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write_png.c
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/*!
\file lib/pngdriver/write_png.c
\brief GRASS png display driver - write PPM image (lower level functions)
(C) 2007-2014 by Glynn Clements 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 Glynn Clements
*/
#include <stdio.h>
#include <stdlib.h>
#include <png.h>
#include <grass/gis.h>
#include <grass/glocale.h>
#include "pngdriver.h"
static void write_data(png_structp png_ptr, png_bytep data, png_size_t length)
{
png_size_t check;
FILE *fp;
if (png_ptr == NULL)
return;
fp = (FILE *)png_get_io_ptr(png_ptr);
if (fp == NULL)
return;
check = fwrite(data, 1, length, fp);
if (check != length)
G_fatal_error(_("Unable to write PNG"));
}
static void output_flush(png_structp png_ptr)
{
FILE *fp;
if (png_ptr == NULL)
return;
fp = (FILE *)png_get_io_ptr(png_ptr);
if (fp == NULL)
return;
fflush(fp);
}
void write_png(void)
{
static jmp_buf jbuf;
static png_struct *png_ptr;
static png_info *info_ptr;
FILE *output;
int x, y;
unsigned int *p;
png_bytep line;
const char *str;
int compress;
png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, &jbuf, NULL, NULL);
if (!png_ptr)
G_fatal_error(_("Unable to allocate PNG structure"));
info_ptr = png_create_info_struct(png_ptr);
if (!info_ptr)
G_fatal_error(_("Unable to allocate PNG structure"));
if (setjmp(png_jmpbuf(png_ptr)))
G_fatal_error(_("Unable to write PNG file"));
output = fopen(png.file_name, "wb");
if (!output)
G_fatal_error(_("Unable to open output PNG file <%s>"), png.file_name);
png_set_write_fn(png_ptr, output, write_data, output_flush);
png_set_IHDR(png_ptr, info_ptr, png.width, png.height, 8,
png.true_color ? PNG_COLOR_TYPE_RGB_ALPHA
: PNG_COLOR_TYPE_PALETTE,
PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT,
PNG_FILTER_TYPE_DEFAULT);
if (png.true_color)
png_set_invert_alpha(png_ptr);
else {
png_color png_pal[256];
int i;
for (i = 0; i < 256; i++) {
png_pal[i].red = png.palette[i][0];
png_pal[i].green = png.palette[i][1];
png_pal[i].blue = png.palette[i][2];
}
png_set_PLTE(png_ptr, info_ptr, png_pal, 256);
if (png.has_alpha) {
png_byte trans = (png_byte)0;
png_set_tRNS(png_ptr, info_ptr, &trans, 1, NULL);
}
}
str = getenv("GRASS_RENDER_FILE_COMPRESSION");
if (str && sscanf(str, "%d", &compress) == 1)
png_set_compression_level(png_ptr, compress);
png_write_info(png_ptr, info_ptr);
line = G_malloc(png.width * 4);
for (y = 0, p = png.grid; y < png.height; y++) {
png_bytep q = line;
if (png.true_color)
for (x = 0; x < png.width; x++, p++) {
unsigned int c = *p;
int r, g, b, a;
png_get_pixel(c, &r, &g, &b, &a);
*q++ = (png_byte)r;
*q++ = (png_byte)g;
*q++ = (png_byte)b;
*q++ = (png_byte)a;
}
else
for (x = 0; x < png.width; x++, p++, q++)
*q = (png_byte)*p;
png_write_row(png_ptr, line);
}
G_free(line);
png_write_end(png_ptr, info_ptr);
png_destroy_write_struct(&png_ptr, &info_ptr);
fclose(output);
}
G_free
void G_free(void *buf)
Free allocated memory.
Definition alloc.c:147
NULL
#define NULL
Definition ccmath.h:32
png_get_pixel
void png_get_pixel(unsigned int pixel, int *r, int *g, int *b, int *a)
Definition color_table.c:110
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
png
struct png_state png
Definition pngdriver/graph_set.c:32
pngdriver.h
GRASS png display driver - header file.
output
void output(const char *fmt,...)
Definition psdriver/graph_set.c:233
write_png
void write_png(void)
Definition write_png.c:55
x
#define x