Setting PageOrientation for the Wpf DocumentViewer PrintDialog

Question

Using the Wpf DocumentViewer control I can't figure out how to set the PageOrientation on the PrintDialog that the DocumentViewer displays when the user clicks the print button. Is there a way to hook into this?

Answer 1

Mike's answer works. The way I chose to implement it was to instead create my own doc viewer derived from DocumentViewer. Also, casting the Document property to FixedDocument wasn't working for me - casting to FixedDocumentSequence was.

GetDesiredPageOrientation is whatever you need it to be. In my case, I'm inspecting the first page's dimensions, because I generate documents that are uniform size and orientation for all pages in the document, and with only one doc in the sequence.

using System;
using System.Collections.Generic;
using System.Text;
using System.Windows.Controls;
using System.Windows.Xps;
using System.Printing;
using System.Windows.Documents;

public class MyDocumentViewer : DocumentViewer
{
    protected override void OnPrintCommand()
    {
        // get a print dialog, defaulted to default printer and default printer's preferences.
        PrintDialog printDialog = new PrintDialog();
        printDialog.PrintQueue = LocalPrintServer.GetDefaultPrintQueue();
        printDialog.PrintTicket = printDialog.PrintQueue.DefaultPrintTicket;

        // get a reference to the FixedDocumentSequence for the viewer.
        FixedDocumentSequence docSeq = this.Document as FixedDocumentSequence;

        // set the default page orientation based on the desired output.
        printDialog.PrintTicket.PageOrientation = GetDesiredPageOrientation(docSeq);

        if (printDialog.ShowDialog() == true)
        {
            // set the print ticket for the document sequence and write it to the printer.
            docSeq.PrintTicket = printDialog.PrintTicket;

            XpsDocumentWriter writer = PrintQueue.CreateXpsDocumentWriter(printDialog.PrintQueue);
            writer.WriteAsync(docSeq, printDialog.PrintTicket);
        }
    }
}