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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 <string.h>
#include <png.h>
static char *argv0;
void
pngerr(png_structp pngs, const char *msg)
{
fprintf(stderr, "%s: libpng: %s\n", argv0, msg);
exit(1);
}
int
main(int argc, char *argv[])
{
png_structp pngs;
png_infop pngi;
uint32_t width, height, outrowlen, tmp32, r, i;
uint16_t *outrow;
uint8_t **png_row_p;
argv0 = argv[0], argc--, argv++;
if (argc) {
fprintf(stderr, "usage: %s\n", argv0);
return 1;
}
/* load png */
pngs = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, pngerr,
NULL);
pngi = png_create_info_struct(pngs);
if (!pngs || !pngi) {
fprintf(stderr, "%s: failed to initialize libpng\n", argv0);
return 1;
}
png_init_io(pngs, stdin);
if (png_get_valid(pngs, pngi, PNG_INFO_tRNS))
png_set_tRNS_to_alpha(pngs);
png_set_add_alpha(pngs, 255*257, PNG_FILLER_AFTER);
png_set_expand_gray_1_2_4_to_8(pngs);
png_set_gray_to_rgb(pngs);
png_set_packing(pngs);
png_read_png(pngs, pngi, PNG_TRANSFORM_PACKING |
PNG_TRANSFORM_EXPAND, NULL);
width = png_get_image_width(pngs, pngi);
height = png_get_image_height(pngs, pngi);
png_row_p = png_get_rows(pngs, pngi);
/* allocate output row buffer */
outrowlen = width * strlen("RGBA");
if (!(outrow = malloc(outrowlen * sizeof(uint16_t)))) {
fprintf(stderr, "%s: malloc: out of memory\n", argv0);
return 1;
}
/* 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(pngs, pngi)) {
case 8:
for (r = 0; r < height; ++r) {
for (i = 0; i < outrowlen; i++) {
outrow[i] = htons(257 * png_row_p[r][i]);
}
if (fwrite(outrow, sizeof(uint16_t), outrowlen,
stdout) != outrowlen) {
goto writerr;
}
}
break;
case 16:
for (r = 0; r < height; ++r) {
for (i = 0; i < outrowlen; ++i) {
outrow[i] = ((uint16_t *)png_row_p[r])[i];
}
if (fwrite(outrow, sizeof(uint16_t), outrowlen,
stdout) != outrowlen) {
goto writerr;
}
}
break;
default:
fprintf(stderr, "%s: invalid bit-depth\n", argv0);
return 1;
}
png_destroy_read_struct(&pngs, &pngi, NULL);
return 0;
writerr:
fprintf(stderr, "%s: fwrite: ", argv0);
perror(NULL);
return 1;
}
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