I'm having a strange issue with one of my Diagrams while upgrading from 3.5 to 4.1.

When I delete a node (either programmatically or with the delete key), the node doesn't actually disappear. If I do another operation, such as move another node, resize the window, zoom in/out, then the drawing updates and the node disappears.  My Diagram uses mainly TemplatedNodes and a few ShapeNodes. The ShapeNodes disappear when deleted, but not the TemplatedNodes.  Any attached Links do disappear.
I have another Diagram in my app, and the TemplatedNodes on that Diagram disappear with no problems. The two Diagrams use completely different templates for the nodes.

Do you have any suggestions on what I should dig into to figure out why just this one Diagram doesn't redraw?  Calling InvalidateVisual() on both the Diagram or the DiagramView doesn't do anything. The TemplatedNode is actually gone from the Diagram's Nodes collection, so there's nothing to call Repaint() on. My Diagram is inside a DiagramView.

Cheers.

I figured out my problem based on your advice.

I see that in VirtualizeItems(), the InternalChildren collection is where the node should be removed.  But what's happening is that in my NodeDeleted event handler I'm running some code that causes a completely different UserControl to run its own MeasureOverride() code, and perhaps because that UserControl is beside the Diagram, it's causing the Diagram's MeasureOverride() function to also run right away.  So then only after the Diagram's MeasureOverride() function runs is when OnRemove() in DiagramItem gets to run, and "standalone" is set to true.  Then finally InvalidateMeasure is called on the Diagram, but I think that since it was already run accidentally by my event handler, WPF decides it doesn't need to be remeasured, and therefore VirtualizeItems() doesn't run again, and the node never gets removed from InternalChildren.

My solution is to delay the MeasureOverride() on my other UserControl, so that I can make sure the Diagram's MeasureOverride() runs at the correct time.

Thanks!

I'm calling UpdateLayout() from the code-behind of my UserControl.  UpdateLayout() is inherited from UIElement.  Again, this UserControl does not contain the Diagram; it simply sits next to another UserControl that contains the Diagram.

When a node is deleted from the Diagram, my NodeDeleted event handler calls into my viewmodel to remove an element from an ObservableCollection.  And then the non-Diagram UserControl reacts to the collection being changed, and that's where UpdateLayout() is called.

Cheers,
Joel.

Yes, that works now!

Do you have a schedule for the next small release?