not realize there are
two kinds of "columns" involved, paper columns and note columns,
which are entirely different things. Note columns are created
per-voice, a note column is either a group of notes that should
share a stem, or a container for a rest (in LilyPond, rests also
have stems, so most note columns have a stem, although those in
GregorianTranscriptionVoice don't as you have found out in
!1677). Then you have musical paper columns, which are the parents
of note columns and more generally of all musical items happening
at one given moment, while non-musical paper columns group
non-musical items happening at a moment. Cf.
https://lilypond.org/doc/v2.23/Documentation/notation/overview-of-object_002dspecific-horizontal-spacing-tweaks.html

get_column () finds the *paper* column that an item is a child of.

So if you want to check that a script happens at the same
moment as a given note column, you can do

script->get_column () == note_column->get_column ()

But be aware that the script could come from another voice than
the one where your NoteColumn was created, so even if that
condition is true, it might not belong to your NoteColumn.
Depending on the context, maybe that case is not possible,
or maybe the condition above is what you actually want,
or maybe you want to find something more specific that
utilizes your knowledge of what the script is more precisely
in order to retain only scripts that actually belong
to the note column.

-Jean