/* * tkImgGIF.c -- * *	A photo image file handler for GIF files. Reads 87a and 89a GIF *	files. At present there is no write function.  GIF images may be *	read using the -data option of the photo image by representing *	the data as BASE64 encoded ascii.  Derived from the giftoppm code *	found in the pbmplus package and tkImgFmtPPM.c in the tk4.0b2 *	distribution. * * Copyright (c) Reed Wade (wade@cs.utk.edu), University of Tennessee * Copyright (c) 1995-1997 Sun Microsystems, Inc. * * See the file "license.terms" for information on usage and redistribution * of this file, and for a DISCLAIMER OF ALL WARRANTIES. * * This file also contains code from the giftoppm program, which is * copyrighted as follows: * * +-------------------------------------------------------------------+ * | 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.           | * +-------------------------------------------------------------------+ * * SCCS: @(#) tkImgGIF.c 1.19 97/08/13 15:23:45 *//* * GIF's are represented as data in base64 format. * base64 strings consist of 4 6-bit characters -> 3 8 bit bytes. * A-Z, a-z, 0-9, + and / represent the 64 values (in order). * '=' is a trailing padding char when the un-encoded data is not a * multiple of 3 bytes.  We'll ignore white space when encountered. * Any other invalid character is treated as an EOF */#define GIF_SPECIAL	 (256)#define GIF_PAD		(GIF_SPECIAL+1)#define GIF_SPACE	(GIF_SPECIAL+2)#define GIF_BAD		(GIF_SPECIAL+3)#define GIF_DONE	(GIF_SPECIAL+4)/* * structure to "mimic" FILE for Mread, so we can look like fread. * The decoder state keeps track of which byte we are about to read, * or EOF. */typedef struct mFile {    unsigned char *data;	/* mmencoded source string */    int c;			/* bits left over from previous character */    int state;			/* decoder state (0-4 or GIF_DONE) */} MFile;#include "tkInt.h"#include "tkPort.h"/* * The format record for the GIF file format: */static int      FileMatchGIF _ANSI_ARGS_((Tcl_Channel chan, char *fileName,		    char *formatString, int *widthPtr, int *heightPtr));static int      FileReadGIF  _ANSI_ARGS_((Tcl_Interp *interp,		    Tcl_Channel chan, char *fileName, char *formatString,		    Tk_PhotoHandle imageHandle, int destX, int destY,		    int width, int height, int srcX, int srcY));static int	StringMatchGIF _ANSI_ARGS_(( char *string,		    char *formatString, int *widthPtr, int *heightPtr));static int	StringReadGIF _ANSI_ARGS_((Tcl_Interp *interp, char *string,		    char *formatString, Tk_PhotoHandle imageHandle,		    int destX, int destY, int width, int height,		    int srcX, int srcY));Tk_PhotoImageFormat tkImgFmtGIF = {	"GIF",			/* name */	FileMatchGIF,   /* fileMatchProc */	StringMatchGIF, /* stringMatchProc */	FileReadGIF,    /* fileReadProc */	StringReadGIF,  /* stringReadProc */	NULL,           /* fileWriteProc */	NULL,           /* stringWriteProc */};#define INTERLACE		0x40#define LOCALCOLORMAP		0x80#define BitSet(byte, bit)	(((byte) & (bit)) == (bit))#define MAXCOLORMAPSIZE		256#define CM_RED			0#define CM_GREEN		1#define CM_BLUE			2#define CM_ALPHA		3#define MAX_LWZ_BITS		12#define LM_to_uint(a,b)         (((b)<<8)|(a))#define ReadOK(file,buffer,len)	(Fread(buffer, len, 1, file) != 0)/* * 			 HACK ALERT!!  HACK ALERT!!  HACK ALERT!! * This code is hard-wired for reading from files.  