Hello,
I'm trying to implement an image-snip% subclass which has
a new field (hash table) to store some metadata.
I follow the example described in the documentation, but
the constructor of my image-snip subclass does not display
the bitmap.
Here is my code.. Thanks in advance.
(define image-data-snip%
(class image-snip%
(inherit set-snipclass
get-flags set-flags
get-admin
get-extent
draw)
(init-field [metadata (make-hash)])
(super-new)
(set-snipclass image-data-snip-class)
(send (get-the-snip-class-list) add image-data-snip-class)
(set-flags (cons 'handles-events (get-flags)))
(define/override (copy)
(new image-data-snip% [metadata metadata]))
(define/override (write f)
(super write f)
(send f put (list->bytes (hash->list metadata))))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;Operations on the metadata ;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(define/public (get-arg-pos arg)
(hash-ref metadata arg '(0.5 0.5)))
(define/public (set-arg-pos arg pos)
(hash-set! metadata arg pos))
(define/public (get-args-pos)
(hash->list metadata))))
(define image-data-snip-class%
(class snip-class%
(inherit set-classname)
(super-new)
(set-classname (~s '(lib "main.rkt" "image-data-snip")))
(define/override (read f)
#;(super read f)
(define size-b (box 0.0))
(send f get size-b)
;; I do not know how can I restore the hash map here
(new image-data-snip% [metadata (bytes->list (unbox size-b))]))))
(define image-data-snip-class (new image-data-snip-class%))
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