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/* See LICENSE file for copyright and license details. */
#include <arpa/inet.h>
#include <errno.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <png.h>
static char *argv0;
void
pngerr(png_structp png_struct_p, png_const_charp msg)
{
fprintf(stderr, "%s: libpng: %s\n", argv0, msg);
exit(1);
}
int
main(int argc, char *argv[])
{
png_structp png_struct_p;
png_infop png_info_p;
png_bytepp png_row_p;
uint32_t width, height, png_row_len, tmp32, r, i;
uint16_t tmp16;
argv0 = argv[0], argc--, argv++;
if (argc) {
fprintf(stderr, "usage: %s\n", argv0);
return 1;
}
/* load png */
png_struct_p = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL,
pngerr, 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", argv0);
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);
width = png_get_image_width(png_struct_p, png_info_p);
height = png_get_image_height(png_struct_p, png_info_p);
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);
if (fwrite(&tmp32, sizeof(uint32_t), 1, stdout) != 1)
goto writerr;
tmp32 = htonl(height);
if (fwrite(&tmp32, sizeof(uint32_t), 1, stdout) != 1)
goto writerr;
/* write data */
switch(png_get_bit_depth(png_struct_p, png_info_p)) {
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]);
if (fwrite(&tmp16, sizeof(uint16_t), 1,
stdout) != 1)
goto writerr;
}
}
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));
if (fwrite(&tmp16, sizeof(uint16_t), 1,
stdout) != 1)
goto writerr;
}
}
break;
default:
fprintf(stderr, "%s: invalid bit-depth\n", argv0);
return 1;
}
png_destroy_read_struct(&png_struct_p, &png_info_p, NULL);
return 0;
writerr:
fprintf(stderr, "%s: fwrite: ", argv0);
perror(NULL);
return 1;
}
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