dgif_lib.c

SigmDesign SMP8634 media decode chip development SDK

        DGifGetWord(GifFile, &GifFile->Image.Height) == GIF_ERROR)
        return GIF_ERROR;
    if (READ(GifFile, Buf, 1) != 1) {
        _GifError = D_GIF_ERR_READ_FAILED;
        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) {
            _GifError = D_GIF_ERR_NOT_ENOUGH_MEM;
            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);
                _GifError = D_GIF_ERR_READ_FAILED;
                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 = (SavedImage *)realloc(GifFile->SavedImages,
                                      sizeof(SavedImage) *
                                      (GifFile->ImageCount + 1))) == NULL) {
            _GifError = D_GIF_ERR_NOT_ENOUGH_MEM;
            return GIF_ERROR;
        }
    } else {
        if ((GifFile->SavedImages =
             (SavedImage *) malloc(sizeof(SavedImage))) == NULL) {
            _GifError = D_GIF_ERR_NOT_ENOUGH_MEM;
            return GIF_ERROR;
        }
    }

    sp = &GifFile->SavedImages[GifFile->ImageCount];
    memcpy(&sp->ImageDesc, &GifFile->Image, sizeof(GifImageDesc));
    if (GifFile->Image.ColorMap != NULL) {
        sp->ImageDesc.ColorMap = MakeMapObject(
                                 GifFile->Image.ColorMap->ColorCount,
                                 GifFile->Image.ColorMap->Colors);
        if (sp->ImageDesc.ColorMap == NULL) {
            _GifError = D_GIF_ERR_NOT_ENOUGH_MEM;
            return GIF_ERROR;
        }
    }
    sp->RasterBits = (unsigned char *)NULL;
    sp->ExtensionBlockCount = 0;
    sp->ExtensionBlocks = (ExtensionBlock *) 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.
 *****************************************************************************/
int
DGifGetLine(GifFileType * GifFile,
            GifPixelType * Line,
            int LineLen) {

    GifByteType *Dummy;
    GifFilePrivateType *Private = (GifFilePrivateType *) GifFile->Private;

    if (!IS_READABLE(Private)) {
        /* This file was NOT open for reading: */
        _GifError = D_GIF_ERR_NOT_READABLE;
        return GIF_ERROR;
    }

    if (!LineLen)
        LineLen = GifFile->Image.Width;

#if defined(__MSDOS__) || defined(__GNUC__)
    if ((Private->PixelCount -= LineLen) > 0xffff0000UL) {
#else
    if ((Private->PixelCount -= LineLen) > 0xffff0000) {
#endif /* __MSDOS__ */
        _GifError = D_GIF_ERR_DATA_TOO_BIG;
        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;
}

/******************************************************************************
 * Put one pixel (Pixel) into GIF file.
 *****************************************************************************/
int
DGifGetPixel(GifFileType * GifFile,
             GifPixelType Pixel) {
    
    GifByteType *Dummy;
    GifFilePrivateType *Private = (GifFilePrivateType *) GifFile->Private;

    if (!IS_READABLE(Private)) {
        /* This file was NOT open for reading: */
        _GifError = D_GIF_ERR_NOT_READABLE;
        return GIF_ERROR;
    }
#if defined(__MSDOS__) || defined(__GNUC__)
    if (--Private->PixelCount > 0xffff0000UL)
#else
    if (--Private->PixelCount > 0xffff0000)
#endif /* __MSDOS__ */
    {
        _GifError = D_GIF_ERR_DATA_TOO_BIG;
        return GIF_ERROR;
    }

    if (DGifDecompressLine(GifFile, &Pixel, 1) == 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.
 *****************************************************************************/
int
DGifGetExtension(GifFileType * GifFile,
                 int *ExtCode,
                 GifByteType ** Extension) {

    GifByteType Buf;
    GifFilePrivateType *Private = (GifFilePrivateType *)GifFile->Private;

    if (!IS_READABLE(Private)) {
        /* This file was NOT open for reading: */
        _GifError = D_GIF_ERR_NOT_READABLE;
        return GIF_ERROR;
    }

    if (READ(GifFile, &Buf, 1) != 1) {
        _GifError = D_GIF_ERR_READ_FAILED;
        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).
 *****************************************************************************/
int
DGifGetExtensionNext(GifFileType * GifFile,
                     GifByteType ** Extension) {
    
    GifByteType Buf;
    GifFilePrivateType *Private = (GifFilePrivateType *)GifFile->Private;

    if (READ(GifFile, &Buf, 1) != 1) {
        _GifError = D_GIF_ERR_READ_FAILED;
        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) {
            _GifError = D_GIF_ERR_READ_FAILED;
            return GIF_ERROR;
        }
    } else
        *Extension = NULL;

    return GIF_OK;
}

/******************************************************************************
 * This routine should be called last, to close the GIF file.
 *****************************************************************************/
int
DGifCloseFile(GifFileType * GifFile) {
    
    GifFilePrivateType *Private;
    FILE *File;

    if (GifFile == NULL)
        return GIF_ERROR;

    Private = (GifFilePrivateType *) GifFile->Private;

    if (!IS_READABLE(Private)) {
        /* This file was NOT open for reading: */
        _GifError = D_GIF_ERR_NOT_READABLE;
        return GIF_ERROR;
    }

    File = Private->File;

    if (GifFile->Image.ColorMap) {
        FreeMapObject(GifFile->Image.ColorMap);
        GifFile->Image.ColorMap = NULL;
    }

    if (GifFile->SColorMap) {
        FreeMapObject(GifFile->SColorMap);
        GifFile->SColorMap = NULL;
    }

    if (Private) {
        free((char *)Private);
        Private = NULL;
    }

    if (GifFile->SavedImages) {
        FreeSavedImages(GifFile);
        GifFile->SavedImages = NULL;
    }

    free(GifFile);

    if (File && (fclose(File) != 0)) {
        _GifError = D_GIF_ERR_CLOSE_FAILED;
        return GIF_ERROR;
    }
    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) {
        _GifError = D_GIF_ERR_READ_FAILED;
        return GIF_ERROR;
    }

    *Word = (((unsigned int)c[1]) << 8) + c[0];
    return GIF_OK;
}

/******************************************************************************
 * Get the image code in compressed form.  This routine can be called if the
 * information needed to be piped out as is. Obviously this is much faster
 * than decoding and encoding again. This routine should be followed by calls
 * to DGifGetCodeNext, until NULL block is returned.
 * The block should NOT be freed by the user (not dynamically allocated).
 *****************************************************************************/
int
DGifGetCode(GifFileType * GifFile,
            int *CodeSize,
            GifByteType ** CodeBlock) {

    GifFilePrivateType *Private = (GifFilePrivateType *)GifFile->Private;

    if (!IS_READABLE(Private)) {
        /* This file was NOT open for reading: */
        _GifError = D_GIF_ERR_NOT_READABLE;
        return GIF_ERROR;
    }

    *CodeSize = Private->BitsPerPixel;

    return DGifGetCodeNext(GifFile, CodeBlock);
}

/******************************************************************************
 * 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).
 *****************************************************************************/
int
DGifGetCodeNext(GifFileType * GifFile,
                GifByteType ** CodeBlock) {

    GifByteType Buf;
    GifFilePrivateType *Private = (GifFilePrivateType *)GifFile->Private;

    if (READ(GifFile, &Buf, 1) != 1) {
        _GifError = D_GIF_ERR_READ_FAILED;
        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) {
            _GifError = D_GIF_ERR_READ_FAILED;
            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 = (GifFilePrivateType *)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;