DiagramControl.QueryConnectionPoints Event

Fires each time the end-user moves the cursor with the active Connector Tool near shapes or their connection points.

Namespace: DevExpress.Xpf.Diagram

Assembly: DevExpress.Xpf.Diagram.v24.2.dll

NuGet Package: DevExpress.Wpf.Diagram

Declaration

C#

public event EventHandler<DiagramQueryConnectionPointsEventArgs> QueryConnectionPoints

VB.NET

Public Event QueryConnectionPoints As EventHandler(Of DiagramQueryConnectionPointsEventArgs)

Event Data

The QueryConnectionPoints event's data class is DiagramQueryConnectionPointsEventArgs. The following properties provide information specific to this event:

Property	Description
Connector	Returns the connector whose point is being moved by the end-user.
ConnectorPointType	Returns the type of the connection point that is being moved by the end-user.
Handled	Gets or sets a value that indicates the present state of the event handling for a routed event as it travels the route. Inherited from RoutedEventArgs.
HoveredItem	Returns the item hovered with the connection point that is being moved by the end-user.
ItemConnectionBorderState	Specifies whether to enable connection to an item and show a visual indication.
ItemConnectionPointStates	Provides access to the collection of objects that represent connection points of a diagram item.
OppositeItem	Returns the diagram item to which the opposite connection point is glued.
OppositeItemPointIndex	Returns the index of the opposite connection point.
OppositePoint	Returns the coordinates of the opposite connection point.
OriginalSource	Gets the original reporting source as determined by pure hit testing, before any possible Source adjustment by a parent class. Inherited from RoutedEventArgs.
RoutedEvent	Gets or sets the RoutedEvent associated with this RoutedEventArgs instance. Inherited from RoutedEventArgs.
Source	Gets or sets a reference to the object that raised the event. Inherited from RoutedEventArgs.

The event data class exposes the following methods:

Method	Description
InvokeEventHandler(Delegate, Object)	When overridden in a derived class, provides a way to invoke event handlers in a type-specific way, which can increase efficiency over the base implementation. Inherited from RoutedEventArgs.
OnSetSource(Object)	When overridden in a derived class, provides a notification callback entry point whenever the value of the Source property of an instance changes. Inherited from RoutedEventArgs.

Remarks

The example below illustrates how to prevent the end-user from attaching connectors to a shape.

C#

void diagram_QueryConnectionPoints(object sender, DiagramQueryConnectionPointsEventArgs e) {
    if ((e.HoveredItem as DiagramShape).Content == "Connection is not allowed") {
        e.ItemConnectionBorderState = ConnectionElementState.Hidden;
        foreach (var p in e.ItemConnectionPointStates)
            p.State = ConnectionElementState.Hidden;
    }
}

VB.NET

Private Sub diagram_QueryConnectionPoints(ByVal sender As Object, ByVal e As DiagramQueryConnectionPointsEventArgs)
    If (TryCast(e.HoveredItem, DiagramShape)).Content = "Connection is not allowed" Then
        e.ItemConnectionBorderState = ConnectionElementState.Hidden
        For Each p In e.ItemConnectionPointStates
            p.State = ConnectionElementState.Hidden
        Next p
    End If
End Sub