suzanne.soy/hyper-literate
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Implement support for converting values to GIFs

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Implement support for convertible GIFs in the HTML renderer, including
width and height attributes to GIFs created from convertible values.
This commit is contained in:
Jack Firth 2020-05-30 05:19:30 -07:00 committed by GitHub
parent 3d7ded8a33
commit 4b3d3a8296
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GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 19 additions and 3 deletions
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4
scribble-doc/scribblings/scribble/core.scrbl
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@ -1848,13 +1848,15 @@ For a @racket[part] that corresponds to an HTML page, adds content to
the @tt{<head>} tag.}
@defstruct[render-convertible-as ([types (listof (or/c 'png-bytes 'svg-bytes))])]{
@defstruct[render-convertible-as ([types (listof (or/c 'png-bytes 'svg-bytes 'gif-bytes))])]{
For a @racket[part] that corresponds to an HTML page,
controls how objects that subscribe to the @racketmodname[file/convertible]
protocol are rendered.
The alternatives in the @racket[types] field are tried in order
and the first one that succeeds is used in the html output.
@history[#:changed "1.34" @elem{Added support for @racket['gif-bytes].}]
}
@defstruct[part-link-redirect ([url url?])]{

2
scribble-lib/scribble/html-properties.rkt
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@ -30,4 +30,4 @@
[link-resource ([path path-string?])]
[head-extra ([xexpr xexpr/c])]
[render-convertible-as ([types (listof (or/c 'png-bytes 'svg-bytes))])])
[render-convertible-as ([types (listof (or/c 'png-bytes 'svg-bytes 'gif-bytes))])])

16
scribble-lib/scribble/html-render.rkt
View File

@ -107,7 +107,7 @@
(define extra-breaking? (make-parameter #f))
(define current-version (make-parameter (version)))
(define current-part-files (make-parameter #f))
(define current-render-convertible-requests (make-parameter '(png@2x-bytes png-bytes svg-bytes)))
(define current-render-convertible-requests (make-parameter '(png@2x-bytes png-bytes svg-bytes gif-bytes)))
(define (url->string* u)
(parameterize ([current-url-encode-mode 'unreserved])
@ -1496,6 +1496,20 @@
`(img
([src ,(install-file "pict.svg" bstr)]
[type "image/svg+xml"]))))))]
[(and (equal? request 'gif-bytes) (convert e 'gif-bytes))
=>
(lambda (gif-bytes)
(define gif-src (install-file "pict.gif" gif-bytes))
;; GIFs store their width and height in the first 4 bytes of the logical screen
;; descriptor, which comes after the 6-byte long header block. The width and height are
;; each represented by 2-byte wide little-endian unsigned fields.
(define width (+ (bytes-ref gif-bytes 6) (* (bytes-ref gif-bytes 7) 256)))
(define height (+ (bytes-ref gif-bytes 8) (* (bytes-ref gif-bytes 9) 256)))
(define image-tag
`(img ([src ,gif-src] [type "image/gif"] [width ,width] [height ,height])))
(list image-tag))]
[else #f])))
;; Add padding for a bounding-box conversion reply: