gifcodec.cpp

来自「symbian 下的helix player源代码」· C++ 代码 · 共 1,349 行 · 第 1/3 页

                    }
                    while (ulBlockSize > 0);
                    break;
                case kCommentExtension:
                case kPlainTextExtension:
                    pBuf += 2;
                    SkipBlocks(pBuf, pBufLimit);
                    break;
                case kApplicationExtension:
                    ParseApplicationExtension(pBuf);
                    break;
                default:
                    // An extension we don't know - just try to
                    // pass it through
                    pBuf += 2;
                    SkipBlocks(pBuf, pBufLimit);
                    break;

            }
        }
        else if (pBuf[0] == kTrailer)
        {
            /* We found a GIF trailer - we should be at the end of the file */
            cMarkList.PushBack((void *) pBuf);
	    break;
        }
        else
        {
            // Sometimes extra 0 blocks get stuck in GIFs. Check for them
            // here - if the current byte is 0, then it's OK. If it's not,
            // then we've gotten lost somewhere.
            if (pBuf[0] == 0x00)
            {
                pBuf++;
            }
            else
            {
                // Something is wrong with the GIF file.
		//
		// XXXMEH - instead of returning an error, we will
		// be lax and just break here. This will have the effect
		// of potentially sending garbage GIFs down to the
		// client. The upside is that there are a lot of 
		// non-standard GIFs out there that will display in
		// browsers and this will allow them to be displayed.
		break;
            }
        }
    }

    /* The last mark is, of course, the end of the file. */
    cMarkList.PushBack((void *) pBufLimit);

    /*
     * Now we convert our list to a more usable array of ParseSegment's. First
     * we compute the number of segments, which is one less than the number
     * of marks.
     */
    m_ulNumSegmentsAllocated = cMarkList.Size() - 1;
    if (m_ulNumSegmentsAllocated == 0 || m_ulNumSegmentsAllocated > cMarkList.Size())
    {
        return HXR_UNEXPECTED;
    }

    /* Allocate memory for the segment array */
    if (m_pSegment)
    {
        delete [] m_pSegment;
        m_pSegment = NULL;
    }
    m_pSegment = new ParseSegment [m_ulNumSegmentsAllocated];
    if (!m_pSegment)
    {
        return HXR_OUTOFMEMORY;
    }

    /*
     * Now run through the list of marks, computing segments. Note that
     * if the mark in the marklist is an extension not necessary for 
     * deompression, we do not make it into a segment.
     */
    m_ulNumSegments         = 0;
    GListIterator itr       = cMarkList.Begin();
    BYTE         *pLastMark = (BYTE *) *itr;
    itr++;
    do
    {
        BYTE *pCurMark = (BYTE *) *itr;

        /*
         * Filter out all unwanted extensions. We don't send application, 
         * comment, or plain text extensions. We also don't send the GIF
         * Trailer
         */
        if (!((pLastMark[0] == kExtension && (pLastMark[1] == kApplicationExtension ||
                                              pLastMark[1] == kCommentExtension     ||
                                              pLastMark[1] == kPlainTextExtension)) ||
               pLastMark[0] == kTrailer))
        {
            m_pSegment[m_ulNumSegments].pMark  = pLastMark;
            m_pSegment[m_ulNumSegments].ulSize = pCurMark - pLastMark;
            m_ulNumSegments++;
        }
        pLastMark = pCurMark;
        itr++;
    }
    while (itr != cMarkList.End());

    /* Now we're done with the list */
    cMarkList.EraseAll();

    /* Set the state */
    m_ulParseState = kStateParseInitialized;

    return HXR_OK;
}

UINT32 CGIFCodec::GetDelayTime(UINT32 i)
{
    if (i >= m_ulNumImages || m_bIsGIF89a == FALSE)
    {
        return 0;
    }

    UINT32        ulDelay;
    ParseSegment *pSeg = &m_pSegment[1 + (i << 1)];
    if (pSeg->pMark[0] == kExtension && pSeg->pMark[1] == kGraphicControlExtension)
    {
        CGIFImage::GraphicControlExtension cGCE;
        CGIFImage::ParseGraphicControlExtension(pSeg->pMark + 3, cGCE);
        ulDelay = cGCE.m_ulDelayTime;
        if (ulDelay == 0)
        {
            ulDelay = 1;
        }
    }
    else
    {
        ulDelay = 0;
    }

    return ulDelay;
}

UINT32 CGIFCodec::GetImageDataSize(UINT32 i)
{
    if (i >= m_ulNumImages)
    {
        return 0;
    }

    return m_pSegment[2 + (i << 1)].ulSize;
}

HX_RESULT CGIFCodec::GetPacketBufferLength(UINT32 &rulLen)
{
    /* Check state */
    if (m_ulParseState != kStateParseInitialized &&
        m_ulParseState != kStateParseInProgress)
    {
        return HXR_UNEXPECTED;
    }

