/* * Gif extracting routines - derived from libungif * * Portions Copyright 2006 Mike McCormack * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA */ /* * Original copyright notice: * * The GIFLIB distribution is Copyright (c) 1997 Eric S. Raymond * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. */ /****************************************************************************** * "Gif-Lib" - Yet another gif library. * * Written by: Gershon Elber IBM PC Ver 1.1, Aug. 1990 ****************************************************************************** * The kernel of the GIF Decoding process can be found here. ****************************************************************************** * History: * 16 Jun 89 - Version 1.0 by Gershon Elber. * 3 Sep 90 - Version 1.1 by Gershon Elber (Support for Gif89, Unique names). *****************************************************************************/ #include <stdlib.h> #include <string.h> #include <stdarg.h> #include "windef.h" #include "winbase.h" #include "ungif.h" static void *ungif_alloc( size_t sz ) { return HeapAlloc( GetProcessHeap(), 0, sz ); } static void *ungif_calloc( size_t num, size_t sz ) { return HeapAlloc( GetProcessHeap(), HEAP_ZERO_MEMORY, num*sz ); } static void *ungif_realloc( void *ptr, size_t sz ) { return HeapReAlloc( GetProcessHeap(), 0, ptr, sz ); } static void ungif_free( void *ptr ) { HeapFree( GetProcessHeap(), 0, ptr ); } #define LZ_MAX_CODE 4095 /* Biggest code possible in 12 bits. */ #define LZ_BITS 12 #define NO_SUCH_CODE 4098 /* Impossible code, to signal empty. */ typedef struct GifFilePrivateType { GifWord BitsPerPixel, /* Bits per pixel (Codes uses at least this + 1). */ ClearCode, /* The CLEAR LZ code. */ EOFCode, /* The EOF LZ code. */ RunningCode, /* The next code algorithm can generate. */ RunningBits, /* The number of bits required to represent RunningCode. */ MaxCode1, /* 1 bigger than max. possible code, in RunningBits bits. */ LastCode, /* The code before the current code. */ CrntCode, /* Current algorithm code. */ StackPtr, /* For character stack (see below). */ CrntShiftState; /* Number of bits in CrntShiftDWord. */ unsigned long CrntShiftDWord; /* For bytes decomposition into codes. */ unsigned long PixelCount; /* Number of pixels in image. */ InputFunc Read; /* function to read gif input (TVT) */ GifByteType Buf[256]; /* Compressed input is buffered here. */ GifByteType Stack[LZ_MAX_CODE]; /* Decoded pixels are stacked here. */ GifByteType Suffix[LZ_MAX_CODE + 1]; /* So we can trace the codes. */ GifPrefixType Prefix[LZ_MAX_CODE + 1]; } GifFilePrivateType; /* avoid extra function call in case we use fread (TVT) */ #define READ(_gif,_buf,_len) \ ((GifFilePrivateType*)_gif->Private)->Read(_gif,_buf,_len) static int DGifGetWord(GifFileType *GifFile, GifWord *Word); static int DGifSetupDecompress(GifFileType *GifFile); static int DGifDecompressLine(GifFileType *GifFile, GifPixelType *Line, int LineLen); static int DGifGetPrefixChar(const GifPrefixType *Prefix, int Code, int ClearCode); static int DGifDecompressInput(GifFileType *GifFile, int *Code); static int DGifBufferedInput(GifFileType *GifFile, GifByteType *Buf, GifByteType *NextByte); static int DGifGetExtensionNext(GifFileType * GifFile, GifByteType ** GifExtension); static int DGifGetCodeNext(GifFileType * GifFile, GifByteType ** GifCodeBlock); /****************************************************************************** * Miscellaneous utility functions *****************************************************************************/ /* return smallest bitfield size n will fit in */ static int BitSize(int n) { register int i; for (i = 1; i <= 8; i++) if ((1 << i) >= n) break; return (i); } /****************************************************************************** * Color map object functions *****************************************************************************/ /* * Allocate a color map of given size; initialize with contents of * ColorMap if that pointer is non-NULL. */ static ColorMapObject * MakeMapObject(int ColorCount, const GifColorType * ColorMap) { ColorMapObject *Object; /*** FIXME: Our ColorCount has to be a power of two. Is it necessary to * make the user know that or should we automatically round up instead? */ if (ColorCount != (1 << BitSize(ColorCount))) { return NULL; } Object = ungif_alloc(sizeof(ColorMapObject)); if (Object == NULL) { return NULL; } Object->Colors = ungif_calloc(ColorCount, sizeof(GifColorType)); if (Object->Colors == NULL) { return NULL; } Object->ColorCount = ColorCount; Object->BitsPerPixel = BitSize(ColorCount); if (ColorMap) { memcpy(Object->Colors, ColorMap, ColorCount * sizeof(GifColorType)); } return (Object); } /* * Free a color map object */ static void FreeMapObject(ColorMapObject * Object) { if (Object != NULL) { ungif_free(Object->Colors); ungif_free(Object); /*** FIXME: * When we are willing to break API we need to make this function * FreeMapObject(ColorMapObject **Object) * and do this assignment to NULL here: * *Object = NULL; */ } } static int AddExtensionBlock(Extensions *New, int Len, const unsigned char ExtData[]) { ExtensionBlock *ep; if (New->ExtensionBlocks == NULL) New->ExtensionBlocks = ungif_alloc(sizeof(ExtensionBlock)); else New->ExtensionBlocks = ungif_realloc(New->ExtensionBlocks, sizeof(ExtensionBlock) * (New->ExtensionBlockCount + 1)); if (New->ExtensionBlocks == NULL) return (GIF_ERROR); ep = &New->ExtensionBlocks[New->ExtensionBlockCount++]; ep->ByteCount=Len + 3; ep->Bytes = ungif_alloc(ep->ByteCount + 3); if (ep->Bytes == NULL) return (GIF_ERROR); /* Extension Header */ ep->Bytes[0] = 0x21; ep->Bytes[1] = New->Function; ep->Bytes[2] = Len; if (ExtData) { memcpy(ep->Bytes + 3, ExtData, Len); ep->Function = New->Function; } return (GIF_OK); } static int AppendExtensionBlock(Extensions *New, int Len, const unsigned char ExtData[]) { ExtensionBlock *ep; if (New->ExtensionBlocks == NULL) return (GIF_ERROR); ep = &New->ExtensionBlocks[New->ExtensionBlockCount - 1]; ep->Bytes = ungif_realloc(ep->Bytes, ep->ByteCount + Len + 1); if (ep->Bytes == NULL) return (GIF_ERROR); ep->Bytes[ep->ByteCount] = Len; if (ExtData) memcpy(ep->Bytes + ep->ByteCount + 1, ExtData, Len); ep->ByteCount += Len + 1; return (GIF_OK); } static void FreeExtension(Extensions *Extensions) { ExtensionBlock *ep; if ((Extensions == NULL) || (Extensions->ExtensionBlocks == NULL)) { return; } for (ep = Extensions->ExtensionBlocks; ep < (Extensions->ExtensionBlocks + Extensions->ExtensionBlockCount); ep++) ungif_free(ep->Bytes); ungif_free(Extensions->ExtensionBlocks); Extensions->ExtensionBlocks = NULL; } /****************************************************************************** * Image block allocation functions ******************************************************************************/ static void FreeSavedImages(GifFileType * GifFile) { SavedImage *sp; if ((GifFile == NULL) || (GifFile->SavedImages == NULL)) { return; } for (sp = GifFile->SavedImages; sp < GifFile->SavedImages + GifFile->ImageCount; sp++) { if (sp->ImageDesc.ColorMap) { FreeMapObject(sp->ImageDesc.ColorMap); sp->ImageDesc.ColorMap = NULL; } ungif_free(sp->RasterBits); if (sp->Extensions.ExtensionBlocks) FreeExtension(&sp->Extensions); } ungif_free(GifFile->SavedImages); GifFile->SavedImages=NULL; } /****************************************************************************** * This