BGD_DECLARE(gdImagePtr) gdImageCreateFromGifCtx(gdIOCtxPtr fd)
{
	int BitPixel;
#if 0
	int ColorResolution;
	int Background;
	int AspectRatio;
#endif
	int Transparent = (-1);
	unsigned char buf[16];
	unsigned char c;
	unsigned char ColorMap[3][MAXCOLORMAPSIZE];
	unsigned char localColorMap[3][MAXCOLORMAPSIZE];
	int imw, imh, screen_width, screen_height;
	int useGlobalColormap;
	int bitPixel, i;
	/*1.4//int             imageCount = 0; */
	/* 2.0.28: threadsafe storage */
	int ZeroDataBlock = FALSE;
	int haveGlobalColormap;

	gdImagePtr im = 0;

	memset(ColorMap, 0, 3 * MAXCOLORMAPSIZE);
	memset(localColorMap, 0, 3 * MAXCOLORMAPSIZE);

	if(!ReadOK(fd, buf, 6)) {
		return 0;
	}

	if(strncmp((char *)buf, "GIF", 3) != 0) {
		return 0;
	}

	if(memcmp((char *)buf + 3, "87a", 3) == 0) {
		/* GIF87a */
	} else if(memcmp((char *)buf + 3, "89a", 3) == 0) {
		/* GIF89a */
	} else {
		return 0;
	}

	if(!ReadOK(fd, buf, 7)) {
		return 0;
	}

	BitPixel = 2 << (buf[4] & 0x07);
#if 0
	ColorResolution = (int) (((buf[4]&0x70)>>3)+1);
	Background = buf[5];
	AspectRatio = buf[6];
#endif
	screen_width = imw = LM_to_uint(buf[0], buf[1]);
	screen_height = imh = LM_to_uint(buf[2], buf[3]);

	haveGlobalColormap = BitSet(buf[4], LOCALCOLORMAP); /* Global Colormap */
	if(haveGlobalColormap) {
		if(ReadColorMap(fd, BitPixel, ColorMap)) {
			return 0;
		}
	}

	for (;;) {
		int top, left;
		int width, height;

		if(!ReadOK(fd, &c, 1)) {
			return 0;
		}

		if (c == ';') { /* GIF terminator */
			goto terminated;
		}

		if(c == '!') { /* Extension */
			if(!ReadOK(fd, &c, 1)) {
				return 0;
			}

			DoExtension(fd, c, &Transparent, &ZeroDataBlock);
			continue;
		}

		if(c != ',') { /* Not a valid start character */
			continue;
		}

		/*1.4//++imageCount; */

		if(!ReadOK(fd, buf, 9)) {
			return 0;
		}

		useGlobalColormap = !BitSet(buf[8], LOCALCOLORMAP);

		bitPixel = 1 << ((buf[8] & 0x07) + 1);
		left = LM_to_uint(buf[0], buf[1]);
		top = LM_to_uint(buf[2], buf[3]);
		width = LM_to_uint(buf[4], buf[5]);
		height = LM_to_uint(buf[6], buf[7]);

		if(((left + width) > screen_width) || ((top + height) > screen_height)) {
			if(VERBOSE) {
				printf("Frame is not confined to screen dimension.\n");
			}
			return 0;
		}

		if(!(im = gdImageCreate(width, height))) {
			return 0;
		}

		im->interlace = BitSet(buf[8], INTERLACE);
		if(!useGlobalColormap) {
			if(ReadColorMap(fd, bitPixel, localColorMap)) {
				gdImageDestroy(im);
				return 0;
			}

			ReadImage(im, fd, width, height, localColorMap, BitSet(buf[8], INTERLACE), &ZeroDataBlock);
		} else {
			if(!haveGlobalColormap) {
				gdImageDestroy(im);
				return 0;
			}

			ReadImage(im, fd, width, height, ColorMap, BitSet(buf[8], INTERLACE), &ZeroDataBlock);
		}

		if(Transparent != (-1)) {
			gdImageColorTransparent(im, Transparent);
		}

		goto terminated;
	}

terminated:
	/* Terminator before any image was declared! */
	if(!im) {
		return 0;
	}

	if(!im->colorsTotal) {
		gdImageDestroy(im);
		return 0;
	}

	/* Check for open colors at the end, so
	 * we can reduce colorsTotal and ultimately
	 * BitsPerPixel */
	for(i = im->colorsTotal - 1; i >= 0; i--) {
		if(im->open[i]) {
			im->colorsTotal--;
		} else {
			break;
		}
	}

	return im;
}
Unknown