/*
* tkImgGIF.c --
*
* A photo image file handler for GIF files. Reads 87a and 89a GIF
* files. At present, there only is a file write function. GIF images
* may be read using the -data option of the photo image. The data may be
* given as a binary string in a Tcl_Obj or 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.
* Copyright (c) 1997 Australian National University
*
* 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. |
* +-------------------------------------------------------------------+
*
* RCS: @(#) $Id: tkImgGIF.c,v 1.24 2003/02/20 15:28:40 dkf Exp $
*/
#include "tkPort.h"
/*
* 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 "tkImgPhoto.h"
#include "tkVMacro.h"
#include "tkPort.h"
/*
* Non-ASCII encoding support:
* Most data in a GIF image is binary and is treated as such. However,
* a few key bits are stashed in ASCII. If we try to compare those pieces
* to the char they represent, it will fail on any non-ASCII (eg, EBCDIC)
* system. To accomodate these systems, we test against the numeric value
* of the ASCII characters instead of the characters themselves. This is
* encoding independant.
*/
static CONST char GIF87a[] = { /* ASCII GIF87a */
0x47, 0x49, 0x46, 0x38, 0x37, 0x61, 0x00
};
static CONST char GIF89a[] = { /* ASCII GIF89a */
0x47, 0x49, 0x46, 0x38, 0x39, 0x61, 0x00
};
# define GIF_TERMINATOR 0x3b /* ASCII ; */
# define GIF_EXTENSION 0x21 /* ASCII ! */
# define GIF_START 0x2c /* ASCII , */
/*
* 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.
* 0==from file; 1==from base64 encoded data; 2==from binary data
*/
typedef struct ThreadSpecificData {
int fromData;
} ThreadSpecificData;
static Tcl_ThreadDataKey dataKey;
/*
* The format record for the GIF file format:
*/
static int FileMatchGIF _ANSI_ARGS_((Tcl_Channel chan, Tcl_Obj *fileName,
Tcl_Obj *format, int *widthPtr, int *heightPtr, Tcl_Interp *interp));
static int FileReadGIF _ANSI_ARGS_((Tcl_Interp *interp,
Tcl_Channel chan, Tcl_Obj *fileName, Tcl_Obj *format,
Tk_PhotoHandle imageHandle, int destX, int destY,
int width, int height, int srcX, int srcY));
static int StringMatchGIF _ANSI_ARGS_((Tcl_Obj *dataObj,
Tcl_Obj *format, int *widthPtr, int *heightPtr, Tcl_Interp *interp));
static int StringReadGIF _ANSI_ARGS_((Tcl_Interp *interp, Tcl_Obj *dataObj,
Tcl_Obj *format, Tk_PhotoHandle imageHandle,
int destX, int destY, int width, int height,
int srcX, int srcY));
static int FileWriteGIF _ANSI_ARGS_((Tcl_Interp *interp,
char *filename, Tcl_Obj *format,
Tk_PhotoImageBlock *blockPtr));
static int CommonWriteGIF _ANSI_ARGS_((Tcl_Interp *interp,
Tcl_Channel handle, Tcl_Obj *format,
Tk_PhotoImageBlock *blockPtr));
#undef tkImgFmtGIF
Tk_PhotoImageFormat tkImgFmtGIF = {
"gif", /* name */
FileMatchGIF, /* fileMatchProc */
StringMatchGIF, /* stringMatchProc */
FileReadGIF, /* fileReadProc */
StringReadGIF, /* stringReadProc */
FileWriteGIF, /* 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)
/*
* 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 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, format, widthPtr, heightPtr, interp)
Tcl_Channel chan; /* The image file, open for reading. */
Tcl_Obj *fileName; /* The name of the image file. */
Tcl_Obj *format; /* User-specified format object, or NULL. */
int *widthPtr, *heightPtr; /* The dimensions of the image are
* returned here if the file is a valid
* raw GIF file. */
Tcl_Interp *interp; /* Interpreter to use for reporting errors. */
{
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 the interp's 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, format, 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. */
Tcl_Obj *fileName; /* The name of the image file. */
Tcl_Obj *format; /* User-specified format object, 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, index = 0, argc = 0, i;
Tcl_Obj **objv;
Tk_PhotoImageBlock block;
unsigned char buf[100];
unsigned char *trashBuffer = NULL;
int bitPixel;
unsigned char colorMap[MAXCOLORMAPSIZE][4];
int transparent = -1;
static CONST char *optionStrings[] = {
"-index", NULL
};
if (format && Tcl_ListObjGetElements(interp, format,
&argc, &objv) != TCL_OK) {
return TCL_ERROR;
}
for (i = 1; i < argc; i++) {
if (Tcl_GetIndexFromObj(interp, objv[i], optionStrings, "option name", 0,
&nBytes) != TCL_OK) {
return TCL_ERROR;
}
if (i == (argc-1)) {
Tcl_AppendResult(interp, "no value given for \"",
Tcl_GetStringFromObj(objv[i], NULL),
"\" option", (char *) NULL);
return TCL_ERROR;
}
if (Tcl_GetIntFromObj(interp, objv[++i], &index) != TCL_OK) {
return TCL_ERROR;
}
}
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;
block.offset[3] = 3;
block.pixelPtr = NULL;
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) {
/*
* GIF terminator.
*/
Tcl_AppendResult(interp,"no image data for this index",
(char *) NULL);
goto error;
}
if (buf[0] == GIF_EXTENSION) {
/*
* This is a GIF extension.
*/
if (Fread(buf, 1, 1, chan) != 1) {
Tcl_SetResult(interp,
"error reading extension function code in GIF image",
TCL_STATIC);
goto error;
}
if (DoExtension(chan, buf[0], &transparent) < 0) {
Tcl_SetResult(interp, "error reading extension in GIF image",
TCL_STATIC);
goto error;
}
continue;
}
if (buf[0] != GIF_START) {
/*
* Not a valid start character; ignore it.
