我用数据绑定的Datagrid创建了一个FlowDocument。 FlowDocumentScrollviewer中的输出是这样的：

接下来，我需要将此FlowDocument转换为固定文档（XPS），以便以A4纸张尺寸进行打印。 但是一旦这样做，我的DataGrid数据就会丢失。

这是我的XAML：

<Window x:Class="Test_Flow.Izpisi.DataGrid_DataTable"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:Test_Flow.Izpisi"
        mc:Ignorable="d"
        Title="DataGrid_DataTable" Height="850" Width="850"
        WindowStartupLocation="CenterScreen">
      <Grid>
        <FlowDocumentScrollViewer Name="Flow_reader" >
            <FlowDocument Name="Flow_dokument" PageHeight="29.7cm" PageWidth="21cm" >
                <Paragraph>Datagrid with DataTable example</Paragraph>
                <BlockUIContainer>
                    <DataGrid BorderThickness="1" ItemsSource="{Binding Dt_Flow}" IsEnabled="False" 
                              AutoGenerateColumns="False" HeadersVisibility="Column" BorderBrush="Black">
                        <DataGrid.Columns>
                            <DataGridTextColumn Header="Name" Binding="{Binding Number}"/>
                            <DataGridTextColumn Header="Surname" Binding="{Binding Surname}"/>
                            <DataGridTextColumn Header="Address" Binding="{Binding Address}"/>
                            <DataGridTextColumn Header="City" Binding="{Binding City}"/>
                        </DataGrid.Columns>
                    </DataGrid>
                </BlockUIContainer>
            </FlowDocument>
        </FlowDocumentScrollViewer>
        <DocumentViewer Name="doc_viewer" Visibility="Collapsed" />
    </Grid>
</Window>

和我的View_Model：

 class My_ViewModel : INotifyPropertyChanged
    {
        public My_ViewModel(DocumentViewer doc_viewer,FlowDocument dokument,FlowDocumentScrollViewer page_viewer)
        {
            Fill_Table(); //Fill some test data

            //Convert to XPS and display It in DocumentViewer
            Convert_to_XPS(doc_viewer,dokument,page_viewer);

        }

        public DataTable Dt_Flow { get; set; } //DataTable for FlowDocument

        private void Convert_to_XPS(DocumentViewer doc_viewer,FlowDocumentScrollViewer page_viewer)
        {
            //Convert FlowDocument to XPS
            MemoryStream ms = new MemoryStream();
            Package pkg = Package.Open(ms,FileMode.Create,Fileaccess.ReadWrite);
            string pack = "pack://report.xps";
            PackageStore.RemovePackage(new Uri(pack));
            PackageStore.AddPackage(new Uri(pack),pkg);
            XpsDocument doc = new XpsDocument(pkg,CompressionOption.Maximum,pack);
            XpsSerializationmanager rsm = new XpsSerializationmanager(new XpsPackagingPolicy(doc),false);

            DocumentPaginator paginator = ((IDocumentPaginatorSource)dokument).DocumentPaginator;

            rsm.SaveAsXaml(paginator);

            //Hide FlowDocumentScrollViwer and show DocumentViewer
            page_viewer.Visibility = Visibility.Collapsed;
            doc_viewer.Document = doc.GetFixedDocumentSequence();
            doc_viewer.Visibility = Visibility.Visible;
        }

        private void Fill_table()
        {
            //Fill test table
            Dt_Flow = new DataTable();

            Dt_Flow.Columns.Add("Number");
            Dt_Flow.Columns.Add("Surname");
            Dt_Flow.Columns.Add("Address");
            Dt_Flow.Columns.Add("City");

            int my_number = 1;

            for (int i = 0; i < 10; i++)
            {
              DataRow _newRow = Dt_Flow.NewRow();
              _newRow["Number"] = my_number + ".";
              _newRow["Surname"] = "Johnson";
              _newRow["Address"] = "Beverly Hills";
              _newRow["City"] = "Los Angeles";

              Dt_Flow.Rows.Add(_newRow);
              my_number++;
            }
        }

        #region INotifyPropertyChanged

        public event PropertyChangedEventHandler PropertyChanged;
        private void OnPropertyChanged(string propertyName)
        {
            PropertyChanged?.Invoke(this,new PropertyChangedEventArgs(propertyName));
        }

        #endregion

    }

为什么会这样，我该如何解决？

编辑：我在“ My_ViewMmodel” 中添加了“ Fill_table” 方法，因此您可以自己测试整个过程。