Method AppendArrayWithOffset

Common/DataModel/vtkCellArray.cxx:515–544

  // offset added to each value.
  template <typename SrcArrayT, typename DstArrayT>
  void AppendArrayWithOffset(
    SrcArrayT* srcArray, DstArrayT* dstArray, vtkIdType offset, bool skipFirst) const
  {
    VTK_ASSUME(srcArray->GetNumberOfComponents() == 1);
    VTK_ASSUME(dstArray->GetNumberOfComponents() == 1);

    using SrcValueType = vtk::GetAPIType<SrcArrayT>;
    using DstValueType = vtk::GetAPIType<DstArrayT>;

    const vtkIdType srcSize =
      skipFirst ? srcArray->GetNumberOfValues() - 1 : srcArray->GetNumberOfValues();
    const vtkIdType dstBegin = dstArray->GetNumberOfValues();
    const vtkIdType dstEnd = dstBegin + srcSize;

    // This extends the allocation of dst to ensure we have enough space
    // allocated:
    {
      vtkDataArrayAccessor<DstArrayT> dstAccessor(dstArray);
      dstAccessor.Insert(dstEnd - 1, static_cast<DstValueType>(0));
    }

    const auto srcRange = vtk::DataArrayValueRange<1, vtkIdType>(srcArray, skipFirst ? 1 : 0);
    auto dstRange = vtk::DataArrayValueRange<1, vtkIdType>(dstArray, dstBegin, dstEnd);
    assert(srcRange.size() == dstRange.size());

    const DstValueType dOffset = static_cast<DstValueType>(offset);

    std::transform(srcRange.cbegin(), srcRange.cend(), dstRange.begin(),
      [&](SrcValueType x) -> DstValueType { return static_cast<DstValueType>(x) + dOffset; });
  }
};

} // end anon namespace