Relative font sizes in QT or the most portable way to define them

Question

Coming from a Web Development background I am now into QT Applications development.

Working with QFonts I have seen that I have only two options apparently, to defin

Answer 1

in qt3, the next code works at least for fixed fonts:

QFont f=font();
int psz=f.pixelSize();
if (psz>0) f.setPixelSize(psz*6/5);
else f.setPointSizeFloat(f.pointSizeFloat()*1.2);