Wpf – Printing a WPF FlowDocument

Important thing to note : You can use XpsDocumentWriter even when printing directly to a physical printer. Don't make the mistake I did of avoiding it just because you're not creating an .xps file!

Anyway - I had this same problem, and none of the DoEvents() hacks seemed to work. I also wasn't particularly happy about having to use them in the first place. In my situation some of the databound controls printed fine, but some others (nested UserControls) didnt. It was as if only one 'level' was being databound and the rest wouldn't bind even with a 'DoEvents()' hack.

The solution was simple though. Use XpsDocumentWriter like this. it will open a dialog where you can choose whichever installed physical printer you want.

        // 8.5 x 11 paper
        Size sz = new Size(96 * 8.5, 96 * 11);

        // create your visual (this is a WPF UserControl)
        var template = new PackingSlipTemplate()
        {
            DataContext = new PackingSlipViewModel(order)
        };

        // arrange
        template.Measure(sz);
        template.Arrange(new Rect(sz));
        template.UpdateLayout();

        // print to XpsDocumentWriter
        // this will open a dialog and you can print to any installed printer
        // not just a 'virtual' .xps file
        PrintDocumentImageableArea area = null;
        XpsDocumentWriter xps = PrintQueue.CreateXpsDocumentWriter(ref area,);

        xps.Write(template);

I found the OReilly book on 'Programming WPF' quite useful with its chapter on Printing - found through Google Books.

If you don't want a print dialog to appear, but want to print directly to the default printer you can do the following. (For me the application is to print packing slips in a warehouse environment - and I don't want a dialog popping up every time).

        var template = new PackingSlipTemplate()
        {
            DataContext = new PackingSlipViewModel(orders.Single())
        };

        // arrange
        template.Measure(sz);
        template.Arrange(new Rect(sz));
        template.UpdateLayout();

        LocalPrintServer localPrintServer = new LocalPrintServer();
        var defaultPrintQueue = localPrintServer.DefaultPrintQueue;

        XpsDocumentWriter xps = PrintQueue.CreateXpsDocumentWriter(defaultPrintQueue);
        xps.Write(template, defaultPrinter.DefaultPrintTicket);

Taking the hint from the comment added to my question, I did this:

private string _previewWindowXaml =
    @"<Window
        xmlns                 ='http://schemas.microsoft.com/netfx/2007/xaml/presentation'
        xmlns:x               ='http://schemas.microsoft.com/winfx/2006/xaml'
        Title                 ='Print Preview - @@TITLE'
        Height                ='200'
        Width                 ='300'
        WindowStartupLocation ='CenterOwner'>
        <DocumentViewer Name='dv1'/>
     </Window>";

internal void DoPreview(string title)
{
    string fileName = System.IO.Path.GetRandomFileName();
    FlowDocumentScrollViewer visual = (FlowDocumentScrollViewer)(_parent.FindName("fdsv1"));
    try
    {
        // write the XPS document
        using (XpsDocument doc = new XpsDocument(fileName, FileAccess.ReadWrite))
        {
            XpsDocumentWriter writer = XpsDocument.CreateXpsDocumentWriter(doc);
            writer.Write(visual);
        }

        // Read the XPS document into a dynamically generated
        // preview Window 
        using (XpsDocument doc = new XpsDocument(fileName, FileAccess.Read))
        {
            FixedDocumentSequence fds = doc.GetFixedDocumentSequence();

            string s = _previewWindowXaml;
            s = s.Replace("@@TITLE", title.Replace("'", "&apos;"));

            using (var reader = new System.Xml.XmlTextReader(new StringReader(s)))
            {
                Window preview = System.Windows.Markup.XamlReader.Load(reader) as Window;

                DocumentViewer dv1 = LogicalTreeHelper.FindLogicalNode(preview, "dv1") as DocumentViewer;
                dv1.Document = fds as IDocumentPaginatorSource;


                preview.ShowDialog();
            }
        }
    }
    finally
    {
        if (File.Exists(fileName))
        {
            try
            {
                File.Delete(fileName);
            }
            catch
            {
            }
        }
    }
} 

What it does: it actually prints the content of a visual into an XPS document. Then it loads the "printed" XPS document and displays it in a very simple XAML file that is stored as a string, rather than as a separate module, and loaded dynamically at runtime. The resulting Window has the DocumentViewer buttons: print, adjust-to-max-page-width, and so on.

I also added some code to hide the Search box. See this answer to WPF: How can I remove the searchbox in a DocumentViewer? for how I did that.

The effect is like this:

The XpsDocument can be found in the ReachFramework dll and the XpsDocumentWriter can be found in the System.Printing dll both of which must be added as references to the project