GRASS GIS 7 Programmer's Manual  7.5.svn(2017)-r71785
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pngdriver/read_ppm.c
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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 
15 #include <stdio.h>
16 #include <stdlib.h>
17 #include <string.h>
18 
19 #include <grass/gis.h>
20 #include "pngdriver.h"
21 
22 void read_ppm(void)
23 {
24  FILE *input;
25  int x, y;
26  int i_width, i_height, maxval;
27  unsigned int rgb_mask = png_get_color(255, 255, 255, 0);
28  unsigned int *p;
29 
30  if (!png.true_color)
31  G_fatal_error("PNG: cannot use PPM/PGM with indexed color");
32 
33  input = fopen(png.file_name, "rb");
34  if (!input)
35  G_fatal_error("PNG: couldn't open input file %s", png.file_name);
36 
37  if (fscanf(input, "P6 %d %d %d", &i_width, &i_height, &maxval) != 3)
38  G_fatal_error("PNG: invalid input file %s", png.file_name);
39 
40  fgetc(input);
41 
42  if (i_width != png.width || i_height != png.height)
44  ("PNG: input file has incorrect dimensions: expected: %dx%d got: %dx%d",
45  png.width, png.height, i_width, i_height);
46 
47  for (y = 0, p = png.grid; y < png.height; y++) {
48  for (x = 0; x < png.width; x++, p++) {
49  unsigned int c = *p;
50 
51  int r = fgetc(input);
52  int g = fgetc(input);
53  int b = fgetc(input);
54 
55  r = r * 255 / maxval;
56  g = g * 255 / maxval;
57  b = b * 255 / maxval;
58 
59  c &= ~rgb_mask;
60  c |= png_get_color(r, g, b, 0);
61 
62  *p = c;
63  }
64  }
65 
66  fclose(input);
67 }
68 
69 void read_pgm(void)
70 {
71  char *mask_name = G_store(png.file_name);
72  FILE *input;
73  int x, y;
74  int i_width, i_height, maxval;
75  unsigned int rgb_mask = png_get_color(255, 255, 255, 0);
76  unsigned int *p;
77 
78  if (!png.true_color)
79  G_fatal_error("PNG: cannot use PPM/PGM with indexed color");
80 
81  mask_name[strlen(mask_name) - 2] = 'g';
82 
83  input = fopen(mask_name, "rb");
84  if (!input)
85  G_fatal_error("PNG: couldn't open input mask file %s", mask_name);
86 
87  if (fscanf(input, "P5 %d %d %d", &i_width, &i_height, &maxval) != 3)
88  G_fatal_error("PNG: invalid input mask file %s", mask_name);
89 
90  fgetc(input);
91 
92  if (i_width != png.width || i_height != png.height)
94  ("PNG: input mask file has incorrect dimensions: expected: %dx%d got: %dx%d",
95  png.width, png.height, i_width, i_height);
96 
97  G_free(mask_name);
98 
99  for (y = 0, p = png.grid; y < png.height; y++) {
100  for (x = 0; x < png.width; x++, p++) {
101  unsigned int c = *p;
102 
103  int k = fgetc(input);
104 
105  k = k * 255 / maxval;
106 
107  c &= rgb_mask;
108  c |= png_get_color(0, 0, 0, 255 - k);
109 
110  *p = c;
111  }
112  }
113 
114  fclose(input);
115 }
void G_free(void *buf)
Free allocated memory.
Definition: gis/alloc.c:149
int width
Definition: pngdriver.h:43
GRASS png display driver - header file.
char * G_store(const char *s)
Copy string to allocated memory.
Definition: strings.c:86
int height
Definition: pngdriver.h:43
#define x
struct png_state png
void G_fatal_error(const char *msg,...)
Print a fatal error message to stderr.
Definition: gis/error.c:159
unsigned int png_get_color(int r, int g, int b, int a)
Definition: color_table.c:120
double b
Definition: r_raster.c:39
char * file_name
Definition: pngdriver.h:33
unsigned int * grid
Definition: pngdriver.h:44
float g
Definition: named_colr.c:8
fclose(fd)
int true_color
Definition: pngdriver.h:35
void read_ppm(void)
double r
Definition: r_raster.c:39
void read_pgm(void)