// ConverterWindow.xaml
     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Window1" Height="300" Width="300">
   
        ToXPS
   

// ConverterWindow.xaml.cs
using System;
using System.Collections.Generic;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Shapes;
using System.IO;
using System.Windows.Markup;
using System.Windows.Xps.Packaging;
using System.Windows.Xps.Serialization;

namespace Xaml2XPS
{
    ///

        public ConverterWindow()
        {
            InitializeComponent();        
        }

        private void btnConvert_Click(object sender, RoutedEventArgs e)
        {
            ParserContext context = new ParserContext();
            context.BaseUri = new Uri(Directory.GetCurrentDirectory() + "//");
            XamlStreamToXps(srcXamlStream, context, destXpsFile);
        }

        public void XamlStreamToXps(Stream srcXamlStream, ParserContext context, string destXpsFile)
        {
            XpsDocument document = null;
            try
            {
                if (System.IO.File.Exists(destXpsFile)) System.IO.File.Delete(destXpsFile);

                document = new XpsDocument(destXpsFile, FileAccess.Write);
                XpsPackagingPolicy packagePolicy = new XpsPackagingPolicy(document);
                XpsSerializationManager serializationMgr =
                    new XpsSerializationManager(packagePolicy, false);

                object parsedDocObject = (null == context) ?
                    XamlReader.Load(srcXamlStream) :
                    XamlReader.Load(srcXamlStream, context);

                serializationMgr.SaveAsXaml(parsedDocObject);
               

                MessageBox.Show("OK");
            }
            catch (Exception ex)
            {
                string exString = ex.Message;
                MessageBox.Show(exString);
            }
            finally
            { 
                if(document != null)   document.Close();
                if (srcXamlStream != null) srcXamlStream.Close();
            }
        }  
    }
}