imfoutputfile.cpp

对gif

    _ofd (ofd),
    _lineBuffer (_ofd->getLineBuffer(number))
{
    //
    // Wait for the lineBuffer to become available
    //

    _lineBuffer->wait ();
    
    //
    // Initialize the lineBuffer data if necessary
    //

    if (!_lineBuffer->partiallyFull)
    {
        _lineBuffer->endOfLineBufferData = _lineBuffer->buffer;

        _lineBuffer->minY = _ofd->minY + number * _ofd->linesInBuffer;

        _lineBuffer->maxY = min (_lineBuffer->minY + _ofd->linesInBuffer - 1,
				 _ofd->maxY);

        _lineBuffer->partiallyFull = true;
    }
    
    _lineBuffer->scanLineMin = max (_lineBuffer->minY, scanLineMin);
    _lineBuffer->scanLineMax = min (_lineBuffer->maxY, scanLineMax);
}


LineBufferTask::~LineBufferTask ()
{
    //
    // Signal that the line buffer is now free
    //

    _lineBuffer->post ();
}


void
LineBufferTask::execute ()
{
    try
    {
        //
        // First copy the pixel data from the
	// frame buffer into the line buffer
        //
        
        int yStart, yStop, dy;

        if (_ofd->lineOrder == INCREASING_Y)
        {
            yStart = _lineBuffer->scanLineMin;
            yStop = _lineBuffer->scanLineMax + 1;
            dy = 1;
        }
        else
        {
            yStart = _lineBuffer->scanLineMax;
            yStop = _lineBuffer->scanLineMin - 1;
            dy = -1;
        }
    
	int y;

        for (y = yStart; y != yStop; y += dy)
        {
            //
            // Gather one scan line's worth of pixel data and store
            // them in _ofd->lineBuffer.
            //
        
            char *writePtr = _lineBuffer->buffer +
                             _ofd->offsetInLineBuffer[y - _ofd->minY];
            //
            // Iterate over all image channels.
            //
        
            for (unsigned int i = 0; i < _ofd->slices.size(); ++i)
            {
                //
                // Test if scan line y of this channel contains any data
		// (the scan line contains data only if y % ySampling == 0).
                //
        
                const OutSliceInfo &slice = _ofd->slices[i];
        
                if (modp (y, slice.ySampling) != 0)
                    continue;
        
                //
                // Find the x coordinates of the leftmost and rightmost
                // sampled pixels (i.e. pixels within the data window
                // for which x % xSampling == 0).
                //
        
                int dMinX = divp (_ofd->minX, slice.xSampling);
                int dMaxX = divp (_ofd->maxX, slice.xSampling);
        
                //
		// Fill the line buffer with with pixel data.
                //
        
                if (slice.zero)
                {
                    //
                    // The frame buffer contains no data for this channel.
                    // Store zeroes in _lineBuffer->buffer.
                    //
                    
                    fillChannelWithZeroes (writePtr, _ofd->format, slice.type,
                                           dMaxX - dMinX + 1);
                }
                else
                {
                    //
                    // If necessary, convert the pixel data to Xdr format.
		    // Then store the pixel data in _ofd->lineBuffer.
                    //
        
                    const char *linePtr = slice.base +
                                          divp (y, slice.ySampling) *
                                          slice.yStride;
        
                    const char *readPtr = linePtr + dMinX * slice.xStride;
                    const char *endPtr  = linePtr + dMaxX * slice.xStride;
    
                    copyFromFrameBuffer (writePtr, readPtr, endPtr,
                                         slice.xStride, _ofd->format,
                                         slice.type);
                }
            }
        
            if (_lineBuffer->endOfLineBufferData < writePtr)
                _lineBuffer->endOfLineBufferData = writePtr;
        
            #ifdef DEBUG
        
                assert (writePtr - (_lineBuffer->buffer +
                        _ofd->offsetInLineBuffer[y - _ofd->minY]) ==
                        (int) _ofd->bytesPerLine[y - _ofd->minY]);
        
            #endif
        
        }
    
        //
        // If the next scanline isn't past the bounds of the lineBuffer
        // then we are done, otherwise compress the linebuffer
        //
    
        if (y >= _lineBuffer->minY && y <= _lineBuffer->maxY)
            return;
    
        _lineBuffer->dataPtr = _lineBuffer->buffer;

        _lineBuffer->dataSize = _lineBuffer->endOfLineBufferData -
                                _lineBuffer->buffer;
    
	//
        // Compress the data
	//

        Compressor *compressor = _lineBuffer->compressor;

        if (compressor)
        {
            const char *compPtr;

            int compSize = compressor->compress (_lineBuffer->dataPtr,
                                                 _lineBuffer->dataSize,
                                                 _lineBuffer->minY, compPtr);
    
            if (compSize < _lineBuffer->dataSize)
            {
                _lineBuffer->dataSize = compSize;
                _lineBuffer->dataPtr = compPtr;
            }
            else if (_ofd->format == Compressor::NATIVE)
            {
                //
                // The data did not shrink during compression, but
                // we cannot write to the file using the machine's
                // native format, so we need to convert the lineBuffer
                // to Xdr.
                //
    
                convertToXdr (_ofd, _lineBuffer->buffer, _lineBuffer->minY,
                              _lineBuffer->maxY, _lineBuffer->dataSize);
            }
        }

        _lineBuffer->partiallyFull = false;
    }
    catch (std::exception &e)
    {
        if (!_lineBuffer->hasException)
        {
            _lineBuffer->exception = e.what ();
            _lineBuffer->hasException = true;
        }
    }
    catch (...)
    {
        if (!_lineBuffer->hasException)
        {
            _lineBuffer->exception = "unrecognized exception";
            _lineBuffer->hasException = true;
        }
    }
}

