Re: Creating a stencil from a markup

[Thomas Morley]

2016-12-14 21:59 GMT+01:00 David Nalesnik <address@hidden>:
> On Wed, Dec 14, 2016 at 2:57 PM, David Nalesnik
> <address@hidden> wrote:
>> Hi Simon,
>>
>> On Wed, Dec 14, 2016 at 2:20 PM, Simon Albrecht <address@hidden> wrote:
>>> Hello everybody,
>>>
>>> I’d like to add a caesura sign on top of a barline by modifying the
>>> barline’s stencil. Here’s my attempt:
>>>
>>> %%%%%%%%%%%%%%%%%%
>>> \version "2.19.49"
>>>
>>> {
>>>   1
>>>   \once\override BarLine.stencil =
>>>   #(ly:stencil-combine-at-edge
>>>      ly:bar-line::print
>>>      1 ; y-axis
>>>      1 ; on top
>>>      (interpret-markup layout props (make-musicglyph-markup
>>> "scripts.caesura.curved"))
>>>      2) %padding
>>>   1
>>> }
>>> %%%%%%%%%%%%%%%%%%
>>>
>>> However, layout is an unbound variable here (and so is props, I assume). How
>>> to do it correctly?
>>>
>>
>> Try:
>>
>> {
>>   1
>>   \once\override Staff.BarLine.stencil =
>>   #(lambda (grob)
>>      (let ((layout (ly:grob-layout grob)))
>>        (ly:stencil-combine-at-edge
>>         (ly:bar-line::print grob)
>>         1 ; y-axis
>>         1 ; on top
>>         (interpret-markup
>>          layout
>>          (ly:grob-alist-chain grob (ly:output-def-lookup layout
>> 'text-font-defaults))
>>          (make-musicglyph-markup "scripts.caesura.curved"))
>>         2))) %padding
>>   1
>> }
>>
>> Best,
>> David
>
>
> For documentation, look at ly:text-interface::interpret-markup here:
> http://lilypond.org/doc/v2.18/Documentation/internals/scheme-functions


You could also use 'grob-interpret-markup' from output-lib.scm.
Usually I's recommend to use ly:stencil-aligned-to as well, to get a
center-aligned stencil. But the font-metrics for
"scripts.caesura.curved" are not symmetric.

Anyway here the code using both (\box only for checking)

\once\override Staff.BarLine.stencil =
  #(lambda (grob)
     (ly:stencil-combine-at-edge
       (ly:bar-line::print grob)
       1 ; y-axis
       1 ; on top
       (ly:stencil-aligned-to
         (grob-interpret-markup
           grob
           #{ \markup \box \musicglyph #"scripts.caesura.curved" #})
         X
         CENTER)
       2))

Cheers.
  Harm