How to: Manually Control Drag-and-Drop

• Apr 15, 2018
• 7 minutes to read

This example demonstrates how to customize Drag-and-Drop functionality in the GridControl using Drag-and-Drop Events.

A drag-and-drop operation changes the Position and Department values depending on the location of a dropped record.

Note

A complete sample project is available at https://github.com/DevExpress-Examples/how-to-manually-control-drag-and-drop-in-the-gridcontrol-e3921.

MainWindow.xaml.cs

using System.Collections.ObjectModel;
using System.Windows;
using DevExpress.Xpf.Core;

namespace WPF_GridControl_Custom_Drag_and_Drop {
    public partial class MainWindow : Window  {
        public class Employee {
            public int ID { get; set; }
            public int ParentID { get; set; }
            public string Name { get; set; }
            public string Position { get; set; }
            public string Department { get; set; }
            public override string ToString() {
                return Name;
            }
        }

        public static class Stuff {
            public static ObservableCollection<Employee> GetStuff() {
                ObservableCollection<Employee> stuff = new ObservableCollection<Employee>();
                stuff.Add(new Employee() { ID = 1, ParentID = 0, Name = "Gregory S. Price", Department = "", Position = "President" });
                stuff.Add(new Employee() { ID = 2, ParentID = 1, Name = "Irma R. Marshall", Department = "Marketing", Position = "Vice President" });
                stuff.Add(new Employee() { ID = 3, ParentID = 1, Name = "John C. Powell", Department = "Operations", Position = "Vice President" });
                stuff.Add(new Employee() { ID = 4, ParentID = 1, Name = "Christian P. Laclair", Department = "Production", Position = "Vice President" });
                stuff.Add(new Employee() { ID = 5, ParentID = 1, Name = "Karen J. Kelly", Department = "Finance", Position = "Vice President" });

                stuff.Add(new Employee() { ID = 6, ParentID = 2, Name = "Brian C. Cowling", Department = "Marketing", Position = "Manager" });
                stuff.Add(new Employee() { ID = 7, ParentID = 2, Name = "Thomas C. Dawson", Department = "Marketing", Position = "Manager" });
                stuff.Add(new Employee() { ID = 8, ParentID = 2, Name = "Angel M. Wilson", Department = "Marketing", Position = "Manager" });
                stuff.Add(new Employee() { ID = 9, ParentID = 2, Name = "Bryan R. Henderson", Department = "Marketing", Position = "Manager" });

                stuff.Add(new Employee() { ID = 10, ParentID = 3, Name = "Harold S. Brandes", Department = "Operations", Position = "Manager" });
                stuff.Add(new Employee() { ID = 11, ParentID = 3, Name = "Michael S. Blevins", Department = "Operations", Position = "Manager" });
                stuff.Add(new Employee() { ID = 12, ParentID = 3, Name = "Jan K. Sisk", Department = "Operations", Position = "Manager" });
                stuff.Add(new Employee() { ID = 13, ParentID = 3, Name = "Sidney L. Holder", Department = "Operations", Position = "Manager" });

                stuff.Add(new Employee() { ID = 14, ParentID = 4, Name = "James L. Kelsey", Department = "Production", Position = "Manager" });
                stuff.Add(new Employee() { ID = 15, ParentID = 4, Name = "Howard M. Carpenter", Department = "Production", Position = "Manager" });
                stuff.Add(new Employee() { ID = 16, ParentID = 4, Name = "Jennifer T. Tapia", Department = "Production", Position = "Manager" });

                stuff.Add(new Employee() { ID = 17, ParentID = 5, Name = "Judith P. Underhill", Department = "Finance", Position = "Manager" });
                stuff.Add(new Employee() { ID = 18, ParentID = 5, Name = "Russell E. Belton", Department = "Finance", Position = "Manager" });
                return stuff;
            }
        }
        public MainWindow() {
            InitializeComponent();
            treeList.ItemsSource = Stuff.GetStuff();
        }

        void OnDropRecord(object sender, DropRecordEventArgs e) {
            object data = e.Data.GetData(typeof(RecordDragDropData));

            foreach (Employee employee in ((RecordDragDropData)data).Records) {
                employee.Position = ((Employee)e.TargetRecord).Position;
                employee.Department = ((Employee)e.TargetRecord).Department;
            }

            if (e.DropPosition == DropPosition.Inside) {
                foreach(Employee employee in ((RecordDragDropData)data).Records) {
                    employee.Position = "";
                }
            }
        }
    }
}

