| /* |
| * 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 "ungif.h" |
| |
| #include <stdarg.h> |
| #include "windef.h" |
| #include "winbase.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(SavedImage * 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; |
| ep->Bytes = ungif_alloc(ep->ByteCount); |
| if (ep->Bytes == NULL) |
| return (GIF_ERROR); |
| |
| if (ExtData) { |
| memcpy(ep->Bytes, ExtData, Len); |
| ep->Function = New->Function; |
| } |
| |
| return (GIF_OK); |
| } |
| |
| static void |
| FreeExtension(SavedImage * Image) |
| { |
| ExtensionBlock *ep; |
| |
| if ((Image == NULL) || (Image->ExtensionBlocks == NULL)) { |
| return; |
| } |
| for (ep = Image->ExtensionBlocks; |
| ep < (Image->ExtensionBlocks + Image->ExtensionBlockCount); ep++) |
| ungif_free(ep->Bytes); |
| ungif_free(Image->ExtensionBlocks); |
| Image->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->ExtensionBlocks) |
| FreeExtension(sp); |
| } |
| 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; |
| 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; |
| BitsPerPixel = (Buf[0] & 0x07) + 1; |
| GifFile->SBackGroundColor = Buf[1]; |
| 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: */ |
| 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) { |
| return GIF_ERROR; |
| } |
| |
| 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; |
| 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; |
| 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: */ |
| 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->RasterBits = NULL; |
| sp->ExtensionBlockCount = 0; |
| sp->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; |
| SavedImage 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->ExtensionBlocks = temp_save.ExtensionBlocks; |
| sp->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->Function = sp->ExtensionBlocks[0].Function; |
| } |
| break; |
| |
| case EXTENSION_RECORD_TYPE: |
| if (DGifGetExtension(GifFile, &temp_save.Function, &ExtData) == |
| GIF_ERROR) |
| return (GIF_ERROR); |
| while (ExtData != NULL) { |
| |
| /* Create an extension block with our data */ |
| if (AddExtensionBlock(&temp_save, ExtData[0], &ExtData[1]) |
| == GIF_ERROR) |
| return (GIF_ERROR); |
| |
| if (DGifGetExtensionNext(GifFile, &ExtData) == GIF_ERROR) |
| return (GIF_ERROR); |
| temp_save.Function = 0; |
| } |
| 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; |
| } |
| |
| ungif_free(GifFile); |
| |
| return GIF_OK; |
| } |
