How do I get info on vertical or horizontal text writing mode?

Q: Can your product get information on vertical or horizontal writing?
I am trying to process some Japanese and Chinese PDF documents and
need to identify whether text is using horizontal/verical mode.

A: This information is stored in the font associated with the text:

Please see pdftron::PDF::Font::IsHorizontalMode ()

For example, element.GetGState().GetFont().IsHorizontalMode()