+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;
+}
+
+static int ismasked(unsigned char **mask, unsigned width, unsigned height)
+{
+ unsigned y, x;
+ for (y = 0; y < height; y++) {
+ for (x = 0; x < width; x++) {
+ if (mask[y][x] == 0) return 1;
+ }
+ }
+
+ return 0;
+}
+
+int outpng(unsigned int frameno,
+ unsigned char **framedata, unsigned char **mask,
+ unsigned int width, unsigned int height,
+ struct lbx_colour palette[static 256])
+{
+ char name[strlen(outname) + sizeof ".65535.png"];
+ unsigned char *row;
+ unsigned int x, y;
+ FILE *of;
+
+ png_structp png;
+ png_infop info;
+
+ assert(frameno < 65536);
+ snprintf(name, sizeof name, "%s.%03d.png", outname, frameno);
+
+ row = malloc(4 * width);
+ if (!row) {
+ errmsg("failed to allocate row buffer: %s\n", strerror(errno));
+ return -1;
+ }
+
+ of = fopen(name, "wb");
+ if (!of) {
+ errmsg("failed to open %s: %s.\n", name, strerror(errno));
+ free(row);
+ 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))) {
+ free(row);
+ png_destroy_write_struct(&png, &info);
+ goto err;
+ }
+
+ png_init_io(png, of);
+
+ if (!ismasked(mask, width, height)) {
+ /*
+ * This case is easy; we can just feed the palette and pixel
+ * data to libpng and let it do its magic.
+ */
+
+ 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_write_png(png, info, PNG_TRANSFORM_IDENTITY, NULL);
+ } else {
+ /*
+ * Unfortunately, LBX doesn't translate nicely to PNG here.
+ * LBX has a 256 colour palette _plus_ transparency.
+ * We'll form an RGBA PNG to deal with this.
+ */
+
+ png_set_IHDR(png, info, width, height, 8,
+ PNG_COLOR_TYPE_RGB_ALPHA, PNG_INTERLACE_NONE,
+ PNG_COMPRESSION_TYPE_DEFAULT,
+ PNG_FILTER_TYPE_DEFAULT);
+
+ png_write_info(png, info);
+
+ for (y = 0; y < height; y++) {
+ for (x = 0; x < width; x++) {
+ row[4*x+0] = palette[framedata[y][x]].red;
+ row[4*x+1] = palette[framedata[y][x]].green;
+ row[4*x+2] = palette[framedata[y][x]].blue;
+ row[4*x+3] = (mask[y][x]) ? -1 : 0;
+ }
+
+ png_write_row(png, row);
+ }
+
+ png_write_end(png, NULL);
+ }
+
+ png_destroy_write_struct(&png, &info);
+ fclose(of);
+
+ if (verbose)
+ printf("wrote %s\n", name);
+
+ return 0;
+
+err:
+ fclose(of);
+ remove(name);
+ free(row);
+ return -1;
+}
+
+static int loadoverride(FILE *f, struct lbx_colour palette[static 256])
+{
+ LBX_IMG *overimg = lbximg_fopen(f);
+ struct lbx_imginfo info;
+
+ if (!overimg) {
+ errmsg("failed to open override image: %s\n", lbx_strerror());
+ return -1;
+ }
+ lbximg_getinfo(overimg, &info);
+
+ if (!info.palettesz) {
+ errmsg("override image has no palette.\n", 0);
+ lbximg_close(overimg);
+ return -1;
+ }
+
+ if (lbximg_getpalette(overimg, palette) == -1) {
+ errmsg("error reading override palette: %s\n", lbx_strerror());
+ lbximg_close(overimg);
+ return -1;
+ }
+
+ lbximg_close(overimg);
+ return 0;
+}
+
+static int loadpalette(LBX_IMG *img, struct lbx_imginfo *info,
+ FILE *palf, FILE *override,
+ struct lbx_colour palette[static 256])
+{
+ int i;
+
+ /* In no-palette mode, use palette indices for colour. */
+ if (!usepalette) {
+ for (i = 0; i < 256; i++) {
+ palette[i] = (struct lbx_colour){i,i,i};
+ }
+
+ return 0;
+ }
+
+ /* For sanity. */
+ if (!palf && !info->palettesz && !override) {
+ errmsg("no palette available.\n", 0);
+ return -1;
+ }
+
+ /* Default the palette to a wonderful pink. */
+ for (i = 0; i < 256; i++) {
+ palette[i] = (struct lbx_colour){0xff, 0x00, 0xff};
+ }
+
+ /* Read the external palette, if any. */
+ if (palf && lbximg_loadpalette(palf, palette) == -1) {
+ errmsg("error reading external palette: %s\n", lbx_strerror());
+ return -1;
+ }
+
+ /* Read the embedded palette, if any. */
+ if (info->palettesz && lbximg_getpalette(img, palette) == -1) {
+ errmsg("error reading embedded palette: %s\n", lbx_strerror());
+ return -1;
+ }
+
+ /* Read the override palette, if any. */
+ if (override && loadoverride(override, palette) == -1) {
+ return -1;
+ }
+
+ return 0;
+}
+
+int decode(LBX_IMG *img, FILE *palf, FILE *override, 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 EXIT_FAILURE;
+ }
+
+ /* 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);
+ }
+ }
+
+ if (loadpalette(img, &info, palf, override, palette) == -1) {
+ goto err;
+ }
+
+ /* Extract the images, in order. */
+ for (i = 0; i < info.nframes; i++) {
+ unsigned char **data;
+ unsigned char **mask;
+
+ if (!(framebits[i / CHAR_BIT] & (1 << (i % CHAR_BIT))))
+ continue;
+
+ data = lbximg_getframe(img, i);
+ if (!data) {
+ errmsg("error in frame %u: %s\n", i, lbx_strerror());
+ continue;
+ }
+
+ mask = lbximg_getmask(img);
+
+ if (!outpng(i, data, mask, 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;
+}
+