DragDropEvents Class

Provides access to a control’s Drag-and-Drop Behavior events.

Namespace: DevExpress.Utils.DragDrop

Assembly: DevExpress.Utils.v19.2.dll

Declaration

C#

public sealed class DragDropEvents :
    Component

VB.NET

Public NotInheritable Class DragDropEvents
    Inherits Component

Related API Members

The following members return DragDropEvents objects:

• DragDropBehaviorProperties.Events

Remarks

The DragDropEvents component is automatically added to your form when you attach the Drag-and-Drop Behavior to a control in the designer. You can find the component’s name in the Behavior editor’s Properties section.

You can add event handlers in the designer or in code.

C#

dragDropEvents1.DragDrop += dragDropEvents1_DragDrop;
dragDropEvents1.DragOver += dragDropEvents1_DragOver;

VB.NET

AddHandler dragDropEvents1.DragDrop, AddressOf dragDropEvents1_DragDrop
AddHandler dragDropEvents1.DragOver, AddressOf dragDropEvents1_DragOver

If you attach the Behavior in code, the DragDropEvents component is not added to the form. Use the DragDropBehavior events to customize drag-and-drop operations in this case.

Example

The Drag-and-Drop Behavior allows you to support drag-and-drop operations between detail views in a grid control.

To allow users to move child rows between detail views, do the following:

• Attach the Behavior to the master view in the Visual Studio Designer or in code.
• Use the ViewRegistered event — to attach the Behavior to the detail view. To detach the Behavior, use the ViewRemoved event.
• Handle the DragDrop event of the Behavior attached to the master view — to move the processed child row from the source detail view to the target detail view.

The code below shows how to implement this approach. It is assumed the behavior Manager is placed to the component tray and the Behavior Manager is attached to the main view in the Visual Studio Designer.

C#

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

gridView1.OptionsBehavior.Editable = false;
gridView1.OptionsSelection.MultiSelect = true;
gridControl1.DataSource = CreateDataTable();
gridControl1.ViewRegistered += GridControl1_ViewRegistered;

private void dragDropEvents1_DragDrop(object sender, DragDropEventArgs e) {
    GridView masterView = e.Source as GridView;
    // Cast the event arguments to the DragDropGridEventArgs type
    // or call the static (Shared in VB) DragDropGridEventArgs.GetDragDropGridEventArgs method
    // to get grid-specific event arguments.
    DragDropGridEventArgs realArgs = (DragDropGridEventArgs)e;
    GridView sourceView = realArgs.Source as GridView;
    GridView targetView = realArgs.Target as GridView;

    var view1 = gridControl1.GetViewAt(gridControl1.PointToClient(e.Location));
    if(sourceView != null && targetView != null) {
        // Get the processed child row's parent ID.
        var newParentId = masterView.GetRowCellValue(targetView.SourceRowHandle, "Id");
        foreach(DataRowView dataRow in realArgs.DataRows) {
            // Update the processed child row's parent ID.
            dataRow.Row["ParentId"] = newParentId;
        }
        e.Handled = true;
    }
}

private void GridControl1_ViewRegistered(object sender, DevExpress.XtraGrid.ViewOperationEventArgs e) {
    if(e.View.IsDetailView) {
        // It is assumed that the Behavior Manager is placed
        // to the component tray in the Visual Studio Designer.
        behaviorManager1.Attach<DragDropBehavior>(e.View);
    }
}

public DataTable CreateDataTable() {
    masterTable = new DataTable();
    masterTable.Columns.Add("Id", typeof(int));
    masterTable.Columns.Add("Name");
    masterTable.Columns.Add("IsActive", typeof(bool));
    masterTable.Columns.Add("OrderCount", typeof(int));
    masterTable.Columns.Add("RegistrationDate", typeof(DateTime));

    for(int i = 0; i < 10; i++) {
        masterTable.Rows.Add(i, "Name" + i, i % 2 == 0, i * 10, DateTime.Now.AddDays(i));
    }

    DataTable childTable = new DataTable();
    childTable.Columns.Add("ParentId", typeof(int));
    childTable.Columns.Add("Id", typeof(int));
    childTable.Columns.Add("Name");

    for(int i = 0; i < 20; i++) {
        childTable.Rows.Add(i % 10, i, "Name" + i);
    }

    DataSet set = new DataSet();
    set.Tables.Add(masterTable);
    set.Tables.Add(childTable);
    set.Relations.Add(masterTable.Columns["Id"], childTable.Columns["ParentId"]);

    return masterTable;
}

VB.NET

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

gridView1.OptionsBehavior.Editable = False
gridView1.OptionsSelection.MultiSelect = True
gridControl1.DataSource = CreateDataTable()
AddHandler gridControl1.ViewRegistered, AddressOf GridControl1_ViewRegistered

Private Sub dragDropEvents1_DragDrop(ByVal sender As Object, ByVal e As DragDropEventArgs) Handles dragDropEvents1.DragDrop
    ' Cast the event arguments to the DragDropGridEventArgs type
    ' or call the static (Shared in VB) DragDropGridEventArgs.GetDragDropGridEventArgs method
    ' to get grid-specific event arguments.
    Dim masterView As GridView = TryCast(e.Source, GridView)
    Dim realArgs As DragDropGridEventArgs = CType(e, DragDropGridEventArgs)
    Dim sourceView As GridView = TryCast(realArgs.Source, GridView)
    Dim targetView As GridView = TryCast(realArgs.Target, GridView)

    Dim view1 = gridControl1.GetViewAt(gridControl1.PointToClient(e.Location))
    If sourceView IsNot Nothing AndAlso targetView IsNot Nothing Then
        ' Get the processed child row's parent ID.
        Dim newParentId = masterView.GetRowCellValue(targetView.SourceRowHandle, "Id")
        For Each dataRow As DataRowView In realArgs.DataRows
            ' Update the processed child row's parent ID.
            dataRow.Row("ParentId") = newParentId
        Next dataRow
        e.Handled = True
    End If
End Sub

Private Sub GridControl1_ViewRegistered(ByVal sender As Object, ByVal e As DevExpress.XtraGrid.ViewOperationEventArgs)
    If e.View.IsDetailView Then
        ' It is assumed that the Behavior Manager is placed
        ' to the component tray in the Visual Studio Designer.
        behaviorManager1.Attach(Of DragDropBehavior)(e.View)
    End If
End Sub

Public Function CreateDataTable() As DataTable
    masterTable = New DataTable()
    masterTable.Columns.Add("Id", GetType(Integer))
    masterTable.Columns.Add("Name")
    masterTable.Columns.Add("IsActive", GetType(Boolean))
    masterTable.Columns.Add("OrderCount", GetType(Integer))
    masterTable.Columns.Add("RegistrationDate", GetType(Date))
    For i As Integer = 0 To 9
        masterTable.Rows.Add(i, "Name" & i, i Mod 2 = 0, i * 10, Date.Now.AddDays(i))
    Next i

    Dim childTable As New DataTable()
    childTable.Columns.Add("ParentId", GetType(Integer))
    childTable.Columns.Add("Id", GetType(Integer))
    childTable.Columns.Add("Name")

    For i As Integer = 0 To 19
        childTable.Rows.Add(i Mod 10, i, "Name" & i)
    Next i

    Dim dataSet As New DataSet()
    dataSet.Tables.Add(masterTable)
    dataSet.Tables.Add(childTable)
    dataSet.Relations.Add(masterTable.Columns("Id"), childTable.Columns("ParentId"))

    Return masterTable
End Function

Inheritance

Object

MarshalByRefObject

Component

DragDropEvents