// ------------------------ GetFixedDocument --------------------------
/// <summary>
///   Returns the fixed document at a given URI within
///   the currently open XPS package.</summary>
/// <param name="fixedDocUri">
///   The URI of the fixed document to return.</param>
/// <returns>
///   The fixed document at a given URI
///   within the current XPS package.</returns>
private FixedDocument GetFixedDocument(Uri fixedDocUri)
{
    FixedDocument fixedDocument = null;

    // Create the URI for the fixed document within the package. The URI
    // is used to set the Parser context so fonts & other items can load.
    Uri tempUri = new Uri(_xpsDocumentPath, UriKind.RelativeOrAbsolute);
    ParserContext parserContext = new ParserContext();
    parserContext.BaseUri = PackUriHelper.Create(tempUri);

    // Retrieve the fixed document.
    PackagePart fixedDocPart = _xpsPackage.GetPart(fixedDocUri);
    if (fixedDocPart != null)
    {
        object fixedObject =
            XamlReader.Load(fixedDocPart.GetStream(), parserContext);
        if (fixedObject != null)
            fixedDocument = fixedObject as FixedDocument;
    }

    return fixedDocument;
}// end:GetFixedDocument()