KeyNotFoundException with MDS layout

[michaelkruglos]

Hi Lev, I tried to modify WpfAplicationSample to show MDS layout, and it throws KeyNotFoundException. Here are my modifications:

diff --git a/GraphLayout/Samples/WpfApplicationSample/WpfApplicationSample.cs b/GraphLayout/Samples/WpfApplicationSample/WpfApplicationSample.cs
index 5a6e6dd..f16ec58 100644
--- a/GraphLayout/Samples/WpfApplicationSample/WpfApplicationSample.cs
+++ b/GraphLayout/Samples/WpfApplicationSample/WpfApplicationSample.cs
@@ -291,6 +291,7 @@ namespace WpfApplicationSample
 //                //graph.LayoutAlgorithmSettings.EdgeRoutingSettings.EdgeRoutingMode = EdgeRoutingMode.SplineBundling;
 //                //layout the graph and draw it
                 Graph graph = new Graph();
+                graph.LayoutAlgorithmSettings=new Microsoft.Msagl.Layout.MDS.MdsLayoutSettings();
                 graph.AddEdge("47", "58");
                 graph.AddEdge("70", "71");

@@ -315,11 +316,11 @@ namespace WpfApplicationSample
                 graph.Attr.LayerDirection = LayerDirection.LR;
                 //graph.LayoutAlgorithmSettings.EdgeRoutingSettings.EdgeRoutingMode = EdgeRoutingMode.Rectilinear;

-                var global = (SugiyamaLayoutSettings) graph.LayoutAlgorithmSettings;
-                var local  = (SugiyamaLayoutSettings) global.Clone();
-                local.Transformation = PlaneTransformation.Rotation(-Math.PI / 2);
+                var global = (Microsoft.Msagl.Layout.MDS.MdsLayoutSettings) graph.LayoutAlgorithmSettings;
+                var local  = (Microsoft.Msagl.Layout.MDS.MdsLayoutSettings) global.Clone();
+                //local.Transformation = PlaneTransformation.Rotation(-Math.PI / 2);
                 subgraph2.LayoutSettings = local;   // for Collapsing\Expanding
-                global.ClusterSettings.Add(subgraph2, local);
+                //global.ClusterSettings.Add(subgraph2, local);

                 graphViewer.Graph = graph;
             }

The line, which throws exception is:

                intEdges.Add(new SimpleIntEdge {Source = nodeIndex[e.Source], Target = nodeIndex[e.Target]});

Checking with debugger, I can see that subgraph2 is missing from nodeIndex dictionary. I have no idea why it happens specifically with MDS, but doesn't happen with Sugiyama. Am I doing something wrong, or is there a bug in MDS layout algorithm? Here's the screenshot of the exception being thrown:

[levnach]

Unfortunately, MDS layout does not support clusters, but the Sugiyama one does. With clusters present, to use the MDS layout, one needs to go through InitialLayoutByClusters. The simple option of assigning viewer.Graph = graph; would not work.