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

[Pavel Roskin]

Quoting Joe Neeman <address@hidden>:

> On Fri, Feb 24, 2012 at 3:04 PM, Pavel Roskin <address@hidden> wrote:
> > I tried writing an engraver that could be added to the StaffGroup
> > context.  Collecting stems is not a problem.  The problem is that even
> > the finalize handler is called to early.  I'm getting a warning:
> >
> > programming error: vertical alignment called before line breaking
> > continuing, cross fingers
>
> It's a little hard to guess what's going wrong without knowing exactly what
> you've tried. Are you trying to do layout logic in the engraver (ie. by
> collecting stems, reading their properties, doing calculations and then
> setting more properties)?

Yes, except that I'm not setting anything yet.  The current file is attached.

> If you are, the first step is to move the layout
> logic into grob callbacks.

I guess I'll need to redefine the stencil for stems.  Or maybe you  
mean some other callback?

I did a similar thing before.  I put all the logic into a function  
that was used to redefine the length property of the stem.  It worked  
for a simple case of two stems, but failed when three stems needed to  
be connected.  The Y-extent for at least one of the stems wasn't  
calculated yet.

I also tried setting Y-extent, but it's read-only.

--
Regards,
Pavel Roskin

stemengraver.ly
Description: Text Data