// --------------------------- OpenDocument ---------------------------
/// <summary>
///   Loads and displays a given XPS document file.</summary>
/// <param name="filename">
///   The path and file name of the XPS
///   document to load and display.</param>
/// <returns>
///   true if the document loads successfully; otherwise false.</returns>
public bool OpenDocument(string xpsFile)
{
    // Check to see if the document is encrypted.
    // If encrypted, use OpenEncryptedDocument().
    if (EncryptedPackageEnvelope.IsEncryptedPackageEnvelope(xpsFile))
        return OpenEncryptedDocument(xpsFile);

    // Document is not encrypted, open normally.
    ShowStatus("Opening '" + Filename(xpsFile) + "'");

    _packageUri = new Uri(xpsFile, UriKind.Absolute);
    try
    {
        _xpsDocument = new XpsDocument(xpsFile, FileAccess.Read);
    }
    catch (System.IO.FileFormatException ex)
    {
        MessageBox.Show(xpsFile + "\n\nThe file " +
            "is not a valid XPS document.\n\n" +
            "Exception: " + ex.Message + "\n\n" +
            ex.GetType().ToString() + "\n\n" + ex.StackTrace,
            "Invalid File Format",
            MessageBoxButton.OK, MessageBoxImage.Error);
        return false;
    }

    // Get the document's PackageStore into which
    // new user annotations will be added and saved.
    _xpsPackage = PackageStore.GetPackage(_packageUri);
    if ((_xpsPackage == null) || (_xpsDocument == null))
    {
        MessageBox.Show("Unable to get Package from file.");
        return false;
    }

    // Get the FixedDocumentSequence from the open document.
    FixedDocumentSequence fds = _xpsDocument.GetFixedDocumentSequence();
    if (fds == null)
    {
        MessageBox.Show(xpsFile + "\n\nThe document package within " +
            "the specified file does not contain a " +
            "FixedDocumentSequence.", "Package Error");
        return false;
    }

    // Load the FixedDocumentSequence to the DocumentViewer control.
    DocViewer.Document = fds;

    // Enable document menu controls.
    menuFileClose.IsEnabled  = true;
    menuFilePrint.IsEnabled  = true;
    menuViewIncreaseZoom.IsEnabled = true;
    menuViewDecreaseZoom.IsEnabled = true;

    // Give the DocumentViewer focus.
    docViewer.Focus();

    this.Title = "RightsManagedPackageViewer SDK Sample - " +
                 Filename(xpsFile);
    return true;
}// end:OpenDocument()