routine should be called before any other DGif calls. Note that * this routine is called automatically from DGif file open routines. *****************************************************************************/ static int DGifGetScreenDesc(GifFileType * GifFile) { int i, BitsPerPixel, SortFlag; GifByteType Buf[3]; /* Put the screen descriptor into the file: */ if (DGifGetWord(GifFile, &GifFile->SWidth) == GIF_ERROR || DGifGetWord(GifFile, &GifFile->SHeight) == GIF_ERROR) return GIF_ERROR; if (READ(GifFile, Buf, 3) != 3) { return GIF_ERROR; } GifFile->SColorResolution = (((Buf[0] & 0x70) + 1) >> 4) + 1; SortFlag = (Buf[0] & 0x08) != 0; BitsPerPixel = (Buf[0] & 0x07) + 1; GifFile->SBackGroundColor = Buf[1]; GifFile->SAspectRatio = Buf[2]; if (Buf[0] & 0x80) { /* Do we have global color map? */ GifFile->SColorMap = MakeMapObject(1 << BitsPerPixel, NULL); if (GifFile->SColorMap == NULL) { return GIF_ERROR; } /* Get the global color map: */ GifFile->SColorMap->SortFlag = SortFlag; for (i = 0; i < GifFile->SColorMap->ColorCount; i++) { if (READ(GifFile, Buf, 3) != 3) { FreeMapObject(GifFile->SColorMap); GifFile->SColorMap = NULL; return GIF_ERROR; } GifFile->SColorMap->Colors[i].Red = Buf[0]; GifFile->SColorMap->Colors[i].Green = Buf[1]; GifFile->SColorMap->Colors[i].Blue = Buf[2]; } } else { GifFile->SColorMap = NULL; } return GIF_OK; } /****************************************************************************** * This routine should be called before any attempt to read an image. *****************************************************************************/ static int DGifGetRecordType(GifFileType * GifFile, GifRecordType * Type) { GifByteType Buf; if (READ(GifFile, &Buf, 1) != 1) { /* Wine-specific behavior: Native accepts broken GIF files that have no * terminator, so we match this by treating EOF as a terminator. */ *Type = TERMINATE_RECORD_TYPE; return GIF_OK; } switch (Buf) { case ',': *Type = IMAGE_DESC_RECORD_TYPE; break; case '!': *Type = EXTENSION_RECORD_TYPE; break; case ';': *Type = TERMINATE_RECORD_TYPE; break; default: *Type = UNDEFINED_RECORD_TYPE; return GIF_ERROR; } return GIF_OK; } /****************************************************************************** * This routine should be called before any attempt to read an image. * Note it is assumed the Image desc. header (',') has been read. *****************************************************************************/ static int DGifGetImageDesc(GifFileType * GifFile) { int i, BitsPerPixel, SortFlag; GifByteType Buf[3]; GifFilePrivateType *Private = GifFile->Private; SavedImage *sp; if (DGifGetWord(GifFile, &GifFile->Image.Left) == GIF_ERROR || DGifGetWord(GifFile, &GifFile->Image.Top) == GIF_ERROR || DGifGetWord(GifFile, &GifFile->Image.Width) == GIF_ERROR || DGifGetWord(GifFile, &GifFile->Image.Height) == GIF_ERROR) return GIF_ERROR; if (READ(GifFile, Buf, 1) != 1) { return GIF_ERROR; } BitsPerPixel = (Buf[0] & 0x07) + 1; SortFlag = (Buf[0] & 0x20) != 0; GifFile->Image.Interlace = (Buf[0] & 0x40); if (Buf[0] & 0x80) { /* Does this image have local color map? */ /*** FIXME: Why do we check both of these in order to do this? * Why do we have both Image and SavedImages? */ if (GifFile->Image.ColorMap && GifFile->SavedImages == NULL) FreeMapObject(GifFile->Image.ColorMap); GifFile->Image.ColorMap = MakeMapObject(1 << BitsPerPixel, NULL); if (GifFile->Image.ColorMap == NULL) { return GIF_ERROR; } /* Get the image local color map: */ GifFile->Image.ColorMap->SortFlag = SortFlag; for (i = 0; i < GifFile->Image.ColorMap->ColorCount; i++) { if (READ(GifFile, Buf, 3) != 3) { FreeMapObject(GifFile->Image.ColorMap); GifFile->Image.ColorMap = NULL; return GIF_ERROR; } GifFile->Image.ColorMap->Colors[i].Red = Buf[0]; GifFile->Image.ColorMap->Colors[i].Green = Buf[1]; GifFile->Image.ColorMap->Colors[i].Blue = Buf[2]; } } else if (GifFile->Image.ColorMap) { FreeMapObject(GifFile->Image.ColorMap); GifFile->Image.ColorMap = NULL; } if (GifFile->SavedImages) { if ((GifFile->SavedImages = ungif_realloc(GifFile->SavedImages, sizeof(SavedImage) * (GifFile->ImageCount + 1))) == NULL) { return GIF_ERROR; } } else { if ((GifFile->SavedImages = ungif_alloc(sizeof(SavedImage))) == NULL) { return GIF_ERROR; } } sp = &GifFile->SavedImages[GifFile->ImageCount]; sp->ImageDesc = GifFile->Image; if (GifFile->Image.ColorMap != NULL) { sp->ImageDesc.ColorMap = MakeMapObject( GifFile->Image.ColorMap->ColorCount, GifFile->Image.ColorMap->Colors); if (sp->ImageDesc.ColorMap == NULL) { return GIF_ERROR; } sp->ImageDesc.ColorMap->SortFlag = GifFile->Image.ColorMap->SortFlag; } sp->RasterBits = NULL; sp->Extensions.ExtensionBlockCount = 0; sp->Extensions.ExtensionBlocks = NULL; GifFile->ImageCount++; Private->PixelCount = (long)GifFile->Image.Width * (long)GifFile->Image.Height; DGifSetupDecompress(GifFile); /* Reset decompress algorithm parameters. */ return GIF_OK; } /****************************************************************************** * Get one full scanned line (Line) of length LineLen from GIF file. *****************************************************************************/ static int DGifGetLine(GifFileType * GifFile, GifPixelType * Line, int LineLen) { GifByteType *Dummy; GifFilePrivateType *Private = GifFile->Private; if (!LineLen) LineLen = GifFile->Image.Width; if ((Private->PixelCount -= LineLen) > 0xffff0000UL) { return GIF_ERROR; } if (DGifDecompressLine(GifFile, Line, LineLen) == GIF_OK) { if (Private->PixelCount == 0) { /* We probably would not be called any more, so lets clean * everything before we return: need to flush out all rest of * image until empty block (size 0) detected. We use GetCodeNext. */ do if (DGifGetCodeNext(GifFile, &Dummy) == GIF_ERROR) return GIF_ERROR; while (Dummy != NULL) ; } return GIF_OK; } else return GIF_ERROR; } /****************************************************************************** * Get an extension block (see GIF manual) from gif file. This routine only * returns the first data block, and DGifGetExtensionNext should be called * after this one until NULL extension is returned. * The Extension should NOT be freed by the user (not dynamically allocated). * Note it is assumed the Extension desc. header ('!') has been read. *****************************************************************************/ static int DGifGetExtension(GifFileType * GifFile, int *ExtCode, GifByteType ** Extension) { GifByteType Buf; if (READ(GifFile, &Buf, 1) != 1) { return GIF_ERROR; } *ExtCode = Buf; return DGifGetExtensionNext(GifFile, Extension); } /****************************************************************************** * Get a following extension block (see GIF manual) from gif file. This * routine should be called until NULL Extension is returned. * The Extension should NOT be freed by the user (not dynamically allocated). *****************************************************************************/ static int DGifGetExtensionNext(GifFileType * GifFile, GifByteType ** Extension) { GifByteType Buf; GifFilePrivateType *Private = GifFile->Private; if (READ(GifFile, &Buf, 1) != 1) { return GIF_ERROR; } if (Buf > 0) { *Extension = Private->Buf; /* Use private unused buffer. */ (*Extension)[0] = Buf; /* Pascal strings notation (pos. 0 is len.). */ if (READ(GifFile, &((*Extension)[1]), Buf) != Buf) { return