2htdp/image: use erase instead of clear to zero out a bitmap

original commit: 54c337e5d3860fa7333fae79a8d3fa39366c1873
This commit is contained in:
Robby Findler 2010-12-27 21:48:27 -06:00
parent f9c8cb6676
commit c36dd1fdfd

View File

@ -221,7 +221,7 @@ has been moved out).
(add1 (inexact->exact (ceiling (bb-right bb))))
(add1 (inexact->exact (ceiling (bb-bottom bb)))))]
[bdc (new bitmap-dc% [bitmap bm])])
(send bdc clear)
(send bdc erase)
(render-image img bdc 0 0)
(begin0
(send bdc get-bitmap)
@ -261,7 +261,7 @@ has been moved out).
(define/private (draw-into bm bdc bytes obj)
(send bdc set-bitmap bm)
(send bdc clear)
(send bdc erase)
(render-image obj bdc 0 0)
(send bdc get-argb-pixels 0 0 (send bm get-width) (send bm get-height) bytes))
@ -650,7 +650,7 @@ has been moved out).
(+ 1 (ceiling (inexact->exact (bb-right bb))))
(+ 1 (ceiling (inexact->exact (bb-bottom bb)))))]
[bdc (make-object bitmap-dc% bm)])
(send bdc clear)
(send bdc erase)
(render-image image bdc 0 0)
(send bdc set-bitmap #f)
(send bm save-file filename kind)))
@ -989,13 +989,13 @@ the mask bitmap and the original bitmap are all together in a single bytes!
(send bdc set-bitmap new-bm)
(send bdc set-scale x-scale y-scale)
(send bdc clear)
(send bdc erase)
(send bdc draw-bitmap orig-bm 0 0)
(when new-mask
(send bdc set-bitmap new-mask)
(send bdc set-scale x-scale y-scale)
(send bdc clear)
(send bdc erase)
(send bdc draw-bitmap orig-mask 0 0))
(send bdc set-bitmap #f)