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fix alpha-channel result of draw-bitmap to monochrome bitmap

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This commit is contained in:
Matthew Flatt 2010-12-16 19:17:36 -07:00
parent 2cb52ed8ef
commit 2ce5c63ea8
1 changed files with 10 additions and 11 deletions
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15
collects/racket/draw/private/dc.rkt
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@ -1473,11 +1473,10 @@
(cond (cond
[(and (collapse-bitmap-b&w?) [(and (collapse-bitmap-b&w?)
(or (send src is-color?) (or (send src is-color?)
(and mask mask))
(send mask is-color?))))
;; Need to ensure that the result is still B&W ;; Need to ensure that the result is still B&W
(let* ([tmp-bm (bitmap-to-b&w-bitmap src src-x src-y src-w src-h style color mask)]) (let* ([tmp-bm (bitmap-to-b&w-bitmap src src-x src-y src-w src-h style color mask)])
(do-draw-bitmap-section tmp-bm dest-x dest-y 0 0 src-w src-h 0 0 'solid #f #t #f clip-mask))] (do-draw-bitmap-section tmp-bm dest-x dest-y 0 0 src-w src-h 0 0 'solid #f #t tmp-bm clip-mask))]
[(and mask [(and mask
(or (and (not black?) (not (send src is-color?))) (or (and (not black?) (not (send src is-color?)))
(alpha . < . 1.0))) (alpha . < . 1.0)))
@ -1584,14 +1583,14 @@
(let ([bstr (make-bytes (* bm-w bm-h 4))]) (let ([bstr (make-bytes (* bm-w bm-h 4))])
(send tmp-bm get-argb-pixels 0 0 bm-w bm-h bstr) (send tmp-bm get-argb-pixels 0 0 bm-w bm-h bstr)
(for ([i (in-range 0 (bytes-length bstr) 4)]) (for ([i (in-range 0 (bytes-length bstr) 4)])
(bytes-set! bstr i (if (= (bytes-ref bstr i) 255) (let ([v (if (= (bytes-ref bstr i) 255)
255 (if (and (= 255 (bytes-ref bstr (+ i 1)))
0))
(let ([v (if (and (= 255 (bytes-ref bstr (+ i 1)))
(= 255 (bytes-ref bstr (+ i 2))) (= 255 (bytes-ref bstr (+ i 2)))
(= 255 (bytes-ref bstr (+ i 3)))) (= 255 (bytes-ref bstr (+ i 3))))
255 255
0)]) 0)
255)])
(bytes-set! bstr i (- 255 v))
(bytes-set! bstr (+ i 1) v) (bytes-set! bstr (+ i 1) v)
(bytes-set! bstr (+ i 2) v) (bytes-set! bstr (+ i 2) v)
(bytes-set! bstr (+ i 3) v))) (bytes-set! bstr (+ i 3) v)))