Method PrepareRender

Rendering/Core/vtkLabeledContourMapper.cxx:548–653

------------------------------------------------------------------------------

//------------------------------------------------------------------------------
bool vtkLabeledContourMapper::PrepareRender(vtkRenderer* ren, vtkActor* act)
{
  if (!this->Internal->SetViewInfo(ren, act))
  {
    return false;
  }

  // Already checked that these exist in CheckInputs()
  vtkPolyData* input = this->GetInput();
  vtkCellArray* lines = input->GetLines();
  vtkDataArray* scalars = input->GetPointData()->GetScalars();
  vtkTextRenderer* tren = vtkTextRenderer::GetInstance();
  if (!tren)
  {
    vtkErrorMacro(<< "Text renderer unavailable.");
    return false;
  }

  // Maps scalar values to text properties:
  typedef std::map<double, vtkTextProperty*> LabelPropertyMapType;
  LabelPropertyMapType labelMap;

  // Initialize with the user-requested mapping, if it exists.
  if (this->TextPropertyMapping != nullptr)
  {
    vtkDoubleArray::Iterator valIt = this->TextPropertyMapping->Begin();
    vtkDoubleArray::Iterator valItEnd = this->TextPropertyMapping->End();
    TextPropLoop tprops(this->TextProperties);
    for (; valIt != valItEnd; ++valIt)
    {
      labelMap.insert(std::make_pair(*valIt, tprops.Next()));
    }
  }

  // Create the list of metrics, but no text property information yet.
  vtkIdType numPts;
  const vtkIdType* ids;
  for (lines->InitTraversal(); lines->GetNextCell(numPts, ids);)
  {
    this->Internal->LabelMetrics.emplace_back();
    LabelMetric& metric = this->Internal->LabelMetrics.back();
    if (!(metric.Valid = (numPts > 0)))
    {
      // Mark as invalid and skip if there are no points.
      continue;
    }
    metric.Value = scalars->GetComponent(ids[0], 0);
    metric.Value = std::fabs(metric.Value) > 1e-6 ? metric.Value : 0.0;
    std::ostringstream str;
    str << metric.Value;
    metric.Text = str.str();

    // Beware future maintainers: The following line of code has been carefully
    // crafted to reach a zen-like harmony of compatibility between various
    // compilers that have differing syntactic requirements for creating a
    // pair containing a nullptr:
    // - Pedantically strict C++11 compilers (e.g. MSVC 2012) will not compile:
    //     std::make_pair<double, X*>(someDouble, nullptr);