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fix PNG reader

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when alpha isn't wanted and image has tRNS
This commit is contained in:
Matthew Flatt 2011-12-09 10:33:35 -07:00
parent 287d5cedf5
commit 40fc46a870
1 changed files with 8 additions and 3 deletions
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11
collects/racket/draw/unsafe/png.rkt
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@ -152,6 +152,7 @@
(define-png png_set_gray_to_rgb (_fun _png_structp -> _void)) (define-png png_set_gray_to_rgb (_fun _png_structp -> _void))
(define-png png_set_tRNS_to_alpha (_fun _png_structp -> _void)) (define-png png_set_tRNS_to_alpha (_fun _png_structp -> _void))
(define-png png_set_strip_16 (_fun _png_structp -> _void)) (define-png png_set_strip_16 (_fun _png_structp -> _void))
(define-png png_set_strip_alpha (_fun _png_structp -> _void))
(define-png png_set_gray_1_2_4_to_8 (_fun _png_structp -> _void) (define-png png_set_gray_1_2_4_to_8 (_fun _png_structp -> _void)
#:fail (lambda () #f)) #:fail (lambda () #f))
(define-png png_set_expand_gray_1_2_4_to_8 (_fun _png_structp -> _void) (define-png png_set_expand_gray_1_2_4_to_8 (_fun _png_structp -> _void)
@ -267,9 +268,13 @@
[(macosx) 1.7] [(macosx) 1.7]
[else 2.0])) [else 2.0]))
gamma)))) gamma))))
(when alpha? (cond
;; Add filler (or alpha) byte (before each RGB triplet) [alpha?
(png_set_filler png 255 PNG_FILLER_AFTER)) ;; Make sure there's an alpha or filler byte (before each RGB triplet):
(png_set_filler png 255 PNG_FILLER_AFTER)]
[tRNS?
;; Make sure there's no alpha channel:
(png_set_strip_alpha png)])
(let ([num-passes (png_set_interlace_handling png)]) (let ([num-passes (png_set_interlace_handling png)])
(png_read_update_info png info) (png_read_update_info png info)
(values (make-reader png info ib num-passes w h) (values (make-reader png info ib num-passes w h)