In order to read * from a data stream, we'll trick fread so we can reuse the same code */ static int fromData=0;/* * Prototypes for local procedures defined in this file: */static int		DoExtension _ANSI_ARGS_((Tcl_Channel chan, int label,			    int *transparent));static int		GetCode _ANSI_ARGS_((Tcl_Channel chan, int code_size,			    int flag));static int		GetDataBlock _ANSI_ARGS_((Tcl_Channel chan,			    unsigned char *buf));static int		LWZReadByte _ANSI_ARGS_((Tcl_Channel chan, int flag,			    int input_code_size));static int		ReadColorMap _ANSI_ARGS_((Tcl_Channel chan, int number,			    unsigned char buffer[MAXCOLORMAPSIZE][4]));static int		ReadGIFHeader _ANSI_ARGS_((Tcl_Channel chan,			    int *widthPtr, int *heightPtr));static int		ReadImage _ANSI_ARGS_((Tcl_Interp *interp,			    char *imagePtr, Tcl_Channel chan,			    int len, int rows,			    unsigned char cmap[MAXCOLORMAPSIZE][4],			    int width, int height, int srcX, int srcY,			    int interlace, int transparent));/* * these are for the BASE64 image reader code only */static int		Fread _ANSI_ARGS_((unsigned char *dst, size_t size,			    size_t count, Tcl_Channel chan));static int		Mread _ANSI_ARGS_((unsigned char *dst, size_t size,			    size_t count, MFile *handle));static int		Mgetc _ANSI_ARGS_((MFile *handle));static int		char64 _ANSI_ARGS_((int c));static void		mInit _ANSI_ARGS_((unsigned char *string,			    MFile *handle));/* *---------------------------------------------------------------------- * * FileMatchGIF -- * *	This procedure is invoked by the photo image type to see if *	a file contains image data in GIF format. * * Results: *	The return value is 1 if the first characters in file f look *	like GIF data, and 0 otherwise. * * Side effects: *	The access position in f may change. * *---------------------------------------------------------------------- */static intFileMatchGIF(chan, fileName, formatString, widthPtr, heightPtr)    Tcl_Channel chan;		/* The image file, open for reading. */    char *fileName;		/* The name of the image file. */    char *formatString;		/* User-specified format string, or NULL. */    int *widthPtr, *heightPtr;	/* The dimensions of the image are				 * returned here if the file is a valid				 * raw GIF file. */{	return ReadGIFHeader(chan, widthPtr, heightPtr);}/* *---------------------------------------------------------------------- * * FileReadGIF -- * *	This procedure is called by the photo image type to read *	GIF format data from a file and write it into a given *	photo image. * * Results: *	A standard TCL completion code.  If TCL_ERROR is returned *	then an error message is left in interp->result. * * Side effects: *	The access position in file f is changed, and new data is *	added to the image given by imageHandle. * *---------------------------------------------------------------------- */static intFileReadGIF(interp, chan, fileName, formatString, imageHandle, destX, destY,	width, height, srcX, srcY)    Tcl_Interp *interp;		/* Interpreter to use for reporting errors. */    Tcl_Channel chan;		/* The image file, open for reading. */    char *fileName;		/* The name of the image file. */    char *formatString;		/* User-specified format string, or NULL. */    Tk_PhotoHandle imageHandle;	/* The photo image to write into. */    int destX, destY;		/* Coordinates of top-left pixel in				 * photo image to be written to. */    int width, height;		/* Dimensions of block of photo image to				 * be written to. */    int srcX, srcY;		/* Coordinates of top-left pixel to be used				 * in image being read. */{    int fileWidth, fileHeight;    int nBytes;    Tk_PhotoImageBlock block;    unsigned char buf[100];    int bitPixel;    unsigned char colorMap[MAXCOLORMAPSIZE][4];    int transparent = -1;    if (!ReadGIFHeader(chan, &fileWidth, &fileHeight)) {	Tcl_AppendResult(interp, "couldn't read GIF header from file \"",		fileName, "\"", NULL);	return TCL_ERROR;    }    if ((fileWidth <= 0) || (fileHeight <= 0)) {	Tcl_AppendResult(interp, "GIF image file \"", fileName,		"\" has dimension(s) <= 