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, NULL);
     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, 255*257, 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_EXPAND, NULL);
     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(uint16_t));
     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, stdout);
     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 }