TreeViewControl.StartRecordDrag Event
Occurs when a drag-and-drop operation is started.
Namespace: DevExpress.Xpf.Grid
Assembly: DevExpress.Xpf.Grid.v24.1.dll
NuGet Package: DevExpress.Wpf.Grid.Core
Declaration
Event Data
The StartRecordDrag event's data class is StartRecordDragEventArgs. The following properties provide information specific to this event:
Property | Description |
---|---|
AllowDrag | Gets or sets whether an end-user can drag records. |
AllowedEffects | Gets a member of the DragDropEffects enumeration that specifies which operations are allowed by the originator of the drag event. |
Data | Gets or sets a data object that contains the data associated with the DataViewBase.StartRecordDrag event. |
DragElement | Gets a drag element that is a control on which the drag-and-drop operation has been initiated. |
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. |
OriginalSource | Gets the original reporting source as determined by pure hit testing, before any possible Source adjustment by a parent class. Inherited from RoutedEventArgs. |
Records | Gets dragged records. |
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
You can use the StartRecordDrag event to cancel a drag operation.
The following code sample allows users to drag only records that do not have children:
<dxg:TreeViewControl x:Name="treeview"
AllowDragDrop="True"
StartRecordDrag="treeview_StartRecordDrag"/>
void treeview_StartRecordDrag(object sender, DevExpress.Xpf.Core.StartRecordDragEventArgs e) {
foreach (Employee employee in e.Records)
e.AllowDrag = !treeview.GetNodeByValue(employee.Name).HasChildren;
e.Handled = true;
}
For information about drag-and-drop operations, refer to the following DevExpress WPF Grid help topic: Drag-and-Drop.
See Also