} // namespace


OutputFile::OutputFile
    (const char fileName[],
     const Header &header,
     int numThreads)
:
    _data (new Data (true, numThreads))
{
    try
    {
	header.sanityCheck();
	_data->os = new StdOFStream (fileName);
	initialize (header);
    }
    catch (Iex::BaseExc &e)
    {
	delete _data;

	REPLACE_EXC (e, "Cannot open image file "
			"\"" << fileName << "\". " << e);
	throw;
    }
    catch (...)
    {
	delete _data;
        throw;
    }
}


OutputFile::OutputFile
    (OStream &os,
     const Header &header,
     int numThreads)
:
    _data (new Data (false, numThreads))
{
    try
    {
	header.sanityCheck();
	_data->os = &os;
	initialize (header);
    }
    catch (Iex::BaseExc &e)
    {
	delete _data;

	REPLACE_EXC (e, "Cannot open image file "
			"\"" << os.fileName() << "\". " << e);
	throw;
    }
    catch (...)
    {
	delete _data;
        throw;
    }
}


void
OutputFile::initialize (const Header &header)
{
    _data->header = header;

    const Box2i &dataWindow = header.dataWindow();

    _data->currentScanLine = (header.lineOrder() == INCREASING_Y)?
				 dataWindow.min.y: dataWindow.max.y;

    _data->missingScanLines = dataWindow.max.y - dataWindow.min.y + 1;
    _data->lineOrder = header.lineOrder();
    _data->minX = dataWindow.min.x;
    _data->maxX = dataWindow.max.x;
    _data->minY = dataWindow.min.y;
    _data->maxY = dataWindow.max.y;

    size_t maxBytesPerLine = bytesPerLineTable (_data->header,
						_data->bytesPerLine);

    for (size_t i = 0; i < _data->lineBuffers.size(); ++i)
    {
        _data->lineBuffers[i] =
	    new LineBuffer (newCompressor (_data->header.compression(),
					   maxBytesPerLine,
					   _data->header));
    }

    LineBuffer *lineBuffer = _data->lineBuffers[0];
    _data->format = defaultFormat (lineBuffer->compressor);
    _data->linesInBuffer = numLinesInBuffer (lineBuffer->compressor);
    _data->lineBufferSize = maxBytesPerLine * _data->linesInBuffer;

    for (size_t i = 0; i < _data->lineBuffers.size(); i++)
        _data->lineBuffers[i]->buffer.resizeErase(_data->lineBufferSize);

    int lineOffsetSize = (dataWindow.max.y - dataWindow.min.y +
			  _data->linesInBuffer) / _data->linesInBuffer;

    _data->lineOffsets.resize (lineOffsetSize);

    offsetInLineBufferTable (_data->bytesPerLine,
			     _data->linesInBuffer,
			     _data->offsetInLineBuffer);

    _data->previewPosition =
	_data->header.writeTo (*_data->os);

    _data->lineOffsetsPosition =
	writeLineOffsets (*_data->os, _data->lineOffsets);

    _data->currentPosition = _data->os->tellp();
}


OutputFile::~OutputFile ()
{
    if (_data)
    {
        {
            if (_data->lineOffsetsPosition > 0)
            {
                try
                {
                    _data->os->seekp (_data->lineOffsetsPosition);
                    writeLineOffsets (*_data->os, _data->lineOffsets);
                }
                catch (...)
                {
                    //
                    // We cannot safely throw any exceptions from here.
                    // This destructor may have been called because the
                    // stack is currently being unwound for another
                    // exception.
                    //
                }
            }
        }

	delete _data;
    }
}


const char *
OutputFile::fileName () const
{
    return _data->os->fileName();
}


const Header &
OutputFile::header () const
{
    return _data->header;
}


void	
OutputFile::setFrameBuffer (const FrameBuffer &frameBuffer)
{
    Lock lock (*_data);
    
    //
    // Check if the new frame buffer descriptor
    // is compatible with the image file header.
    //

    const ChannelList &channels = _data->header.channels();

    for (ChannelList::ConstIterator i = channels.begin();
	 i != channels.end();
	 ++i)
    {
	FrameBuffer::ConstIterator j = frameBuffer.find (i.name());

	if (j == frameBuffer.end())
	    continue;

	if (i.channel().type != j.slice().type)
	{
	    THROW (Iex::ArgExc, "Pixel type of \"" << i.name() << "\" channel "
			        "of output file \"" << fileName() << "\" is "
			        "not compatible with the frame buffer's "
			        "pixel type.");
	}

	if (i.channel().xSampling != j.slice().xSampling ||
	    i.channel().ySampling != j.slice().ySampling)
	{
	    THROW (Iex::ArgExc, "X and/or y subsampling factors "
				"of \"" << i.name() << "\" channel "
				"of output file \"" << fileName() << "\" are "
				"not compatible with the frame buffer's "
				"subsampling factors.");
	}
    }
    
    //
    // Initialize slice table for writePixels().
    //

    vector<OutSliceInfo> slices;

    for (ChannelList::ConstIterator i = channels.begin();
	 i != channels.end();
	 ++i)
    {
	FrameBuffer::ConstIterator j = frameBuffer.find (i.name());

	if (j == frameBuffer.end())
	{
	    //
	    // Channel i is not present in the frame buffer.
	    // In the file, channel i will contain only zeroes.