blob: 39711e9ff4d1147c62a8ec23b5bd9287ed635db5 (
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
85
86
87
88
89
90
91
|
;;; 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 (image-format pnm pgm)
(export make-pgm-image
%make-pgm-image)
(import (scheme base)
(scheme case-lambda)
(image-format pnm image)
(image-format pnm private checker)
(image-format pnm private double-byte))
(begin
(define make-pgm-image
(case-lambda
((width height)
(make-pgm-image width height 255 #f))
((width height maxval)
(make-pgm-image width height maxval #f))
((width height maxval unsafe?)
(when (or (< maxval 0)
(< 65536 maxval))
(error "(image-format pnm pgm) make-pgm: maxval is out of range"))
(let* ((byte-count (* width height
(if (< maxval 256)
1
2)))
(data (make-bytevector byte-count 0)))
(%make-pgm-image width height maxval data unsafe?)))))
(define (%make-pgm-image width height maxval data unsafe?)
(define (make-safe-pixel-getter pixel-getter)
(let ((check-xy (make-xy-checker width height)))
(lambda (x y)
(check-xy x y)
(pixel-getter x y))))
(define (make-safe-pixel-setter pixel-setter)
(let ((check-xy (make-xy-checker width height))
(check-value (make-value-checker maxval 'v)))
(lambda (x y v)
(check-xy x y)
(check-value v)
(pixel-setter x y v))))
(when (or (< maxval 0)
(< 65536 maxval))
(error "(image-format pnm pgm) make-pgm: maxval is out of range"))
(if (< maxval 256)
(let ((byte-count (* width height)))
(define (xy->idx x y)
(+ x (* y width)))
(define (pixel-getter x y)
(let ((idx (xy->idx x y)))
(bytevector-u8-ref data idx)))
(define (pixel-setter x y v)
(let ((idx (xy->idx x y)))
(bytevector-u8-set! data idx v)))
(unless (= byte-count (bytevector-length data))
(error (string-append "(image-format pnm pbm) make-pbm-image: Invalid bytevector length" byte-count)))
(make-pnm-image 'pgm width height maxval data
(if unsafe? pixel-getter (make-safe-pixel-getter pixel-getter))
(if unsafe? pixel-setter (make-safe-pixel-setter pixel-setter))))
(let ((byte-count (* width height 2)))
(define (xy->idx x y) (+ x (* y width)))
(define (pixel-getter x y)
(let ((idx (xy->idx x y)))
(combine-bytes (bytevector-u8-ref data idx)
(bytevector-u8-ref data (+ idx 1)))))
(define (pixel-setter x y v)
(let ((idx (xy->idx x y)))
(let-values (((v1 v2) (split-double-byte v)))
(bytevector-u8-set! data idx v1)
(bytevector-u8-set! data (+ idx 1) v2))))
(unless (= byte-count (bytevector-length data))
(error (string-append "(image-format pnm pbm) make-pbm-image: Invalid bytevector length" byte-count)))
(make-pnm-image 'pgm width height maxval data
(if unsafe? pixel-getter (make-safe-pixel-getter pixel-getter))
(if unsafe? pixel-setter (make-safe-pixel-setter pixel-setter))))))))
|
