Den tir. 10. sep. 2019 kl. 14.54 skrev George Neuner <gneun...@comcast.net>:
>
> Or create a region with a hole through it and use it to clip the drawing.
>
Great suggestion. That's much better than using pict->bitmap.
I have extended "clipped" to handle regions defined by more than one path.
Now (clipped c ... p) will make a region from the curves c ... and use
the region to clip the pict p. Most common uses:
(clipped c p) the part of p inside c
(clipped c1 c2 p) the part of p between c1 and c2 (if c2 is inside c1)
The example now becomes:
#lang racket
(require metapict metapict/polygons)
(define (cutout p x y r)
(defv (w h) (pict-size p))
(with-window (window 0 w 0 h)
(clipped (rectangle (pt 0 0) (pt w h))
(circle (pt x y) r)
p)))
(set-curve-pict-size 400 400)
(def p (brushcolor "red" (fill (regular-polygon 5))))
(cutout p 200 200 50)
Before only one curve was supported and the result of clipped was the
interior,
so the old clipped couldn't cut holes.
/Jens Axel
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