Method AddSingleValueToDataset

IO/HDF/vtkHDFWriterImplementation.cxx:523–580

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//------------------------------------------------------------------------------
bool vtkHDFWriter::Implementation::AddSingleValueToDataset(
  hid_t dataset, vtkIdType value, bool offset, bool trim)
{
  vtkDebugWithObjectMacro(this->Writer, "Adding 1 value to " << this->GetGroupName(dataset));
  // Create a new dataspace containing a single value
  constexpr hsize_t addedDims[1] = { 1 };
  vtkHDF::ScopedH5SHandle newDataspace = H5Screate_simple(1, addedDims, nullptr);
  if (newDataspace == H5I_INVALID_HID)
  {
    return false;
  }

  // Recover dataset and dataspace
  vtkHDF::ScopedH5SHandle currentDataspace = H5Dget_space(dataset);
  if (currentDataspace == H5I_INVALID_HID)
  {
    return false;
  }

  // Retrieve current dataspace dimensions
  hsize_t currentdims[1] = { 0 };
  H5Sget_simple_extent_dims(currentDataspace, currentdims, nullptr);
  const hsize_t newdims[1] = { currentdims[0] + addedDims[0] };

  // Add the last value of the dataset if we want an offset (only for arrays of stride 1)
  if (offset && currentdims[0] > 0)
  {
    std::vector<vtkIdType> allValues;
    allValues.resize(currentdims[0]);
    H5Dread(dataset, H5T_STD_I64LE, currentDataspace, H5S_ALL, H5P_DEFAULT, allValues.data());
    value += allValues.back();
  }

  // Resize dataset
  if (!trim)
  {
    if (H5Dset_extent(dataset, newdims) < 0)
    {
      return false;
    }
    currentDataspace = H5Dget_space(dataset);
    if (currentDataspace == H5I_INVALID_HID)
    {
      return false;
    }
  }
  hsize_t start[1] = { currentdims[0] - trim };
  hsize_t count[1] = { addedDims[0] };
  H5Sselect_hyperslab(currentDataspace, H5S_SELECT_SET, start, nullptr, count, nullptr);

  // Write new data to the dataset
  if (H5Dwrite(dataset, H5T_STD_I64LE, newDataspace, currentDataspace, H5P_DEFAULT, &value) < 0)
  {
    return false;
  }

  return true;
}