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cairodriver/write_bmp.c
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/*!
\file lib/cairodriver/write_bmp.c
\brief GRASS cairo display driver - write bitmap (lower level functions)
(C) 2007-2008 by Lars Ahlzen and the GRASS Development Team
This program is free software under the GNU General Public License
(>=v2). Read the file COPYING that comes with GRASS for details.
\author Lars Ahlzen <lars ahlzen.com> (original contributor)
\author Glynn Clements
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <grass/gis.h>
#include <grass/glocale.h>
#include "cairodriver.h"
static unsigned char *put_2(unsigned char *p, unsigned int n)
{
*p++ = n & 0xFF;
n >>= 8;
*p++ = n & 0xFF;
return p;
}
static unsigned char *put_4(unsigned char *p, unsigned int n)
{
*p++ = n & 0xFF;
n >>= 8;
*p++ = n & 0xFF;
n >>= 8;
*p++ = n & 0xFF;
n >>= 8;
*p++ = n & 0xFF;
return p;
}
static void make_bmp_header(unsigned char *p)
{
*p++ = 'B';
*p++ = 'M';
p = put_4(p, HEADER_SIZE + ca.width * ca.height * 4);
p = put_4(p, 0);
p = put_4(p, HEADER_SIZE);
p = put_4(p, 40);
p = put_4(p, ca.width);
p = put_4(p, -ca.height);
p = put_2(p, 1);
p = put_2(p, 32);
p = put_4(p, 0);
p = put_4(p, ca.width * ca.height * 4);
p = put_4(p, 0);
p = put_4(p, 0);
p = put_4(p, 0);
p = put_4(p, 0);
}
void cairo_write_bmp(void)
{
unsigned char header[HEADER_SIZE];
FILE *output;
output = fopen(ca.file_name, "wb");
if (!output)
G_fatal_error(_("Cairo: unable to open output file <%s>"),
ca.file_name);
memset(header, 0, sizeof(header));
make_bmp_header(header);
fwrite(header, sizeof(header), 1, output);
fwrite(ca.grid, ca.stride, ca.height, output);
fclose(output);
}
cairo_write_bmp
void cairo_write_bmp(void)
Definition cairodriver/write_bmp.c:65
cairodriver.h
GRASS cairo display driver - header file.
HEADER_SIZE
#define HEADER_SIZE
Definition cairodriver.h:46
ca
struct cairo_state ca
Definition cairodriver/graph.c:42
G_fatal_error
void G_fatal_error(const char *msg,...)
Print a fatal error message to stderr.
Definition gis/error.c:159
output
void output(const char *fmt,...)
Definition psdriver/graph_set.c:233