Created
August 8, 2013 18:09
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Match expanders and color% objects
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#lang racket | |
(require racket/draw (for-syntax syntax/parse) pict unstable/gui/pict) | |
(define-syntax defv (make-rename-transformer #'define-values)) | |
(define-syntax defm (make-rename-transformer #'match-define)) | |
(define-syntax def (make-rename-transformer #'define)) | |
(define-match-expander color: | |
(λ (stx) | |
(syntax-parse stx | |
[(_ r g b a) | |
#'(or (and (? string?) | |
(app (λ(s) (def c (send the-color-database find-color s)) | |
(list (send c red) (send c green) (send c blue) (send c alpha))) | |
(list r g b a))) | |
(and (? object?) | |
(app (λ(c) (list (send c red) (send c green) (send c blue) (send c alpha))) | |
(list r g b a))))]))) | |
(define (color-make r g b α) | |
(def (f x) (min 255 (max 0 (exact-floor x)))) | |
(make-object color% (f r) (f g) (f b) (max 0.0 (min 1.0 α)))) | |
(define (color+ color1 color2) | |
(defm (color: r1 g1 b1 α1) color1) | |
(defm (color: r2 g2 b2 α2) color2) | |
(def (add s t) (min 255 (+ s t))) | |
(color-make (add r1 r2) (add g1 g2) (add b1 b2) α1)) | |
(define (color-tuple c) | |
(defm (color: r g b α) c) | |
(list r g b α)) | |
(define (color* k c) | |
(defm (color: r g b α) c) | |
(color-make (* k r) (* k g) (* k g) α)) | |
(define (color-med t c1 c2) | |
; mediate (interpolate) between colors 0<=t<=1 | |
(color+ (color* t c1) (color* (- 1 t) c2))) | |
(define (change-red c r) (defm (color: _ g b α) c) (color-make r g b α)) | |
(define (change-green c g) (defm (color: r _ b α) c) (color-make r g b α)) | |
(define (change-blue c b) (defm (color: r g _ α) c) (color-make r g b α)) | |
(define (change-alpha c α) (defm (color: r g b _) c) (color-make r g b α)) | |
(for/list ([i (in-range 0 1.1 .1)]) | |
(color (color-med i "red" "blue") (disk 40))) |
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