' ------------------------- LoadDocumentViewer -----------------------
''' <summary>
'''   Loads content from a file to a DocumentViewer control.</summary>
''' <param name="xpsFilename">
'''   The path and name of the XPS file to
'''   load to the DocumentViewer control.</param>
''' <remarks>
'''   Exception handling should be added if the xpsFilename may not be
'''   valid or if the FixedDocumentSequence contained in the file is
'''   incorrect.  (In this sample the files are hardcoded.)</remarks>
Private Sub LoadDocumentViewer(ByVal xpsFilename As String)
    ' Save a reference to the currently open XPS package.
    Dim oldXpsPackage As XpsDocument = _xpsPackage

    ' Open the package for the new XPS document.
    _xpsPackage = New XpsDocument(xpsFilename, FileAccess.Read, CompressionOption.NotCompressed)

    ' Get the FixedDocumentSequence from the package.
    Dim fixedDocumentSequence As FixedDocumentSequence = _xpsPackage.GetFixedDocumentSequence()

    ' Set the new FixedDocumentSequence as
    ' the DocumentViewer's paginator source.
    docViewer.Document = TryCast(fixedDocumentSequence, IDocumentPaginatorSource)

    ' If there was an old XPS package, close it now that
    ' DocumentViewer no longer needs to access it.
    If oldXpsPackage IsNot Nothing Then
        oldXpsPackage.Close()
    End If

    ' Leave the new _xpsPackage open for DocumentViewer
    ' to access additional required resources.

End Sub