GRASS GIS 8 Programmer's Manual 8.4.1(2025)-45ca3179ab
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get_window.c
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1/*!
2 \file lib/gis/get_window.c
3
4 \brief GIS Library - Get window (i.e. GRASS region)
5
6 (C) 2001-2009, 2011 by 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 Original author CERL
12 */
13
14#include <stdlib.h>
15
16#include <grass/gis.h>
17#include <grass/glocale.h>
18
19#include "G.h"
20#include "gis_local_proto.h"
21
22static struct state {
23 int initialized;
24 struct Cell_head dbwindow;
25} state;
26
27static struct state *st = &state;
28
29/*!
30 \brief Get the current region
31
32 Reads the region as stored in the WIND file in the user's current
33 mapset into region.
34
35 3D values are set to defaults if not available in WIND file. An
36 error message is printed and exit() is called if there is a problem
37 reading the region.
38
39 <b>Note:</b> GRASS applications that read or write raster maps
40 should not use this routine since its use implies that the active
41 module region will not be used. Programs that read or write raster
42 map data (or vector data) can query the active module region using
43 Rast_window_rows() and Rast_window_cols().
44
45 \param[out] window pointer to Cell_head
46 */
47void G_get_window(struct Cell_head *window)
48{
49 const char *regvar;
50
51 if (G_is_initialized(&st->initialized)) {
52 *window = st->dbwindow;
53 return;
54 }
55
56 /* Optionally read the region from environment variable */
57 regvar = getenv("GRASS_REGION");
58
59 if (regvar) {
60 char **tokens = G_tokenize(regvar, ";");
61
62 G__read_Cell_head_array(tokens, &st->dbwindow);
63 G_free_tokens(tokens);
64 }
65 else {
66 char *wind = getenv("WIND_OVERRIDE");
67
68 if (wind)
69 G_get_element_window(&st->dbwindow, "windows", wind, G_mapset());
70 else
71 G_get_element_window(&st->dbwindow, "", "WIND", G_mapset());
72 }
73
74 *window = st->dbwindow;
75
76 if (!G__.window_set) {
77 G__.window_set = 1;
78 G__.window = st->dbwindow;
79 }
80
81 G_initialize_done(&st->initialized);
82}
83
84/*!
85 \brief Get the default region
86
87 Reads the default region for the location into <i>region.</i> 3D
88 values are set to defaults if not available in WIND file.
89
90 An error message is printed and exit() is called if there is a
91 problem reading the default region.
92
93 \param[out] window pointer to Cell_head
94 */
95void G_get_default_window(struct Cell_head *window)
96{
97 G_get_element_window(window, "", "DEFAULT_WIND", "PERMANENT");
98}
99
100/*!
101 \brief Get region for selected element (raster, vector, window, etc.)
102
103 G_fatal_error() is called on error
104
105 \param[out] window pointer to Cell_head
106 \param element element type
107 \param name element name
108 \param mapset mapset name
109 */
110void G_get_element_window(struct Cell_head *window, const char *element,
111 const char *name, const char *mapset)
112{
113 FILE *fp;
114
115 G_zero(window, sizeof(struct Cell_head));
116
117 /* Read from file */
118 fp = G_fopen_old(element, name, mapset);
119 if (!fp)
120 G_fatal_error(_("Unable to open element file <%s> for <%s@%s>"),
121 element, name, mapset);
122
123 G_fseek(fp, 0, SEEK_END);
124 if (!G_ftell(fp))
125 G_fatal_error(_("Region file %s/%s/%s is empty"), mapset, element,
126 name);
127 G_fseek(fp, 0, SEEK_SET);
128 G__read_Cell_head(fp, window);
129 fclose(fp);
130}
131
132/*!
133 \brief Unset current region
134 */
136{
137 st->initialized = 0;
138 G__.window_set = 0;
139}
void G_initialize_done(int *p)
Definition counter.c:77
int G_is_initialized(int *p)
Definition counter.c:60
void G_get_window(struct Cell_head *window)
Get the current region.
Definition get_window.c:47
void G_get_element_window(struct Cell_head *window, const char *element, const char *name, const char *mapset)
Get region for selected element (raster, vector, window, etc.)
Definition get_window.c:110
void G_unset_window(void)
Unset current region.
Definition get_window.c:135
void G_get_default_window(struct Cell_head *window)
Get the default region.
Definition get_window.c:95
void G_fatal_error(const char *msg,...)
Print a fatal error message to stderr.
Definition gis/error.c:159
FILE * G_fopen_old(const char *element, const char *name, const char *mapset)
Open a database file for reading.
Definition gis/open.c:251
void G_fseek(FILE *fp, off_t offset, int whence)
Change the file position of the stream.
Definition gis/seek.c:50
off_t G_ftell(FILE *fp)
Get the current file position of the stream.
Definition gis/seek.c:29
const char * G_mapset(void)
Get current mapset name.
Definition mapset.c:33
const char * name
Definition named_colr.c:6
void G__read_Cell_head_array(char **array, struct Cell_head *cellhd)
Read window from NULL terminated array of strings (for internal use only)
Definition rd_cellhd.c:96
void G__read_Cell_head(FILE *fd, struct Cell_head *cellhd)
Read cell header (for internal use only)
Definition rd_cellhd.c:56
Definition G.h:5
int window_set
Definition G.h:7
struct Cell_head window
Definition G.h:6
void G_free_tokens(char **tokens)
Free memory allocated to tokens.
Definition token.c:198
char ** G_tokenize(const char *buf, const char *delim)
Tokenize string.
Definition token.c:47
void G_zero(void *buf, int i)
Zero out a buffer, buf, of length i.
Definition zero.c:23