    /* Is this our first time here? */
    if (m_ulParseState == kStateParseInitialized)
    {
        /* This is the first time here - we need to find the header length */
        UINT32 ulLen = 8                    +  /* Container header size, num images */
                       8 * m_ulNumImages    +  /* Image header size and compressed data size */
                       m_pSegment[0].ulSize;   /* Container header */
        /*
         * Add the individual image header sizes - these are the segments which
         * begin with either an Image Descriptor or a GCE.
         */
        UINT32 i;
        for (i = 0; i < m_ulNumSegments; i++)
        {
            BYTE *pMark = m_pSegment[i].pMark;
            if ( pMark[0] == kImageDescriptor ||
                (pMark[0] == kExtension && pMark[1] == kGraphicControlExtension))
            {
                ulLen += m_pSegment[i].ulSize;
            }
        }

        /* Set the initial segment for data packet parsing */
        m_ulCurSegIndex  = 2;
        m_ulCurSegOffset = 0;

        /* We have our length */
        rulLen = ulLen;
    }
    else
    {
        /* This is NOT the first time here - we need to find the data packet length */
        BYTE  *pBufStart = m_pSegment[m_ulCurSegIndex].pMark;
        BYTE  *pBuf      = pBufStart + m_ulCurSegOffset;
        UINT32 ulSize    = 0;

        /* If we are at the beginning of a LZW segment, we need to skip the min code size */
        if (m_ulCurSegOffset == 0)
        {
            pBuf++;
            ulSize++;
        }

        /* Advance through the blocks, until we reach the ideal packet size */
        UINT32 ulBlockSize;
        do
        {
            ulBlockSize = *pBuf;
            ulSize     += ulBlockSize + 1;
            pBuf       += ulBlockSize + 1;
        }
        while (ulBlockSize > 0 && ulSize < kIdealPacketSize);

        /*
         * Make a check to see if what's left over is not less than the
         * minimum packet size. If it IS less than the minimum packet size,
         * then go ahead and get the rest of it.
         */
        UINT32 ulBytesLeftInSegment = pBufStart + m_pSegment[m_ulCurSegIndex].ulSize - pBuf;
        if (ulBytesLeftInSegment > 0 && ulBytesLeftInSegment < kMinimumPacketSize)
        {
            ulSize += ulBytesLeftInSegment;
        }

        /* Now we have our length */
        rulLen = ulSize;
    }

    return HXR_OK;
}

UINT32 CGIFCodec::ComputeLZWDataSize(BYTE *pLZW)
{
    /* Skip the minimum code size */
    pLZW++;

    /* Run through blocks, adding up sizes */
    UINT32 ulSum = 0;
    UINT32 ulBlockSize;
    do
    {
        ulBlockSize = *pLZW++;
        ulSum      += ulBlockSize;
        pLZW       += ulBlockSize;
    }
    while (ulBlockSize > 0);

    return ulSum;
}

HX_RESULT CGIFCodec::GetPacketBuffer(BYTE *pBuffer, UINT32 ulLen, BOOL &rbFirstInImage)
{
    /* Check for input error conditions */
    if (pBuffer == NULL || ulLen == 0)
    {
        return HXR_INVALID_PARAMETER;
    }

    /* Check state */
    if (m_ulParseState != kStateParseInitialized &&
        m_ulParseState != kStateParseInProgress)
    {
        return HXR_UNEXPECTED;
    }

    /* Is this our first time here? */
    if (m_ulParseState == kStateParseInitialized)
    {
        /* Conainer header size */
        Pack32(m_pSegment[0].ulSize, pBuffer);
        pBuffer += 4;
        /* Number of Images */
        Pack32(m_ulNumImages,      pBuffer);
        pBuffer += 4;
        /* Individual image parameters */
        UINT32 i;
        for (i = 0; i < m_ulNumImages; i++)
        {
            /* Individual image header size */
            Pack32(m_pSegment[1 + (i << 1)].ulSize, pBuffer);
            pBuffer += 4;

            /* Individual image compressed data size */
            Pack32(ComputeLZWDataSize(m_pSegment[2 + (i << 1)].pMark), pBuffer);
            pBuffer += 4;
        }

        /* Copy container header */
        memcpy(pBuffer, m_pSegment[0].pMark, m_pSegment[0].ulSize); /* Flawfinder: ignore */
        pBuffer += m_pSegment[0].ulSize;

        /* Copy each individual image header */
        for (i = 0; i < m_ulNumImages; i++)
        {
            ParseSegment *pSegment = &m_pSegment[1 + (i << 1)];
            memcpy(pBuffer, pSegment->pMark, pSegment->ulSize); /* Flawfinder: ignore */
            pBuffer += pSegment->ulSize;
        }

        /* Clear the flag */
        rbFirstInImage = FALSE;

        /* Set the new state */
        m_ulParseState = kStateParseInProgress;
    }
    else
    {
        /* Copy the data packet */
        memcpy(pBuffer, /* Flawfinder: ignore */
               m_pSegment[m_ulCurSegIndex].pMark + m_ulCurSegOffset,
               ulLen);

        /* Was this the first packet for one of the images? */
        if (m_ulCurSegOffset == 0)
        {
            rbFirstInImage = TRUE;
        }
        else
        {
            rbFirstInImage = FALSE;
        }

