VTKWriter.h

// Copyright (C) 2010 Garth N. Wells
//
// This file is part of DOLFIN.
//
// DOLFIN is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// DOLFIN is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with DOLFIN. If not, see <http://www.gnu.org/licenses/>.
//
// First added:  2010-07-19
// Last changed:

#ifndef __VTK_WRITER_H
#define __VTK_WRITER_H

#include <cstdint>
#include <string>
#include <vector>
#include "Encoder.h"

namespace dolfin
{

  class Function;
  class Mesh;


  class VTKWriter
  {
  public:

    static void write_mesh(const Mesh& mesh, std::size_t cell_dim,
                           std::string file,
                           bool binary, bool compress);

    static void write_cell_data(const Function& u, std::string file,
                                bool binary, bool compress);

    template<typename T>
    static std::string encode_stream(const std::vector<T>& data,
                                     bool compress);
  //friend class VTKFile;

  private:

    // Write cell data (ascii)
    static std::string ascii_cell_data(const Mesh& mesh,
                                       const std::vector<std::size_t>& offset,
                                       const std::vector<double>& values,
                                       std::size_t dim, std::size_t rank);

    // Write cell data (base64)
    static std::string base64_cell_data(const Mesh& mesh,
                                        const std::vector<std::size_t>& offset,
                                        const std::vector<double>& values,
                                        std::size_t dim, std::size_t rank,
                                        bool compress);

    // Mesh writer (ascii)
    static void write_ascii_mesh(const Mesh& mesh, std::size_t cell_dim,
                                 std::string file);

    // Mesh writer (base64)
    static void write_base64_mesh(const Mesh& mesh, std::size_t cell_dim,
                                  std::string file, bool compress);

    // Get VTK cell type
    static std::uint8_t vtk_cell_type(const Mesh& mesh, std::size_t cell_dim);

    // Compute base64 encoded stream for VTK
    template<typename T>
    static std::string encode_inline_base64(const std::vector<T>& data);

    // Compute compressed base64 encoded stream for VTK
    template<typename T>
    static std::string encode_inline_compressed_base64(const std::vector<T>&
                                                       data);

  };

  //--------------------------------------------------------------------------
  template<typename T>
  std::string VTKWriter::encode_stream(const std::vector<T>& data,
                                       bool compress)
  {
    std::stringstream stream;

    if (compress)
    {
      #ifdef HAS_ZLIB
      return encode_inline_compressed_base64(data);
      #else
      warning("zlib must be configured to enable compressed VTK output. Using uncompressed base64 encoding instead.");
      return encode_inline_base64(data);
      #endif
    }
    else
      return encode_inline_base64(data);
  }
  //--------------------------------------------------------------------------
  template<typename T>
  std::string VTKWriter::encode_inline_base64(const std::vector<T>& data)
  {
    std::stringstream stream;

    const std::uint32_t size = data.size()*sizeof(T);
    Encoder::encode_base64(&size, 1, stream);
    Encoder::encode_base64(data, stream);

    return stream.str();
  }
  //--------------------------------------------------------------------------
  #ifdef HAS_ZLIB
  template<typename T>
  std::string VTKWriter::encode_inline_compressed_base64(const std::vector<T>&
                                                         data)
  {
    std::stringstream stream;

    std::uint32_t header[4];
    header[0] = 1;
    header[1] = data.size()*sizeof(T);
    header[2] = 0;

    // Compress data
    std::vector<unsigned char> compressed_data
      = Encoder::compress_data(data);

    // Length of compressed data
    header[3] = compressed_data.size();

    // Encode header
    Encoder::encode_base64(&header[0], 4, stream);

    // Encode data
    Encoder::encode_base64(compressed_data.data(),
                           compressed_data.size(), stream);

    return stream.str();
  }
  #endif
  //--------------------------------------------------------------------------

}

#endif