0", (char *) NULL);	return TCL_ERROR;    }    if (Fread(buf, 1, 3, chan) != 3) {	return TCL_OK;    }    bitPixel = 2<<(buf[0]&0x07);    if (BitSet(buf[0], LOCALCOLORMAP)) {    /* Global Colormap */	if (!ReadColorMap(chan, bitPixel, colorMap)) {	    Tcl_AppendResult(interp, "error reading color map",		    (char *) NULL);	    return TCL_ERROR;	}    }    if ((srcX + width) > fileWidth) {	width = fileWidth - srcX;    }    if ((srcY + height) > fileHeight) {	height = fileHeight - srcY;    }    if ((width <= 0) || (height <= 0)	    || (srcX >= fileWidth) || (srcY >= fileHeight)) {	return TCL_OK;    }    Tk_PhotoExpand(imageHandle, destX + width, destY + height);    block.width = width;    block.height = height;    block.pixelSize = 4;    block.pitch = block.pixelSize * block.width;    block.offset[0] = 0;    block.offset[1] = 1;    block.offset[2] = 2;    nBytes = height * block.pitch;    block.pixelPtr = (unsigned char *) ckalloc((unsigned) nBytes);    while (1) {	if (Fread(buf, 1, 1, chan) != 1) {	    /*	     * Premature end of image.  We should really notify	     * the user, but for now just show garbage.	     */	    break;	}	if (buf[0] == ';') {	    /*	     * GIF terminator.	     */	    break;	}	if (buf[0] == '!') {	    /*	     * This is a GIF extension.	     */	    if (Fread(buf, 1, 1, chan) != 1) {		interp->result =			"error reading extension function code in GIF image";		goto error;	    }	    if (DoExtension(chan, buf[0], &transparent) < 0) {		interp->result = "error reading extension in GIF image";		goto error;	    }	    continue;	}	if (buf[0] != ',') {	    /*	     * Not a valid start character; ignore it.	     */	    continue;	}	if (Fread(buf, 1, 9, chan) != 9) {	    interp->result = "couldn't read left/top/width/height in GIF image";	    goto error;	}	bitPixel = 1<<((buf[8]&0x07)+1);	if (BitSet(buf[8], LOCALCOLORMAP)) {	    if (!ReadColorMap(chan, bitPixel, colorMap)) {		    Tcl_AppendResult(interp, "error reading color map", 			    (char *) NULL);		    goto error;	    }	}	if (ReadImage(interp, (char *) block.pixelPtr, chan, width,		height, colorMap, fileWidth, fileHeight, srcX, srcY,		BitSet(buf[8], INTERLACE), transparent) != TCL_OK) {	    goto error;	}	break;   }    if (transparent == -1) {	Tk_PhotoPutBlock(imageHandle, &block, destX, destY, width, height);    } else {	int x, y, end;	unsigned char *imagePtr, *rowPtr, *pixelPtr;	imagePtr = rowPtr = block.pixelPtr;	for (y = 0; y < height; y++) {	    x = 0;	    pixelPtr = rowPtr;	    while(x < width) {		/* search for first non-transparent pixel */		while ((x < width) && !(pixelPtr[CM_ALPHA])) {		    x++; pixelPtr += 4;		}		end = x;		/* search for first transparent pixel */		while ((end < width) && pixelPtr[CM_ALPHA]) {		    end++; pixelPtr += 4;		}		if (end > x) {		    block.pixelPtr = rowPtr + 4 * x;		    Tk_PhotoPutBlock(imageHandle, &block, destX+x,			    destY+y, end-x, 1);		}		x = end;	    }	    rowPtr += block.pitch;	}	block.pixelPtr = imagePtr;    }    ckfree((char *) block.pixelPtr);    return TCL_OK;    error:    ckfree((char *) block.pixelPtr);    return TCL_ERROR;}/* *---------------------------------------------------------------------- * * StringMatchGIF -- * *  This procedure is invoked by the photo image type to see if *  a string contains image data in GIF format. * * Results: *  The return value is 1 if the first characters in the string *  like GIF data, and 0 otherwise. * * Side effects: *  the size of the image is placed in widthPre and heightPtr. * *---------------------------------------------------------------------- */static intStringMatchGIF(string, formatString, widthPtr, heightPtr)    char *string;		/* the string containing the image data */    char *formatString;		/* the image format string */    int *widthPtr;		/* where to put the string width */    int *heightPtr;		/* where to put the string height */{    unsigned char header[10];    int got;    MFile handle;    mInit((unsigned char *) string, &handle);    got = Mread(header, 10, 1, &handle);    if (got != 10	    || ((strncmp("GIF87a", (char *) header, 6) != 0)	    && (strncmp("GIF89a", (char *) header, 6) != 0))) {	return 0;    }    *widthPtr = LM_to_uint(header[6],header[7]);    *heightPtr = LM_to_uint(header[8],header[9]);    return 1;}/* *---------------------------------------------------------------------- * * StringReadGif -- -- * *	This procedure is called by the photo image type to read *	GIF format data from a base64 encoded string, and give it to *	the photo image. * * Results: *	A standard TCL completion code.  If TCL_ERROR is returned *	then an error message is left in interp->result. * * Side effects: *	new data is added to the image given by imageHandle.  This *	procedure calls FileReadGif by redefining the operation of *	fprintf temporarily. * *---------------------------------------------------------------------- */static intStringReadGIF(interp,string,formatString,imageHandle,	destX, destY, width, height, srcX, srcY)    Tcl_Interp *interp;		/* interpreter for reporting errors in */    char *string;		/* string containing the image */    char *formatString;		/* format string if any */    Tk_PhotoHandle imageHandle;	/* the image to write this data into */    int destX, destY;		/* The rectangular region of the  */    int  width, height;		/*   image to copy */    int srcX, srcY;{	int result;	MFile handle;	mInit((unsigned char *)string,&handle);	fromData = 1;	result = FileReadGIF(interp, (Tcl_Channel) &handle, "inline data",		formatString, imageHandle, destX, destY, width, height,		srcX, srcY);	fromData = 0;	return(result);}/* *---------------------------------------------------------------------- * * ReadGIFHeader -- * *	This procedure reads the GIF header from the beginning of a *	GIF file and returns the dimensions of the image. * * Results: *	The return value is 1 if file "f" appears to start with *	a valid GIF header, 0 otherwise.  If the header is valid, *	then *widthPtr and *heightPtr are modified to hold the *	dimensions of the image. * * Side effects: *	The access position in f advances. * *---------------------------------------------------------------------- */static intReadGIFHeader(chan, widthPtr, heightPtr)    Tcl_Channel chan;		/* Image file to read the header from */    int *widthPtr, *heightPtr;	/* The dimensions of the image are				 * returned here. */{    unsigned char buf[7];    if ((Fread(buf, 1, 6, chan) != 6)	    || ((strncmp("GIF87a", (char *) buf, 6) != 0)	    && (strncmp("GIF89a", (char *) buf, 6) != 0))) {	return 0;    }    if (Fread(buf, 1, 4, chan) != 4) {	return 0;    }    *widthPtr = LM_to_uint(buf[0],buf[1]);    *heightPtr = LM_to_uint(buf[2],buf[3]);    return 1;}/* *----------------------------------------------------------------- * The code below is copied from the giftoppm program and modified * just slightly. *----------------------------------------------------------------- */static intReadColorMap(chan, number, buffer)     Tcl_Channel chan;     int number;     unsigned char buffer[MAXCOLORMAPSIZE][4];{	int i;	unsigned char rgb[3];	for (i = 0; i < number; ++i) {	    if (! ReadOK(chan, rgb, sizeof(rgb))) {		return 0;	    }	    	    buffer[i][CM_RED] = rgb[0] ;	    buffer[i][CM_GREEN] = rgb[1] ;	    buffer[i][CM_BLUE] = rgb[2] ;	    buffer[i][CM_ALPHA] = 255 ;	}	return 1;}static intDoExtension(chan, label, transparent)     Tcl_Channel chan;     int label;