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;;; R7RS-PNM --- Library for reading and writing PNM (Portable Any Map) files for R7RS
;;; Copyright © 2024 Masaya Tojo <masaya@tojo.tokyo>
;;;
;;; This file is part of R7RS-PNM.
;;;
;;; R7RS-PNM is free software: you can redistribute it and/or modify it
;;; under the terms of the GNU Lesser General Public License as published
;;; by the Free Software Foundation, either version 3 of the License, or
;;; (at your option) any later version.
;;;
;;; R7RS-PNM is distributed in the hope that it will be useful, but
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;;; GNU Lesser General Public License for more details.
;;;
;;; You should have received a copy of the GNU Lesser General Public License
;;; along with R7RS-PNM. If not, see <https://www.gnu.org/licenses/>.
(define-library (pnm write)
(export image-write)
(import (scheme base)
(scheme case-lambda)
(pnm image))
(begin
(define image-write
(case-lambda
((image out)
(case (image-type image)
((ppm)
(write-string-u8 "P6\n" out))
((pgm)
(write-string-u8 "P5\n" out))
((pbm)
(write-string-u8 "P4\n" out))
(else
(error "(pnm write) image-write: Not supported type" (image-type image))))
(write-string-u8 (number->string (image-width image)) out)
(write-string-u8 " " out)
(write-string-u8 (number->string (image-height image)) out)
(write-string-u8 "\n" out)
(case (image-type image)
((pgm ppm)
(write-string-u8 (number->string (image-maxval image)) out)
(write-string-u8 "\n" out)))
(write-bytevector (image-data image) out))
((image out plain?)
(if plain?
(image-write/plan image out)
(image-write image out)))))
(define (image-write/plan image out)
(case (image-type image)
((ppm)
(write-string-u8 "P3\n" out))
((pgm)
(write-string-u8 "P2\n" out))
((pbm)
(write-string-u8 "P1\n" out))
(else
(error "(pnm write) image-write: Not supported type" (image-type image))))
(write-string-u8 (number->string (image-width image)) out)
(write-string-u8 " " out)
(write-string-u8 (number->string (image-height image)) out)
(write-string-u8 "\n" out)
(case (image-type image)
((pgm ppm)
(write-string-u8 (number->string (image-maxval image)) out)
(write-string-u8 "\n" out)))
(let-values (((write-token write-newline)
(limit-line-length-writer 70 out)))
(let ((width (image-width image))
(height (image-height image)))
(define (write-raster write-pixel)
(do ((y 0 (+ y 1)))
((= y height))
(write-pixel 0 y)
(do ((x 1 (+ x 1)))
((= x width))
(write-pixel x y))
(write-newline)))
(case (image-type image)
((ppm)
(write-raster
(lambda (x y)
(let-values (((r g b) (image-ref image x y)))
(write-token (number->string r))
(write-token (number->string g))
(write-token (number->string b))))))
((pgm)
(write-raster
(lambda (x y)
(let ((v (image-ref image x y)))
(write-token (number->string v))))))
((pbm)
(write-raster
(lambda (x y)
(let ((b (image-ref image x y)))
(write-token (if b "1" "0"))))))))))
(define (write-string-u8 str out)
(string-for-each (lambda (c) (write-u8 (char->integer c) out))
str))
(define (limit-line-length-writer limit out)
(let ((current-length 0))
(define (write-token str)
(let ((str-len (string-length str)))
(cond ((zero? current-length)
(write-string-u8 str out)
(set! current-length str-len))
((<= (+ current-length str-len 1) limit)
(write-string-u8 " " out)
(write-string-u8 str out)
(set! current-length (+ current-length 1 str-len)))
(else
(write-string-u8 "\n" out)
(write-string-u8 str out)
(set! current-length str-len)))))
(define (write-newline)
(write-string-u8 "\n" out)
(set! current-length 0))
(values write-token
write-newline)))))
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