color_gif.c

图像置乱代码

/* GIF loader for tina tools.
 * loosely based upon ... */


/* +-------------------------------------------------------------------+ */
/* | Copyright 1990, David Koblas.                                     | */
/* |   Permission to use, copy, modify, and distribute this software   | */
/* |   and its documentation for any purpose and without fee is hereby | */
/* |   granted, provided that the above copyright notice appear in all | */
/* |   copies and that both that copyright notice and this permission  | */
/* |   notice appear in supporting documentation.  This software is    | */
/* |   provided "as is" without express or implied warranty.           | */
/* +-------------------------------------------------------------------+ */

/* sam 13.7.1995 */

#include <tina/gif.h>

int	GetPixel( int x, int y );
void compress( int init_bits, FILE *outfile, ifunptr ReadValue );
void output( code_int code );
void cl_block (void);
void	cl_hash(register count_int hsize);
void	writeerr(void);
void char_init(void);
void char_out( int c );
void	flush_char(void);




pixel	*Image = NULL;
Imrect	*OpIm	= NULL;
static int	verbose;
int	showComment;

extern Imrect *ReadGIF(char *fn, int imageNumber)
{
	unsigned char	buf[16];
	unsigned char	c;
	unsigned char	localColorMap[3][MAXCOLORMAPSIZE];
	int		useGlobalColormap;
	int		bitPixel;
	int		imageCount = 0;
	char		version[4];
	Imrect	*opim=NULL;
	FILE	*fd;
		
	fd=fopen(fn,"rb");

	if (fd==NULL)
	{
		error("GIF:cannot load file.\n",non_fatal);
		return NULL;
	}

	if (! ReadOK(fd,buf,6)) {
		error("GIF:error reading magic number\n" , non_fatal);
		return;
	}

	if (strncmp(buf,"GIF",3) != 0)
	{
		error("GIF:not a GIF file\n", non_fatal );
		return;
	}

	strncpy(version, buf + 3, 3);
	version[3] = '\0';

	if ((strcmp(version, "87a") != 0) && (strcmp(version, "89a") != 0))
	{
		error("GIF:bad version number, not '87a' or '89a'\n",non_fatal );
		return;
	}

	if (!ReadOK(fd,buf,7))
	{
		error("GIF:failed to read screen descriptor", non_fatal );
		return;
	}	

	GifScreen.Width           = LM_to_uint(buf[0],buf[1]);
	GifScreen.Height          = LM_to_uint(buf[2],buf[3]);
	GifScreen.BitPixel        = 2<<(buf[4]&0x07);
	GifScreen.ColorResolution = (((buf[4]&0x70)>>3)+1);
	GifScreen.Background      = buf[5];
	GifScreen.AspectRatio     = buf[6];

	#ifdef DEBUG
		fprintf(stdout, "Found image %dx%d\n", GifScreen.Width,
						 GifScreen.Height);
	#endif

	if (BitSet(buf[4], LOCALCOLORMAP)) {	/* Global Colormap */
		if (ReadColorMap(fd,GifScreen.BitPixel,GifScreen.ColorMap))
		{
			error("GIF:error reading global colormap\n", non_fatal );
			return;
		}
	}

	if (GifScreen.AspectRatio != 0 && GifScreen.AspectRatio != 49) {
		float	r;
		r = ( (float) GifScreen.AspectRatio + 15.0 ) / 64.0;
		pm_message("warning - non-square pixels; to fix do a 'pnmscale -%cscale %g'" );
	}

	for (;;) 
	{
		if (!ReadOK(fd,&c,1))
		{
			/*error("GIF:EOF1 / read error on image data\n", non_fatal );*/
			/* sam. we always get this error ... */
			break;
		}

		if (c == ';') {		/* GIF terminator */
			if (imageCount < imageNumber)
			{
				error("GIF:too few images found in file", non_fatal);
				return;
			}
		}

		if (c == '!') { 	/* Extension */
			if (! ReadOK(fd,&c,1))
			{
				error("GIF:OF / read error on extention function code\n",non_fatal);
				return;
			}
			DoExtension(fd, c);
			continue;
		}

		if (c != ',') {		/* Not a valid start character */
			pm_message("bogus character 0x%02x, ignoring" );
			continue;
		}

		++imageCount;

		if (! ReadOK(fd,buf,9))
		{
			error("GIF:couldn't read left/top/width/height\n",non_fatal);
			return;
		}