*/
continue;
}
if (Fread(buf, 1, 9, chan) != 9) {
Tcl_SetResult(interp,
"couldn't read left/top/width/height in GIF image",
TCL_STATIC);
goto error;
}
fileWidth = LM_to_uint(buf[4],buf[5]);
fileHeight = LM_to_uint(buf[6],buf[7]);
bitPixel = 1<<((buf[8]&0x07)+1);
if (index--) {
/*
* This is not the image we want to read: skip it.
*/
if (BitSet(buf[8], LOCALCOLORMAP)) {
if (!ReadColorMap(chan, bitPixel, colorMap)) {
Tcl_AppendResult(interp,
"error reading color map", (char *) NULL);
goto error;
}
}
/*
* If we've not yet allocated a trash buffer, do so now.
*/
if (trashBuffer == NULL) {
nBytes = fileWidth * fileHeight * 3;
trashBuffer =
(unsigned char *) ckalloc((unsigned int) nBytes);
}
/*
* Slurp! Process the data for this image and stuff it in
* a trash buffer.
*
* Yes, it might be more efficient here to *not* store the
* data (we're just going to throw it away later).
* However, I elected to implement it this way for good
* reasons. First, I wanted to avoid duplicating the
* (fairly complex) LWZ decoder in ReadImage. Fine, you
* say, why didn't you just modify it to allow the use of
* a NULL specifier for the output buffer? I tried that,
* but it negatively impacted the performance of what I
* think will be the common case: reading the first image
* in the file. Rather than marginally improve the speed
* of the less frequent case, I chose to maintain high
* performance for the common case.
*/
if (ReadImage(interp, (char *) trashBuffer, chan, fileWidth,
fileHeight, colorMap, 0, 0, 0, 0, 0, -1) != TCL_OK) {
goto error;
}
continue;
}
if (BitSet(buf[8], LOCALCOLORMAP)) {
if (!ReadColorMap(chan, bitPixel, colorMap)) {
Tcl_AppendResult(interp, "error reading color map",
(char *) NULL);
goto error;
}
}
index = LM_to_uint(buf[0],buf[1]);
srcX -= index;
if (srcX<0) {
destX -= srcX; width += srcX;
srcX = 0;
}
if (width > fileWidth) {
width = fileWidth;
}
index = LM_to_uint(buf[2],buf[3]);
srcY -= index;
if (index > srcY) {
destY -= srcY; height += srcY;
srcY = 0;
}
if (height > fileHeight) {
height = fileHeight;
}
if ((width <= 0) || (height <= 0)) {
block.pixelPtr = 0;
goto noerror;
}
block.width = width;
block.height = height;
block.pixelSize = (transparent>=0) ? 4 : 3;
block.offset[3] = (transparent>=0) ? 3 : 0;
block.pitch = block.pixelSize * fileWidth;
nBytes = block.pitch * fileHeight;
block.pixelPtr = (unsigned char *) ckalloc((unsigned) nBytes);
if (ReadImage(interp, (char *) block.pixelPtr, chan, fileWidth,
fileHeight, colorMap, fileWidth, fileHeight, srcX, srcY,
BitSet(buf[8], INTERLACE), transparent) != TCL_OK) {
goto error;
}
break;
}
Tk_PhotoPutBlock(imageHandle, &block, destX, destY, width, height,
TK_PHOTO_COMPOSITE_SET);
noerror:
/*
* If a trash buffer has been allocated, free it now.
*/
if (trashBuffer != NULL) {
ckfree((char *)trashBuffer);
}
if (block.pixelPtr) {
ckfree((char *) block.pixelPtr);
}
Tcl_AppendResult(interp, tkImgFmtGIF.name, (char *) NULL);
return TCL_OK;
error:
/*
* If a trash buffer has been allocated, free it now.
*/
if (trashBuffer != NULL) {
ckfree((char *)trashBuffer);
}
if (block.pixelPtr) {
ckfree((char *) block.pixelPtr);
}
return TCL_ERROR;
}
/*
*----------------------------------------------------------------------
*
* StringMatchGIF --
*
* This procedure is invoked by the photo image type to see if
* an object contains image data in GIF format.
*
* Results:
* The return value is 1 if the first characters in the data are
* like GIF data, and 0 otherwise.
*
* Side effects:
* the size of the image is placed in widthPre and heightPtr.
*
*----------------------------------------------------------------------
*/
static int
StringMatchGIF(dataObj, format, widthPtr, heightPtr, interp)
Tcl_Interp *interp; /* Interpreter to use for reporting errors. */
Tcl_Obj *dataObj; /* the object containing the image data */
Tcl_Obj *format; /* the image format object, or NULL */
int *widthPtr; /* where to put the string width */
int *heightPtr; /* where to put the string height */
{
unsigned char *data, header[10];
int got, length;
MFile handle;
data = Tcl_GetByteArrayFromObj(dataObj, &length);
/*
* Header is a minimum of 10 bytes.
*/
if (length < 10) {
return 0;
}
/*
* Check whether the data is Base64 encoded.
