TreeViewControl.DragRecordOver Event

Occurs continuously while a drag-and-drop operation is in progress.

Assembly : DevExpress.Xpf.Grid.v25.2.dll

NuGet Package : DevExpress.Wpf.Grid.Core

Declaration

C#
VB.NET

csharp

public event EventHandler<DragRecordOverEventArgs> DragRecordOver

Public Event DragRecordOver As EventHandler(Of DragRecordOverEventArgs)

Event Data

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

Property	Description
AllowedEffects	Gets a member of the DragDropEffects enumeration that specifies which operations are allowed by the originator of the drag event. Inherited from DragEventArgsBase.
Data	Gets or sets a data object that contains the data associated with the corresponding drag event. Inherited from DragEventArgsBase.
DropPosition	Gets a drop position that specifies how a record is placed after it has been dropped. Inherited from DragEventArgsBase.
DropPositionRelativeCoefficient	Gets a number between 0 and 1, presenting a drop position relative to the target record.
Effects	Gets or sets the target drag-and-drop operation. Inherited from DragEventArgsBase.
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.
IsFromOutside	Gets whether the dragged record is from another control. Inherited from DragEventArgsBase.
KeyStates	Gets a flag enumeration indicating the current state of the SHIFT, CTRL, and ALT keys, as well as the state of the mouse buttons. Inherited from DragEventArgsBase.
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.
TargetRecord	Gets a record that is drop target. Inherited from DragEventArgsBase.
TargetRowHandle	Gets the target row handle. Inherited from DragEventArgsBase.

The event data class exposes the following methods:

Method	Description
GetRecordType()	Gets the Type of the transferred records. Inherited from DragEventArgsBase.
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 following code sample does not allow users to drop records to the root level.

XAML

xaml

<dxg:TreeViewControl x:Name="treeview"
                     AllowDragDrop="True"
                     DragRecordOver="treeview_DragRecordOver"/>

C#
VB.NET

csharp

void treeview_DragRecordOver(object sender, DevExpress.Xpf.Core.DragRecordOverEventArgs e) {
    TreeListNode node = treeview.GetNodeByRowHandle(e.TargetRowHandle);
    if (node != null && node.Level == 0) {
        e.Effects = DragDropEffects.None;
        e.Handled = true;
    }
}

Private Sub treeview_DragRecordOver(ByVal sender As Object, ByVal e As DevExpress.Xpf.Core.DragRecordOverEventArgs)
    Dim node As TreeListNode = treeview.GetNodeByRowHandle(e.TargetRowHandle)

    If node IsNot Nothing AndAlso node.Level = 0 Then
        e.Effects = DragDropEffects.None
        e.Handled = True
    End If
End Sub

For information about drag-and-drop operations, refer to the following DevExpress WPF Grid help topic: Drag-and-Drop.