MainWindow.xaml

<Window x:Class="WPF_GridControl_Custom_Drag_and_Drop.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:dx="http://schemas.devexpress.com/winfx/2008/xaml/core" 
        xmlns:dxc="http://schemas.devexpress.com/winfx/2008/xaml/core" 
        xmlns:dxg="http://schemas.devexpress.com/winfx/2008/xaml/grid"
        xmlns:dxmvvm="http://schemas.devexpress.com/winfx/2008/xaml/mvvm"
        Height="350" Width="525">
    <Grid>
        <dxg:GridControl Name="treeList" SelectionMode="Row">
            <dxg:GridControl.Columns>
                <dxg:GridColumn FieldName="Name" ReadOnly="True"/>
                <dxg:GridColumn FieldName="Department" ReadOnly="True"/>
                <dxg:GridColumn FieldName="Position" ReadOnly="True"/>
            </dxg:GridControl.Columns>
            <dxg:GridControl.View>
                <dxg:TreeListView KeyFieldName="ID" ParentFieldName="ParentID" AutoExpandAllNodes="True" AllowDragDrop="True" DropRecord="OnDropRecord" />
            </dxg:GridControl.View>
        </dxg:GridControl>
    </Grid>
</Window>

Application.xaml.vb

' Developer Express Code Central Example:
' An example of custom Drag and Drop
' 
' This example demonstrates how to customize Drag and Drop feature for the
' TreeList using Drag and Drop-related events.
' Values of the "Position" and
' "Department" fields change depending on the new location of a record.
' 
' You can find sample updates and versions for different programming languages here:
' http://www.devexpress.com/example=E3921

Imports System
Imports System.Collections.Generic
Imports System.Configuration
Imports System.Data
Imports System.Linq
Imports System.Threading.Tasks
Imports System.Windows

Namespace WPF_GridControl_Custom_Drag_and_Drop
    ''' <summary>
    ''' Interaction logic for App.xaml
    ''' </summary>
    Partial Public Class App
        Inherits Application

    End Class
End Namespace

MainWindow.xaml.vb

Imports System.Collections.ObjectModel
Imports System.Windows
Imports DevExpress.Xpf.Core

Namespace WPF_GridControl_Custom_Drag_and_Drop
    Partial Public Class MainWindow
        Inherits Window

        Public Class Employee
            Public Property ID() As Integer
            Public Property ParentID() As Integer
            Public Property Name() As String
            Public Property Position() As String
            Public Property Department() As String
            Public Overrides Function ToString() As String
                Return Name
            End Function
        End Class

        Public NotInheritable Class Stuff

            Private Sub New()
            End Sub

            Public Shared Function GetStuff() As ObservableCollection(Of Employee)

                Dim stuff_Renamed As New ObservableCollection(Of Employee)()
                stuff_Renamed.Add(New Employee() With { _
                    .ID = 1, _
                    .ParentID = 0, _
                    .Name = "Gregory S. Price", _
                    .Department = "", _
                    .Position = "President" _
                })
                stuff_Renamed.Add(New Employee() With { _
                    .ID = 2, _
                    .ParentID = 1, _
                    .Name = "Irma R. Marshall", _
                    .Department = "Marketing", _
                    .Position = "Vice President" _
                })
                stuff_Renamed.Add(New Employee() With { _
                    .ID = 3, _
                    .ParentID = 1, _
                    .Name = "John C. Powell", _
                    .Department = "Operations", _
                    .Position = "Vice President" _
                })
                stuff_Renamed.Add(New Employee() With { _
                    .ID = 4, _
                    .ParentID = 1, _
                    .Name = "Christian P. Laclair", _
                    .Department = "Production", _
                    .Position = "Vice President" _
                })
                stuff_Renamed.Add(New Employee() With { _
                    .ID = 5, _
                    .ParentID = 1, _
                    .Name = "Karen J. Kelly", _
                    .Department = "Finance", _
                    .Position = "Vice President" _
                })