GIF_ERROR; } } else *Extension = NULL; return GIF_OK; } /****************************************************************************** * Get 2 bytes (word) from the given file: *****************************************************************************/ static int DGifGetWord(GifFileType * GifFile, GifWord *Word) { unsigned char c[2]; if (READ(GifFile, c, 2) != 2) { return GIF_ERROR; } *Word = (((unsigned int)c[1]) << 8) + c[0]; return GIF_OK; } /****************************************************************************** * Continue to get the image code in compressed form. This routine should be * called until NULL block is returned. * The block should NOT be freed by the user (not dynamically allocated). *****************************************************************************/ static int DGifGetCodeNext(GifFileType * GifFile, GifByteType ** CodeBlock) { GifByteType Buf; GifFilePrivateType *Private = GifFile->Private; if (READ(GifFile, &Buf, 1) != 1) { return GIF_ERROR; } if (Buf > 0) { *CodeBlock = Private->Buf; /* Use private unused buffer. */ (*CodeBlock)[0] = Buf; /* Pascal strings notation (pos. 0 is len.). */ if (READ(GifFile, &((*CodeBlock)[1]), Buf) != Buf) { return GIF_ERROR; } } else { *CodeBlock = NULL; Private->Buf[0] = 0; /* Make sure the buffer is empty! */ Private->PixelCount = 0; /* And local info. indicate image read. */ } return GIF_OK; } /****************************************************************************** * Setup the LZ decompression for this image: *****************************************************************************/ static int DGifSetupDecompress(GifFileType * GifFile) { int i, BitsPerPixel; GifByteType CodeSize; GifPrefixType *Prefix; GifFilePrivateType *Private = GifFile->Private; READ(GifFile, &CodeSize, 1); /* Read Code size from file. */ BitsPerPixel = CodeSize; Private->Buf[0] = 0; /* Input Buffer empty. */ Private->BitsPerPixel = BitsPerPixel; Private->ClearCode = (1 << BitsPerPixel); Private->EOFCode = Private->ClearCode + 1; Private->RunningCode = Private->EOFCode + 1; Private->RunningBits = BitsPerPixel + 1; /* Number of bits per code. */ Private->MaxCode1 = 1 << Private->RunningBits; /* Max. code + 1. */ Private->StackPtr = 0; /* No pixels on the pixel stack. */ Private->LastCode = NO_SUCH_CODE; Private->CrntShiftState = 0; /* No information in CrntShiftDWord. */ Private->CrntShiftDWord = 0; Prefix = Private->Prefix; for (i = 0; i <= LZ_MAX_CODE; i++) Prefix[i] = NO_SUCH_CODE; return GIF_OK; } /****************************************************************************** * The LZ decompression routine: * This version decompress the given gif file into Line of length LineLen. * This routine can be called few times (one per scan line, for example), in * order the complete the whole image. *****************************************************************************/ static int DGifDecompressLine(GifFileType * GifFile, GifPixelType * Line, int LineLen) { int i = 0; int j, CrntCode, EOFCode, ClearCode, CrntPrefix, LastCode, StackPtr; GifByteType *Stack, *Suffix; GifPrefixType *Prefix; GifFilePrivateType *Private = GifFile->Private; StackPtr = Private->StackPtr; Prefix = Private->Prefix; Suffix = Private->Suffix; Stack = Private->Stack; EOFCode = Private->EOFCode; ClearCode = Private->ClearCode; LastCode = Private->LastCode; if (StackPtr != 0) { /* Let pop the stack off before continuing to read the gif file: */ while (StackPtr != 0 && i < LineLen) Line[i++] = Stack[--StackPtr]; } while (i < LineLen) { /* Decode LineLen items. */ if (DGifDecompressInput(GifFile, &CrntCode) == GIF_ERROR) return GIF_ERROR; if (CrntCode == EOFCode) { /* Note, however, that