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cairodriver/read_ppm.c
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/*!
\file lib/cairodriver/read_ppm.c
\brief GRASS cairo display driver - read PPM image (lower level functions)
(C) 2007-2008, 2011 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 <grass/glocale.h>
#include "cairodriver.h"
void cairo_read_ppm(void)
{
char *mask_name = G_store(ca.file_name);
FILE *input, *mask;
int x, y;
int i_width, i_height, maxval;
input = fopen(ca.file_name, "rb");
if (!input)
G_fatal_error(_("Cairo: unable to open input file <%s>"), ca.file_name);
if (fscanf(input, "P6 %d %d %d", &i_width, &i_height, &maxval) != 3)
G_fatal_error(_("Cairo: invalid input file <%s>"), ca.file_name);
if (fgetc(input) == EOF)
G_fatal_error(_("Cairo: unexpected EOF reading <%s>"), ca.file_name);
if (i_width != ca.width || i_height != ca.height)
G_fatal_error(_("Cairo: input file has incorrect dimensions: "
"expected: %dx%d got: %dx%d"),
ca.width, ca.height, i_width, i_height);
mask_name[strlen(mask_name) - 2] = 'g';
mask = fopen(mask_name, "rb");
if (!mask)
G_fatal_error(_("Cairo: unable to open input mask file <%s>"),
mask_name);
if (fscanf(mask, "P5 %d %d %d", &i_width, &i_height, &maxval) != 3)
G_fatal_error(_("Cairo: invalid input mask file <%s>"), mask_name);
if (fgetc(mask) == EOF)
G_fatal_error(_("Cairo: unexpected EOF reading mask <%s>"), mask_name);
if (i_width != ca.width || i_height != ca.height)
G_fatal_error(_("Cairo: input mask file has incorrect dimensions: "
"expected: %dx%d got: %dx%d"),
ca.width, ca.height, i_width, i_height);
G_free(mask_name);
for (y = 0; y < ca.height; y++) {
unsigned int *row = (unsigned int *)(ca.grid + y * ca.stride);
for (x = 0; x < ca.width; x++) {
int r = fgetc(input);
int g = fgetc(input);
int b = fgetc(input);
int a = fgetc(mask);
r = r * 255 / maxval;
g = g * 255 / maxval;
b = b * 255 / maxval;
a = a * 255 / maxval;
if (a > 0 && a < 0xFF) {
r = r * a / 0xFF;
g = g * a / 0xFF;
b = b * a / 0xFF;
}
row[x] = (a << 24) | (r << 16) | (g << 8) | (b << 0);
}
}
fclose(input);
fclose(mask);
}
G_free
void G_free(void *buf)
Free allocated memory.
Definition alloc.c:147
cairo_read_ppm
void cairo_read_ppm(void)
Definition cairodriver/read_ppm.c:19
cairodriver.h
GRASS cairo display driver - header file.
ca
struct cairo_state ca
Definition cairodriver/graph.c:42
b
double b
Definition driver/set_window.c:5
r
double r
Definition driver/set_window.c:5
G_fatal_error
void G_fatal_error(const char *msg,...)
Print a fatal error message to stderr.
Definition gis/error.c:159
g
float g
Definition named_colr.c:7
G_store
char * G_store(const char *s)
Copy string to allocated memory.
Definition strings.c:87
x
#define x