*/
if ((strncmp(GIF87a, (char *) data, 6) != 0) &&
(strncmp(GIF89a, (char *) data, 6) != 0)) {
/*
* Try interpreting the data as Base64 encoded
*/
mInit((unsigned char *) data, &handle);
got = Mread(header, 10, 1, &handle);
if (got != 10
|| ((strncmp(GIF87a, (char *) header, 6) != 0)
&& (strncmp(GIF89a, (char *) header, 6) != 0))) {
return 0;
}
} else {
memcpy((VOID *) header, (VOID *) data, 10);
}
*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 an object, optionally base64 encoded,
* 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 the interp's 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, dataObj, format, imageHandle,
destX, destY, width, height, srcX, srcY)
Tcl_Interp *interp; /* interpreter for reporting errors in */
Tcl_Obj *dataObj; /* object containing the image */
Tcl_Obj *format; /* format object, or NULL */
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;
ThreadSpecificData *tsdPtr = (ThreadSpecificData *)
Tcl_GetThreadData(&dataKey, sizeof(ThreadSpecificData));
Tcl_Channel dataSrc;
char *data;
Tcl_Obj *name;
/*
* Check whether the data is Base64 encoded
*/
data = (char *) Tcl_GetByteArrayFromObj(dataObj, NULL);
if ((strncmp(GIF87a, data, 6) != 0) && (strncmp(GIF89a, data, 6) != 0)) {
mInit((unsigned char *)data, &handle);
tsdPtr->fromData = 1;
dataSrc = (Tcl_Channel) &handle;
} else {
tsdPtr->fromData = 2;
mInit((unsigned char *)data, &handle);
dataSrc = (Tcl_Channel) &handle;
}
name = Tcl_NewStringObj("inline data",0);
result = FileReadGIF(interp, dataSrc, name,
format, imageHandle, destX, destY, width, height, srcX, srcY);
Tcl_DecrRefCount(name);
tsdPtr->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;
}
if (buffer) {
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;
int *transparent;
{
static unsigned char buf[256];
int count;
switch (label) {
case 0x01: /* Plain Text Extension */
break;
case 0xff: /* Application Extension */
break;
case 0xfe: /* Comment Extension */
do {
count = GetDataBlock(chan, (unsigned char*) buf);
} while (count > 0);
return count;
case 0xf9: /* Graphic Control Extension */
count = GetDataBlock(chan, (unsigned char*) buf);
if (count < 0) {
return 1;
}
if ((buf[0] & 0x1) != 0) {
*transparent = buf[3];
}
do {
count = GetDataBlock(chan, (unsigned char*) buf);
} while (count > 0);
return count;
}
do {
count = GetDataBlock(chan, (unsigned char*) buf);
} while (count > 0);
return count;
}
static int
GetDataBlock(chan, buf)
Tcl_Channel chan;
unsigned char *buf;
{
unsigned char count;
if (! ReadOK(chan, &count,1)) {
return -1;
}
if ((count != 0) && (! ReadOK(chan, buf, count))) {
return -1;
}
return count;
}
/*
*----------------------------------------------------------------------
*
* ReadImage --
*
* Process a GIF image from a given source, with a given height,
* width, transparency, etc.
*
* This code is based on the code found in the ImageMagick GIF decoder,
* which is (c) 2000 ImageMagick Studio.
*
* Some thoughts on our implementation:
* It sure would be nice if ReadImage didn't take 11 parameters! I think
* that if we were smarter, we could avoid doing that.
*
* Possible further optimizations: we could pull the GetCode function
* directly into ReadImage, which would improve our speed.
*
* Results:
* Processes a GIF image and loads the pixel data into a memory array.
*
* Side effects:
* None.
*
*----------------------------------------------------------------------
*/
static int
ReadImage(interp, imagePtr, chan, len, rows, cmap,
width, height, srcX, srcY, interlace, transparent)
Tcl_Interp *interp;
char *imagePtr;
Tcl_Channel chan;
int len, rows;
unsigned char cmap[MAXCOLORMAPSIZE][4];
int width, height;
int srcX, srcY;
int interlace;
int transparent;
{
unsigned char initialCodeSize;
int v;
int xpos = 0, ypos = 0, pass = 0, i;
register char *pixelPtr;
CONST static int interlaceStep[] = { 8, 8, 4, 2 };
CONST static int interlaceStart[] = { 0, 4, 2, 1 };
unsigned short prefix[(1 << MAX_LWZ_BITS)];
unsigned char append[(1 << MAX_LWZ_BITS)];
unsigned char stack[(1 << MAX_LWZ_BITS)*2];
register unsigned char *top;
int codeSize, clearCode, inCode, endCode, oldCode, maxCode;
int code, firstCode;
/*
* Initialize the decoder
*/
if (! ReadOK(chan, &initialCodeSize, 1)) {
Tcl_AppendResult(interp, "error reading GIF image: ",
Tcl_PosixError(interp), (char *) NULL);
return TCL_ERROR;
}
if (transparent != -1) {
cmap[transparent][CM_RED] = 0;
cmap[transparent][CM_GREEN] = 0;
cmap[transparent][CM_BLUE] = 0;
cmap[transparent][CM_ALPHA] = 0;
}
pixelPtr = imagePtr;
/*
* Initialize the decoder.
*
* Set values for "special" numbers:
* clear code reset the decoder
* end code stop decoding
* code size size of the next code to retrieve
* max code next available table position
*/
clearCode = 1 << (int) initialCodeSize;
endCode = clearCode + 1;
codeSize = (int) initialCodeSize + 1;
maxCode = clearCode + 2;
oldCode = -1;
firstCode = -1;
memset((void *)prefix, 0, (1 << MAX_LWZ_BITS) * sizeof(short));
memset((void *)append, 0, (1 << MAX_LWZ_BITS) * sizeof(char));
for (i = 0; i < clearCode; i++) {
append[i] = i;
}
top = stack;
GetCode(chan, 0, 1);
/*
* Read until we finish the image
*/
for (i = 0, ypos = 0; i < rows; i++) {
for (xpos = 0; xpos < len; ) {
if (top == stack) {
/*
* Bummer -- our stack is empty. Now we have to work!
*/
code = GetCode(chan, codeSize, 0);
if (code < 0) {
return TCL_OK;
}
if (code > maxCode || code == endCode) {
/*
* If we're doing things right, we should never
* receive a code that is greater than our current
* maximum code. If we do, bail, because our decoder
* does not yet have that code set up.
*
* If the code is the magic endCode value, quit.
*/
return TCL_OK;
}
if (code == clearCode) {
/*
* Reset the decoder.
*/
codeSize = initialCodeSize + 1;
maxCode = clearCode + 2;
oldCode = -1;
continue;
}
if (oldCode == -1) {
/*
* Last pass reset the decoder, so the first code we
* see must be a singleton. Seed the stack with it,
* and set up the old/first code pointers for
* insertion into the string table. We can't just
* roll this into the clearCode test above, because
* at that point we have not yet read the next code.
