blob: 17a7c4305e7cd2b011c4528501968ebae4eac54c (
about) (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
|
;;; 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 ppm)
(export make-ppm-image)
(import (scheme base)
(scheme case-lambda)
(pnm image))
(begin
(define make-ppm-image
(case-lambda
((width height maxval)
(when (or (< maxval 0)
(< 65536 maxval))
(error "(pnm ppm) make-ppm-image: maxval is out of range"))
(let ((data (make-bytevector (* width
height
(if (< maxval 256)
3
6))
0)))
(make-ppm-image width height maxval data)))
((width height maxval data)
(when (or (< maxval 0)
(< 65536 maxval))
(error "(pnm ppm) make-ppm-image: maxval is out of range"))
(if (< maxval 256)
(let* ((w*3 (* width 3)))
(define (xy->idx x y) (+ (* 3 x) (* y w*3)))
(define (getter x y)
(let ((idx (xy->idx x y)))
(values (bytevector-u8-ref data idx)
(bytevector-u8-ref data (+ idx 1))
(bytevector-u8-ref data (+ idx 2)))))
(define (setter x y r g b)
(let ((idx (xy->idx x y)))
(bytevector-u8-set! data idx r)
(bytevector-u8-set! data (+ idx 1) g)
(bytevector-u8-set! data (+ idx 2) b)))
(make-image 'ppm width height maxval data getter setter))
(let* ((w*6 (* width 6)))
(define (xy->idx x y) (+ (* 6 x) (* y w*6)))
(define (getter x y)
(let ((idx (xy->idx x y)))
(values (combine-values (bytevector-u8-ref data idx)
(bytevector-u8-ref data (+ idx 1)))
(combine-values (bytevector-u8-ref data (+ idx 2))
(bytevector-u8-ref data (+ idx 3)))
(combine-values (bytevector-u8-ref data (+ idx 4))
(bytevector-u8-ref data (+ idx 5))))))
(define (setter x y r g b)
(let ((idx (xy->idx x y)))
(let-values (((r1 r2) (split-value r))
((g1 g2) (split-value g))
((b1 b2) (split-value b)))
(bytevector-u8-set! data idx r1)
(bytevector-u8-set! data (+ idx 1) r2)
(bytevector-u8-set! data (+ idx 2) g1)
(bytevector-u8-set! data (+ idx 3) g2)
(bytevector-u8-set! data (+ idx 4) b1)
(bytevector-u8-set! data (+ idx 5) b2))))
(make-image 'ppm width height maxval data getter setter))))))
(define (split-value v)
(values (modulo (quotient v 256) 256)
(modulo v 256)))
(define (combine-values l r)
(+ (* 256 l) r))))
|
