Method PlaceLabels

Rendering/Context2D/vtkLabeledContourPolyDataItem.cxx:544–593

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//------------------------------------------------------------------------------
bool vtkLabeledContourPolyDataItem::PlaceLabels()
{
  vtkPolyData* input = this->PolyData;
  vtkPoints* points = input->GetPoints();
  vtkCellArray* lines = input->GetLines();

  // Progression of smoothness tolerances to use.
  std::vector<double> tols;
  tols.push_back(0.010);
  tols.push_back(0.025);
  tols.push_back(0.050);
  tols.push_back(0.100);
  tols.push_back(0.200);
  tols.push_back(0.300);

  typedef std::vector<PDILabelMetric>::const_iterator MetricsIterator;
  MetricsIterator metric = this->Internal->LabelMetrics.begin();

  // Identify smooth parts of the isoline for labeling
  vtkIdType numIds;
  const vtkIdType* origIds;
  this->Internal->LabelInfos.reserve(this->Internal->LabelMetrics.size());
  for (lines->InitTraversal(); lines->GetNextCell(numIds, origIds); ++metric)
  {
    assert(metric != this->Internal->LabelMetrics.end());

    this->Internal->LabelInfos.emplace_back();

    // Test if it is possible to place a label (e.g. the line is big enough
    // to not be completely obscured)
    if (this->Internal->LineCanBeLabeled(points, numIds, origIds, *metric))
    {
      std::vector<PDILabelInfo>& infos = this->Internal->LabelInfos.back();
      PDILabelInfo info;
      // If no labels are found, increase the tolerance:
      for (std::vector<double>::const_iterator it = tols.begin(), itEnd = tols.end();
           it != itEnd && infos.empty(); ++it)
      {
        vtkIdType nIds = numIds;
        const vtkIdType* ids = origIds;
        while (this->Internal->NextLabel(points, nIds, ids, *metric, info, *it, this->SkipDistance))
        {
          infos.push_back(info);
        }
      }
    }
  }

  return true;
}

//------------------------------------------------------------------------------
bool vtkLabeledContourPolyDataItem::ResolveLabels()