*/
*top++ = append[code];
oldCode = code;
firstCode = code;
continue;
}
inCode = code;
if (code == maxCode) {
/*
* maxCode is always one bigger than our highest assigned
* code. If the code we see is equal to maxCode, then
* we are about to add a new string to the table. ???
*/
*top++ = firstCode;
code = oldCode;
}
while (code > clearCode) {
/*
* Populate the stack by tracing the string in the
* string table from its tail to its head
*/
*top++ = append[code];
code = prefix[code];
}
firstCode = append[code];
/*
* If there's no more room in our string table, quit.
* Otherwise, add a new string to the table
*/
if (maxCode >= (1 << MAX_LWZ_BITS)) {
return TCL_OK;
}
/*
* Push the head of the string onto the stack.
*/
*top++ = firstCode;
/*
* Add a new string to the string table
*/
prefix[maxCode] = oldCode;
append[maxCode] = firstCode;
maxCode++;
/*
* maxCode tells us the maximum code value we can accept.
* If we see that we need more bits to represent it than
* we are requesting from the unpacker, we need to increase
* the number we ask for.
*/
if ((maxCode >= (1 << codeSize))
&& (maxCode < (1<<MAX_LWZ_BITS))) {
codeSize++;
}
oldCode = inCode;
}
/*
* Pop the next color index off the stack.
*/
v = *(--top);
if (v < 0) {
return TCL_OK;
}
/*
* If pixelPtr is null, we're skipping this image (presumably
* there are more in the file and we will be called to read
* one of them later)
*/
*pixelPtr++ = cmap[v][CM_RED];
*pixelPtr++ = cmap[v][CM_GREEN];
*pixelPtr++ = cmap[v][CM_BLUE];
if (transparent >= 0) {
*pixelPtr++ = cmap[v][CM_ALPHA];
}
xpos++;
}
/*
* If interlacing, the next ypos is not just +1
*/
if (interlace) {
ypos += interlaceStep[pass];
while (ypos >= height) {
pass++;
if (pass > 3) {
return TCL_OK;
}
ypos = interlaceStart[pass];
}
} else {
ypos++;
}
pixelPtr = imagePtr + (ypos) * len * ((transparent>=0)?4:3);
}
return TCL_OK;
}
/*
*----------------------------------------------------------------------
*
* GetCode --
*
* Extract the next compression code from the file. In GIF's, the
* compression codes are between 3 and 12 bits long and are then
* packed into 8 bit bytes, left to right, for example:
* bbbaaaaa
* dcccccbb
* eeeedddd
* ...
* We use a byte buffer read from the file and a sliding window
* to unpack the bytes. Thanks to ImageMagick for the sliding window
* idea.
* args: chan the channel to read from
* code_size size of the code to extract
* flag boolean indicating whether the extractor
* should be reset or not
*
* Results:
* code the next compression code
*
* Side effects:
* May consume more input from chan.
*
*----------------------------------------------------------------------
*/
static int
GetCode(chan, code_size, flag)
Tcl_Channel chan;
int code_size;
int flag;
{
static unsigned char buf[280];
static int bytes = 0, done;
static unsigned char *c;
static unsigned int window;
static int bitsInWindow = 0;
int ret;
if (flag) {
/*
* Initialize the decoder.
*/
bitsInWindow = 0;
bytes = 0;
window = 0;
done = 0;
c = NULL;
return 0;
}
while (bitsInWindow < code_size) {
/*
* Not enough bits in our window to cover the request.
*/
if (done) {
return -1;
}
if (bytes == 0) {
/*
* Not enough bytes in our buffer to add to the window.
*/
bytes = GetDataBlock(chan, buf);
c = buf;
if (bytes <= 0) {
done = 1;
break;
}
}
/*
* Tack another byte onto the window, see if that's enough.
*/
window += (*c) << bitsInWindow;
c++;
bitsInWindow += 8;
bytes--;
}
/*
* The next code will always be the last code_size bits of the window.
*/
ret = window & ((1 << code_size) - 1);
/*
* Shift data in the window to put the next code at the end.
*/
window >>= code_size;
bitsInWindow -= code_size;
return ret;
}
/*
*----------------------------------------------------------------------
*
* Minit -- --
*
* This procedure initializes a base64 decoder handle
*
* Results:
* none
*
* Side effects:
* the base64 handle is initialized
*
*----------------------------------------------------------------------
*/
static void
mInit(string, handle)
unsigned char *string; /* string containing initial mmencoded data */
MFile *handle; /* mmdecode "file" handle */
{
handle->data = string;
handle->state = 0;
handle->c = 0;
}
/*
*----------------------------------------------------------------------
*
* Mread --
*
* This procedure is invoked by the GIF file reader as a
* temporary replacement for "fread", to get GIF data out
* of a string (using Mgetc).
*
* Results:
* The return value is the number of characters "read"
*
* Side effects:
* The base64 handle will change state.
*
*----------------------------------------------------------------------
*/
static int
Mread(dst, chunkSize, numChunks, handle)
unsigned char *dst; /* where to put the result */
size_t chunkSize; /* size of each transfer */
size_t numChunks; /* number of chunks */
MFile *handle; /* mmdecode "file" handle */
{
register int i, c;
int count = chunkSize * numChunks;
for(i=0; i<count && (c=Mgetc(handle)) != GIF_DONE; i++) {
*dst++ = c;
}
return i;
}
/*
* get the next decoded character from an mmencode handle
* This causes at least 1 character to be "read" from the encoded string
*/
/*
*----------------------------------------------------------------------
*
* Mgetc --
*
* This procedure decodes and returns the next byte from a base64
* encoded string.
*
* Results:
* The next byte (or GIF_DONE) is returned.
*
* Side effects:
* The base64 handle will change state.
