Hi.

Is it possible to use the topological Layout Engine with more than one row of DiagramNodes?
I use this Layout to draw a statemachine an if there are more than 5 States the diagram is getting really wide.
Does anyone has a solution for this?
Or has anyone a better idea for drawing a statenmachine?

thanks for all hints.

I tried to use these layouts. but these layouts dont have round / bezier links. so it dont look that good.

But thanks for help

E.g. this code creates the following kind of layout:

void SpringLayoutBezier(Diagram diagram)
{
	Diagram clone = new Diagram();
	clone.LoadFromString(diagram.SaveToString());
	var virtualNodes = AddVirtualNodes(clone);

	SpringLayout layout = new SpringLayout();
	layout.MinimizeCrossings = true;
	layout.NodeDistance /= 3;
	layout.IterationCount *= 3;
	layout.Arrange(clone);

	ApplyLayout(diagram, clone, virtualNodes);
}

Dictionary<DiagramNode, DiagramLink> AddVirtualNodes(Diagram diagram)
{
	var virtualNodes = new Dictionary<DiagramNode, DiagramLink>();

	DiagramLinkCollection originalLinks = diagram.Links.Clone();
	foreach (DiagramLink link in originalLinks)
	{
		PointF m = MiddlePoint(link);

		ShapeNode v1 = diagram.Factory.CreateShapeNode(m, new SizeF(1, 1));
		v1.Tag = 1;
		ShapeNode v2 = diagram.Factory.CreateShapeNode(m, new SizeF(1, 1));
		v2.Tag = 2;
		virtualNodes[v1] = virtualNodes[v2] = link;

		diagram.Factory.CreateDiagramLink(link.Origin, v1);
		diagram.Factory.CreateDiagramLink(v1, v2);
		diagram.Factory.CreateDiagramLink(v2, link.Destination);

		link.IgnoreLayout = true;
	}

	return virtualNodes;
}

private void ApplyLayout(Diagram diagram, Diagram clone, Dictionary<DiagramNode, DiagramLink> virtualNodes)
{
	foreach (DiagramNode node in diagram.Nodes)
	{
		int index = node.ZIndex;
		var clonedNode = clone.Items[index] as DiagramNode;
		node.Bounds = clonedNode.Bounds;
	}

	foreach (DiagramLink link in diagram.Links)
	{
		link.Style = LinkStyle.Polyline;
		link.Style = LinkStyle.Bezier;
		link.SegmentCount = 1;
	}

	foreach (DiagramNode vnode in virtualNodes.Keys)
	{
		var link = virtualNodes[vnode];
		int index = link.ZIndex;
		var originalLink = diagram.Items[index] as DiagramLink;
		 int pointIndex = (int)vnode.Tag;

		originalLink.ControlPoints[pointIndex] = vnode.Bounds.Location;
		if (pointIndex == 1)
			originalLink.ControlPoints[0] = vnode.IncomingLinks[0].ControlPoints[0];
		else
			originalLink.ControlPoints[3] = vnode.OutgoingLinks[0].ControlPoints[1];
		originalLink.UpdateFromPoints();
	}
}

private PointF MiddlePoint(DiagramLink link)
{
	PointCollection p = link.ControlPoints;
	PointF m = new PointF(
		(p[0].X + p[p.Count - 1].X) / 2,
		(p[0].Y + p[p.Count - 1].Y) / 2);
	return m;
}
 

Hi,

This code assumes the diagram defaults for the links are polyline with one segment. If your LinkStyle and SegmentCount are different than that, you will have to replace the right-hand side of this assignment -

originalLink.ControlPoints[3] = vnode.OutgoingLinks[0].ControlPoints[1];

with one that takes ControlPoints[ControlPoints.Count - 1] rather than ControlPoints[1].

Or set the default properties to polyline/1 on the 'clone' diagram before creating links.

I hope that helps,
Stoyan

Now we've noticed there is a small problem with this approach - the MinimizeLinks option does not work that well when there are three times as many nodes... So you might run the layout once on the original graph to minimize the crossings, and then run the code above to create the curved links.

I hope that helps,
Stoyan