https://www.cnblogs.com/zeoy/archive/2013/01/09/2852941.html
https://blog.csdn.net/jafucong/article/details/78980276
PdfDocument doc = new PdfDocument();
doc.LoadFromFile(xpsFile,FileFormat.XPS);
doc.SaveToFile(pdfFile, FileFormat.PDF);
原文：https://www.cnblogs.com/changbaishan/p/11527529.html