*
*----------------------------------------------------------------------
*/
static int
Mgetc(handle)
MFile *handle; /* Handle containing decoder data and state */
{
int c;
int result = 0; /* Initialization needed only to prevent
* gcc compiler warning. */
if (handle->state == GIF_DONE) {
return GIF_DONE;
}
do {
c = char64(*handle->data);
handle->data++;
} while (c == GIF_SPACE);
if (c>GIF_SPECIAL) {
handle->state = GIF_DONE;
return handle->c;
}
switch (handle->state++) {
case 0:
handle->c = c<<2;
result = Mgetc(handle);
break;
case 1:
result = handle->c | (c>>4);
handle->c = (c&0xF)<<4;
break;
case 2:
result = handle->c | (c>>2);
handle->c = (c&0x3) << 6;
break;
case 3:
result = handle->c | c;
handle->state = 0;
break;
}
return result;
}
/*
*----------------------------------------------------------------------
*
* char64 --
*
* This procedure converts a base64 ascii character into its binary
* equivalent. This code is a slightly modified version of the
* char64 proc in N. Borenstein's metamail decoder.
*
* Results:
* The binary value, or an error code.
*
* Side effects:
* None.
*----------------------------------------------------------------------
*/
static int
char64(c)
int c;
{
switch(c) {
case 'A': return 0; case 'B': return 1; case 'C': return 2;
case 'D': return 3; case 'E': return 4; case 'F': return 5;
case 'G': return 6; case 'H': return 7; case 'I': return 8;
case 'J': return 9; case 'K': return 10; case 'L': return 11;
case 'M': return 12; case 'N': return 13; case 'O': return 14;
case 'P': return 15; case 'Q': return 16; case 'R': return 17;
case 'S': return 18; case 'T': return 19; case 'U': return 20;
case 'V': return 21; case 'W': return 22; case 'X': return 23;
case 'Y': return 24; case 'Z': return 25; case 'a': return 26;
case 'b': return 27; case 'c': return 28; case 'd': return 29;
case 'e': return 30; case 'f': return 31; case 'g': return 32;
case 'h': return 33; case 'i': return 34; case 'j': return 35;
case 'k': return 36; case 'l': return 37; case 'm': return 38;
case 'n': return 39; case 'o': return 40; case 'p': return 41;
case 'q': return 42; case 'r': return 43; case 's': return 44;
case 't': return 45; case 'u': return 46; case 'v': return 47;
case 'w': return 48; case 'x': return 49; case 'y': return 50;
case 'z': return 51; case '0': return 52; case '1': return 53;
case '2': return 54; case '3': return 55; case '4': return 56;
case '5': return 57; case '6': return 58; case '7': return 59;
case '8': return 60; case '9': return 61; case '+': return 62;
case '/': return 63;
case ' ': case '\t': case '\n': case '\r': case '\f':
return GIF_SPACE;
case '=':
return GIF_PAD;
case '\0':
return GIF_DONE;
default:
return GIF_BAD;
}
}
/*
*----------------------------------------------------------------------
*
* Fread --
*
* This procedure calls either fread or Mread to read data
* from a file or a base64 encoded string.
*
* Results: - same as fread
*
*----------------------------------------------------------------------
*/
static int
Fread(dst, hunk, count, chan)
unsigned char *dst; /* where to put the result */
size_t hunk,count; /* how many */
Tcl_Channel chan;
{
ThreadSpecificData *tsdPtr = (ThreadSpecificData *)
Tcl_GetThreadData(&dataKey, sizeof(ThreadSpecificData));
MFile *handle;
switch (tsdPtr->fromData) {
case 1:
return Mread(dst, hunk, count, (MFile *) chan);
case 2:
handle = (MFile *) chan;
memcpy((VOID *)dst, (VOID *) handle->data, (size_t) (hunk * count));
handle->data += hunk * count;
return (int)(hunk * count);
default:
return Tcl_Read(chan, (char *) dst, (int) (hunk * count));
}
}
/*
* ChanWriteGIF - writes a image in GIF format.
*-------------------------------------------------------------------------
* Author: Lolo
* Engeneering Projects Area
* Department of Mining
* University of Oviedo
* e-mail zz11425958@zeus.etsimo.uniovi.es
* lolo@pcsig22.etsimo.uniovi.es
* Date: Fri September 20 1996
*
* Modified for transparency handling (gif89a) and miGIF compression
* by Jan Nijtmans <j.nijtmans@chello.nl>
*
*----------------------------------------------------------------------
* FileWriteGIF-
*
* This procedure is called by the photo image type to write
* GIF format data from a photo image into a given file
*
* Results:
* A standard TCL completion code. If TCL_ERROR is returned
* then an error message is left in interp->result.
*
*----------------------------------------------------------------------
*/
/*
* Types, defines and variables needed to write and compress a GIF.
