Programming WPF, 2nd Edition

XPS File Generation Features

As we've seen, you can use the same code path to generate both printed output and XPS files by using the XpsDocumentWriter class. However, you can build some extra features into an XPS file that would not be useful for print output, but which can enhance its usefulness as a standalone file. Indeed, unless you plan to exploit some of these features, there's probably not much point in adding a "save as XPS" feature to your application—Windows automatically offers basic XPS generation to any application that can print.

Tip

Any machine with either .NET 3.0 or the Microsoft XPS Essentials Pack^[107] installed will have a "Microsoft XPS Document Writer" printer. Windows Vista has .NET 3.0 built in. You can install .NET 3.0 on Windows XP or Windows Server 2003. You can install the XPS Essentials Pack on these systems, and on Windows 2000 machines.

When an application "prints" to this printer, an XPS file is created. At the start of the print process, a dialog opens asking the user where he'd like to save the XPS file, and once printing is complete, the XPS viewer application will run, displaying the results.

This is very useful because it means that any print-enabled application can generate an XPS file. However, it is possible for applications to build a richer, more useful XPS file than this pseudoprinter can. An application knows things about its documents that the print system cannot, and can use this to enhance the XPS file. For example, XPS files can contain ...