Re: Using Scheme inside Lilypond

[Richard Shann]

On Sat, 2021-09-04 at 22:21 +0200, Jean Abou Samra wrote:
> Le 04/09/2021 à 20:39, Richard Shann a écrit :
> > (I'm trying to write code that will draw a box round A4 or letter
> > paper
> > with just a change of some scaling factors - I can work around it
> > but
> > it's distressing not to understand what is going on).
> 
> Is this the kind of thing you're looking for?
> 
> \version "2.22.1"
> 
> #(define-markup-command (page-box layout props left-padding top-
> padding 
> right-padding bottom-padding)
>     (number? number? number? number?)
>     #:properties ((thickness 0.1))
>     (let* ((paper-width (ly:output-def-lookup layout 'paper-width))
>            (paper-height (ly:output-def-lookup layout 'paper-height))
>            (left-margin (ly:output-def-lookup layout 'left-margin))
>            (top-margin (ly:output-def-lookup layout 'top-margin))
>            (start-x (- left-padding left-margin))
>            (start-y (- (- top-padding top-margin)))
>            (end-x (- paper-width right-padding left-margin))
>            (end-y (- (- paper-height bottom-padding top-margin))))
>       (ly:stencil-outline
>         (interpret-markup layout props
>           (make-path-markup
>             thickness
>             `((moveto ,start-x ,start-y)
>               (lineto ,start-x ,end-y)
>               (lineto ,end-x ,end-y)
>               (lineto ,end-x ,start-y)
>               (closepath))))
>         empty-stencil)))
> 
> \paper {
>    #(set-paper-size "a5landscape")
> }
> 
> \markup \combine
>    \override #'(thickness . 0.3) \page-box #2 #2 #3 #1
>    \page-box #3 #3 #4 #2

That's very kind of you - I would have slogged away for a day or two to
generate something not even half as general and elegant. I'll slot that
in...

Richard