You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
40 lines
1.3 KiB
Racket
40 lines
1.3 KiB
Racket
7 years ago
|
#lang br
|
||
|
|
(require pitfall/binprint binparser)
|
||
|
|
|
||
|
|
;; http://www.matthewflickinger.com/lab/whatsinagif/bits_and_bytes.asp
|
||
|
|
|
||
|
|
|
||
|
|
(define-rule gif (:seq signature version logical-screen-descriptor #:type hash?))
|
||
|
|
(define-rule signature (:atomic 3 #:type string/ascii?))
|
||
|
|
(define-rule version (:atomic 3 #:type string/ascii?))
|
||
|
|
|
||
|
|
(define-rule logical-screen-descriptor (:seq width height lsd-flags bgcolor-idx aspect #:type hash?))
|
||
|
|
(define-rule width (:atomic 2 #:type integer?))
|
||
|
|
(define-rule height (:atomic 2 #:type integer?))
|
||
|
|
(define-rule lsd-flags (:seq reserved disposal user-input transparent #:type hash?))
|
||
|
|
(define-rule reserved (:atomic .3))
|
||
|
|
(define-rule disposal (:atomic .3))
|
||
|
|
(define-rule user-input (:atomic .1))
|
||
|
|
(define-rule transparent (:atomic .1))
|
||
|
|
(define-rule bgcolor-idx (:atomic 1 #:type integer?))
|
||
|
|
(define-rule aspect (:atomic 1 #:type integer?))
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
(gif (open-input-file "test.gif"))
|
||
|
|
|
||
|
|
|
||
|
|
#;(check-equal? (gif (gif (open-input-file "test.gif"))) (read-bytes 13 (open-input-file "test.gif")))
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
(require rackunit)
|
||
|
|
#;(check-equal? (parse-with-template "test.gif" gif)
|
||
|
|
(cons 'gif
|
||
|
|
(make-hasheq (list (cons 'logical-screen-descriptor '(162 162 (#f #t #f #f #f #t #f #t) 0 0))
|
||
|
|
'(signature . "GIF")
|
||
|
|
'(version . "87a")))))
|