Cpdf::setCurrentFont
sets up the current font, based on the font families, and the current text state note that this system is quite flexible, a bold-italic font can be completely different to a italic-bold font, and even bold-bold will have to be defined within the family to have meaning This function is to be called whenever the currentTextState is changed, it will update the currentFont setting to whatever the appropriate family one is.
If the user calls selectFont themselves then that will reset the currentBaseFont, and the currentFont This function will change the currentFont to whatever it should be, but will not change the currentBaseFont.
Signature
private function setCurrentFont()