So, I can get font name but also I need to know is font bold/italic/light etc. I try to investigate in code of this library but I have no success.
On demo page of this library you can find a lot of information but no doc is present about it.
About italic I have idea that we can detect it by post->italicAngle (according to demo page). It should be non-zero value.
Is this correct?
Read through the OS/2 and name tables ("Name IDs" section especially) for how all that information is organised. PHP-font-lib exposes the OpenType table data to you, so reading up on how to work with that data is your responsibility.