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/* See LICENSE file for copyright and license details. */
#include <arpa/inet.h>
#include <errno.h>
#include <setjmp.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <png.h>
int
main(int argc, char *argv[])
{
png_structp png_struct_p;
png_infop png_info_p;
png_bytepp png_row_p;
int depth, color, ret = 0;
uint32_t width, height, png_row_len, tmp32, r, i;
uint16_t tmp16;
if (argc > 1) {
fprintf(stderr, "usage: %s\n", argv[0]);
return 1;
}
/* load png */
png_struct_p = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL,
NULL, NULL);
png_info_p = png_create_info_struct(png_struct_p);
if (!png_struct_p || !png_info_p) {
fprintf(stderr, "%s: failed to initialize libpng\n", argv[0]);
return 1;
}
if (setjmp(png_jmpbuf(png_struct_p)))
return 1;
png_init_io(png_struct_p, stdin);
if (png_get_valid(png_struct_p, png_info_p, PNG_INFO_tRNS))
png_set_tRNS_to_alpha(png_struct_p);
png_set_add_alpha(png_struct_p, 255*257, PNG_FILLER_AFTER);
png_set_expand_gray_1_2_4_to_8(png_struct_p);
png_set_gray_to_rgb(png_struct_p);
png_set_packing(png_struct_p);
png_read_png(png_struct_p, png_info_p, PNG_TRANSFORM_PACKING |
PNG_TRANSFORM_EXPAND, NULL);
png_get_IHDR(png_struct_p, png_info_p, &width, &height, &depth,
&color, NULL, NULL, NULL);
png_row_len = png_get_rowbytes(png_struct_p, png_info_p);
png_row_p = png_get_rows(png_struct_p, png_info_p);
/* write header */
fputs("farbfeld", stdout);
tmp32 = htonl(width);
fwrite(&tmp32, sizeof(uint32_t), 1, stdout);
tmp32 = htonl(height);
fwrite(&tmp32, sizeof(uint32_t), 1, stdout);
/* write data */
switch(depth) {
case 8:
for (r = 0; r < height; ++r) {
for (i = 0; i < png_row_len; i++) {
/* ((2^16-1) / 255) == 257 */
tmp16 = htons(257 * png_row_p[r][i]);
fwrite(&tmp16, sizeof(uint16_t), 1, stdout);
}
}
break;
case 16:
for (r = 0; r < height; ++r) {
for (i = 0; i < png_row_len / 2; i++) {
tmp16 = *((uint16_t *)
(png_row_p[r] + 2 * i));
fwrite(&tmp16, sizeof(uint16_t), 1, stdout);
}
}
break;
default:
fprintf(stderr, "%s: format error\n", argv[0]);
return 1;
}
png_destroy_read_struct(&png_struct_p, &png_info_p, NULL);
/* flush output */
if (fflush(stdout)) {
fprintf(stderr, "%s: fflush stdout: ", argv[0]);
perror(NULL);
ret = 1;
}
if (fclose(stdout) && !ret) {
fprintf(stderr, "%s: fclose stdout: ", argv[0]);
perror(NULL);
ret = 1;
}
return ret;
}
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