tkimggif.c

linux系统下的音频通信

/*
 * 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 ([e-mail]), 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 int
FileMatchGIF(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 int
FileReadGIF(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 int
StringMatchGIF(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 int
StringReadGIF(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 int
ReadGIFHeader(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 int
ReadColorMap(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 int
DoExtension(chan, label, transparent)
     Tcl_Channel chan;
     int label;