Method CreateCompressionHeader

IO/XML/vtkXMLWriter.cxx:1327–1366

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//------------------------------------------------------------------------------
int vtkXMLWriter::CreateCompressionHeader(size_t size)
{
  // Allocate and initialize the compression header.
  // The format is this:
  //  struct header {
  //    HeaderType number_of_blocks;
  //    HeaderType uncompressed_block_size;
  //    HeaderType uncompressed_last_block_size;
  //    HeaderType compressed_block_sizes[number_of_blocks];
  //  }

  // Find the size and number of blocks.
  size_t numFullBlocks = size / this->BlockSize;
  size_t lastBlockSize = size % this->BlockSize;
  size_t numBlocks = numFullBlocks + (lastBlockSize ? 1 : 0);
  this->CompressionHeader = vtkXMLDataHeader::New(this->HeaderType, 3 + numBlocks);

  // Write out dummy header data.
  this->CompressionHeaderPosition = this->Stream->tellp();
  int result = (this->DataStream->StartWriting() &&
    this->DataStream->Write(this->CompressionHeader->Data(), this->CompressionHeader->DataSize()) &&
    this->DataStream->EndWriting());

  this->Stream->flush();
  if (this->Stream->fail())
  {
    this->SetErrorCode(vtkErrorCode::GetLastSystemError());
    return 0;
  }

  // Fill in known header data now.
  this->CompressionHeader->Set(0, numBlocks);
  this->CompressionHeader->Set(1, this->BlockSize);
  this->CompressionHeader->Set(2, lastBlockSize);

  // Initialize counter for block writing.
  this->CompressionBlockNumber = 0;

  return result;
}

//------------------------------------------------------------------------------
int vtkXMLWriter::WriteCompressionBlock(unsigned char* data, size_t size)