Method UpdateTicksValueAndPosition

Rendering/Annotation/vtkAxisActor2D.cxx:624–675

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//------------------------------------------------------------------------------
void vtkAxisActor2D::UpdateTicksValueAndPosition(vtkViewport* viewport)
{
  // viewport distances
  const double viewportAxisLength = this->GetViewportAxisLength(viewport);
  const double viewportRulerDistance = this->GetViewportRulerDistance(viewport);

  // normalized on axis size.
  const double majorLengthRatio = this->RulerMode ? viewportRulerDistance / viewportAxisLength
                                                  : 1. / (this->AdjustedNumberOfLabels - 1);
  const double minorLengthRatio = majorLengthRatio / (this->NumberOfMinorTicks + 1);

  // values (in `Range` unit)
  const double majorDelta = (this->AdjustedRange[1] - this->AdjustedRange[0]) * majorLengthRatio;
  const double minorDelta = (this->AdjustedRange[1] - this->AdjustedRange[0]) * minorLengthRatio;

  // factor for Range to Axis normalized value conversion.
  const double scale = 1. / (this->Range[1] - this->Range[0]);

  this->TickValues.clear();
  this->NormalizedTickPositions.clear();

  const double minValue = std::min(this->Range[0], this->Range[1]);
  const double maxValue = std::max(this->Range[0], this->Range[1]);

  int startingTick = this->SkipFirstTick ? 1 : 0;
  for (int major = startingTick; major < this->AdjustedNumberOfLabels; major++)
  {
    double value = this->AdjustedRange[0] + major * majorDelta;
    double position = (value - this->Range[0]) * scale;

    if (position < 0 || value < minValue || position > 1 || value > maxValue)
    {
      continue;
    }

    this->NormalizedTickPositions.push_back(position);
    this->TickValues.push_back(value);

    for (int minor = 1; minor <= this->NumberOfMinorTicks; minor++)
    {
      value = value + minorDelta;
      position = (value - this->Range[0]) * scale;
      if (position > 1)
      {
        continue;
      }
      this->NormalizedTickPositions.push_back(position);
    }
  }

  this->NumberOfLabelsBuilt = static_cast<int>(this->TickValues.size());
}

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void vtkAxisActor2D::BuildTicksPolyData(vtkViewport* viewport)