usually we will not be here as we will stop * decoding as soon as we got all the pixel, or EOF code will * not be read at all, and DGifGetLine/Pixel clean everything. */ if (i != LineLen - 1 || Private->PixelCount != 0) { return GIF_ERROR; } i++; } else if (CrntCode == ClearCode) { /* We need to start over again: */ for (j = 0; j <= LZ_MAX_CODE; j++) Prefix[j] = NO_SUCH_CODE; Private->RunningCode = Private->EOFCode + 1; Private->RunningBits = Private->BitsPerPixel + 1; Private->MaxCode1 = 1 << Private->RunningBits; LastCode = Private->LastCode = NO_SUCH_CODE; } else { /* It's a regular code - if in pixel range simply add it to output * stream, otherwise trace to codes linked list until the prefix * is in pixel range: */ if (CrntCode < ClearCode) { /* This is simple - its pixel scalar, so add it to output: */ Line[i++] = CrntCode; } else { /* It's a code to be traced: trace the linked list * until the prefix is a pixel, while pushing the suffix * pixels on our stack. If we done, pop the stack in reverse * order (that's what stack is good for!) for output. */ if (Prefix[CrntCode] == NO_SUCH_CODE) { /* Only allowed if CrntCode is exactly the running code: * In that case CrntCode = XXXCode, CrntCode or the * prefix code is last code and the suffix char is * exactly the prefix of last code! */ if (CrntCode == Private->RunningCode - 2) { CrntPrefix = LastCode; Suffix[Private->RunningCode - 2] = Stack[StackPtr++] = DGifGetPrefixChar(Prefix, LastCode, ClearCode); } else { return GIF_ERROR; } } else CrntPrefix = CrntCode; /* Now (if image is O.K.) we should not get a NO_SUCH_CODE * during the trace. As we might loop forever, in case of * defective image, we count the number of loops we trace * and stop if we got LZ_MAX_CODE. Obviously we cannot * loop more than that. */ j = 0; while (j++ <= LZ_MAX_CODE && CrntPrefix > ClearCode && CrntPrefix <= LZ_MAX_CODE) { Stack[StackPtr++] = Suffix[CrntPrefix]; CrntPrefix = Prefix[CrntPrefix]; } if (j >= LZ_MAX_CODE || CrntPrefix > LZ_MAX_CODE) { return GIF_ERROR; } /* Push the last character on stack: */ Stack[StackPtr++] = CrntPrefix; /* Now lets pop all the stack into output: */ while (StackPtr != 0 && i < LineLen) Line[i++] = Stack[--StackPtr]; } if (LastCode != NO_SUCH_CODE) { Prefix[Private->RunningCode - 2] = LastCode; if (CrntCode == Private->RunningCode - 2) { /* Only allowed if CrntCode is exactly the running code: * In that case CrntCode = XXXCode, CrntCode or the * prefix code is last code and the suffix char is * exactly the prefix of last code! */ Suffix[Private->RunningCode - 2] = DGifGetPrefixChar(Prefix, LastCode, ClearCode); } else { Suffix[Private->RunningCode - 2] = DGifGetPrefixChar(Prefix, CrntCode, ClearCode); } } LastCode = CrntCode; } } Private->LastCode = LastCode; Private->StackPtr = StackPtr; return GIF_OK; } /****************************************************************************** * Routine to trace the Prefixes linked list until we get a prefix which is * not code, but a pixel value (less than ClearCode). Returns that pixel value. * If image is defective, we might loop here forever, so we limit the loops to * the maximum possible if image O.k. - LZ_MAX_CODE times. *****************************************************************************/ static int DGifGetPrefixChar(const GifPrefixType *Prefix, int Code, int ClearCode) { int i = 0; while (Code > ClearCode && i++ <= LZ_MAX_CODE) Code = Prefix[Code]; return Code; } /****************************************************************************** * The LZ decompression input routine: * This routine is responsible for the decompression of the bit stream from * 8 bits (bytes) packets, into