`vtkAxisActor2D` setting label font size doesn't work

Development
1

Hi,

I’m trying to set constant font size for vtkAxisActor2D labels.
Acoordint to the documentation there is a method UseFontSizeFromPropertyOn() wich should be used if we want to manually set font size via text property i.e.:

  axis->GetLabelTextProperty()->SetFontSize(1);
  axis->UseFontSizeFromPropertyOn();

But it seems that no matter what font size I choose the size of actually displayed numbers will be changed along with rendering window size changes.

Here is the code snippet (try to run and resze the window):

#include <vtkActor.h>
#include <vtkAxisActor.h>
#include <vtkAxisActor2D.h>
#include <vtkCamera.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkSmartPointer.h>
#include <vtkStringArray.h>
#include <vtkTextProperty.h>

int main(int argc, char *argv[]) {
  // Create the axis actor
  vtkNew<vtkAxisActor2D> axis;

  axis->GetPoint1Coordinate()->SetCoordinateSystemToDisplay();
  axis->GetPoint2Coordinate()->SetCoordinateSystemToDisplay();

  axis->SetPoint1(500, 15.0); 
  axis->SetPoint2(100, 15.0);
  axis->SetNumberOfLabels(11);
  axis->SetNumberOfMinorTicks(5);

  axis->GetLabelTextProperty()->SetFontSize(1);
//  axis->SizeFontRelativeToAxisOn();
  axis->UseFontSizeFromPropertyOn();

  axis->SetTickVisibility(1);
  axis->SetRange(-5, 5);

  // Create the RenderWindow, Renderer and both Actors
  vtkNew<vtkRenderer> renderer;
  vtkNew<vtkRenderWindow> renderWindow;
  renderWindow->AddRenderer(renderer);
  renderWindow->SetWindowName("AxisActor");

  vtkNew<vtkRenderWindowInteractor> interactor;
  interactor->SetRenderWindow(renderWindow);

  renderer->AddActor(axis);

  renderWindow->SetSize(640, 480);
  renderer->ResetCamera();
  renderer->ResetCameraClippingRange();

  // render the image
  renderWindow->Render();

  interactor->Initialize();
  interactor->Start();

  return 0;
}