WPF: How do you print in Landscape mode?

private void PrintClick(object sender, RoutedEventArgs e)
{
   PrintDialog dialog = new PrintDialog();
   if (dialog.ShowDialog() == true)
      { 
         dialog.PrintTicket.PageOrientation=System.Printing.PageOrientation.Landscape;
         dialog.PrintVisual(this, "First LandScape"); 
      }
 }

You need to add a reference to ReachFramework.dll and System.Printing.dll each.

Original Answer This has already been answered: Setting PageOrientation for the Wpf DocumentViewer PrintDialog

End Original Answer

Edit:

It appears there is a problem with the PrintTicket and printing visuals, check out: Same question on MSDN

The original poster on the MSDN forum posted on the last post that the work around they used was to basically capture the visual and convert to xps document for printing, this will allow the usage of PrintTicket to set the orientation of the printed document.

Edit: Fixed variable name, mentioned by @SHIN JaeGuk

private void PrintClick(object sender, RoutedEventArgs e)
{
    PrintDialog dialog = new PrintDialog();
    if (dialog.ShowDialog() == true)
    { 
        //Set PageOrientation to Landscape
        dialog.PrintTicket.PageOrientation = PageOrientation.Landscape;
        dialog.PrintVisual(_PrintCanvas, "My Canvas"); 
    }
}