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

		bitPixel = 1<<((buf[8]&0x07)+1);

		if (! useGlobalColormap) {
			if (ReadColorMap(fd, bitPixel, localColorMap))
			{
				error("GIF:error reading local colormap\n" , non_fatal);
				return;
			}
			opim=ReadImage(fd, LM_to_uint(buf[4],buf[5]),
				  LM_to_uint(buf[6],buf[7]), localColorMap,
				  BitSet(buf[8], INTERLACE), imageCount != imageNumber);
		} else {
			opim=ReadImage(fd, LM_to_uint(buf[4],buf[5]),
				  LM_to_uint(buf[6],buf[7]), GifScreen.ColorMap,
				  BitSet(buf[8], INTERLACE), imageCount != imageNumber);
		}

	}

	return opim;
}

extern int	ReadColorMap(FILE *fd,int number,unsigned char buffer[3][MAXCOLORMAPSIZE] )
{
	int		i;
	unsigned char	rgb[3];

	for (i = 0; i < number; ++i) {
		if (! ReadOK(fd, rgb, sizeof(rgb)))
		{
			error("GIF:bad colormap\n",non_fatal );
			return;
		}

		buffer[CM_RED][i] = rgb[0] ;
		buffer[CM_GREEN][i] = rgb[1] ;
		buffer[CM_BLUE][i] = rgb[2] ;
	}
	return FALSE;
}


extern int DoExtension(FILE *fd, int label)
{
	static char	buf[256];
	char		*str;

	switch (label) {
	case 0x01:		/* Plain Text Extension */
		str = "Plain Text Extension";
#ifdef notdef
		if (GetDataBlock(fd, (unsigned char*) buf) == 0)
			;

		lpos   = LM_to_uint(buf[0], buf[1]);
		tpos   = LM_to_uint(buf[2], buf[3]);
		width  = LM_to_uint(buf[4], buf[5]);
		height = LM_to_uint(buf[6], buf[7]);
		cellw  = buf[8];
		cellh  = buf[9];
		foreground = buf[10];
		background = buf[11];

		while (GetDataBlock(fd, (unsigned char*) buf) != 0) {
			PPM_ASSIGN(image[ypos][xpos],
					cmap[CM_RED][v],
					cmap[CM_GREEN][v],
					cmap[CM_BLUE][v]);
			++index;
		}

		return FALSE;
#else
		break;
#endif
	case 0xff:		/* Application Extension */
		str = "Application Extension";
		break;
	case 0xfe:		/* Comment Extension */
		str = "Comment Extension";
		while (GetDataBlock(fd, (unsigned char*) buf) != 0) {
			if (showComment)
				pm_message("gif comment: %s" );
		}
		return FALSE;
	case 0xf9:		/* Graphic Control Extension */
		str = "Graphic Control Extension";
		(void) GetDataBlock(fd, (unsigned char*) buf);
		Gif89.disposal    = (buf[0] >> 2) & 0x7;
		Gif89.inputFlag   = (buf[0] >> 1) & 0x1;
		Gif89.delayTime   = LM_to_uint(buf[1],buf[2]);
		if ((buf[0] & 0x1) != 0)
			Gif89.transparent = buf[3];

		while (GetDataBlock(fd, (unsigned char*) buf) != 0)
			;
		return FALSE;
	default:
		str = buf;
		sprintf(buf, "UNKNOWN (0x%02x)", label);
		break;
	}

	pm_message("got a '%s' extension - please report this to [e-mail]" );

	while (GetDataBlock(fd, (unsigned char*) buf) != 0)
		;

	return FALSE;
}

int	ZeroDataBlock = FALSE;

extern int GetDataBlock(FILE *fd, unsigned char *buf)
{
	unsigned char	count;

	if (! ReadOK(fd,&count,1)) {
		pm_message("error in getting DataBlock size" );
		return -1;
	}

