itkVTKImageIO2.cxx

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void VTKImageIO2::StripSymmetricTensorBinaryBufferSymmetry( const void *fullBuffer,
  void *strippedBuffer,
  StreamingImageIOBase::SizeType num )
{
  std::streamsize bytesRemaining = num;
  const SizeType  componentSize = this->GetComponentSize();
  SizeType        pixelSize = componentSize * 6;
  char            zero[1024];

  std::memset( zero, 0, 1024 );

  if( this->GetNumberOfComponents() != 6 )
    {
    itkExceptionMacro(<< "Unsupported tensor dimension.");
    }
  while( bytesRemaining )
    {
    // row 1
    std::memcpy( strippedBuffer, fullBuffer, 3 * componentSize );
    strippedBuffer = static_cast< char * >(strippedBuffer) + 3 * componentSize;
    fullBuffer     = static_cast< char * >(fullBuffer)     + 3 * componentSize;
    // row 2
    fullBuffer     = static_cast< char * >(fullBuffer)     + componentSize;
    std::memcpy( strippedBuffer, fullBuffer, 2 * componentSize );
    strippedBuffer = static_cast< char * >(strippedBuffer) + 2 * componentSize;
    fullBuffer     = static_cast< char * >(fullBuffer)     + 2 * componentSize;
    // row 3
    fullBuffer     = static_cast< char * >(fullBuffer)     + 2 * componentSize;
    std::memcpy( strippedBuffer, fullBuffer, componentSize );
    strippedBuffer = static_cast< char * >(strippedBuffer) + componentSize;
    fullBuffer     = static_cast< char * >(fullBuffer)     + componentSize;
    bytesRemaining -= pixelSize;
    }
}

void VTKImageIO2::Read(void *buffer)
{
  std::ifstream file;

  if ( this->RequestedToStream() )
    {
    itkAssertOrThrowMacro(m_FileType != ASCII, "Can not stream with ASCII type files");

      itkExceptionMacro(<< "Cannot stream read binary second rank tensors.");
      }

    // open and stream read
    this->OpenFileForReading( file, this->m_FileName.c_str() );

    itkAssertOrThrowMacro(this->GetHeaderSize() != 0, "Header size is unknown when it shouldn't be!");

    if( this->GetPixelType() == ImageIOBase::SYMMETRICSECONDRANKTENSOR )
      {
      SizeType tempBufferSize = ( this->GetImageSizeInBytes() * 2 * this->GetNumberOfDimensions() ) /
        ( this->GetNumberOfDimensions() + 1 );
      std::streamoff seekPos = 0;
      size_t subDimensionQuantity = 1;
      for( unsigned int i = 0; i < this->m_IORegion.GetImageDimension(); ++i )
        {
        seekPos += static_cast< std::streamoff >( subDimensionQuantity * m_IORegion.GetIndex()[i] );
        subDimensionQuantity *= this->GetDimensions( i );
        }
      seekPos = ( seekPos * 2 * this->GetNumberOfDimensions() ) / ( this->GetNumberOfDimensions() + 1 );
      itk::Array< char > tempArray( tempBufferSize );
      char* tempBuffer = tempArray.data_block();
      this->StreamReadBufferAsBinary( file, tempBuffer, tempBufferSize, seekPos );
      this->StripSymmetricTensorBinaryBufferSymmetry( tempBuffer, buffer, tempBufferSize );
      }
    else
      {
      this->StreamReadBufferAsBinary( file, buffer );
      }
    }
  else
    {
    // open the file
    this->OpenFileForReading( file, this->m_FileName.c_str() );

    itkAssertOrThrowMacro(this->GetHeaderSize() != 0, "Header size is unknown when it shouldn't be!");

    if ( file.fail() )
      {
      itkExceptionMacro(<< "Failed seeking to data position");
      }

    // seek pass the header
    std::streampos dataPos = static_cast< std::streampos >( this->GetHeaderSize() );
    file.seekg(dataPos, std::ios::beg);

    //We are positioned at the data. The data is read depending on whether
    //it is ASCII or binary.
    if ( m_FileType == ASCII )
      {
      this->ReadBufferAsASCII( file, buffer, this->GetComponentType(),
                               this->GetImageSizeInComponents()
                               );
      }
    else
      {
      // read the image
      if( this->GetPixelType() == ImageIOBase::SYMMETRICSECONDRANKTENSOR )
        {
        SizeType tempBufferSize = ( this->GetImageSizeInBytes() * 2 * this->GetNumberOfDimensions() ) /
          ( this->GetNumberOfDimensions() + 1 );
        itk::Array< char > tempArray( tempBufferSize );
        char* tempBuffer = tempArray.data_block();
        this->ReadBufferAsBinary( file, tempBuffer, tempBufferSize );
        this->StripSymmetricTensorBinaryBufferSymmetry( tempBuffer, buffer, tempBufferSize );
        }
      else
        {
        this->ReadBufferAsBinary( file, buffer, this->GetImageSizeInBytes() );
        }

      int size = this->GetComponentSize();
      switch ( size )
        {
        case 1:
          break;
        case 2:
          ByteSwapper< uint16_t >::SwapRangeFromSystemToBigEndian( (uint16_t *)buffer, this->GetImageSizeInComponents() );
          break;
        case 4:
          ByteSwapper< uint32_t >::SwapRangeFromSystemToBigEndian( (uint32_t *)buffer, this->GetImageSizeInComponents() );
          break;
        case 8:
          ByteSwapper< uint64_t >::SwapRangeFromSystemToBigEndian( (uint64_t *)buffer, this->GetImageSizeInComponents() );
          break;
        default:
          itkExceptionMacro(<< "Unknown component size" << size);
        }
      }
    }
}

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