TreeList.BeforeDropNode Event
Fires when a node is about to be dropped, and allows you to cancel the operation.
Namespace: DevExpress.XtraTreeList
Assembly: DevExpress.XtraTreeList.v21.2.dll
NuGet Packages: DevExpress.Win.Design, DevExpress.Win.TreeList
Declaration
Event Data
The BeforeDropNode event's data class is DevExpress.XtraTreeList.BeforeDropNodeEventArgs.
Remarks
TreeList control nodes can be moved using drag-and-drop operations if the TreeListOptionsDragAndDrop.DragNodesMode option (accessible through the TreeList.OptionsBehavior property) is set to Single or Multiple.
The BeforeDropNode event fires when a node is about to be dropped, and allows you to cancel the operation. The BeforeDropNodeEventArgs.SourceNode property allows you to determine the node being processed. To get the destination parent node, read the DestinationNode property.
Unlike the TreeList.BeforeDragNode event, which allows you to cancel a drag-and-drop operation when it starts, the BeforeDropNode event allows you to cancel the operation when the node being dragged is about to be dropped. The code snippet below shows how to prohibit dropping nodes onto parent nodes that correspond to a particular condition.
private void treeList1_BeforeDropNode(object sender, DevExpress.XtraTreeList.BeforeDropNodeEventArgs e){
if (e.DestinationNode.HasChildren == false) e.Cancel = true;
}
After the BeforeDropNode event is fired, the TreeList.AfterDropNode event fires.