I have XPS documents being generated from XAML User Controls that act as templates. I want to convert the XPS documents into alternative formats, mainly PDF, programmaticall
If you have OneNote, you can print to OneNote and then export as PDF at least in OneNote 2013. This seems better than having to install another third party tool.
You can also use ABCpdf PDF Component for .NET . Version 7 can serve your purpose. see http://www.websupergoo.com/abcpdf-12.htm.
it provides fully functional trial version unlike NiXPS and almost equally as fast as NiXPS.
After much searching, I found this SDK:
NiXPS
Its kindof expensive but works wonderfully. Goodbye fop!
The way I have done this in the past is print my XPS file to a PDF printer. I use cutePDF for this. So when you select to print, you print to cutePDF which prints a PDF version.
I am not sure if this will meet your needs but it has worked well for me in the past.
If you want to do this in your own program, CloudConvert has a free and open source API built on the .NET framework by MadScripter.
https://github.com/MadScripter/CloudConvert-.NET-Wrapper/