Re: [frogs] After capo handler comes capo key

[Carl Sorensen <c_sorensen@xxxxxxx>]

On 7/31/11 3:32 PM, "Wols Lists" <antlists@xxxxxxxxxxxxxxx> wrote:

> This is mostly saying "where do I start", so hints and clues are fine
> ... but what I want to do is have syntax along the lines of
> 
> \key C \major
> \capokey A
> 
> ie capokey comes after key (and relies on being able to find out that
> information).
> 
> The problem I've got is that I guess I don't want to do a markup if I
> can avoid it (I want this to print the relevant text, and it goes above
> all the clef/timesig/keysig clutter at the start of the piece).
> 
> And I want it to calculate and set capopitch at the same time, but
> that's probably trivial compared to getting it to print the text.
> 
> So basically, it's do I need to return the text as a markup? If not,
> what? If yes, what do I attach it to, and how?

There are two fundamentally different ways to approach this.

The first is to return the text as a markup.  You could attach it to nothing
if it were a top-level markup.  But I don't know if that's feasible or not.
If you want to do it this way, you would probably define \capoKey as a music
function.

The second is to create a capo_engraver that will create a Capo grob.

I think the second is the best way to do it, but it will be more complex.

If I were doing it, I'd probably start with the music function.

> 
> I'm guessing it's best written in scheme, so also there's which
> directory (and what file) should I put the code in, and how do I get
> lilypond to autoload it?

Probably written in scheme, but in a .ly file, using define-music-function.
Most likely ly/music-functions-init.ly.

Any helper functions that are pure scheme would probably be in
scm/chord-names.scm.   They're already autoloaded.

scm/lily.scm handles the autoloading of the .scm files.  See line 400.

HTH,

Carl


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