*/
typedef int (* ifunptr) _ANSI_ARGS_((void));
#define LSB(a) ((unsigned char) (((short)(a)) & 0x00FF))
#define MSB(a) ((unsigned char) (((short)(a)) >> 8))
#define GIFBITS 12
#define HSIZE 5003 /* 80% occupancy */
static int ssize;
static int csize;
static int rsize;
static unsigned char *pixelo;
static int pixelSize;
static int pixelPitch;
static int greenOffset;
static int blueOffset;
static int alphaOffset;
static int num;
static unsigned char mapa[MAXCOLORMAPSIZE][3];
/*
* Definition of new functions to write GIFs
*/
static int color _ANSI_ARGS_((int red,int green, int blue,
unsigned char mapa[MAXCOLORMAPSIZE][3]));
static void compress _ANSI_ARGS_((int init_bits, Tcl_Channel handle,
ifunptr readValue));
static int nuevo _ANSI_ARGS_((int red, int green ,int blue,
unsigned char mapa[MAXCOLORMAPSIZE][3]));
static void savemap _ANSI_ARGS_((Tk_PhotoImageBlock *blockPtr,
unsigned char mapa[MAXCOLORMAPSIZE][3]));
static int ReadValue _ANSI_ARGS_((void));
static int
FileWriteGIF(interp, filename, format, blockPtr)
Tcl_Interp *interp; /* Interpreter to use for reporting errors. */
char *filename;
Tcl_Obj *format;
Tk_PhotoImageBlock *blockPtr;
{
Tcl_Channel chan = NULL;
int result;
chan = Tcl_OpenFileChannel(interp, (char *) filename, "w", 0644);
if (!chan) {
return TCL_ERROR;
}
if (Tcl_SetChannelOption(interp, chan, "-translation", "binary") != TCL_OK) {
Tcl_Close(NULL, chan);
return TCL_ERROR;
}
result = CommonWriteGIF(interp, chan, format, blockPtr);
if (Tcl_Close(interp, chan) == TCL_ERROR) {
return TCL_ERROR;
}
return result;
}
#define Mputc(c,handle) Tcl_Write(handle,(char *) &c,1)
static int
CommonWriteGIF(interp, handle, format, blockPtr)
Tcl_Interp *interp;
Tcl_Channel handle;
Tcl_Obj *format;
Tk_PhotoImageBlock *blockPtr;
{
int resolution;
long width,height,x;
unsigned char c;
unsigned int top,left;
top = 0;
left = 0;
pixelSize = blockPtr->pixelSize;
greenOffset = blockPtr->offset[1]-blockPtr->offset[0];
blueOffset = blockPtr->offset[2]-blockPtr->offset[0];
alphaOffset = blockPtr->offset[0];
if (alphaOffset < blockPtr->offset[2]) {
alphaOffset = blockPtr->offset[2];
}
if (++alphaOffset < pixelSize) {
alphaOffset -= blockPtr->offset[0];
} else {
alphaOffset = 0;
}
Tcl_Write(handle, (char *) (alphaOffset ? GIF89a : GIF87a), 6);
for (x=0 ; x<MAXCOLORMAPSIZE ; x++) {
mapa[x][CM_RED] = 255;
mapa[x][CM_GREEN] = 255;
mapa[x][CM_BLUE] = 255;
}
width = blockPtr->width;
height = blockPtr->height;
pixelo = blockPtr->pixelPtr + blockPtr->offset[0];
pixelPitch = blockPtr->pitch;
savemap(blockPtr,mapa);
if (num >= MAXCOLORMAPSIZE) {
Tcl_AppendResult(interp, "too many colors", (char *) NULL);
return TCL_ERROR;
}
if (num<2) {
num = 2;
}
c = LSB(width);
Mputc(c,handle);
c = MSB(width);
Mputc(c,handle);
c = LSB(height);
Mputc(c,handle);
c = MSB(height);
Mputc(c,handle);
resolution = 0;
while (num >> resolution) {
resolution++;
}
c = 111 + resolution * 17;
Mputc(c,handle);
num = 1 << resolution;
/*
* background color
*/
c = 0;
Mputc(c,handle);
/*
* zero for future expansion.
*/
Mputc(c,handle);
for (x=0 ; x<num ; x++) {
c = mapa[x][CM_RED];
Mputc(c,handle);
c = mapa[x][CM_GREEN];
Mputc(c,handle);
c = mapa[x][CM_BLUE];
Mputc(c,handle);
}
/*
* Write out extension for transparent colour index, if necessary.
*/
if (alphaOffset) {
c = GIF_EXTENSION;
Mputc(c, handle);
Tcl_Write(handle, "\371\4\1\0\0\0", 7);
}
c = GIF_START;
Mputc(c,handle);
c = LSB(top);
Mputc(c,handle);
c = MSB(top);
Mputc(c,handle);
c = LSB(left);
Mputc(c,handle);
c = MSB(left);
Mputc(c,handle);
c = LSB(width);
Mputc(c,handle);
c = MSB(width);
Mputc(c,handle);
c = LSB(height);
Mputc(c,handle);
c = MSB(height);
Mputc(c,handle);
c = 0;
Mputc(c,handle);
c = resolution;
Mputc(c,handle);
ssize = rsize = blockPtr->width;
csize = blockPtr->height;
compress(resolution+1, handle, ReadValue);
c = 0;
Mputc(c,handle);
c = GIF_TERMINATOR;
Mputc(c,handle);
return TCL_OK;
}
static int
color(red, green, blue, mapa)
int red;
int green;
int blue;
unsigned char mapa[MAXCOLORMAPSIZE][3];
{
int x;
for (x=(alphaOffset != 0) ; x<=MAXCOLORMAPSIZE ; x++) {
if ((mapa[x][CM_RED] == red) && (mapa[x][CM_GREEN] == green) &&
(mapa[x][CM_BLUE] == blue)) {
return x;
}
}
return -1;
}
static int
nuevo(red, green, blue, mapa)
int red,green,blue;
unsigned char mapa[MAXCOLORMAPSIZE][3];
{
int x = (alphaOffset != 0);
for (; x<=num ; x++) {
if ((mapa[x][CM_RED] == red) && (mapa[x][CM_GREEN] == green) &&
(mapa[x][CM_BLUE] == blue)) {
return 0;
}
}
return 1;
}
static void
savemap(blockPtr,mapa)
Tk_PhotoImageBlock *blockPtr;
unsigned char mapa[MAXCOLORMAPSIZE][3];
{
unsigned char *colores;
int x,y;
unsigned char red,green,blue;
if (alphaOffset) {
num = 0;
mapa[0][CM_RED] = 0xd9;
mapa[0][CM_GREEN] = 0xd9;
mapa[0][CM_BLUE] = 0xd9;
} else {
num = -1;
}
for(y=0 ; y<blockPtr->height ; y++) {
colores = blockPtr->pixelPtr + blockPtr->offset[0]
+ y * blockPtr->pitch;
for(x=0 ; x<blockPtr->width ; x++) {
if (!alphaOffset || (colores[alphaOffset] != 0)) {
red = colores[0];
green = colores[greenOffset];
blue = colores[blueOffset];
if (nuevo(red,green,blue,mapa)) {
num++;
if (num >= MAXCOLORMAPSIZE) {
return;
}
mapa[num][CM_RED] = red;
mapa[num][CM_GREEN] = green;
mapa[num][CM_BLUE] = blue;
}
}
colores += pixelSize;
}
}
return;
}
static int
ReadValue()
{
unsigned int col;
if (csize == 0) {
return EOF;
}
if (alphaOffset && (pixelo[alphaOffset] == 0)) {
col = 0;
} else {
col = color(pixelo[0], pixelo[greenOffset], pixelo[blueOffset], mapa);
}
pixelo += pixelSize;
if (--ssize <= 0) {
ssize = rsize;
csize--;
pixelo += pixelPitch - (rsize * pixelSize);
}
return col;
}
/*
*-----------------------------------------------------------------------
*
* miGIF Compression - mouse and ivo's GIF-compatible compression
*
* -run length encoding compression routines-
*
* Copyright (C) 1998 Hutchison Avenue Software Corporation
* http://www.hasc.com
* info@hasc.com
*
* 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." The Hutchison Avenue Software Corporation
* disclaims all warranties, either express or implied, including but
* not limited to implied warranties of merchantability and fitness
* for a particular purpose, with respect to this code and
* accompanying documentation.
