Hi all,

I call layout.Arrange(diagram) on a SpringLayout periodically from a worker thread (using diagramView.Invoke for safety), and this works really well! It's even possible to modify the diagram during this (setting LayoutTraits.Freeze on the modified node during its modification). This is so cool!

I noticed a strange behaviour, though. Here's a screencast showing the issue:  http://youtu.be/fkux7L_Kn1Q

Sometimes (not always), single nodes suddenly "jump" to a completely different location (see the linked screencast). I didn't interfer with the diagram in any way during the "jumps".

This looks like some computation error inside the layout algorithm or something...

Can you explain this behaviour?


Thanks,
  Tim

We have a similar AnimatedLayout example coming with WPF version of the control, and now I see that it explicitly sets layout.MinimizeCrossings = false; so that's it I suppose.

Well, it seems to still occur, even with no parallelism. sigh.

I'll investigate further.

I noticed, though, that it seems to happen only with the rightmost nodes - could it be some issue with the diagram's bounds?

I'll try to prepare an isolated testcase and will send it to you. Until then, thanks so far

That happens because when you call Arrange, SpringLayout calculates initial layout area based on number and size of nodes, and pulls all nodes inside it. After a few hundred Arrange calls the rightmost node gets outside the calculated area and you see it pulled back in.

You could use the built-in animation methods of SpringLayout (BeginArrange, Iterate, EndArrange), and the layout area check will be done only in the beginning:

this.diagram1.LoadFromFile("test.diag");

var sl = new SpringLayout
{
	Anchoring = Anchoring.Ignore,
	IterationCount = 5,
	NodeDistance = 50,
	MinimizeCrossings = false,
	GrowToFit = false,
	EnableClusters = false,
	LinkType = SpringLayoutLinkType.Straight,
	//EnableParallelism = false,
	Randomize = false // nicht random, sondern die initiale Partitionierung (s.o.) beachten!
};
sl.BeginArrange(diagram1, null);
this.layout = sl;

private void HandlesAnimTimerTick(object sender, EventArgs args)
{
	var sl = this.layout as SpringLayout;
	if (sl != null)
		sl.Iterate(0, 5);  // this won't pull back nodes anymore
} 

Alternatively keep using Arrange, but set SpringLayout.LayoutArea to the GetContentBounds() rectangle inflated by some margin area before each Arrange call.

I hope that helps,
Stoyan