Method ParseHeader2

libs/indexer/feature.cpp:352–448

TODO: One of the free bits could be used for a closed line flag to avoid storing identical first + last points.

// TODO: One of the free bits could be used for a closed line flag to avoid storing identical first + last points.
void FeatureType::ParseHeader2()
{
  if (m_parsed.m_header2)
    return;

  ParseCommon();

  m_parsed.m_header2 = true;

  auto const headerGeomType = static_cast<HeaderGeomType>(Header(m_data) & HEADER_MASK_GEOMTYPE);
  if (headerGeomType != HeaderGeomType::Line && headerGeomType != HeaderGeomType::Area)
  {
    m_offsets.m_relations = m_offsets.m_header2;
    return;
  }

  BitSource bitSource(m_data.data() + m_offsets.m_header2);
  uint8_t elemsCount = bitSource.Read(4);
  uint8_t geomScalesMask = 0;

  if (m_loadInfo->m_version == DatSectionHeader::Version::V0)
  {
    // For outer geometry read the geom scales (offsets) mask.
    // For inner geometry remaining 4 bits are not used.
    if (elemsCount == 0)
      geomScalesMask = bitSource.Read(4);
  }
  else
  {
    ASSERT(m_loadInfo->m_version >= DatSectionHeader::Version::V1, ());
    bool const isOuter = (bitSource.Read(1) == 1);
    if (isOuter)
    {
      geomScalesMask = elemsCount;
      elemsCount = 0;
    }

    m_hasRelations = (bitSource.Read(1) == 1);
  }

  ArrayByteSource src(bitSource.RoundPtr());
  serial::GeometryCodingParams const & cp = m_loadInfo->GetDefGeometryCodingParams();

  if (headerGeomType == HeaderGeomType::Line)
  {
    if (elemsCount > 0)
    {
      // Inner geometry.
      // Number of bytes in simplification mask:
      // first and last points are never simplified/discarded,
      // 2 bits are used per each other point, i.e.
      // 3-6 pts - 1 byte, 7-10 pts - 2b, 11-14 pts - 3b.
      /// @see FeatureBuilder::SerializeForMwm
      int const count = (elemsCount - 2 + 3) / 4;
      ASSERT_LESS(count, 4, ());

      for (int i = 0; i < count; ++i)
      {