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#lang racket/base
(require racket/match
racket/pretty
"image.rkt")
(provide set-print-parameters)
(define (set-print-parameters pretty? columns pixels/char)
(cond [pretty?
(current-print pretty-print-handler)
(pretty-print-columns columns)
(pretty-print-size-hook (make-pretty-print-size-hook pixels/char))
(pretty-print-print-hook (make-pretty-print-print-hook))]
[else
(current-print plain-print-handler)])
(print-syntax-width +inf.0))
(define (plain-print-handler v)
(unless (void? v)
(println (match (convert-image v)
[(cons path-name _pixel-width) path-name]
[_ v]))))
;; pretty-print uses separate size and print hooks -- and the size
;; hook can even be called more than once per object. Avoid calling
;; convert-image two (or more!) times per object. That could be slow
;; for large images; furthermore each call creates a temp file.
;;
;; Instead: Call convert-image once in the size hook, storing the
;; result in a hash-table for use across later calls to the size
;; and/or print hook. Remove in the print hook.
;;
;; (Note: Although I had tried using the pre-print and post-print
;; hooks, they seemed to be called inconsistently.)
(define ht (make-hasheq))
(define (make-pretty-print-size-hook pixels/char)
(define (racket-mode-size-hook value _display? _port)
(define (not-found)
(match (convert-image value)
[(cons path-name pixel-width)
(define char-width (ceiling (/ pixel-width pixels/char)))
(define path+width (cons path-name char-width))
path+width]
[#f #f]))
(match (hash-ref! ht value not-found)
[(cons _path-name char-width) char-width]
[#f #f]))
racket-mode-size-hook)
(define (make-pretty-print-print-hook)
(define orig (pretty-print-print-hook))
(define (racket-mode-print-hook value display? port)
(match (hash-ref ht value #f)
[(cons path-name _char-width)
(hash-remove! ht value)
((if display? display print) path-name port)]
[#f (orig value display? port)]))
racket-mode-print-hook)
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