Re: [frogs] Changing subproperties with grob-set-property (working on bug #40)

[Marc Hohl <marc@xxxxxxxxxx>]

Neil Puttock schrieb:
> 2009/11/19 Marc Hohl <marc@xxxxxxxxxx>:
>
>   
> > How can I get access to the fingering grob? I need its x-extent and the
> > orientation, but strangely, I cannot use the same mechanism as for
> > accidentals;
> > here (ly:grob-object right-bound 'accidental-grob) works, but it seems that
> > there
> > is no (ly:grob-object right-bound 'fingering).
> >     
>
> Why is that strange?  Accidentals are a completely different kettle of
> fish to fingerings: they influence all sorts of typesetting decisions,
> so it's important for a NoteHead to cache them.
>
> Fingerings are just boring scripts placed near a notehead.  :)
>   
From the musical point of view, yes; from a more practical/technical
point of view however, accidentals are some signs sticked on a note head,
and so are fingerings...
>   
> > In scm/translation-functions.scm are some routines concerning fingerings, so
> > I found out how to check whether there is a fingering or not, but I still
> > cannot
> > access its grob (I fear this is just an easy function call someplace, but I
> > just don't see
> > it now, and this will show my lack of deeper scheme knowledge as well :-( )
> >     
>
> There's no easy way, I'm afraid.
>
> Since you can't access children from a grob unless they're explicitly
> added as a grob-array, I think the only method would be to use
> 'all-elements from the System grob, filtering out all the
> undesirables.  This would be very expensive computationally.
>
>   
Is it then possible to create a fingering grob with the
gained informations on the fly, get its dimensions, and
kill it thereafter?

Or can I get the information about the used font and can extract the width
of a digit somehow?

> >              (let* ((accidental-width (cdr (ly:grob-extent accidental
> > accidental X)))
> >     
>
> Careful here: the car isn't always zero (see for example the extent of
> a flat), though in practice, the spacing difference probably isn't
> that noticeable.
>
>   
Ah, thanks for pointing that out!

Marc
> Regards,
> Neil
>
>   


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