ungif.c

这是一个开放源代码的与WINNT/WIN2K/WIN2003兼容的操作系统

/*
 * 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_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(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 ((ColorMapObject *) NULL);
    }

    Object = ungif_alloc(sizeof(ColorMapObject));
    if (Object == (ColorMapObject *) NULL) {
        return ((ColorMapObject *) NULL);
    }

    Object->Colors = ungif_calloc(ColorCount, sizeof(GifColorType));
    if (Object->Colors == (GifColorType *) 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,
                  unsigned char ExtData[]) {

    ExtensionBlock *ep;

    if (New->ExtensionBlocks == NULL)
        New->ExtensionBlocks = ungif_alloc(sizeof(ExtensionBlock));
    else
        New->ExtensionBlocks = 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;