	ZeroDataBlock = count == 0;

	if ((count != 0) && (! ReadOK(fd, buf, count))) {
		pm_message("error in reading DataBlock" );
		return -1;
	}

	return count;
}

extern int GetCode(FILE *fd, int code_size, int flag)
{
	static unsigned char	buf[280];
	static int		curbit, lastbit, done, last_byte;
	int			i, j, ret;
	unsigned char		count;

	if (flag) {
		curbit = 0;
		lastbit = 0;
		done = FALSE;
		return 0;
	}

	if ( (curbit+code_size) >= lastbit) {
		if (done) {
			if (curbit >= lastbit)
			{
				error("GIF:ran off the end of my bits\n",non_fatal );
				return;
			}
			return -1;
		}
		buf[0] = buf[last_byte-2];
		buf[1] = buf[last_byte-1];

		if ((count = GetDataBlock(fd, &buf[2])) == 0)
			done = TRUE;

		last_byte = 2 + count;
		curbit = (curbit - lastbit) + 16;
		lastbit = (2+count)*8 ;
	}

	ret = 0;
	for (i = curbit, j = 0; j < code_size; ++i, ++j)
		ret |= ((buf[ i / 8 ] & (1 << (i % 8))) != 0) << j;

	curbit += code_size;

	return ret;
}

extern int LWZReadByte(FILE *fd, int flag, int input_code_size)
{
	static int	fresh = FALSE;
	int		code, incode;
	static int	code_size, set_code_size;
	static int	max_code, max_code_size;
	static int	firstcode, oldcode;
	static int	clear_code, end_code;
	static int	table[2][(1<< MAX_LWZ_BITS)];
	static int	stack[(1<<(MAX_LWZ_BITS))*2], *sp;
	register int	i;

	if (flag) {
		set_code_size = input_code_size;
		code_size = set_code_size+1;
		clear_code = 1 << set_code_size ;
		end_code = clear_code + 1;
		max_code_size = 2*clear_code;
		max_code = clear_code+2;

		GetCode(fd, 0, TRUE);
		
		fresh = TRUE;

		for (i = 0; i < clear_code; ++i) {
			table[0][i] = 0;
			table[1][i] = i;
		}
		for (; i < (1<<MAX_LWZ_BITS); ++i)
			table[0][i] = table[1][0] = 0;

		sp = stack;

		return 0;
	} else if (fresh) {
		fresh = FALSE;
		do {
			firstcode = oldcode =
				GetCode(fd, code_size, FALSE);
		} while (firstcode == clear_code);
		return firstcode;
	}

	if (sp > stack)
		return *--sp;

	while ((code = GetCode(fd, code_size, FALSE)) >= 0) {
		if (code == clear_code) {
			for (i = 0; i < clear_code; ++i) {
				table[0][i] = 0;
				table[1][i] = i;
			}
			for (; i < (1<<MAX_LWZ_BITS); ++i)
				table[0][i] = table[1][i] = 0;
			code_size = set_code_size+1;
			max_code_size = 2*clear_code;
			max_code = clear_code+2;
			sp = stack;
			firstcode = oldcode =
					GetCode(fd, code_size, FALSE);
			return firstcode;
		} else if (code == end_code) {
			int		count;
			unsigned char	buf[260];

			if (ZeroDataBlock)
				return -2;

			while ((count = GetDataBlock(fd, buf)) > 0)
				;

			if (count != 0)
				pm_message("missing EOD in data stream (common occurence)");
			return -2;
		}

		incode = code;

		if (code >= max_code) {
			*sp++ = firstcode;
			code = oldcode;
		}

		while (code >= clear_code) {
			*sp++ = table[1][code];
			if (code == table[0][code])
			{
				error("GIF:circular table entry BIG ERROR\n",non_fatal);
				return;
			}
			code = table[0][code];
		}

		*sp++ = firstcode = table[1][code];

		if ((code = max_code) <(1<<MAX_LWZ_BITS)) {
			table[0][code] = oldcode;
			table[1][code] = firstcode;
			++max_code;
			if ((max_code >= max_code_size) &&
				(max_code_size < (1<<MAX_LWZ_BITS))) {
				max_code_size *= 2;
				++code_size;
			}
		}

		oldcode = incode;

		if (sp > stack)
			return *--sp;
	}
	return code;
}


extern Imrect *ReadImage(FILE *fd, int len, int height, 
			unsigned char cmap[3][MAXCOLORMAPSIZE], int interlace, int ignore)
{
	unsigned char	c;	
	int		v;
	int		xpos = 0, ypos = 0, pass = 0;
	pixel		**image,pxl;
	Imrect		*opim;

	#ifdef DEBUG
		long	pix_count=0;
	#endif

	/*
	**  Initialize the Compression routines
	*/

	#ifdef DEBUG
		printf("Reading Image ...\n");
	#endif

	if (!ReadOK(fd,&c,1))
	{
		error("GIF:EOF2 / read error on image data\n",non_fatal );
		return;
	}

	if (LWZReadByte(fd, TRUE, c) < 0)
	{
		error("GIF:error reading image\n", non_fatal );
		return;
	}

