Dynamo.Graph.Workspaces.WorkspaceModel.GenerateCombinedGraph C# (CSharp) Method

        private void GenerateCombinedGraph(bool isGroupLayout)
        {
            LayoutSubgraphs = new List<GraphLayout.Graph>();
            LayoutSubgraphs.Add(new GraphLayout.Graph());

            GraphLayout.Graph combinedGraph = LayoutSubgraphs.First();
            SubgraphClusters = new List<List<GraphLayout.Node>>();

            if (!isGroupLayout)
            {
                foreach (AnnotationModel group in Annotations)
                {
                    // Treat a group as a graph layout node/vertex
                    combinedGraph.AddNode(group.GUID, group.Width, group.Height, group.X, group.Y,
                        group.IsSelected || DynamoSelection.Instance.Selection.Count == 0);
                }
            }

            foreach (NodeModel node in Nodes)
            {
                if (!isGroupLayout)
                {
                    AnnotationModel group = Annotations.Where(
                        g => g.SelectedModels.Contains(node)).ToList().FirstOrDefault();

                    // Do not process nodes within groups
                    if (group == null)
                    {
                        combinedGraph.AddNode(node.GUID, node.Width, node.Height, node.X, node.Y,
                            node.IsSelected || DynamoSelection.Instance.Selection.Count == 0);
                    }
                }
                else
                {
                    // Process all nodes inside the selection
                    combinedGraph.AddNode(node.GUID, node.Width, node.Height, node.X, node.Y,
                        node.IsSelected || DynamoSelection.Instance.Selection.Count == 0);
                }
            }

            foreach (ConnectorModel edge in Connectors)
            {
                if (!isGroupLayout)
                {
                    AnnotationModel startGroup = null, endGroup = null;
                    startGroup = Annotations.Where(
                        g => g.SelectedModels.Contains(edge.Start.Owner)).ToList().FirstOrDefault();
                    endGroup = Annotations.Where(
                        g => g.SelectedModels.Contains(edge.End.Owner)).ToList().FirstOrDefault();

                    // Treat a group as a node, but do not process edges within a group
                    if (startGroup == null || endGroup == null || startGroup != endGroup)
                    {
                        combinedGraph.AddEdge(
                            startGroup == null ? edge.Start.Owner.GUID : startGroup.GUID,
                            endGroup == null ? edge.End.Owner.GUID : endGroup.GUID,
                            edge.Start.Center.X, edge.Start.Center.Y, edge.End.Center.X, edge.End.Center.Y);
                    }
                }
                else
                {
                    // Edges within a group are also processed
                    combinedGraph.AddEdge(edge.Start.Owner.GUID, edge.End.Owner.GUID,
                        edge.Start.Center.X, edge.Start.Center.Y, edge.End.Center.X, edge.End.Center.Y);
                }
            }

            foreach (NoteModel note in Notes)
            {
                AnnotationModel group = Annotations.Where(
                    g => g.SelectedModels.Contains(note)).ToList().FirstOrDefault();

                GraphLayout.Node nd = null;

                if (!isGroupLayout || group == null)
                {
                    // If note is not part of a group, link to the nearest node in the graph
                    nd = combinedGraph.Nodes.OrderBy(node =>
                        Math.Pow(node.X + node.Width / 2 - note.X - note.Width / 2, 2) +
                        Math.Pow(node.Y + node.Height / 2 - note.Y - note.Height / 2, 2)).FirstOrDefault();
                }
                else
                {
                    // If note is part of a group, link to the nearest node in the group
                    NodeModel ndm = group.SelectedModels.OfType<NodeModel>().OrderBy(node =>
                        Math.Pow(node.X + node.Width / 2 - note.X - note.Width / 2, 2) +
                        Math.Pow(node.Y + node.Height / 2 - note.Y - note.Height / 2, 2)).FirstOrDefault();

                    // Skip processing the group if there is no node in the group
                    if (ndm == null) continue;

                    // If the nearest point is a node model
                    nd = combinedGraph.FindNode(ndm.GUID);

                    // If the nearest point is a group model
                    nd = nd ?? combinedGraph.FindNode(group.GUID);
                }

                // Otherwise, leave the note unchanged
                if (nd != null)
                {
                    nd.LinkNote(note, note.Width, note.Height);
                }
            }

            if (!isGroupLayout)
            {
                // Add all nodes to one big cluster
                List<GraphLayout.Node> bigcluster = new List<GraphLayout.Node>();
                bigcluster.AddRange(combinedGraph.Nodes);
                SubgraphClusters.Add(bigcluster);
            }
            else
            {
                // Each group becomes one cluster
                foreach (AnnotationModel group in DynamoSelection.Instance.Selection.OfType<AnnotationModel>())
                {
                    List<GraphLayout.Node> cluster = new List<GraphLayout.Node>();
                    cluster.AddRange(group.SelectedModels.OfType<NodeModel>().Select(x => combinedGraph.FindNode(x.GUID)));
                    SubgraphClusters.Add(cluster);
                }
            }

        }