how to set vtkScalarBarActor title's font?

Support
1

My VTK’s version is 9.1, I set vtkScalarBarActor’s title, but can’t set the title’s font, I check the conresponding header file, there is no funciton provided for setting title’s font, some code like below to set the font doesn’t work

		vtkSmartPointer< vtkScalarBarActor > scalarBarActor = vtkSmartPointer< vtkScalarBarActor >::New();
		scalarBarActor->SetOrientationToHorizontal();
		scalarBarActor->SetLookupTable(lut);
		scalarBarActor->SetTitle("Z(m)");
	    scalarBarActor->SetVerticalTitleSeparation(100);
		scalarBarActor->GetTitleTextProperty()->SetColor(1.0, 1.0, 1.0);
		scalarBarActor->GetTitleTextProperty()->SetFontSize(50);

setting color take effect, but font size not, so how to change the title’s font?

2

Have you tried SetUnconstrainedFontSize()?

3

I have tried the SetUnconstrainedFontSize(), It can change default font(bold), but

	    scalarBarActor->SetTitle("Z(m)");
	    scalarBarActor->SetVerticalTitleSeparation(10);
		scalarBarActor->GetTitleTextProperty()->SetColor(1.0, 1.0, 1.0);
		scalarBarActor->GetTitleTextProperty()->SetFontFamilyToTimes();
		//scalarBarActor->GetTextActor()->SetTextScaleModeToNone()
		scalarBarActor->GetTitle();
		//scalarBarActor->GetTitleTextProperty()->SetFontSize(20);
		//scalarBarActor->GetTitleTextProperty()->SetUnconstrainedFontSize(10);
		scalarBarActor->SetUnconstrainedFontSize(60);

is same as

        scalarBarActor->SetTitle("Z(m)");
	    scalarBarActor->SetVerticalTitleSeparation(10);
		scalarBarActor->GetTitleTextProperty()->SetColor(1.0, 1.0, 1.0);
		scalarBarActor->GetTitleTextProperty()->SetFontFamilyToTimes();
		//scalarBarActor->GetTextActor()->SetTextScaleModeToNone()
		scalarBarActor->GetTitle();
		//scalarBarActor->GetTitleTextProperty()->SetFontSize(20);
		//scalarBarActor->GetTitleTextProperty()->SetUnconstrainedFontSize(10);
		scalarBarActor->SetUnconstrainedFontSize(10);

It kind of weird. font 60 is same as font 10