How do I treat a re-link as a link delete and add

GoDiagram (6 and previous)
1

I’m trying to keep all my node and link change handling in one location, in View.OnDocumentchanged. Works great for node creation/deleation and link creation/deleation, using:

e.Hint == GoLayer.RemovedObject
e.Hint == GoLayer.InsertedObject
I also want to treat re-linking as a link deleate and link add. I've tried using:
e.Hint == GoDocument.ChangedObject
e.SubHint == GoLink.ChangedFromPort
e.SubHint == GoLink.ChangedToPort
e.SubHint == GoPort.ChangedRemovedLink
e.SubHint == GoPort.ChangedAddedLink
When a link is detached the following events are fired:
(SubHint)
ChangedRemovedLink
ChangedToPort
ChangedRemovedLink
ChangedFromPort
When attached to some other port the following events are fired:
ChangedAddedLink
ChangedFromPort
ChangedAddedLink
ChangedToPort
Convoluted but still workable. However, when links are deleted the following event is fired
ChangedRemovedLink
and ChangedAddedLink is fired when a link is drawn. Making it difficult to distingwish between link creation/deleation and re-linking.
I guess I could switch my link creation detection from GoLayer.InsertedObject to GoLayer.ChangedObject/GoPort.ChangedAddedLink, with a flag to fire the link creation once (since I get two ChangedAddedLink events).
But I can help think I'm going about this all wrong and that there is some simpler way of doing this?
Any help would be appreciated.
Thank You
Jack
2

GoView has both LinkCreated and LinkRelinked Events… perhaps you could use those.

3
On a LinkRelinked Event, how do I figure out what node the link was previously connected to (i.e. the node that lost the link in the re-linking operation).
Thank You
Jack
4

That GoView event doesn’t pass the old port information along. But I don’t think you need to use that event anyway.

You’re just seeking why some document change occurred, right? So that you can discriminate between changes with the same Hint and SubHint?

At the time that you are looking at GoDocument.Changed events you can just look at the GoView.Tool. In your case you can check to see if it is an instance of GoToolRelinking.