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Rackety

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This commit is contained in:
Robby Findler 2010-07-10 08:35:16 -05:00
parent 49ad309630
commit 1f89bea08d
1 changed files with 42 additions and 41 deletions
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83
collects/file/gif.rkt
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@ -14,13 +14,13 @@
*****************************************************************************/
|#
#lang at-exp scheme/base
#lang at-exp racket/base
(require scheme/contract
(require racket/contract
scribble/srcdoc
(prefix-in octree: file/private/octree-quantize))
(require/doc scheme/base
(require/doc racket/base
scribble/manual)
(define LZ_MAX_CODE 4095)
@ -31,34 +31,35 @@
(proc-doc gif-stream?
(([v any/c]) () . ->d . [_ boolean?])
@{Returns @scheme[#t] if @scheme[v] is a GIF stream created by
@scheme[gif-write], @scheme[#f] otherwise.})
@scheme[gif-write], @scheme[#f] otherwise.})
(proc-doc image-ready-gif-stream?
(([v any/c]) () . ->d . [_ boolean?])
@{Returns @scheme[#t] if @scheme[v] is a GIF stream that is not in
@scheme['done] mode, @scheme[#f] otherwise.})
@{Returns @racket[#t] if @racket[v] is a GIF stream that is not in
@racket['done] mode, @racket[#f] otherwise.})
(proc-doc image-or-control-ready-gif-stream?
(([v any/c]) () . ->d . [_ boolean?])
@{Returns @scheme[#t] if @scheme[v] is a GIF stream that is in
@scheme['init] or @scheme['image-or-control] mode, @scheme[#f]
@{Returns @racket[#t] if @racket[v] is a GIF stream that is in
@racket['init] or @racket['image-or-control] mode, @racket[#f]
otherwise.})
(proc-doc empty-gif-stream?
(([v any/c]) () . ->d . [_ boolean?])
@{Returns @scheme[#t] if @scheme[v] is a GIF stream that in
@scheme['init] mode, @scheme[#f] otherwise.})
@{Returns @racket[#t] if @racket[v] is a GIF stream that in
@racket['init] mode, @racket[#f] otherwise.})
(proc-doc gif-colormap?
(([v any/c]) () . ->d . [_ boolean?])
@{Returns @scheme[#t] if @scheme[v] represets a colormap,
@scheme[#f] otherwise. A colormap is a list whose size is a power
@{Returns @racket[#t] if @racket[v] represets a colormap,
@racket[#f] otherwise. A colormap is a list whose size is a power
of @math{2} between @math{2^1} and @math{2^8}, and whose elements
are vectors of size 3 containing colors (i.e., exact integers
between @math{0} and @math{255} inclusive).})
(proc-doc color?
(([v any/c]) () . ->d . [_ boolean?])
@{The same as @scheme[byte?].})
@{The same as @racket[byte?].})
(proc-doc dimension?
(([v any/c]) () . ->d . [_ boolean?])
@{Returns @scheme[#t] if @scheme[v] is an exact integer between
@scheme[#x0] and @scheme[#xFFFF] inclusive, @scheme[#f]
@{Returns @racket[#t] if @racket[v] is an exact integer between
@racket[#x0] and @scheme[#xFFFF] inclusive, @racket[#f]
otherwise.}))
(define-struct gif-stream
@ -105,7 +106,7 @@
(provide/doc (proc-doc gif-state
(([stream gif-stream?]) () . ->d . [_ symbol?])
@{Returns the state of @scheme[stream].}))
@{Returns the state of @racket[stream].}))
(define (gif-state GifFile)
(gif-stream-FileState GifFile))
@ -194,12 +195,12 @@
[bstr bytes?])
()
. ->d . [_ void?])
@{Writes an image to the given GIF stream. The @scheme[left],
@scheme[top], @scheme[width], and @scheme[height] values
@{Writes an image to the given GIF stream. The @racket[left],
@racket[top], @racket[width], and @racket[height] values
specify the location and size of the image within the overall
GIF image's virtual space.
