DragDropEvents.DragOver Event

Occurs when a data element is dragged over the control’s bounds.

Namespace: DevExpress.Utils.DragDrop

Assembly: DevExpress.Utils.v23.2.dll

NuGet Packages: DevExpress.Utils, DevExpress.Wpf.Core

Declaration

C#

[DXCategory("DragDrop")]
public event DragOverEventHandler DragOver

VB.NET

<DXCategory("DragDrop")>
Public Event DragOver As DragOverEventHandler

Event Data

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

Property	Description
Action	Gets or sets the drag-and-drop action (Copy, Move, etc.) to perform. Inherited from DXDragEventArgs.
Cursor	Gets or sets the mouse pointer. Inherited from DXDragEventArgs.
Data	Gets or sets the data elements being dragged. Inherited from DXDragEventArgs.
Handled	Gets or sets whether the event was handled and allows you to suppress the default action. Inherited from DXDefaultEventArgs.
InsertIndicator	Gets or sets an image that represents the insert indicator.
InsertIndicatorLocation	Gets or sets the location of the default insert indicator.
InsertIndicatorSize	Gets or sets the size of the default insert indicator.
InsertType	Gets or sets whether dragged data elements are inserted before or after a data element under the mouse pointer, or as a child (for tree list only). Inherited from DragOverEventArgsBase.
KeyState	Gets the pressed mouse buttons (left, middle, right) and modifier keys (Shift, Ctrl, Alt). Inherited from DXDragEventArgs.
Location	Gets the mouse cursor’s position. Inherited from DXDragEventArgs.
Source	Gets the source control. Inherited from DXDragEventArgs.
Tag	Gets or sets custom data associated with the drag-and-drop operation. Inherited from DragOverEventArgsBase.
Target	Gets the target control. Inherited from DXDragEventArgs.

The event data class exposes the following methods:

Method	Description
Default()	Invokes the default action the attached control performs on the current drag-and-drop operation stage. Inherited from DXDefaultEventArgs.
GetData<T>()	Returns the data elements being dragged. Inherited from DXDragEventArgs.

Examples

The example below shows how to cancel an operation if Ctrl is not pressed.

C#

using DevExpress.Utils.DragDrop;

//The operation is only allowed when Ctrl is pressed.
private void dragDropEvents1_DragOver(object sender, DragOverEventArgs e) {
    e.Default();
    if (e.KeyState.HasFlag(DragDropKeyState.Control)) {
        e.Cursor = Cursors.Arrow;
        e.Action = DevExpress.Utils.DragDrop.DragDropActions.Copy;
    } else {
        e.Cursor = Cursors.No;
        e.Action = DragDropActions.None;
    }
}

VB.NET

Imports DevExpress.Utils.DragDrop

'The operation is only allowed when Ctrl is pressed.
Private Sub dragDropEvents1_DragOver(ByVal sender As Object, ByVal e As DevExpress.Utils.DragDrop.DragOverEventArgs) _
    Handles dragDropEvents1.DragOver
    e.Default()
    If e.KeyState.HasFlag(DragDropKeyState.Control) Then
        e.Cursor = Cursors.Arrow
        e.Action = DevExpress.Utils.DragDrop.DragDropActions.Copy
    Else
        e.Cursor = Cursors.No
        e.Action = DragDropActions.None
    End If
End Sub

Note

When you handle the DragOver event for a grid view, use the static (Shared in VB) DragOverGridEventArgs.GetDragOverGridEventArgs method to calculate arguments specific to the grid view.

C#

using DevExpress.Utils.DragDrop;
using DevExpress.XtraGrid.Views.Grid;

dragDropEvents1.DragOver += Behavior_DragOver;

private void Behavior_DragOver(object sender, DragOverEventArgs e) {
   DragOverGridEventArgs args = DragOverGridEventArgs.GetDragOverGridEventArgs(e);
   //You can also cast DragOverEventArgs to DragOverGridEventArgs.
   //DragOverGridEventArgs args = (DragOverGridEventArgs)e;
}

VB.NET

Imports DevExpress.Utils.DragDrop
Imports DevExpress.XtraGrid.Views.Grid

AddHandler dragDropEvents1.DragOver, AddressOf Behavior_DragOver

Private Sub Behavior_DragOver(ByVal sender As Object, ByVal e As DragOverEventArgs)
   Dim args As DragOverGridEventArgs = DragOverGridEventArgs.GetDragOverGridEventArgs(e)
   'You can also cast DragOverEventArgs to DragOverGridEventArgs.
   'Dim args As DragOverGridEventArgs = CType(e, DragOverGridEventArgs)
End Sub

Note

Run the XtraTreeList or XtraGrid demo and click Open Solution for more examples.

The code below shows how to prohibit the user to drag an item to the tree list’s third level or lower. The example uses the CalcHitInfo(Point) method to get the tree list’s visual element under the mouse pointer. To determine the hierarchy level at which a particular node resides, use the Level property.

C#

using DevExpress.Utils.DragDrop;
using DevExpress.XtraTreeList;

private void dragDropEvents1_DragOver(object sender, DevExpress.Utils.DragDrop.DragOverEventArgs e) {
    TreeList treeList = e.Target as TreeList;
    var hitInfo = treeList.CalcHitInfo(treeList.PointToClient(e.Location));
    var treeListNode = hitInfo.Node;
    if (treeListNode.Level >= 3) {
        e.Default();
        e.Action = DragDropActions.None;
    }
}

VB.NET

Imports DevExpress.Utils.DragDrop
Imports DevExpress.XtraTreeList

Private Sub dragDropEvents1_DragOver(ByVal sender As Object, ByVal e As DevExpress.Utils.DragDrop.DragOverEventArgs) _
    Handles dragDropEvents1.DragOver
    Dim treeList As TreeList = TryCast(e.Target, TreeList)
    Dim hitInfo = treeList.CalcHitInfo(treeList.PointToClient(e.Location))
    Dim treeListNode = hitInfo.Node
    If treeListNode.Level >= 3 Then
        e.Default()
        e.Action = DragDropActions.None
    End If
End Sub