Re: Centering a stencil on another stencil

[Paul Morris]

> On Jul 27, 2015, at 6:14 PM, Thomas Morley <address@hidden> wrote:
> 
> We've already ly:stencil-aligned-to and centered-stencil, leading to:
> 
> circle = #(make-circle-stencil 3 0.4 #f)
> 
> square =
> #(stencil-with-color
>  (make-connected-path-stencil
>   '((0 0) (3 0) (3 3) (0 3) (0 0))
>   0.4 1 1 #f #f)
>  blue)
> 
> \markup \line {
>  \stencil #(ly:stencil-add circle square)
>  "   "
>  \stencil #(ly:stencil-add circle (ly:stencil-aligned-to square X CENTER))
>  "   "
>  \stencil #(ly:stencil-add circle (ly:stencil-aligned-to square Y CENTER))
>  "   "
>  \stencil #(ly:stencil-add circle (centered-stencil square))
> }
> 
> So I see no advantage in a new LSR-snippet.

Hi Harm,  Just catching up with email after being away myself…

The trouble is that centered-stencil moves the stencil so it is centered on the 
X,Y point 0,0 

from stencil.scm:

(define-public (centered-stencil stencil)
  "Center stencil @var{stencil} in both the X and Y directions."
  (ly:stencil-aligned-to (ly:stencil-aligned-to stencil X CENTER) Y CENTER))

But in my actual use case I need the first stencil to stay at its given 
location, and then center the second stencil on it.  (It is a note head 
stencil, and I believe moving it to 0,0 will mess up the position of the stem, 
etc.)  So that’s the reason for the snippet.  It could be made more explicit in 
comments, description, example, etc.  Let me know what you think.

-Paul