If @scheme[interlaced?] is true, then @scheme[bstr] should
If @racket[interlaced?] is true, then @racket[bstr] should
provide bytes ininterlaced order instead of top-to-bottom
order. Interlaced order is:
@ -208,23 +209,23 @@
@item{every 4th row, starting with 2}
@item{every 2nd row, starting with 1})
If a global color is provided with @scheme[gif-start], a
@scheme[#f] value can be provided for @scheme[cmap].
If a global color is provided with @racket[gif-start], a
@racket[#f] value can be provided for @racket[cmap].
The @scheme[bstr] argument specifies the pixel content of the
The @racket[bstr] argument specifies the pixel content of the
image. Each byte specifies a color (i.e., an index in the
colormap). Each row is provided left-to-right, and the rows
provided either top-to-bottom or in interlaced order (see
above). If the image is prefixed with a control that specifies
an transparent index (see @scheme[gif-add-control]), then the
an transparent index (see @racket[gif-add-control]), then the
corresponding ``color'' doesn't draw into the overall GIF
image.
An exception is raised if any byte value in @scheme[bstr] is
larger than the colormap's length, if the @scheme[bstr] length
is not @scheme[width] times @scheme[height], or if the
@scheme[top], @scheme[left], @scheme[width], and
@scheme[height] dimensions specify a region beyond the overall
An exception is raised if any byte value in @racket[bstr] is
larger than the colormap's length, if the @racket[bstr] length
is not @racket[width] times @racket[height], or if the
@racket[top], @racket[left], @racket[width], and
@racket[height] dimensions specify a region beyond the overall
GIF image's virtual space.}))
(define (gif-add-image GifFile Left Top Width Height Interlace ColorMap Line)
@ -307,32 +308,32 @@
removed from the overall image before proceeding to the next
one (also for GIF animation).
The @scheme[disposal] argument specifies how to proceed:
The @racket[disposal] argument specifies how to proceed:
@(itemize @item{@scheme['any] : doesn't matter (perhaps because
@(itemize @item{@racket['any] : doesn't matter (perhaps because
the next image completely overwrites the
current one)}
@item{@scheme['keep] : leave the image in place}
@item{@scheme['restore-bg] : replace the image with
@item{@racket['keep] : leave the image in place}
@item{@racket['restore-bg] : replace the image with
the background color}
@item{@scheme['restore-prev] : restore the overall
@item{@racket['restore-prev] : restore the overall
image content to the content before the image
is added})
If @scheme[wait-for-input?] is true, then the display program
If @racket[wait-for-input?] is true, then the display program
may wait for some cue from the user (perhaps a mouse click)
before adding the image.
The @scheme[delay] argument specifies a delay in 1/100s of a
The @racket[delay] argument specifies a delay in 1/100s of a
second.
If the @scheme[transparent] argument is a color, then it
If the @racket[transparent] argument is a color, then it
determines an index that is used to represent transparent
pixels in the follow image (as opposed to the color specified
by the colormap for the index).
An exception is raised if a control is already added to
@scheme[stream] without a corresponding image.}))
@racket[stream] without a corresponding image.}))
(define (gif-add-control GifFile
Disposal
@ -569,18 +570,18 @@
(values [_ bytes?] [_ gif-colormap?] [_ (or/c false/c color?)]))
@{Each image in a GIF stream is limited to 256 colors, including the
transparent ``color,'' if any. The @scheme[quantize] function
transparent ``color,'' if any. The @racket[quantize] function
converts a 24-bit image (plus alpha channel) into an
indexed-color image, reducing the number of colors if necessary.
Given a set of pixels expressed in ARGB format (i.e., each four
bytes is a set of values for one pixel: alpha, red, blue, and
green), @scheme[quantize] produces produces
green), @racket[quantize] produces produces
@(itemize @item{bytes for the image (i.e., a array of colors,
expressed as a byte string)}
@item{a colormap}
@item{either @scheme[#f] or a color index for the
@item{either @racket[#f] or a color index for the
transparent ``color''})
The conversion treats alpha values less than 128 as transparent
@ -592,6 +593,6 @@
To convert a collection of images all with the same quantization,
simply append them for the input of a single call of
@scheme[quantize], and then break apart the result bytes.}))
@racket[quantize], and then break apart the result bytes.}))
(define (quantize argb)
(octree:quantize argb))