*
* The miGIF compression routines do not, strictly speaking, generate
* files conforming to the GIF spec, since the image data is not
* LZW-compressed (this is the point: in order to avoid transgression
* of the Unisys patent on the LZW algorithm.) However, miGIF
* generates data streams that any reasonably sane LZW decompresser
* will decompress to what we want.
*
* miGIF compression uses run length encoding. It compresses
* horizontal runs of pixels of the same color. This type of
* compression gives good results on images with many runs, for
* example images with lines, text and solid shapes on a solid-colored
* background. It gives little or no compression on images with few
* runs, for example digital or scanned photos.
*
* der Mouse
* mouse@rodents.montreal.qc.ca
* 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B
*
* ivo@hasc.com
*
* The Graphics Interchange Format(c) is the Copyright property of
* CompuServe Incorporated. GIF(sm) is a Service Mark property of
* CompuServe Incorporated.
*
*-----------------------------------------------------------------------
*/
static int rl_pixel;
static int rl_basecode;
static int rl_count;
static int rl_table_pixel;
static int rl_table_max;
static int just_cleared;
static int out_bits;
static int out_bits_init;
static int out_count;
static int out_bump;
static int out_bump_init;
static int out_clear;
static int out_clear_init;
static int max_ocodes;
static int code_clear;
static int code_eof;
static unsigned int obuf;
static int obits;
static Tcl_Channel ofile;
static unsigned char oblock[256];
static int oblen;
/*
* Used only when debugging GIF compression code
*/
/* #define MIGIF_DEBUGGING_ENVARS */
#ifdef MIGIF_DEBUGGING_ENVARS
static int verbose_set = 0;
static int verbose;
#define MIGIF_VERBOSE (verbose_set?verbose:set_verbose())
#define DEBUGMSG(printf_args) if (MIGIF_VERBOSE) { printf printf_args; }
static int
set_verbose(void)
{
verbose = !!getenv("MIGIF_VERBOSE");
verbose_set = 1;
return verbose;
}
static CONST char *
binformat(v, nbits)
unsigned int v;
int nbits;
{
static char bufs[8][64];
static int bhand = 0;
unsigned int bit;
int bno;
char *bp;
bhand--;
if (bhand < 0) {
bhand = (sizeof(bufs) / sizeof(bufs[0])) - 1;
}
bp = &bufs[bhand][0];
for (bno=nbits-1,bit=((unsigned int)1)<<bno ; bno>=0 ; bno--,bit>>=1) {
*bp++ = (v & bit) ? '1' : '0';
if (((bno&3) == 0) && (bno != 0)) {
*bp++ = '.';
}
}
*bp = '\0';
return &bufs[bhand][0];
}
#else
#define MIGIF_VERBOSE 0
#define DEBUGMSG(printf_args) /* do nothing */
#endif
static void
write_block()
{
int i;
unsigned char c;
if (MIGIF_VERBOSE) {
printf("write_block %d:", oblen);
for (i=0 ; i<oblen ; i++) {
printf(" %02x", oblock[i]);
}
printf("\n");
}
c = oblen;
Tcl_Write(ofile, (char *) &c, 1);
Tcl_Write(ofile, (char *) &oblock[0], oblen);
oblen = 0;
}
static void
block_out(c)
unsigned char c;
{
DEBUGMSG(("block_out %s\n", binformat(c, 8)));
oblock[oblen++] = c;
if (oblen >= 255) {
write_block();
}
}
static void
block_flush()
{
DEBUGMSG(("block_flush\n"));
if (oblen > 0) {
write_block();
}
}
static void
output(val)
int val;
{
DEBUGMSG(("output %s [%s %d %d]\n", binformat(val, out_bits),
binformat(obuf, obits), obits, out_bits));
obuf |= val << obits;
obits += out_bits;
while (obits >= 8) {
block_out(obuf&0xff);
obuf >>= 8;
obits -= 8;
}
DEBUGMSG(("output leaving [%s %d]\n", binformat(obuf, obits), obits));
}
static void
output_flush()
{
DEBUGMSG(("output_flush\n"));
if (obits > 0) {
block_out(obuf);
}
block_flush();
}
static void
did_clear()
{
DEBUGMSG(("did_clear\n"));
out_bits = out_bits_init;
out_bump = out_bump_init;
out_clear = out_clear_init;
out_count = 0;
rl_table_max = 0;
just_cleared = 1;
}
static void
output_plain(c)
int c;
{
DEBUGMSG(("output_plain %s\n", binformat(c, out_bits)));
just_cleared = 0;
output(c);
out_count++;
if (out_count >= out_bump) {
out_bits++;
out_bump += 1 << (out_bits - 1);
}
if (out_count >= out_clear) {
output(code_clear);
did_clear();
}
}
static unsigned int
isqrt(x)
unsigned int x;
{
unsigned int r;
unsigned int v;
if (x < 2) {
return x;
}
for (v=x,r=1 ; v ; v>>=2,r<<=1);
while (1) {
v = ((x / r) + r) / 2;
if (v==r || v==r+1) {
