Re: Cross-staff stem engraver (was: New frog in an empty pond?)

[Pavel Roskin]

Quoting Joe Neeman <address@hidden>:

> > I'm getting a message "Weird stem", and I don't see how to avoid it.
> > Perhaps I should create a totally new grob with a unique name, such as
> > StemSpan.  Is that possible?  What would be needed?
>
> It would be nice to do this eventually, because having a different grob
> name would make it easier for the users to tweak it. I think it would
> involve editing scm/define-grobs.scm, but there may be a way to do it from
> an .ly file also

It turn out the message comes from ly:stem::offset-callback and can be  
suppressed by redefining X-offset.

> Don't use ly:axis-group-interface::add-element, because stems don't
> implement the axis-group-interface. (Removing this will also remove the
> axes warning.) Instead, use ly:grob-set-parent!. You'll probably want to
> set both the X parent and the Y parent. Then the X and Y offsets of
> new-stem will be measured relative to stem (instead of relative to the
> whole system, which is the default).

That was it!  I have a working solution now!  It will need to be  
improved to ignore rests and other invisible stems, check the  
cross-staff property, avoid connecting incompatible stems and so on.   
The old stems should be made transparent.  But all that should be  
simple.  Once I have something easy to use, I plan to submit it to the  
LSR.

Actually, it looks like System is a better Y-parent for the new stem.   
Perhaps I'll try to use the common reference of the stems to be  
connected.

Here's what I have now (attached).

Thank you for your help!

--
Regards,
Pavel Roskin

stemspan.ly
Description: Text Data