Applies to: Nevron Diagram for .NET
How to make the port of a shape to only accept one connection?
To make the port of a shape to only accept one connection, you can limit the number of plugs that the port will allow. The diagram will raise the Connecting event of the document event sink service, whenever a port is connected to a plug. Cancelling this event will effectively prohibit the connection.
For example, the following code will allow only one connection to the top port of the shape:
[C#]
…
document.EventSinkService.Connecting += new ConnectionCancelEventHandler(OnConnecting);
…
void OnConnecting(NConnectionCancelEventArgs args)
{
// get the port in the connection
NPort port = document.GetElementFromUniqueId(args.UniqueId1) as NPort;
if (port == null)
{
port = document.GetElementFromUniqueId(args.UniqueId2) as NPort;
if (port == null)
return;
}
// typically the top port has the "Top" name
if (port.Name != "Top")
return;
// if the port is already connected to at least one plug -> cancel the connection
if (port.Plugs.Count < 1)
return;
args.Cancel = true;
return;
}
[VB.NET]
…
AddHandler document.EventSinkService.Connecting, AddressOf OnConnecting
…
Private Sub OnConnecting(args As NConnectionCancelEventArgs)
' get the port in the connection
Dim port As NPort = TryCast(document.GetElementFromUniqueId(args.UniqueId1), NPort)
If port Is Nothing Then
port = TryCast(document.GetElementFromUniqueId(args.UniqueId2), NPort)
If port Is Nothing Then
Return
End If
End If
' typically the top port has the “Top” name
If port.Name <> Top Then
Return
End If
' if the port is already connected to at least one plug -> cancel the connection
If port.Plugs.Count < 1 Then
Return
End If
args.Cancel = True
Return
End Sub
Article ID: 23, Created On: 9/29/2010, Modified: 5/5/2011