Re: Issue 3918: Add \alternatingTimeSignatures (issue 97110045)

[David Kastrup]

Paul Morris <address@hidden> writes:

> David Kastrup wrote
>> You mean with regard to patches?  Let's first figure out what we want to
>> arrive at.  Personally, I'm not really enthused about any proposal
>> including my own ones yet.  But maybe we can manage to find something
>> making most people happier yet.
>
> I like the idea of something like \appearance and working out a general
> solution. Some suggestions for a verb name: \replace, \redraw  (I like how
> redraw emphasizes the visual aspect.)
>
> As a first step (just working with \override X.X.stencil =) could there be
> an easier way to just override a stencil with a markup (that gets converted
> into a stencil)?

That would end up a very invasive mess.  A stencil is really a stencil
and referenced as such.  Stencils intended to be replaceable with
markups tend to have ly:text-interface::print as their function which
then references the markup in the "text" property.

> \override Score.TimeSignature.stencil = 
>   \markup \fraction-list "-" #'((6 8)(5 4))
>
> Maybe LilyPond could automatically convert a markup into a stencil for you
> in this case?  (Maybe that's a bad idea since it would obscure the
> difference between markups and stencils?)  Or if you could manually convert
> the markup to a stencil with something like:
>
> \override Score.TimeSignature.stencil = 
>   \markupToStencil \markup \fraction-list "-" #'((6 8)(5 4))

Markups cannot be converted to stencils without knowledge of the
respective layout/properties.  They can be derived from a grob, but
something like \markupToStencil does not have an inherent relation to a
grob: if \markupToStencil were to return a grob callback (like you can
use in a stencil override), it would magically fail to work as a stencil
anywhere but in a stencil override.  So it makes more sense to devise a
command that _includes_ the stencil override (or tweak) since it will
not work as a stencil anywhere else.

-- 
David Kastrup