Re: collision of rehearsal marks, y-parent

[Han-Wen Nienhuys]

Werner LEMBERG wrote:
> > > Is it possible to add a collision resolver for rehearsal marks?  The
> > preventing what kind of collisions?
>
> Almost everything:
>
>  note heads and rests (with attached articulation grobs)
>  stems
>  beams
>  octavation lines, trills, tuplets, etc.
>  slurs and ties
>  bar numbers
>  clefs
>
> Dynamics and scripts are probably not necessary because they are below
> the staff line normally.

This is a problem: almost everything is not very specific. I will put it 
on the sponsorable feature list. Is there a general pattern of collision 
resolution that you can spot (ie. always sideways, or always upwards?)

> > > But what is the `Y-parent'?
> > it depends. In case of teh rehearsal mark, I guess it will be the
> > System grob.
>
> You `guess'.  Interesting :-)
>
> Where can I find information about this?  Is it documented somewhere?

No, not really. Parent-child relationships are generally determined by 
contexts, but it can vary. Eg. a fingering instruction typically has a 
notehead both as X and Y-parent, so the fingering always moves along 
with any collision resolution for the head.

 For Y-side positioning it doesn't really matter, since the 
side-positioning will compensate for any movements that the Y-parent 
might make.

If you really want to find out, you can either

a. look at the engravers source code

b. add a small Scheme-callback to the rehearsalmark that prints the 
result of ly:grob-parent ; eg. you could attach it to the 'text property.

--

Han-Wen Nienhuys - address@hidden - http://www.xs4all.nl/~hanwen

LilyPond Software Design
 -- Code for Music Notation
http://www.lilypond-design.com