/* * 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 1.24.2.4 2006/03/27 12:13:56 dkf Exp $ */ /* * 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 length; /* Length of string in bytes */ int c; /* bits left over from previous character */ int state; /* decoder state (0-4 or GIF_DONE) */ } MFile; #include "tkInt.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, CONST char *fileName, Tcl_Obj *format, int *widthPtr, int *heightPtr, Tcl_Interp *interp)); static int FileReadGIF _ANSI_ARGS_((Tcl_Interp *interp, Tcl_Channel chan, CONST char *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, CONST 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)); 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, int length, 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. */ CONST char *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; /* not used */ { 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. */ CONST char *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, imageWidth, imageHeight; 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. */ Tcl_AppendResult(interp,"premature end of image data for this index", (char *) NULL); goto error; } 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; } imageWidth = LM_to_uint(buf[4],buf[5]); imageHeight = 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, imageWidth, imageHeight, 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 > imageWidth) { width = imageWidth; } index = LM_to_uint(buf[2],buf[3]); srcY -= index; if (index > srcY) { destY -= srcY; height += srcY; srcY = 0; } if (height > imageHeight) { height = imageHeight; } 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 * imageWidth; nBytes = block.pitch * imageHeight; block.pixelPtr = (unsigned char *) ckalloc((unsigned) nBytes); if (ReadImage(interp, (char *) block.pixelPtr, chan, imageWidth, imageHeight, 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_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 */ Tcl_Interp *interp; /* not used */ { 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, length, &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, length; MFile handle; ThreadSpecificData *tsdPtr = (ThreadSpecificData *) Tcl_GetThreadData(&dataKey, sizeof(ThreadSpecificData)); Tcl_Channel dataSrc; char *data; /* * Check whether the data is Base64 encoded */ data = (char *) Tcl_GetByteArrayFromObj(dataObj, &length); if ((strncmp(GIF87a, data, 6) != 0) && (strncmp(GIF89a, data, 6) != 0)) { mInit((unsigned char *)data, length, &handle); tsdPtr->fromData = 1; dataSrc = (Tcl_Channel) &handle; } else { tsdPtr->fromData = 2; mInit((unsigned char *)data, length, &handle); dataSrc = (Tcl_Channel) &handle; } result = FileReadGIF(interp, dataSrc, "inline data", format, imageHandle, destX, destY, width, height, srcX, srcY); 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<= 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, length, handle) unsigned char *string; /* string containing initial mmencoded data */ int length; /* Length of string */ MFile *handle; /* mmdecode "file" handle */ { handle->data = string; handle->length = length; 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; istate == GIF_DONE) { return GIF_DONE; } do { if (handle->length-- <= 0) { handle->state = GIF_DONE; return GIF_DONE; } 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; if (handle->length <= 0 || (size_t)handle->length < (size_t) (hunk * count)) { return -1; } memcpy((VOID *)dst, (VOID *) handle->data, (size_t) (hunk * count)); handle->data += hunk * count; handle->length -= 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 * *---------------------------------------------------------------------- * 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. */ CONST 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 ; xwidth; 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 ; xwidth; 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 ; yheight ; y++) { colores = blockPtr->pixelPtr + blockPtr->offset[0] + y * blockPtr->pitch; for(x=0 ; xwidth ; 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)<=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= 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(UCHAR(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(UCHAR(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. * *----------------------------------------------------------------------- */