Re: Centering a stencil on another stencil

[Thomas Morley]

2015-08-12 0:22 GMT+02:00 Thomas Morley <address@hidden>:
> Hi Paul,
>
> 2015-08-11 17:36 GMT+02:00 Paul Morris <address@hidden>:
>
>>
>> Nice!  Much simpler.  I’ve updated the LSR snippet with your simpler code.  
>> I also changed it so that the circle is moved so it is centered on the 
>> square, which helps show the need for the function (as opposed to 
>> centered-stencil).
>>
>> http://lsr.di.unimi.it/LSR/Item?id=1009
>>
>> Let me know if there are any further revisions to make.
>
> I'm still not happy with the example, because the second stencil, the
> circle, is centered already.
> Below, you could replace the line between the ;;;; with 'stil-b' and
> would still get the same output.
>
> #(define (center-stencil-on-stencil axis stil-a stil-b)
>   "Return a copy of stencil @var{stil-b} that has been
>    moved so it is centered on stencil @var{stil-a} on
>    @var{axis}. @var{axis} is 0 for X axis, 1 for Y axis."
>    (ly:stencil-translate-axis
> ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
>      (ly:stencil-aligned-to stil-b axis CENTER)
> ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
>      (interval-center (ly:stencil-extent stil-a axis))
>      axis))
>
> The advantage of this coding is that it will work, whether the stencil
> is centered or not!!
> Therefore I'd extent the example:
>
> square =
> #(make-connected-path-stencil
>   '((0 0) (4 0) (4 4) (0 4) (0 0))
>   0.4 1 1 #f #f)
>
> green-square =
> #(stencil-with-color (make-filled-box-stencil '(0 . 2) '(0 . 2)) green)
>
> circle =
> #(stencil-with-color (make-circle-stencil 1 0.3 #f) green)
>
> \markup \line {
>  \stencil #(ly:stencil-add square circle)
>  "   "
>  \stencil #(ly:stencil-add square (center-stencil-on-stencil X square circle))
>  "   "
>  \stencil #(ly:stencil-add square (center-stencil-on-stencil Y square circle))
>  "   "
>  \stencil #(ly:stencil-add
>              square
>              (center-stencil-on-stencil Y square
>                (center-stencil-on-stencil X square circle)))
> }
>
> \markup \line {
>  \stencil #(ly:stencil-add square green-square)
>  "   "
>  \stencil #(ly:stencil-add square (center-stencil-on-stencil X square
> green-square))
>  "   "
>  \stencil #(ly:stencil-add square (center-stencil-on-stencil Y square
> green-square))
>  "   "
>  \stencil #(ly:stencil-add
>              square
>              (center-stencil-on-stencil Y square
>                (center-stencil-on-stencil X square green-square)))
> }
>
>
> As a thought I extended the coding to get the possibility of a
> centered stencil in both directions in one go:
>
>
> #(define (center-stencil-on-stencil axis stil-a stil-b)
>   "Return a copy of stencil @var{stil-b} that has been
>    moved so it is centered on stencil @var{stil-a} on
>    @var{axis}. @var{axis} is 0 for X axis, 1 for Y axis.
>    @var{axis} may be set @code{#t}, moving the new stencil:

read: in both directions

>    in directions"
>    (if (and (boolean? axis) axis)
>        (ly:stencil-translate
>          (centered-stencil stil-b)
>          (cons
>            (interval-center (ly:stencil-extent stil-a X))
>            (interval-center (ly:stencil-extent stil-a Y))))
>        (ly:stencil-translate-axis
>          (ly:stencil-aligned-to stil-b axis CENTER)
>          (interval-center (ly:stencil-extent stil-a axis))
>          axis)))
>
> test =
> #(define-scheme-function (parser location stil-1 stil-2)
>   (ly:stencil? ly:stencil?)
>   #{
>     \markup
>       \override #'(word-space . 3)
>       \line {
>       \stencil #(ly:stencil-add stil-1 stil-2)
>       \stencil #(ly:stencil-add stil-1
>                                 (center-stencil-on-stencil X stil-1 stil-2))
>       \stencil #(ly:stencil-add stil-1
>                                 (center-stencil-on-stencil Y stil-1 stil-2))
>       \stencil #(ly:stencil-add stil-1
>                                 (center-stencil-on-stencil #t stil-1 stil-2))
>     }
>   #})
>
> square =
> #(make-connected-path-stencil
>   '((0 0) (4 0) (4 4) (0 4) (0 0))
>   0.4 1 1 #f #f)
>
> green-square =
> #(stencil-with-color (make-filled-box-stencil '(0 . 2) '(0 . 2)) green)
>
> circle =
> #(stencil-with-color (make-circle-stencil 1 0.3 #f) green)
>
> \test #square #circle
> \test #square #green-square
>
>
> Though, it's probably overdone.
> What do you think?
>
>
> Cheers,
>   Harm