imfscanlineinputfile.cpp

对gif

            //
    
            const char *readPtr = _lineBuffer->uncompressedData +
                                  _ifd->offsetInLineBuffer[y - _ifd->minY];
    
            //
            // Iterate over all image channels.
            //
    
            for (unsigned int i = 0; i < _ifd->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 InSliceInfo &slice = _ifd->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 (_ifd->minX, slice.xSampling);
                int dMaxX = divp (_ifd->maxX, slice.xSampling);
    
                //
		// Fill the frame buffer with pixel data.
                //
    
                if (slice.skip)
                {
                    //
                    // The file contains data for this channel, but
                    // the frame buffer contains no slice for this channel.
                    //
    
                    skipChannel (readPtr, slice.typeInFile, dMaxX - dMinX + 1);
                }
                else
                {
                    //
                    // The frame buffer contains a slice for this channel.
                    //
    
                    char *linePtr  = slice.base +
                                        divp (y, slice.ySampling) *
                                        slice.yStride;
    
                    char *writePtr = linePtr + dMinX * slice.xStride;
                    char *endPtr   = linePtr + dMaxX * slice.xStride;
                    
                    copyIntoFrameBuffer (readPtr, writePtr, endPtr,
                                         slice.xStride, slice.fill,
                                         slice.fillValue, _lineBuffer->format,
                                         slice.typeInFrameBuffer,
                                         slice.typeInFile);
                }
            }
        }
    }
    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;
        }
    }
}


LineBufferTask *
newLineBufferTask
    (TaskGroup *group,
     ScanLineInputFile::Data *ifd,
     int number,
     int scanLineMin,
     int scanLineMax)
{
    //
    // Wait for a line buffer to become available, fill the line
    // buffer with raw data from the file if necessary, and create
    // a new LineBufferTask whose execute() method will uncompress
    // the contents of the buffer and copy the pixels into the
    // frame buffer.
    //

    LineBuffer *lineBuffer = ifd->getLineBuffer (number);

    try
    {
	lineBuffer->wait ();
	
	if (lineBuffer->number != number)
	{
	    lineBuffer->minY = ifd->minY + number * ifd->linesInBuffer;
	    lineBuffer->maxY = lineBuffer->minY + ifd->linesInBuffer - 1;
	    
	    lineBuffer->number = number;
	    lineBuffer->uncompressedData = 0;

	    readPixelData (ifd, lineBuffer->minY,
			   lineBuffer->buffer,
			   lineBuffer->dataSize);
	}
    }
    catch (...)
    {
	//
	// Reading from the file caused an exception.
	// Signal that the line buffer is free, and
	// re-throw the exception.
	//

	lineBuffer->number = -1;
	lineBuffer->post();
	throw;
    }
    
    scanLineMin = max (lineBuffer->minY, scanLineMin);
    scanLineMax = min (lineBuffer->maxY, scanLineMax);

    return new LineBufferTask (group, ifd, lineBuffer,
			       scanLineMin, scanLineMax);
}

} // namespace


ScanLineInputFile::ScanLineInputFile
    (const Header &header,
     IStream *is,
     int numThreads)
:
    _data (new Data (is, numThreads))
{
    try
    {
	_data->header = header;

	_data->lineOrder = _data->header.lineOrder();

	const Box2i &dataWindow = _data->header.dataWindow();

	_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));
        }

        _data->linesInBuffer =
	    numLinesInBuffer (_data->lineBuffers[0]->compressor);

        _data->lineBufferSize = maxBytesPerLine * _data->linesInBuffer;

        if (!_data->is->isMemoryMapped())
            for (size_t i = 0; i < _data->lineBuffers.size(); i++)
                _data->lineBuffers[i]->buffer = new char[_data->lineBufferSize];

	_data->nextLineBufferMinY = _data->minY - 1;

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

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

	_data->lineOffsets.resize (lineOffsetSize);

	readLineOffsets (*_data->is,
			 _data->lineOrder,
			 _data->lineOffsets,
			 _data->fileIsComplete);
    }
    catch (...)
    {
	delete _data;
	throw;
    }
}


ScanLineInputFile::~ScanLineInputFile ()
{
    if (!_data->is->isMemoryMapped())
        for (size_t i = 0; i < _data->lineBuffers.size(); i++)
            delete [] _data->lineBuffers[i]->buffer;

    delete _data;
}


const char *
ScanLineInputFile::fileName () const
{
    return _data->is->fileName();
}


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


int
ScanLineInputFile::version () const
{
    return _data->version;
}


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

	if (i == channels.end())
	    continue;

	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 input file \"" << fileName() << "\" are "
				"not compatible with the frame buffer's "
				"subsampling factors.");
    }