        /* Check to see if we're done with this segment */
        if (m_ulCurSegOffset + ulLen >= m_pSegment[m_ulCurSegIndex].ulSize)
        {
            m_ulCurSegIndex += 2;
            m_ulCurSegOffset = 0;
        }
        else
        {
            m_ulCurSegOffset += ulLen;
        }

        /* Check to see if we finished */
        if (m_ulCurSegIndex >= m_ulNumSegments)
        {
            m_ulParseState = kStateParseFinished;
        }
    }

    return HXR_OK;
}

void CGIFCodec::ParseLogicalScreenDescriptor(BYTE *pBuffer, LogicalScreenDescriptor &cLSD)
{
    /* Read Logical Screen Descriptor */
    cLSD.m_ulLogicalScreenWidth     =  (pBuffer[1] << 8) | pBuffer[0];
    cLSD.m_ulLogicalScreenHeight    =  (pBuffer[3] << 8) | pBuffer[2];
    cLSD.m_bGlobalColorTablePresent =  (pBuffer[4] & 0x80 ? TRUE : FALSE);
    cLSD.m_ulOriginalColorBits      = ((pBuffer[4] & 0x70) >> 4) + 1;
    cLSD.m_bColorsSorted            =  (pBuffer[4] & 0x08 ? TRUE : FALSE);
    cLSD.m_ulColorTableBits         =  (pBuffer[4] & 0x07) + 1;
    cLSD.m_ulColorTableNumEntries   = 1 << cLSD.m_ulColorTableBits;
    cLSD.m_ulBackgroundColorIndex   =   pBuffer[5];
    cLSD.m_ulPixelAspectRatio       =   pBuffer[6];
    cLSD.m_fPixelAspectRatio        = (cLSD.m_ulPixelAspectRatio + 15.0F) / 64.0F;
}

HX_RESULT CGIFCodec::ParseContainerHeader(BYTE * &pBuffer)
{
    /* Verify the signature */
    if (pBuffer[0] != 'G' || pBuffer[1] != 'I' || pBuffer[2] != 'F')
    {
        return HXR_INVALID_OPERATION;
    }
    pBuffer += 3;

    /* Get the version */
    if (pBuffer[0] == '8' && pBuffer[1] == '9' && pBuffer[2] == 'a')
    {
        m_bIsGIF89a = TRUE;
    }
    else if (pBuffer[0] == '8' && pBuffer[1] == '7' && pBuffer[2] == 'a')
    {
        m_bIsGIF89a = FALSE;
    }
    else
    {
        return HXR_INVALID_OPERATION;
    }
    pBuffer += 3;

    /* Read the Logical Screen Descriptor */
    ParseLogicalScreenDescriptor(pBuffer, m_cLSD);
    pBuffer += 7;

    /* Read the colortable if present */
    if (m_cLSD.m_bGlobalColorTablePresent == TRUE)
    {
        /* Allocate space for the global color table */
        if (m_pucGlobalColorMap)
        {
            delete [] m_pucGlobalColorMap;
            m_pucGlobalColorMap = NULL;
        }
        UINT32 ulColorTableBytes = m_cLSD.m_ulColorTableNumEntries * 3;
        m_pucGlobalColorMap = new BYTE [ulColorTableBytes];
        if (!m_pucGlobalColorMap)
        {
            return HXR_OUTOFMEMORY;
        }

        /* Copy the global color table */
        memcpy(m_pucGlobalColorMap, pBuffer, ulColorTableBytes); /* Flawfinder: ignore */

        /* Advance the pointer */
        pBuffer += ulColorTableBytes;

        /* Loop through the images, setting the global color map */
        UINT32 i;
        for (i = 0; i < m_ulNumImages; i++)
        {
            m_pImage[i].SetGlobalColorMap(m_cLSD.m_ulColorTableNumEntries,
                                          m_pucGlobalColorMap);
        }
    }

    // Reset the delay time sum
    m_ulDelayTimeSum = 0;
    /* Here we loop through looking for Image Descriptors or Graphic Control Extensions */
    HX_RESULT retVal;
    UINT32    ulImageNum = 0;
    for (;;)
    {
        UINT32 ulMarker = *pBuffer;

        switch(ulMarker)
        {
            case kImageDescriptor:
                retVal = m_pImage[ulImageNum].InitDecompress(pBuffer, m_pImageHeaderSize[ulImageNum]);
                if (retVal != HXR_OK)
                {
                    return retVal;
                }
                retVal = m_pImage[ulImageNum].SetCompressedBufferSize(m_pCompressedBufferSize[ulImageNum]);
                if (retVal != HXR_OK)
                {
                    return retVal;
                }
                pBuffer += m_pImageHeaderSize[ulImageNum];
                ulImageNum++;
                break;
            case kExtension:
                if (pBuffer[1] == kGraphicControlExtension)
                {
                    retVal = m_pImage[ulImageNum].InitDecompress(pBuffer, m_pImageHeaderSize[ulImageNum]);
                    if (retVal != HXR_OK)