Method ExtractPolygon

IO/GeoJSON/vtkGeoJSONFeature.cxx:221–288

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//------------------------------------------------------------------------------
vtkPolyData* vtkGeoJSONFeature::ExtractPolygon(
  const Json::Value& coordinate, vtkPolyData* outputData)
{
  // Check if Coordinate Array corresponds to Polygon
  if (!IsPolygon(coordinate))
  {
    vtkErrorMacro(<< "Wrong data format for a Polygon!");
    return nullptr;
  }

  bool POLYGON_WITH_HOLES = coordinate.size() > 1;

  vtkPoints* points = outputData->GetPoints();
  vtkAbstractArray* array = outputData->GetCellData()->GetAbstractArray("feature-id");
  vtkStringArray* ids = vtkArrayDownCast<vtkStringArray>(array);

  // Output is either vtkPolygon or vtkPolyLine,
  // depending on OutputPolygons option.
  vtkCellArray* polys = nullptr;
  vtkCell* exteriorPoly = nullptr;
  if (this->OutlinePolygons)
  {
    polys = outputData->GetLines();
    exteriorPoly = vtkPolyLine::New();
  }
  else
  {
    polys = outputData->GetPolys();
    exteriorPoly = vtkPolygon::New();
  }

  // For exterior Polygon
  const Json::Value& exteriorPolygon = coordinate[0];

  int EXTERIOR_POLYGON_VERTEX_COUNT = exteriorPolygon.size() - 1;
  exteriorPoly->GetPointIds()->SetNumberOfIds(EXTERIOR_POLYGON_VERTEX_COUNT);

  double point[3];
  // Remember first point, if needed for polyline
  this->CreatePoint(exteriorPolygon[0], point);
  vtkIdType idPoint0 = points->InsertNextPoint(point);
  exteriorPoly->GetPointIds()->SetId(0, idPoint0);

  // Add points for rest of polygon
  for (int i = 1; i < EXTERIOR_POLYGON_VERTEX_COUNT; i++)
  {
    this->CreatePoint(exteriorPolygon[i], point);
    vtkIdType id = points->InsertNextPoint(point);
    exteriorPoly->GetPointIds()->SetId(i, id);
  }

  // For outline mode, add first point to the end
  if (this->OutlinePolygons)
  {
    exteriorPoly->GetPointIds()->InsertNextId(idPoint0);
  }

  polys->InsertNextCell(exteriorPoly);