Hi Mat,

Preventing a user from dropping a node into a container:

private void diagram_NodeModifying(object sender, MindFusion.Diagramming.NodeValidationEventArgs e)
{
	if (diagram.GetNodeAt(e.MousePosition, true, true) is ContainerNode)
		e.Cancel = true;
}
 

Setting e.Cancel = true should automatically move the node back to its original position and container.

If you derive from ContainerNode, you could do something similar by returning false from OnDragOver and OnDragDrop.

To prevent a node from being dragged out of a container:

childNode.Constraints.KeepInsideParent = true;
 

I hope that helps,
Stoyan

Hi.

Thx for your code "(based on Stoyo's) prevents the creation of nested ContainerNode's"...

If you are dragging container "A" into container "B" this code is ok only if drop is permormed directly over container "B". If in "B" is any shape and drop is performed over it --> it doesnt work.

So I guess I should to use "GetNodesAt" function instead of "GetNodeAt" and iterate DiagramNodeCollection object which is returned by this function.

My two solutions:
1) - handling NodeModifying event

 Private Sub fcDiagram_NodeModifying(ByVal sender As Object, ByVal e As MindFusion.Diagramming.NodeValidationEventArgs) Handles fcDiagram.NodeModifying
'preventing nesting of containers
   Select Case e.Node.GetType.Name
      Case "ClsMMContainerNode"
         Dim LoDiagramNodeCollection As DiagramNodeCollection = Me.fcDiagram.GetNodesAt(e.MousePosition)

         For Each LoNode As DiagramNode In LoDiagramNodeCollection
            If (LoNode.GetType.Name = "ClsMMContainerNode") And (Not LoNode.Equals(e.Node)) Then 'prevention of selfchecking
               e.Cancel = True
               Exit For
            End If
         Next
   End Select
End sub
 

2) - deriving from ContainerNode

'overrided sub - when a diagram item is being dragged over this node
    Public Overrides Function OnDragOver(ByVal item As MindFusion.Diagramming.DiagramItem) As Boolean
        If item.GetType.Name = "ClsMMContainerNode" Then
            Return False
        Else
            Return MyBase.OnDragOver(item)
        End If
    End Function
'overrided sub - when a diagram item is dropped over this node
    Public Overrides Function OnDropOver(ByVal item As MindFusion.Diagramming.DiagramItem) As Boolean
        If item.GetType.Name = "ClsMMContainerNode" Then
            Return False
        Else
            Return MyBase.OnDropOver(item)
        End If
    End Function
 

In first case there is presented also "feature" - Setting e.Cancel = true should automatically move the node back to its original position and container.

In second case node is not returned back to original position.

It seems MyBase.OnDropOver performs any other operations because if I return true instead of MyBase.OnDropOver nothing is happen.

Any comment guys? Any suggestion for improoving procedure "Cancel dropping nodes in containers"?

Thx.

...MUDO...

Hi,

I have overrided the OnDropOver method in my derived ContainerNode class.
As you've mentionned in this thread, I'm using the
Parent.Interaction.Cancel(Parent); to cancel the operation and get the node back to its original position.

This is working perfectly if one node is selected and dropped. But if multiple nodes are selected and dropped, cancelling the operation does not move the nodes back to their original position. The nodes stay at the dropping position.

Is there a way to have all selected nodes back to their original position when the operation is cancelled?

Thanks in advance.

Isabelle.