Initial data commit

Task/Bitmap-Bresenhams-line-algorithm/Racket/bitmap-bresenhams-line-algorithm.rkt

@@ -0,0 +1,33 @@
+#lang racket
+(require racket/draw)
+
+(define (draw-line dc x0 y0 x1 y1)
+  (define dx (abs (- x1 x0)))
+  (define dy (abs (- y1 y0)))
+  (define sx (if (> x0 x1) -1 1))
+  (define sy (if (> y0 y1) -1 1))
+  (cond
+    [(> dx dy)
+     (let loop ([x x0] [y y0] [err (/ dx 2.0)])
+       (unless (= x x1)
+         (send dc draw-point x y)
+         (define newerr (- err dy))
+         (if (< newerr 0)
+             (loop (+ x sx) (+ y sy) (+ newerr dx))
+             (loop (+ x sx)    y        newerr))))]
+    [else
+     (let loop ([x x0] [y y0] [err (/ dy 2.0)])
+       (unless (= y y1)
+         (send dc draw-point x y)
+         (define newerr (- err dy))
+         (if (< newerr 0)
+             (loop (+ x sx) (+ y sy)    newerr)
+             (loop    x     (+ y sy) (+ newerr dy)))))]))
+
+(define bm (make-object bitmap% 17 17))
+(define dc (new bitmap-dc% [bitmap bm]))
+(send dc set-smoothing 'unsmoothed)
+(send dc set-pen "red" 1 'solid)
+(for ([points '((1 8 8 16) (8 16 16 8) (16 8 8 1) (8 1 1 8))])
+  (apply draw-line  (cons dc points)))
+bm