    //
    // Initialize the slice table for readPixels().
    //

    vector<InSliceInfo> slices;
    ChannelList::ConstIterator i = channels.begin();

    for (FrameBuffer::ConstIterator j = frameBuffer.begin();
	 j != frameBuffer.end();
	 ++j)
    {
	while (i != channels.end() && strcmp (i.name(), j.name()) < 0)
	{
	    //
	    // Channel i is present in the file but not
	    // in the frame buffer; data for channel i
	    // will be skipped during readPixels().
	    //

	    slices.push_back (InSliceInfo (i.channel().type,
					   i.channel().type,
					   0, // base
					   0, // xStride
					   0, // yStride
					   i.channel().xSampling,
					   i.channel().ySampling,
					   false,  // fill
					   true, // skip
					   0.0)); // fillValue
	    ++i;
	}

	bool fill = false;

	if (i == channels.end() || strcmp (i.name(), j.name()) > 0)
	{
	    //
	    // Channel i is present in the frame buffer, but not in the file.
	    // In the frame buffer, slice j will be filled with a default value.
	    //

	    fill = true;
	}

	slices.push_back (InSliceInfo (j.slice().type,
				       fill? j.slice().type:
				             i.channel().type,
				       j.slice().base,
				       j.slice().xStride,
				       j.slice().yStride,
				       j.slice().xSampling,
				       j.slice().ySampling,
				       fill,
				       false, // skip
				       j.slice().fillValue));

	if (i != channels.end() && !fill)
	    ++i;
    }

    //
    // Store the new frame buffer.
    //

    _data->frameBuffer = frameBuffer;
    _data->slices = slices;
}


const FrameBuffer &
ScanLineInputFile::frameBuffer () const
{
    Lock lock (*_data);
    return _data->frameBuffer;
}


bool
ScanLineInputFile::isComplete () const
{
    return _data->fileIsComplete;
}


void	
ScanLineInputFile::readPixels (int scanLine1, int scanLine2)
{
    try
    {
        Lock lock (*_data);

	if (_data->slices.size() == 0)
	    throw Iex::ArgExc ("No frame buffer specified "
			       "as pixel data destination.");

	int scanLineMin = min (scanLine1, scanLine2);
	int scanLineMax = max (scanLine1, scanLine2);

	if (scanLineMin < _data->minY || scanLineMax > _data->maxY)
	    throw Iex::ArgExc ("Tried to read scan line outside "
			       "the image file's data window.");

        //
        // We impose a numbering scheme on the lineBuffers where the first
        // scanline is contained in lineBuffer 1.
        //
        // Determine the first and last lineBuffer numbers in this scanline
        // range. We always attempt to read the scanlines in the order that
        // they are stored in the file.
        //

        int start, stop, dl;

        if (_data->lineOrder == INCREASING_Y)
        {
            start = (scanLineMin - _data->minY) / _data->linesInBuffer;
            stop  = (scanLineMax - _data->minY) / _data->linesInBuffer + 1;
            dl = 1;
        }
        else
        {
            start = (scanLineMax - _data->minY) / _data->linesInBuffer;
            stop  = (scanLineMin - _data->minY) / _data->linesInBuffer - 1;
            dl = -1;
        }

        //
        // Create a task group for all line buffer tasks.  When the
	// task group goes out of scope, the destructor waits until
	// all tasks are complete.
        //
        
        {
            TaskGroup taskGroup;
    
            //
            // Add the line buffer tasks.
            //
            // The tasks will execute in the order that they are created
            // because we lock the line buffers during construction and the
            // constructors are called by the main thread.  Hence, in order
	    // for a successive task to execute the previous task which
	    // used that line buffer must have completed already.
            //
    
            for (int l = start; l != stop; l += dl)
            {
                ThreadPool::addGlobalTask (newLineBufferTask (&taskGroup,
                                                              _data, l,
                                                              scanLineMin,
                                                              scanLineMax));
            }
        
	    //
            // finish all tasks
	    //
        }
        
	//
	// Exeption handling:
	//
	// LineBufferTask::execute() may have encountered exceptions, but
	// those exceptions occurred in another thread, not in the thread
	// that is executing this call to ScanLineInputFile::readPixels().
	// LineBufferTask::execute() has caught all exceptions and stored
	// the exceptions' what() strings in the line buffers.
	// Now we check if any line buffer contains a stored exception; if
	// this is the case then we re-throw the exception in this thread.
	// (It is possible that multiple line buffers contain stored
	// exceptions.  We re-throw the first exception we find and
	// ignore all others.)
	//

	const string *exception = 0;

        for (int i = 0; i < _data->lineBuffers.size(); ++i)
	{
            LineBuffer *lineBuffer = _data->lineBuffers[i];

	    if (lineBuffer->hasException && !exception)
		exception = &lineBuffer->exception;

	    lineBuffer->hasException = false;
	}

	if (exception)
	    throw Iex::IoExc (*exception);
    }
    catch (Iex::BaseExc &e)
    {
	REPLACE_EXC (e, "Error reading pixel data from image "
		        "file \"" << fileName() << "\". " << e);
	throw;
    }
}


void	
ScanLineInputFile::readPixels (int scanLine)
{
    readPixels (scanLine, scanLine);
}


void
ScanLineInputFile::rawPixelData (int firstScanLine,
				 const char *&pixelData,
				 int &pixelDataSize)
{
    try
    {
        Lock lock (*_data);

	if (firstScanLine < _data->minY || firstScanLine > _data->maxY)
	{
	    throw Iex::ArgExc ("Tried to read scan line outside "
			       "the image file's data window.");
	}

        int minY = lineBufferMinY
	    (firstScanLine, _data->minY, _data->linesInBuffer);

	readPixelData
	    (_data, minY, _data->lineBuffers[0]->buffer, pixelDataSize);

	pixelData = _data->lineBuffers[0]->buffer;
    }
    catch (Iex::BaseExc &e)
    {
	REPLACE_EXC (e, "Error reading pixel data from image "
		        "file \"" << fileName() << "\". " << e);
	throw;
    }
}

} // namespace Imf