                stuff_Renamed.Add(New Employee() With { _
                    .ID = 6, _
                    .ParentID = 2, _
                    .Name = "Brian C. Cowling", _
                    .Department = "Marketing", _
                    .Position = "Manager" _
                })
                stuff_Renamed.Add(New Employee() With { _
                    .ID = 7, _
                    .ParentID = 2, _
                    .Name = "Thomas C. Dawson", _
                    .Department = "Marketing", _
                    .Position = "Manager" _
                })
                stuff_Renamed.Add(New Employee() With { _
                    .ID = 8, _
                    .ParentID = 2, _
                    .Name = "Angel M. Wilson", _
                    .Department = "Marketing", _
                    .Position = "Manager" _
                })
                stuff_Renamed.Add(New Employee() With { _
                    .ID = 9, _
                    .ParentID = 2, _
                    .Name = "Bryan R. Henderson", _
                    .Department = "Marketing", _
                    .Position = "Manager" _
                })

                stuff_Renamed.Add(New Employee() With { _
                    .ID = 10, _
                    .ParentID = 3, _
                    .Name = "Harold S. Brandes", _
                    .Department = "Operations", _
                    .Position = "Manager" _
                })
                stuff_Renamed.Add(New Employee() With { _
                    .ID = 11, _
                    .ParentID = 3, _
                    .Name = "Michael S. Blevins", _
                    .Department = "Operations", _
                    .Position = "Manager" _
                })
                stuff_Renamed.Add(New Employee() With { _
                    .ID = 12, _
                    .ParentID = 3, _
                    .Name = "Jan K. Sisk", _
                    .Department = "Operations", _
                    .Position = "Manager" _
                })
                stuff_Renamed.Add(New Employee() With { _
                    .ID = 13, _
                    .ParentID = 3, _
                    .Name = "Sidney L. Holder", _
                    .Department = "Operations", _
                    .Position = "Manager" _
                })

                stuff_Renamed.Add(New Employee() With { _
                    .ID = 14, _
                    .ParentID = 4, _
                    .Name = "James L. Kelsey", _
                    .Department = "Production", _
                    .Position = "Manager" _
                })
                stuff_Renamed.Add(New Employee() With { _
                    .ID = 15, _
                    .ParentID = 4, _
                    .Name = "Howard M. Carpenter", _
                    .Department = "Production", _
                    .Position = "Manager" _
                })
                stuff_Renamed.Add(New Employee() With { _
                    .ID = 16, _
                    .ParentID = 4, _
                    .Name = "Jennifer T. Tapia", _
                    .Department = "Production", _
                    .Position = "Manager" _
                })

                stuff_Renamed.Add(New Employee() With { _
                    .ID = 17, _
                    .ParentID = 5, _
                    .Name = "Judith P. Underhill", _
                    .Department = "Finance", _
                    .Position = "Manager" _
                })
                stuff_Renamed.Add(New Employee() With { _
                    .ID = 18, _
                    .ParentID = 5, _
                    .Name = "Russell E. Belton", _
                    .Department = "Finance", _
                    .Position = "Manager" _
                })
                Return stuff_Renamed
            End Function
        End Class
        Public Sub New()
            InitializeComponent()
            treeList.ItemsSource = Stuff.GetStuff()
        End Sub

        Private Sub OnDropRecord(ByVal sender As Object, ByVal e As DropRecordEventArgs)
            Dim data As Object = e.Data.GetData(GetType(RecordDragDropData))

            For Each employee As Employee In DirectCast(data, RecordDragDropData).Records
                employee.Position = CType(e.TargetRecord, Employee).Position
                employee.Department = CType(e.TargetRecord, Employee).Department
            Next employee

            If e.DropPosition = DropPosition.Inside Then
                For Each employee As Employee In DirectCast(data, RecordDragDropData).Records
                    employee.Position = ""
                Next employee
            End If
        End Sub
    End Class
End Namespace

Application.xaml

<Application x:Class="WPF_GridControl_Custom_Drag_and_Drop.App"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             StartupUri="MainWindow.xaml">
    <Application.Resources>

    </Application.Resources>
</Application>