将Xml解码为mxGraph .Net

mxGraph graph = new mxGraph();
        Object parent = graph.GetDefaultParent();

        graph.Model.BeginUpdate();
        try
        {
            Object v1 = graph.InsertVertex(parent, null, "Hello,", 20, 20, 80, 30);
            Object v2 = graph.InsertVertex(parent, null, "World!", 200, 150, 80, 30);
            Object e1 = graph.InsertEdge(parent, null, "Edge", v1, v2);
        }
        finally
        {
            graph.Model.EndUpdate();
        }

        mxCodec codec = new mxCodec();
        Xml = mxUtils.GetXml(codec.Encode(graph.Model));
        var xmlString = mxUtils.GetXml(xml);

我正在尝试执行逆操作.

XmlDocument doc = mxUtils.ParseXml(xmlString);

        mxGraph graphNew = new mxGraph();

        var decoder = new mxCodec(doc);



        decoder.Decode(doc, graphNew.Model);

        Object parentNew = graphNew.GetDefaultParent();

但是对象“parentNew”没有孩子.

decoder.Decode(doc, graphNew.Model);

应该用以下代码替换：

decoder.Decode(doc.DocumentElement, graphNew.Model);