Method SetLabelPositions

Rendering/Annotation/vtkAxisActor.cxx:470–536

------------------------------------------------------------------------------ Determine and set scale factor and position for labels. ------------------------------------------------------------------------------

// Determine and set scale factor and position for labels.
//------------------------------------------------------------------------------
void vtkAxisActor::SetLabelPositions(vtkViewport* viewport, bool force)
{
  if (!force && (!this->LabelVisibility || this->NumberOfLabelsBuilt == 0))
  {
    return;
  }

  //
  // xadjust & yadjust are used for positioning the label correctly
  // depending upon the 'orientation' of the axis as determined
  // by its position in view space (via transformed bounds).
  //
  double displayBounds[6] = { 0., 0., 0., 0., 0., 0. };
  this->TransformBounds(viewport, displayBounds);

  double bounds[6], tickBottom[3], tickTop[3], pos[3];
  double labelAngle = vtkMath::RadiansFromDegrees(this->LabelTextProperty->GetOrientation());
  double labelCos = fabs(cos(labelAngle));
  double labelSin = fabs(sin(labelAngle));
  vtkAxisFollower* pAxisFollower = nullptr;

  for (int i = 0, ptIdx = 0;
       i < this->NumberOfLabelsBuilt && ((ptIdx + 1) < this->MajorTickPts->GetNumberOfPoints());
       i++, ptIdx += 4)
  {
    this->MajorTickPts->GetPoint(ptIdx, tickTop);
    this->MajorTickPts->GetPoint(ptIdx + 1, tickBottom);

    pAxisFollower = this->LabelProps[i]->GetFollower();

    // get Label actor Transform matrix
    vtkRenderer* ren = vtkRenderer::SafeDownCast(viewport);
    if (ren)
    {
      pAxisFollower->ComputeTransformMatrix(ren);
    }

    // WARNING: calling GetBounds() before ComputeTransformMatrix(), prevent this->Transform to be
    // updated

    // previous version: this->LabelActors[i]->GetMapper()->GetBounds(bounds); didn't include scale
    // labels
    // vtkProp3D::GetBounds() include previous transform (scale, orientation, translation)
    pAxisFollower->GetBounds(bounds);
    double labelWidth = (bounds[1] - bounds[0]);
    double labelHeight = (bounds[3] - bounds[2]);
    double labelMagnitude = sqrt(labelWidth * labelWidth + labelHeight * labelHeight);

    if (this->TickVisibility)
    {
      pos[0] = tickBottom[0];
      pos[1] = tickBottom[1];
      pos[2] = tickBottom[2];
    }
    else
    {
      pos[0] = (tickTop[0] + tickBottom[0]) / 2;
      pos[1] = (tickTop[1] + tickBottom[1]) / 2;