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Add a disposal arg to write-animated-gif

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This commit is contained in:
Martin DeMello 2014-10-18 20:08:42 -07:00 committed by Matthew Flatt
parent 1f4edfd0f6
commit bc5d86f494
2 changed files with 17 additions and 10 deletions
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10
pkgs/gui-pkgs/gui-doc/mrlib/scribblings/gif.scrbl
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@ -27,7 +27,8 @@ transparent pixels in the generated GIF image.}
[filename path-string?]
[#:loop? loop? any/c (and delay-csec #t)]
[#:one-at-a-time? one-at-a-time? any/c #f]
[#:last-frame-delay last-frame-delay (or/c (integer-in 0 #xFFFFFFFF) #f) #f])
[#:last-frame-delay last-frame-delay (or/c (integer-in 0 #xFFFFFFFF) #f) #f]
[#:disposal disposal (or/c 'any 'keep 'restore-bg 'restore-prev) 'any])
void?]{
Writes the bitmaps in @racket[bitmaps] to @racket[filename] as an
@ -54,4 +55,9 @@ the resulting file large.
If @racket[last-frame-delay] is not false, a delay of
@racket[last-frame-delay] (in 1/100s of a second) is added to the last
frame. This extra delay is useful when @racket[loop?] is true.}
frame. This extra delay is useful when @racket[loop?] is true.
The @racket[disposal] argument specifies the frame disposal method, which determines
how the previous frame is treated when writing a transparent frame. The same
disposal method is applied to every frame. See @racket[gif-add-control] for the
meaning of the various disposal options.}

17
pkgs/gui-pkgs/gui-lib/mrlib/gif.rkt
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@ -18,7 +18,7 @@
(cons (subbytes b offset (+ offset len))
(split-bytes b len (+ offset len)))))
(define (write-gifs bms delay filename one-at-a-time? last-frame-delay loop?)
(define (write-gifs bms delay filename one-at-a-time? last-frame-delay loop? disposal)
(let* ([init (force-bm (car bms))]
[w (send init get-width)]
[h (send init get-height)])
@ -46,10 +46,10 @@
(let-values ([(pixels colormap transparent)
(quantize (argb-thunk))])
(when (or transparent delay)
(gif-add-control gif 'any #f (or delay 0) transparent))
(gif-add-control gif disposal #f (or delay 0) transparent))
(gif-add-image gif 0 0 w h #f colormap pixels)
(when (and last-frame-delay (eq? argb-thunk last-argb-thunk))
(gif-add-control gif 'any #f last-frame-delay transparent)
(gif-add-control gif disposal #f last-frame-delay transparent)
(gif-add-image gif 0 0 w h #f colormap pixels))))
argb-thunks))
(gif-end gif))))
@ -69,7 +69,7 @@
(gif-add-control gif 'any #f (or delay 0) transparent))
(gif-add-image gif 0 0 w h #f #f pixels)
(when (and last-frame-delay (eq? pixels last-pixels))
(gif-add-control gif 'any #f last-frame-delay transparent)
(gif-add-control gif disposal #f last-frame-delay transparent)
(gif-add-image gif 0 0 w h #f colormap pixels)))
pixelss))
(gif-end gif)))))))))
@ -84,12 +84,13 @@
(filename (or/c path? string?)))
(#:one-at-a-time? (one-at-a-time? any/c)
#:last-frame-delay (last-frame-delay (or/c (integer-in 0 4294967295) false/c))
#:loop? (Loop? (delay) (lambda (x) (and delay #t))))
#:loop? (Loop? (delay) (lambda (x) (and delay #t)))
#:disposal (disposal (or/c 'any 'keep 'restore-bg 'restore-prev)))
any)])
(define (write-animated-gif bms delay filename
#:one-at-a-time? [one-at-a-time? #f]
#:last-frame-delay [last-frame-delay #f]
#:loop? [loop? (and delay #t)])
(write-gifs bms delay filename one-at-a-time? last-frame-delay loop?))
#:loop? [loop? (and delay #t)]
#:disposal [disposal 'any])
(write-gifs bms delay filename one-at-a-time? last-frame-delay loop? disposal))