Re: Markup command \beam

[Jean Abou Samra]

Le 16/08/2022 à 13:09, Andrew Bernard a écrit :
> How is \beam intended to be used in markup? Can it replace the beaming 
> of notes? I would not imagine - so I am unsure what this command is for.


It seems to me that \beam kind of misnamed due to a quirk of history.
In old times, it was the way to create a stencil with the kind 'beam.
LilyPond represents the internals of a stencil as a Scheme list whose
car is the stencil expression "kind" and whose cdr holds the parameters.
To understand better, try

\version "2.22.2"

{
  \once \override TextScript.after-line-breaking =
    #(lambda (grob)
       (pretty-print (ly:stencil-expr (ly:grob-property grob 'stencil))))
  c'^\markup { a b c \with-color "red" \italic d \draw-circle #5 #0.1 ##t }
}


Historically, there was a 'beam stencil expression kind. \beam was a
way to construct an expression of this kind. I did not check the details
of history, but this has been eliminated in favor of 'polygon which
is more general.

So \beam now is just a handy command that draws the shape of a beam,
which you can use for whatever has this shape even if it's not a beam.
For example, LilyPond uses it for the default slashSeparator:


slashSeparator = \markup {
  \center-align
  \vcenter \combine
  \beam #2.0 #0.5 #0.48
  \raise #0.7 \beam #2.0 #0.5 #0.48
}


Best,
Jean