	/*
	**  If this is an "uninteresting picture" ignore it.
	*/
	if (ignore) {
		if (verbose)
			pm_message("skipping image..." );

		while (LWZReadByte(fd, FALSE, c) >= 0)
			;
		return;
	}

	if ((image = ppm_allocarray(len, height)) == NULL)
	{
		error("GIF:couldn't alloc space for image\n", non_fatal );
		return;
	}

	if (verbose)
		pm_message("reading %d by %d%s GIF image" );

	while ((v = LWZReadByte(fd,FALSE,c)) >= 0 ) {
		pxl.r = cmap[CM_RED][v];
		pxl.g = cmap[CM_GREEN][v];
		pxl.b = cmap[CM_BLUE][v];
	
		image[ypos][xpos].r = pxl.r;
		image[ypos][xpos].g = pxl.g;
		image[ypos][xpos].b = pxl.b;
		
		#ifdef DEBUG
			pix_count++;
		#endif
		

		++xpos;
		if (xpos == len) {
			xpos = 0;
			if (interlace) {
				switch (pass) {
				case 0:
				case 1:
					ypos += 8; break;
				case 2:
					ypos += 4; break;
				case 3:
					ypos += 2; break;
				}

				if (ypos >= height) {
					++pass;
					switch (pass) {
					case 1:
						ypos = 4; break;
					case 2:
						ypos = 2; break;
					case 3:
						ypos = 1; break;
					default:
						goto fini;
					}
				}
			} else {
				++ypos;
			}
		}

		if (ypos >= height)
			break;
	}

fini:
	if (LWZReadByte(fd,FALSE,c)>=0)
		pm_message("too much input data, ignoring extra...");

	#ifdef DEBUG
		printf("Read %ld pixels \n",pix_count);
	#endif

	/* and NOW convert the data to an Imrect */
	opim= PixelToImrect( image, len, height );

	free(image);

	return opim;
}


Imrect	*PixelToImrect( pixel **image, int width, int height)
{
	Imrect	*opm;
	pixel	p;
	int		i,j,pix;

	#ifdef DEBUG
		printf("Converting to imrect ...\n");
	#endif

	opm= im_alloc( height,width, NULL, int_v);
	if (opm==NULL)
	{
		error("GIF: unable to allocate imrect \n", non_fatal);
		return NULL;
	}
	
	for (j=0;j<height;j++)
	{
		for (i=0;i<width;i++)
		{
			p.r = image[j][i].r;
			p.g = image[j][i].g;
			p.b = image[j][i].b;
		
			pix = p.r + p.g + p.b;
			pix /=3;
			IM_PIX_SET( opm, j, i, pix);
		}
	}

	return opm;
}


/* sam 13.7.1995 */
void	pm_message(char *m)
{
	format("Gif");
	format(m);
	format("\n");
}


FILE	*pm_openr(char *name)
{
	return fopen(name,"rb");
}


void	pm_close(FILE *fn)
{
	fclose(fn);
}

char** pm_allocarray( int cols, int rows, int size )
{
	int		i;
	char	**p;

	p = (char **) malloc( rows * sizeof(char *));
	for (i=0;i<rows;i++)
		*(p+i) = (char *)malloc(cols * size);

	return  p;
}

/* Case-insensitive keyword matcher. */

int pm_keymatch( char* str, char* keyword, int minchars )
{
	return strncmp(str,keyword,minchars);
}


void	gif_write_file(Imrect *opm, char *pn)
{
	int	rows = opm->height,cols = opm->width,i;	
	int interlace =0;
	int BitsPerPixel = 8;
    int Red[MAXCOLORS], Green[MAXCOLORS], Blue[MAXCOLORS];

	FILE *opf;

	if ((opf = fopen( pn , "w+b"))==NULL)
	{
		error("gif:Unable to open op file!\n", non_fatal);
		return;
	}


	/* make up a palette */
	for (i=0;i<256;i++)
	{
		Red[i]=Green[i]=Blue[i]=i;
	}

	OpIm = opm;

    GIFEncode( opf, cols, rows, interlace, 0, BitsPerPixel, 
				Red, Green, Blue, GetPixel );

	fclose(opf);
}

void	gif_write_file_color(Imrect *opm, char *pn)
{
	int	rows = opm->height,cols = opm->width,i;	
	int interlace =0;
	int BitsPerPixel = 8;
    int Red[MAXCOLORS], Green[MAXCOLORS], Blue[MAXCOLORS];