GRASS GIS 8 Programmer's Manual 8.3.2(2024)-exported
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pngdriver/read_ppm.c
Go to the documentation of this file.
1/*!
2 \file lib/pngdriver/read_ppm.c
3
4 \brief GRASS png display driver - read image (lower level functions)
5
6 (C) 2007-2014 by Glynn Clements and the GRASS Development Team
7
8 This program is free software under the GNU General Public License
9 (>=v2). Read the file COPYING that comes with GRASS for details.
10
11 \author Glynn Clements
12 */
13
14#include <stdio.h>
15#include <stdlib.h>
16#include <string.h>
17
18#include <grass/gis.h>
19#include "pngdriver.h"
20
21void read_ppm(void)
22{
23 FILE *input;
24 int x, y;
25 int i_width, i_height, maxval;
26 unsigned int rgb_mask = png_get_color(255, 255, 255, 0);
27 unsigned int *p;
28
29 if (!png.true_color)
30 G_fatal_error("PNG: cannot use PPM/PGM with indexed color");
31
32 input = fopen(png.file_name, "rb");
33 if (!input)
34 G_fatal_error("PNG: couldn't open input file %s", png.file_name);
35
36 if (fscanf(input, "P6 %d %d %d", &i_width, &i_height, &maxval) != 3)
37 G_fatal_error("PNG: invalid input file %s", png.file_name);
38
39 fgetc(input);
40
41 if (i_width != png.width || i_height != png.height)
42 G_fatal_error("PNG: input file has incorrect dimensions: expected: "
43 "%dx%d got: %dx%d",
44 png.width, png.height, i_width, i_height);
45
46 for (y = 0, p = png.grid; y < png.height; y++) {
47 for (x = 0; x < png.width; x++, p++) {
48 unsigned int c = *p;
49
50 int r = fgetc(input);
51 int g = fgetc(input);
52 int b = fgetc(input);
53
54 r = r * 255 / maxval;
55 g = g * 255 / maxval;
56 b = b * 255 / maxval;
57
58 c &= ~rgb_mask;
59 c |= png_get_color(r, g, b, 0);
60
61 *p = c;
62 }
63 }
64
65 fclose(input);
66}
67
68void read_pgm(void)
69{
70 char *mask_name = G_store(png.file_name);
71 FILE *input;
72 int x, y;
73 int i_width, i_height, maxval;
74 unsigned int rgb_mask = png_get_color(255, 255, 255, 0);
75 unsigned int *p;
76
77 if (!png.true_color)
78 G_fatal_error("PNG: cannot use PPM/PGM with indexed color");
79
80 mask_name[strlen(mask_name) - 2] = 'g';
81
82 input = fopen(mask_name, "rb");
83 if (!input)
84 G_fatal_error("PNG: couldn't open input mask file %s", mask_name);
85
86 if (fscanf(input, "P5 %d %d %d", &i_width, &i_height, &maxval) != 3)
87 G_fatal_error("PNG: invalid input mask file %s", mask_name);
88
89 fgetc(input);
90
91 if (i_width != png.width || i_height != png.height)
92 G_fatal_error("PNG: input mask file has incorrect dimensions: "
93 "expected: %dx%d got: %dx%d",
94 png.width, png.height, i_width, i_height);
95
96 G_free(mask_name);
97
98 for (y = 0, p = png.grid; y < png.height; y++) {
99 for (x = 0; x < png.width; x++, p++) {
100 unsigned int c = *p;
101
102 int k = fgetc(input);
103
104 k = k * 255 / maxval;
105
106 c &= rgb_mask;
107 c |= png_get_color(0, 0, 0, 255 - k);
108
109 *p = c;
110 }
111 }
112
113 fclose(input);
114}
void G_free(void *buf)
Free allocated memory.
Definition alloc.c:150
unsigned int png_get_color(int r, int g, int b, int a)
double b
double r
void G_fatal_error(const char *msg,...)
Print a fatal error message to stderr.
Definition gis/error.c:159
float g
Definition named_colr.c:7
struct png_state png
void read_ppm(void)
void read_pgm(void)
GRASS png display driver - header file.
char * G_store(const char *s)
Copy string to allocated memory.
Definition strings.c:87
char * file_name
Definition pngdriver.h:32
int true_color
Definition pngdriver.h:34
int height
Definition pngdriver.h:42
unsigned int * grid
Definition pngdriver.h:43
int width
Definition pngdriver.h:42
#define x