Re: Help with custom noteheads

[Jean Abou Samra]

Le 11/08/2022 à 14:32, Valentin Petzel a écrit :
> Hello Andrew,
>
> is there any reason for using a custom circle approximation instead of simply
> using (make-circle-stencil r th #f)?
>
> The reason why your note heads are off is that a path stencil does not have an
> extent. A path cotains arbitrary drawing commands, which means that Lilypond
> does not really know how large the result would be. As such your Note Heads
> are handled as points, but then draw outside of this, which means that
> Lilypond cannot handle spacing properly.
>
> What you need to do is to give the stencil an actual extent by using
> ly:stencil-outline, as done here:
>
> \version "2.23.11"
>
> circa =
> #(let* ((k 0.5522)
>          (r 1)
>          (th 0.1)
>          (th2 (/ th 2))
>          (rth (+ r th2)))
>     (ly:stencil-outline
>         (ly:make-stencil `(path ,th
>                           (moveto ,r 0
>                           curveto ,r ,k ,k ,r 0 ,r
>                           curveto ,(- k) ,r ,(- r) ,k ,(- r) 0
>                           curveto ,(- r) ,(- k) ,(- k) ,(- r) 0 ,(- r)
>                           curveto ,k -1 1 ,(- k) 1 0
>                           ))
>                           (cons 1 1) (cons 1 1))
>         (make-filled-box-stencil (cons (- rth) rth) (cons (- rth) rth))))



You could also just replace the two (cons 1 1), which specify
the X and Y extents, with (cons (- rth) rth).

Better yet: use make-path-stencil, which computes the extents
automatically. (It used to do it wrongly in some cases, but I
fixed that in 2.23.11.)

Better yet: use make-circle-stencil, which draws a true circle
with the right extents, as you already said, and as demonstrated in
the message I sent at exactly the same time.

Cheers,
Jean