On Tue, Feb 28, 2012 at 2:56 PM, Pavel Roskin
<address@hidden> wrote:
Hello, Joe!
> In case it wasn't clear from what I said before, engravers in lilypond
> don't do the actual layout. Instead, they build the grobs and set up
> the connections between them. Most of the layout is done in callback
> functions.
Yes, I realize it now. Your suggestion to create a new stem worked
fine. I can get the relative coordinates of themes on different staves.
The attached file shows where I am now. There are many minor issues,
and I hope I can solve most of them, but I'll certainly appreciate help.
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
How do I make the new stem start at the same point as the original
one. I tried this:
(set! (ly:grob-property stem 'axes) (list X))
I don't understand how it works. Not setting axes leads to:
programming error: axes should be nonempty
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).
Cheers,
Joe