Re: print transposed guitar chords on piano sheets (issue4626094)

[Carl Sorensen]

On 7/7/11 7:30 AM, "address@hidden" <address@hidden> wrote:

>> Mmmm...
>> 
>> Do we have generic procedures for "combine markup" and "stack markup"?
>> If not, there'll be a flurry of frog emails as I try and write them :-)
>> (note to self - ly:stencil-combine-at-edge)
>> 
> 
> line and column
> (see line 1074 and line 1426 of scm/define-markup-commands.scm)
> 
>> Because the chord_name_capo_proc will basically be "if vertical then
>> stack else combine".
>> 
>> Should my scheme function go in the scm directory?
> 
> Yes, likely in define-markup-commands.scm.

I think not in define-markup-commands.scm, since this is not a general
markup command.   I'd recommend scm/chord-name.scm
> 
>> And what would be a good name for it?
> 
> Something descriptive :)

capo-chord-name

> 
>> Do those functions get loaded into lily automatically?
> 
> Yes.
> 
>>> 
>> Moving on slightly, if I'm messing about with scheme for markup, how do
>> I mess around with scheme for engravers. It looks like they're defined
>> inside lilypond code - do they go in the ly directory?
>> 
> 
> Engravers are defined in the lily/ directory (C++), but you can also define
> theme from scheme (see the scheme engraver regtest).  If you're thinking that
> this should become part of LilyPond, I'd write it in C++ for the time being.
> The community's gonna have a discussion about Scheme vs C++ in the not too
> distant future, but at the present moment, no Scheme engravers (that I know
> of) are part of the source.

The problem we have with Scheme engravers is that we have no automatic way
of including them in the documentation.  So at present, C++ is preferred
over Scheme because they become part of the internals.

Probably Scheme engravers should be .ily, and go (at least temporarily) in
the ly/ directory.

Nicolas Sceaux shared a marvelous example of a Scheme engraver on -user:

http://lists.gnu.org/archive/html/lilypond-user/2011-06/msg00581.html

As you create a capo_engraver, realize that you will need to adjust the
parser and/or lexer so that a capo music event is generated for the capo
engraver to listen to.

HTH,

Carl