return r;
}
r = v;
}
}
static unsigned int
compute_triangle_count(count, nrepcodes)
unsigned int count;
unsigned int nrepcodes;
{
unsigned int perrep;
unsigned int cost;
cost = 0;
perrep = (nrepcodes * (nrepcodes+1)) / 2;
while (count >= perrep) {
cost += nrepcodes;
count -= perrep;
}
if (count > 0) {
unsigned int n;
n = isqrt(count);
while (n*(n+1) >= 2*count) {
n--;
}
while (n*(n+1) < 2*count) {
n++;
}
cost += n;
}
return cost;
}
static void
max_out_clear()
{
out_clear = max_ocodes;
}
static void
reset_out_clear()
{
out_clear = out_clear_init;
if (out_count >= out_clear) {
output(code_clear);
did_clear();
}
}
static void
rl_flush_fromclear(count)
int count;
{
int n;
DEBUGMSG(("rl_flush_fromclear %d\n", count));
max_out_clear();
rl_table_pixel = rl_pixel;
n = 1;
while (count > 0) {
if (n == 1) {
rl_table_max = 1;
output_plain(rl_pixel);
count--;
} else if (count >= n) {
rl_table_max = n;
output_plain(rl_basecode+n-2);
count -= n;
} else if (count == 1) {
rl_table_max++;
output_plain(rl_pixel);
count = 0;
} else {
rl_table_max++;
output_plain(rl_basecode+count-2);
count = 0;
}
if (out_count == 0) {
n = 1;
} else {
n++;
}
}
reset_out_clear();
DEBUGMSG(("rl_flush_fromclear leaving table_max=%d\n", rl_table_max));
}
static void
rl_flush_clearorrep(count)
int count;
{
int withclr;
DEBUGMSG(("rl_flush_clearorrep %d\n", count));
withclr = 1 + compute_triangle_count(count, max_ocodes);
if (withclr < count) {
output(code_clear);
did_clear();
rl_flush_fromclear(count);
} else {
for (; count>0 ; count--) {
output_plain(rl_pixel);
}
}
}
static void
rl_flush_withtable(count)
int count;
{
int repmax;
int repleft;
int leftover;
DEBUGMSG(("rl_flush_withtable %d\n", count));
repmax = count / rl_table_max;
leftover = count % rl_table_max;
repleft = (leftover ? 1 : 0);
if (out_count+repmax+repleft > max_ocodes) {
repmax = max_ocodes - out_count;
leftover = count - (repmax * rl_table_max);
repleft = 1 + compute_triangle_count(leftover, max_ocodes);
}
DEBUGMSG(("rl_flush_withtable repmax=%d leftover=%d repleft=%d\n",
repmax, leftover, repleft));
if (1+(int)compute_triangle_count(count, max_ocodes) < repmax+repleft) {
output(code_clear);
did_clear();
rl_flush_fromclear(count);
return;
}
max_out_clear();
for (; repmax>0 ; repmax--) {
output_plain(rl_basecode + rl_table_max - 2);
}
if (leftover) {
if (just_cleared) {
rl_flush_fromclear(leftover);
} else if (leftover == 1) {
output_plain(rl_pixel);
} else {
output_plain(rl_basecode + leftover - 2);
}
}
reset_out_clear();
}
static void
rl_flush()
{
DEBUGMSG(("rl_flush [ %d %d\n", rl_count, rl_pixel));
if (rl_count == 1) {
output_plain(rl_pixel);
rl_count = 0;
DEBUGMSG(("rl_flush ]\n"));
return;
}
if (just_cleared) {
rl_flush_fromclear(rl_count);
} else if ((rl_table_max < 2) || (rl_table_pixel != rl_pixel)) {
rl_flush_clearorrep(rl_count);
} else {
rl_flush_withtable(rl_count);
}
DEBUGMSG(("rl_flush ]\n"));
rl_count = 0;
}
static void
compress(init_bits, handle, readValue)
int init_bits;
Tcl_Channel handle;
ifunptr readValue;
{
int c;
ofile = handle;
obuf = 0;
obits = 0;
oblen = 0;
code_clear = 1 << (init_bits - 1);
code_eof = code_clear + 1;
rl_basecode = code_eof + 1;
out_bump_init = (1 << (init_bits - 1)) - 1;
/*
* For images with a lot of runs, making out_clear_init larger
* will give better compression.
*/
out_clear_init = (init_bits <= 3) ? 9 : (out_bump_init-1);
#ifdef MIGIF_DEBUGGING_ENVARS
{
const char *ocienv;
ocienv = getenv("MIGIF_OUT_CLEAR_INIT");
if (ocienv) {
out_clear_init = atoi(ocienv);
DEBUGMSG(("[overriding out_clear_init to %d]\n", out_clear_init));
}
}
#endif
out_bits_init = init_bits;
max_ocodes = (1 << GIFBITS) - ((1 << (out_bits_init - 1)) + 3);
did_clear();
output(code_clear);
rl_count = 0;
while (1) {
c = readValue();
if ((rl_count > 0) && (c != rl_pixel)) {
rl_flush();
}
if (c == EOF) {
break;
}
if (rl_pixel == c) {
rl_count++;
} else {
rl_pixel = c;
rl_count = 1;
}
}
output(code_eof);
output_flush();
}
/*
*-----------------------------------------------------------------------
*
* End of miGIF section - See copyright notice at start of section.
*
*-----------------------------------------------------------------------
*/