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reactos/dll/win32/windowscodecs/ungif.c

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/*
* 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"
#include "wine/debug.h"
WINE_DEFAULT_DEBUG_CHANNEL(wincodecs);
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) {
ungif_free(Object);
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? */
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)
{
WARN("GIF is not properly terminated\n");
break;
}
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;
if (ExtData)
{
/* Create an extension block with our data */
if (AddExtensionBlock(Extensions, ExtData[0], &ExtData[1]) == GIF_ERROR)
return (GIF_ERROR);
}
else /* Empty extension block */
{
if (AddExtensionBlock(Extensions, 0, NULL) == 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;
}
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