the real codes. * Returns GIF_OK if read successfully. *****************************************************************************/ static int DGifDecompressInput(GifFileType * GifFile, int *Code) { GifFilePrivateType *Private = GifFile->Private; GifByteType NextByte; static const unsigned short CodeMasks[] = { 0x0000, 0x0001, 0x0003, 0x0007, 0x000f, 0x001f, 0x003f, 0x007f, 0x00ff, 0x01ff, 0x03ff, 0x07ff, 0x0fff }; /* The image can't contain more than LZ_BITS per code. */ if (Private->RunningBits > LZ_BITS) { return GIF_ERROR; } while (Private->CrntShiftState < Private->RunningBits) { /* Needs to get more bytes from input stream for next code: */ if (DGifBufferedInput(GifFile, Private->Buf, &NextByte) == GIF_ERROR) { return GIF_ERROR; } Private->CrntShiftDWord |= ((unsigned long)NextByte) << Private->CrntShiftState; Private->CrntShiftState += 8; } *Code = Private->CrntShiftDWord & CodeMasks[Private->RunningBits]; Private->CrntShiftDWord >>= Private->RunningBits; Private->CrntShiftState -= Private->RunningBits; /* If code cannot fit into RunningBits bits, must raise its size. Note * however that codes above 4095 are used for special signaling. * If we're using LZ_BITS bits already and we're at the max code, just * keep using the table as it is, don't increment Private->RunningCode. */ if (Private->RunningCode < LZ_MAX_CODE + 2 && ++Private->RunningCode > Private->MaxCode1 && Private->RunningBits < LZ_BITS) { Private->MaxCode1 <<= 1; Private->RunningBits++; } return GIF_OK; } /****************************************************************************** * This routines read one gif data block at a time and buffers it internally * so that the decompression routine could access it. * The routine returns the next byte from its internal buffer (or read next * block in if buffer empty) and returns GIF_OK if successful. *****************************************************************************/ static int DGifBufferedInput(GifFileType * GifFile, GifByteType * Buf, GifByteType * NextByte) { if (Buf[0] == 0) { /* Needs to read the next buffer - this one is empty: */ if (READ(GifFile, Buf, 1) != 1) { return GIF_ERROR; } /* There shouldn't be any empty data blocks here as the LZW spec * says the LZW termination code should come first. Therefore we * shouldn't be inside this routine at that point. */ if (Buf[0] == 0) { return GIF_ERROR; } if (READ(GifFile, &Buf[1], Buf[0]) != Buf[0]) { return GIF_ERROR; } *NextByte = Buf[1]; Buf[1] = 2; /* We use now the second place as last char read! */ Buf[0]--; } else { *NextByte = Buf[Buf[1]++]; Buf[0]--; } return GIF_OK; } /****************************************************************************** * This routine reads an entire GIF into core, hanging all its state info off * the GifFileType pointer. Call DGifOpenFileName() or DGifOpenFileHandle() * first to initialize I/O. Its inverse is EGifSpew(). ******************************************************************************/ int DGifSlurp(GifFileType * GifFile) { int ImageSize; GifRecordType RecordType; SavedImage *sp; GifByteType *ExtData; Extensions temp_save; temp_save.ExtensionBlocks = NULL; temp_save.ExtensionBlockCount = 0; do { if (DGifGetRecordType(GifFile, &RecordType) == GIF_ERROR) return (GIF_ERROR); switch (RecordType) { case IMAGE_DESC_RECORD_TYPE: if (DGifGetImageDesc(GifFile) == GIF_ERROR) return (GIF_ERROR); sp = &GifFile->SavedImages[GifFile->ImageCount - 1]; ImageSize = sp->ImageDesc.Width * sp->ImageDesc.Height; sp->RasterBits = ungif_alloc(ImageSize * sizeof(GifPixelType)); if (sp->RasterBits == NULL) { return GIF_ERROR; } if (DGifGetLine(GifFile, sp->RasterBits, ImageSize) == GIF_ERROR) return (GIF_ERROR); if (temp_save.ExtensionBlocks) { sp->Extensions.ExtensionBlocks = temp_save.ExtensionBlocks; sp->Extensions.ExtensionBlockCount = temp_save.ExtensionBlockCount; temp_save.ExtensionBlocks = NULL; temp_save.ExtensionBlockCount = 0; /* FIXME: The following is wrong. It is left in only for * backwards compatibility. Someday it should go away. Use * the sp->ExtensionBlocks->Function variable instead. */ sp->Extensions.Function = sp->Extensions.ExtensionBlocks[0].Function; } break; case EXTENSION_RECORD_TYPE: { int Function; Extensions *Extensions; if (DGifGetExtension(GifFile, &Function, &ExtData) == GIF_ERROR) return (GIF_ERROR); if (GifFile->ImageCount || Function == GRAPHICS_EXT_FUNC_CODE) Extensions = &temp_save; else Extensions = &GifFile->Extensions; Extensions->Function = Function; /* Create an extension block with our data */ if (AddExtensionBlock(Extensions, ExtData[0], &ExtData[1]) == GIF_ERROR) return (GIF_ERROR); while (ExtData != NULL) { int Len; GifByteType *Data; if (DGifGetExtensionNext(GifFile, &ExtData) == GIF_ERROR) return (GIF_ERROR); if (ExtData) { Len = ExtData[0]; Data = &ExtData[1]; } else { Len = 0; Data = NULL; } if (AppendExtensionBlock(Extensions, Len, Data) == GIF_ERROR) return (GIF_ERROR); } break; } case TERMINATE_RECORD_TYPE: break; default: /* Should be trapped by DGifGetRecordType */ break; } } while (RecordType != TERMINATE_RECORD_TYPE); /* Just in case the Gif has an extension block without an associated * image... (Should we save this into a savefile structure with no image * instead? Have to check if the present writing code can handle that as * well.... */ if (temp_save.ExtensionBlocks) FreeExtension(&temp_save); return (GIF_OK); } /****************************************************************************** * GifFileType constructor with user supplied input function (TVT) *****************************************************************************/ GifFileType * DGifOpen(void *userData, InputFunc readFunc) { unsigned char Buf[GIF_STAMP_LEN + 1]; GifFileType *GifFile; GifFilePrivateType *Private; GifFile = ungif_alloc(sizeof(GifFileType)); if (GifFile == NULL) { return NULL; } memset(GifFile, '\0', sizeof(GifFileType)); Private = ungif_alloc(sizeof(GifFilePrivateType)); if (!Private) { ungif_free(GifFile); return NULL; } GifFile->Private = (void*)Private; Private->Read = readFunc; /* TVT */ GifFile->UserData = userData; /* TVT */ /* Lets see if this is a GIF file: */ if (READ(GifFile, Buf, GIF_STAMP_LEN) != GIF_STAMP_LEN) { ungif_free(Private); ungif_free(GifFile); return NULL; } /* The GIF Version number is ignored at this time. Maybe we should do * something more useful with it. */ Buf[GIF_STAMP_LEN] = 0; if (memcmp(GIF_STAMP, Buf, GIF_VERSION_POS) != 0) { ungif_free(Private); ungif_free(GifFile); return NULL; } if (DGifGetScreenDesc(GifFile) == GIF_ERROR) { ungif_free(Private); ungif_free(GifFile); return NULL; } return GifFile; } /****************************************************************************** * This routine should be called last, to close the GIF file. *****************************************************************************/ int DGifCloseFile(GifFileType * GifFile) { GifFilePrivateType *Private; if (GifFile == NULL) return GIF_ERROR; Private = GifFile->Private; if (GifFile->Image.ColorMap) { FreeMapObject(GifFile->Image.ColorMap); GifFile->Image.ColorMap = NULL; } if (GifFile->SColorMap) { FreeMapObject(GifFile->SColorMap); GifFile->SColorMap = NULL; } ungif_free(Private); Private = NULL; if (GifFile->SavedImages) { FreeSavedImages(GifFile); GifFile->SavedImages = NULL; } FreeExtension(&GifFile->Extensions); ungif_free(GifFile); return GIF_OK; }