Re: Changing MulitMeasureRest.stencil to a squiggle

[Marc Hohl]

Am 06.09.2016 um 16:09 schrieb David Nalesnik:
> Hi Marc,
>
> On Tue, Sep 6, 2016 at 7:28 AM, Marc Hohl <address@hidden> wrote:
> > Hi list,
> >
> > I want to change the MultiMeasureRest.stencil to a squiggle as shown in the
> > appendices (quite roughly pasted together in GIMP).
> > Searching the LSR and the web does not give any informations about this
> > topic (the only thing I found was using the percent stencil, which is also
> > hardcoded in the C++ sources).
> >
> > I tried to override the stencil by
> >
> > \override MultiMeasureRest.stencil = #ly:line-spanner::print
> >
> > but this causes errors like
> >
> > "MultiMeasureRest has empty extent and non-empty stencil."
>
> Even if you for this to work, your mockup shows a line more complex
> than a squiggle.

Yes, of course, but that would have been a starting point ... ;-)

> You'd only be able to get a simple zigzag line,
> without the refinement at the ends, and without control of the
> "amplitude" (as if my simple example below).
>
> > Any ideas?
>
> The easiest way to get what you want is to create a stencil callback
> which uses the default stencil for dimensions of a replacement
> stencil.  The code below is a simple demonstration, which draws lines
> like you would get with ly:line-spanner::print.
> (Note that you need at least 2.19.27 for this to work.)
>
>
> \version "2.19.46"
>
> #(define my-stencil
>    (lambda (grob)
>      (let* ((default-stil (ly:multi-measure-rest::print grob))
>             (X-ext (ly:stencil-extent default-stil X)))
>        (ly:line-interface::line grob (car X-ext) 0 (cdr X-ext) 0))))

Ah, that's the way to do it: getting the x-ext from the original stencil!
And I wasn't aware that ly:line-interface::line exists, so your answer 
is pretty useful for future solutions.

Thanks,

Marc