How to restrict duplicate connection entries of a node when undoing the delete action in WinForms Diagram?

In the WinForms Diagram control, you can restrict duplicate connection entries of a node when undoing the delete action by handling the NodeCollectionChanging event. In this event, ensure that connections are correctly re-established using the Connect method.

The changes mentioned below ensure that connectors are properly managed when a node is removed, thereby preventing any duplication issues upon undoing the delete action. We have provided the code example for how to achieve this.

Code Snippet :

private void EventSink_NodeCollectionChanging(CollectionExEventArgs evtArgs)
{
   if (rbHealWhenChanging.Checked)
   {
       // Heal Connection when a node is removed

       if (evtArgs.ChangeType == CollectionExChangeType.Remove && evtArgs.Elements.Count == 1 && healCB.Checked)
       {
           var deleteNode = evtArgs.Element as Node;
           var edgesEntering = (deleteNode.EdgesEntering as ArrayList).ToArray();
           var edgesLeaving = (deleteNode.EdgesLeaving as ArrayList).ToArray();

           // Disconnecting the existing connection with the history manager is in a paused state,
           // as this data has already been documented internally by the history manager.

           diagram1.Model.HistoryManager.Pause();
           deleteNode.CentralPort.DisconnectAll();
           diagram1.Model.HistoryManager.Resume();

           if (edgesLeaving.Count() == 1)
           {
               var outConnector = edgesLeaving.First() as ConnectorBase;
               if (outConnector != null)
               {
                   // Saving the to-node of the out-connector and deleting the out-connector from the diagram.
                  var leavingEdgeToNode = outConnector.ToNode as Node;
                   diagram1.Model.Nodes.Remove(outConnector);
                   if (leavingEdgeToNode != null && edgesEntering.Count() > 0)
                   {
                       // Linking the in-connectors to the new to-node.
                       foreach (var inEdge in edgesEntering)
                       {
                           if (inEdge is ConnectorBase)
                           {
                               leavingEdgeToNode.CentralPort.Connect((inEdge as ConnectorBase).HeadEndPoint);
                           }
                       }
                   }
               }
           }

           else if (edgesEntering.Count() == 1)
           {
               var inConnector = edgesEntering.First() as ConnectorBase;
               if (inConnector != null)
               {
                   // Saving the from-node of the in-connector and deleting the in-connector from the diagram.
                   var enteringEdgeFromNode = inConnector.FromNode as Node;
                   diagram1.Model.Nodes.Remove(inConnector);
                   if (enteringEdgeFromNode != null && edgesLeaving.Count() > 0)
                   {
                       // Linking the out-connectors to the new from-node.

                       foreach (var outEdge in edgesLeaving)
                       {
                           if (outEdge is ConnectorBase)
                           {
                               enteringEdgeFromNode.CentralPort.Connect((outEdge as ConnectorBase).TailEndPoint);
                           }
                       }
                   }
               }
           }
       }
   }
} 

Conclusion:

I hope you enjoyed learning about How to restrict duplicate connection entries in a node when undoing the delete action in WinForms Diagram

You can refer to our WinForms Diagram feature tour page to learn about its other groundbreaking feature representations. You can also explore our WinForms Diagram documentation to understand how to create and manipulate data.

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