From 256bcecd3a9a7666c81bb175095402f984379b77 Mon Sep 17 00:00:00 2001
From: Nick Bowler <draconx@gmail.com>
Date: Mon, 31 Dec 2007 02:25:15 -0500
Subject: [PATCH] Implement decoding for lbximg.

---
 src/lbximg.c | 197 ++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 195 insertions(+), 2 deletions(-)

diff --git a/src/lbximg.c b/src/lbximg.c
index 0770049..409936a 100644
--- a/src/lbximg.c
+++ b/src/lbximg.c
@@ -2,11 +2,20 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <limits.h>
+#include <assert.h>
 #include <getopt.h>
+#include <errno.h>
+
+#include <png.h>
 
 #include "image.h"
 #include "lbx.h"
 
+/* Global flags */
+static int verbose = 0;
+static char *outname = "out";
+
 static const char *progname;
 #define errmsg(fmt, ...) (\
 	fprintf(stderr, "%s: " fmt, progname, __VA_ARGS__)\
@@ -18,9 +27,190 @@ enum {
 	MODE_IDENT,
 };
 
+int parserange(struct lbx_imginfo *info, char *str, unsigned char *bits)
+{
+	unsigned long start, end;
+	unsigned int i;
+	char *endptr;
+
+	start = strtoul(str, &endptr, 0);
+	if (start >= info->nframes) {
+		errmsg("frame %lu out of range.\n", start);
+		return -1;
+	}
+
+	if (endptr == str) {
+		errmsg("invalid frame range: %s.\n", str);
+		return -1;
+	}
+
+	switch (*endptr) {
+	case '\0':
+		end = start;
+		break;
+	case '-':
+		end = strtoul(endptr+1, &endptr, 0);
+		if (end >= info->nframes) {
+			errmsg("frame %lu out of range.\n", end);
+			return -1;
+		}
+
+		if (endptr == str)
+			end = info->nframes - 1;
+		break;
+	default:
+		errmsg("invalid frame range: %s.\n", str);
+		return -1;
+	}
+
+	if (end < start) {
+		errmsg("invalid frame range: %s.\n", str);
+		return -1;
+	}
+
+	for (i = start; i <= end; i++) {
+		bits[i / CHAR_BIT] |= 1 << (i % CHAR_BIT);
+	}
+
+	return 0;
+}
+
+int outpng(unsigned int frameno, unsigned char **framedata,
+           unsigned int width,   unsigned int height,
+           struct lbx_colour palette[static 256])
+{
+	char name[strlen(outname) + sizeof ".65535.png"];
+	FILE *of;
+
+	png_structp png;
+	png_infop   info;
+
+	assert(frameno < 65536);
+	snprintf(name, sizeof name, "%s.%03d.png", outname, frameno);
+	
+	of = fopen(name, "wb");
+	if (!of) {
+		errmsg("failed to open %s: %s.\n", name, strerror(errno));
+		return -1;
+	}
+
+	png = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
+	if (!png) {
+		errmsg("failed to init libpng.\n", 0);
+		goto err;
+	}
+
+	info = png_create_info_struct(png);
+	if (!info) {
+		errmsg("failed to init libpng.\n", 0);
+		png_destroy_write_struct(&png, NULL);
+		goto err;
+	}
+
+	if (setjmp(png_jmpbuf(png))) {
+		png_destroy_write_struct(&png, &info);
+		goto err;
+	}
+
+	png_set_IHDR(png, info, width, height, 8, PNG_COLOR_TYPE_PALETTE,
+	             PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT,
+	             PNG_FILTER_TYPE_DEFAULT);
+	png_set_PLTE(png, info, (png_colorp)palette, 256);
+	png_set_rows(png, info, framedata);
+
+	png_init_io(png, of);
+	png_write_png(png, info, PNG_TRANSFORM_IDENTITY, NULL);
+
+	png_destroy_write_struct(&png, &info);
+	fclose(of);
+
+	if (verbose)
+		printf("wrote %s\n", name);
+
+	return 0;
+err:
+	fclose(of);
+	remove(name);
+	return -1;
+}
+
+int decode(LBX_IMG *img, FILE *palf, char **argv)
+{
+	unsigned char *framebits;
+	struct lbx_colour palette[256];
+	struct lbx_imginfo info;
+	int extracted = 0;
+	unsigned int i;
+
+	lbximg_getinfo(img, &info);
+
+	framebits = malloc(info.nframes / CHAR_BIT + 1);
+	if (!framebits) {
+		return -1;
+	}
+
+	/* Figure out what images we're extracting. */
+	if (!argv[0]) {
+		/* extract all images by default. */
+		memset(framebits, -1, info.nframes / CHAR_BIT + 1);
+	} else {
+		for (i = 0; argv[i]; i++) {
+			parserange(&info, argv[i], framebits);
+		}
+	}
+
+	/* Read image palette */
+	if (palf) {
+		if (lbximg_loadpalette(palf, palette) == -1) {
+			errmsg("error reading palette: %s\n", lbx_strerror());
+			goto err;
+		}
+	} else {
+		fprintf(stderr, "warning: no palette specified; "
+		                "decoded images will likely be very pink.\n");
+
+		for (i = 0; i < 256; i++)
+			palette[i] = (struct lbx_colour){0xff, 0x00, 0xff};
+	}
+
+	if (lbximg_getpalette(img, palette) == -1) {
+		errmsg("error reading palette override: %s\n", lbx_strerror());
+		goto err;
+	}
+
+	/* Extract the images, in order. */
+	for (i = 0; i < info.nframes; i++) {
+		unsigned char **framedata;
+
+		if (!(framebits[i / CHAR_BIT] & (1 << (i % CHAR_BIT))))
+			continue;
+
+		framedata = lbximg_getframe(img, i);
+		if (!framedata) {
+			errmsg("error in frame %u: %s\n", i, lbx_strerror());
+			continue;
+		}
+
+		if (!outpng(i, framedata, info.width, info.height, palette)) {
+			extracted = 1;
+		}
+	}
+
+	if (!extracted) {
+		errmsg("no frames extracted.\n", 0);
+		goto err;
+	}
+	
+	free(framebits);
+	return EXIT_SUCCESS;
+err:
+	free(framebits);
+	return EXIT_FAILURE;
+}
+
 int main(int argc, char **argv)
 {
-	int mode = MODE_NONE, verbose = 0;
+	int mode = MODE_NONE;
 	FILE *inf = stdin, *palf = NULL;
 	const char *name = "stdin";
 	LBX_IMG *img;
@@ -96,7 +286,10 @@ int main(int argc, char **argv)
 
 	switch (mode) {
 	case MODE_DECODE:
-		errmsg("decode function not yet implemented.\n", 0);
+		if (decode(img, palf, &argv[optind])) {
+			lbximg_close(img);
+			return EXIT_FAILURE;
+		}
 		break;
 	}
 
-- 
2.43.2