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	png2ff.c - farbfeld - suckless image format with conversion tools
	git clone git://git.suckless.org/farbfeld
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	png2ff.c (1996B)
	---
	1 /* See LICENSE file for copyright and license details. */
	2 #include <arpa/inet.h>
	3
	4 #include <errno.h>
	5 #include <stdint.h>
	6 #include <stdio.h>
	7 #include <stdlib.h>
	8 #include <string.h>
	9
	10 #include <png.h>
	11
	12 #include "util.h"
	13
	14 static void
	15 png_err(png_struct pngs, const char msg)
	16 {
	17 (void)pngs;
	18 die("libpng: %s", msg);
	19 }
	20
	21 static void
	22 png_setup_reader(png_struct s, png_info i, uint32_t w, uint32_t h)
	23 {
	24 *s = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, png_err…
	25 i = png_create_info_struct(s);
	26
	27 if (!s \|\| !i) {
	28 die("Failed to initialize libpng");
	29 }
	30
	31 png_init_io(*s, stdin);
	32 if (png_get_valid(s, i, PNG_INFO_tRNS)) {
	33 png_set_tRNS_to_alpha(*s);
	34 }
	35 png_set_add_alpha(s, 255257, PNG_FILLER_AFTER);
	36 png_set_expand_gray_1_2_4_to_8(*s);
	37 png_set_gray_to_rgb(*s);
	38 png_set_packing(*s);
	39 png_read_png(s, i, PNG_TRANSFORM_PACKING \| PNG_TRANSFORM_EXPAN…
	40 w = png_get_image_width(s, *i);
	41 h = png_get_image_height(s, *i);
	42 }
	43
	44 static void
	45 usage(void)
	46 {
	47 die("usage: %s", argv0);
	48 }
	49
	50 int
	51 main(int argc, char *argv[])
	52 {
	53 png_struct *pngs;
	54 png_info *pngi;
	55 uint32_t width, height, rowlen, r, i;
	56 uint16_t *row;
	57 uint8_t **pngrows;
	58
	59 /* arguments */
	60 argv0 = argv[0], argc--, argv++;
	61
	62 if (argc) {
	63 usage();
	64 }
	65
	66 /* prepare */
	67 png_setup_reader(&pngs, &pngi, &width, &height);
	68 row = ereallocarray(NULL, width, (sizeof("RGBA") - 1) * sizeof(u…
	69 rowlen = width * (sizeof("RGBA") - 1);
	70 pngrows = png_get_rows(pngs, pngi);
	71
	72 /* write data */
	73 ff_write_header(width, height);
	74
	75 switch(png_get_bit_depth(pngs, pngi)) {
	76 case 8:
	77 for (r = 0; r < height; ++r) {
	78 for (i = 0; i < rowlen; i++) {
	79 row[i] = htons(257 * pngrows[r][i]);
	80 }
	81 efwrite(row, sizeof(uint16_t), rowlen, stdout);
	82 }
	83 break;
	84 case 16:
	85 for (r = 0; r < height; ++r) {
	86 efwrite(pngrows[r], sizeof(uint16_t), rowlen, st…
	87 }
	88 break;
	89 default:
	90 die("Invalid bit-depth");
	91 }
	92
	93 /* clean up */
	94 png_destroy_read_struct(&pngs, &pngi, NULL);
	95
	96 return fshut(stdout, "<stdout>");
	97 }