Combining RadDragDropService and OLE Drag and Drop

Updated over 6 months ago

This article demonstrates a sample approach how to achieve drag and drop functionality between RadScheduler and RadListControl. For this purpose, we will use a combination between the RadDragDropService, supported by the RadScheduler control, and the OLE drag-and-drop, which is supported by all controls from the Telerik UI for WinForms suite.

Let’s assume that our RadScheduler is in bound mode and the RadListControl is populated manually with items. Set the AllowDrop property to true for both of the controls.

Drag and Drop from RadScheduler to RadListControl Using RadDragDropService

To implement drag and drop functionality for this scenario, we will use the SchedulerElement.DragDropBehavior, which is a derivative of the RadDragDropService. Subscribe to its PreviewDragOver and PreviewDragDrop events. In the PreviewDragOver event allow dropping over a RadListElement. The PreviewDragDrop event performs the actual inserting of the dragged appointment into the RadListControl.Items collection:

Behavior PreviewDragOver

C#

        
private void DragDropBehavior_PreviewDragOver(object sender, Telerik.WinControls.RadDragOverEventArgs e)
{
    e.CanDrop = e.HitTarget is RadListElement;
}
        
private void DragDropBehavior_PreviewDragDrop(object sender, Telerik.WinControls.RadDropEventArgs e)
{
    DragFeedbackElement draggedInstance = e.DragInstance as DragFeedbackElement;
    if (draggedInstance == null)
    {
        return;
    }
    RadListElement listElement = e.HitTarget as RadListElement;
    if (listElement == null)
    {
        return;
    }
    e.Handled = true;
    RadListControl listControl = listElement.ElementTree.Control as RadListControl;
    RadListVisualItem targetItem = listControl.ElementTree.GetElementAtPoint(e.DropLocation) as RadListVisualItem;
    int indexToInsert;
    if (targetItem != null)
    {
        indexToInsert = targetItem.Data.RowIndex;
    }
    else
    {
        indexToInsert = listControl.Items.Count;
    }
    Appointment draggedAppointment = draggedInstance.AssociatedAppointment as Appointment;
    SchedulerUIHelper.DeleteAppointment(draggedAppointment, this.radScheduler1);
    RadListDataItem newItem = new RadListDataItem(draggedAppointment.Summary);
    listControl.Items.Insert(indexToInsert, newItem);
    //save changes to data base
    SaveChanges();
}
public void SaveChanges()
{
    appointmentsResourcesTableAdapter.Adapter.AcceptChangesDuringUpdate = false;
    SchedulerDataDataSet.AppointmentsResourcesDataTable deletedChildRecords =
        this.schedulerDataDataSet.AppointmentsResources.GetChanges(DataRowState.Deleted)
        as SchedulerDataDataSet.AppointmentsResourcesDataTable;
    SchedulerDataDataSet.AppointmentsResourcesDataTable newChildRecords =
        this.schedulerDataDataSet.AppointmentsResources.GetChanges(DataRowState.Added)
        as SchedulerDataDataSet.AppointmentsResourcesDataTable;
    SchedulerDataDataSet.AppointmentsResourcesDataTable modifiedChildRecords =
        this.schedulerDataDataSet.AppointmentsResources.GetChanges(DataRowState.Modified)
        as SchedulerDataDataSet.AppointmentsResourcesDataTable;
    try
    {
        if (deletedChildRecords != null)
        {
            appointmentsResourcesTableAdapter.Update(deletedChildRecords);
        }
        appointmentsTableAdapter.Update(this.schedulerDataDataSet.Appointments);
        if (newChildRecords != null)
        {
            appointmentsResourcesTableAdapter.Update(newChildRecords);
        }
        if (modifiedChildRecords != null)
        {
            appointmentsResourcesTableAdapter.Update(modifiedChildRecords);
        }
        this.schedulerDataDataSet.AcceptChanges();
    }
    catch (Exception ex)
    {
        MessageBox.Show(string.Format("An error occurred during the update process:\n{0}", ex.Message));
    }
    finally
    {
        if (deletedChildRecords != null)
        {
            deletedChildRecords.Dispose();
        }
        if (newChildRecords != null)
        {
            newChildRecords.Dispose();
        }
        if (modifiedChildRecords != null)
        {
            modifiedChildRecords.Dispose();
        }
    }
}

VB.NET

Private Sub DragDropBehavior_PreviewDragOver(sender As Object, e As Telerik.WinControls.RadDragOverEventArgs)
    e.CanDrop = TypeOf e.HitTarget Is RadListElement
End Sub
Private Sub DragDropBehavior_PreviewDragDrop(sender As Object, e As Telerik.WinControls.RadDropEventArgs)
    Dim draggedInstance As DragFeedbackElement = TryCast(e.DragInstance, DragFeedbackElement)
    If draggedInstance Is Nothing Then
        Return
    End If
    Dim listElement As RadListElement = TryCast(e.HitTarget, RadListElement)
    If listElement Is Nothing Then
        Return
    End If
    e.Handled = True
    Dim listControl As RadListControl = TryCast(listElement.ElementTree.Control, RadListControl)
    Dim targetItem As RadListVisualItem = TryCast(listControl.ElementTree.GetElementAtPoint(e.DropLocation), RadListVisualItem)
    Dim indexToInsert As Integer
    If targetItem IsNot Nothing Then
        indexToInsert = targetItem.Data.RowIndex
    Else
        indexToInsert = listControl.Items.Count
    End If
    Dim draggedAppointment As Appointment = TryCast(draggedInstance.AssociatedAppointment, Appointment)
    SchedulerUIHelper.DeleteAppointment(draggedAppointment, Me.RadScheduler1)
    Dim newItem As New RadListDataItem(draggedAppointment.Summary)
    listControl.Items.Insert(indexToInsert, newItem)
    'save changes to data base
    SaveChanges()
End Sub
Public Sub SaveChanges()
    AppointmentsResourcesTableAdapter.Adapter.AcceptChangesDuringUpdate = False
    Dim deletedChildRecords As SchedulerDataDataSet.AppointmentsResourcesDataTable = TryCast(Me.SchedulerDataDataSet.AppointmentsResources.GetChanges(DataRowState.Deleted), SchedulerDataDataSet.AppointmentsResourcesDataTable)
    Dim newChildRecords As SchedulerDataDataSet.AppointmentsResourcesDataTable = TryCast(Me.SchedulerDataDataSet.AppointmentsResources.GetChanges(DataRowState.Added), SchedulerDataDataSet.AppointmentsResourcesDataTable)
    Dim modifiedChildRecords As SchedulerDataDataSet.AppointmentsResourcesDataTable = TryCast(Me.SchedulerDataDataSet.AppointmentsResources.GetChanges(DataRowState.Modified), SchedulerDataDataSet.AppointmentsResourcesDataTable)
    Try
        If deletedChildRecords IsNot Nothing Then
            AppointmentsResourcesTableAdapter.Update(deletedChildRecords)
        End If
        AppointmentsTableAdapter.Update(Me.SchedulerDataDataSet.Appointments)
        If newChildRecords IsNot Nothing Then
            AppointmentsResourcesTableAdapter.Update(newChildRecords)
        End If
        If modifiedChildRecords IsNot Nothing Then
            AppointmentsResourcesTableAdapter.Update(modifiedChildRecords)
        End If
        Me.SchedulerDataDataSet.AcceptChanges()
    Catch ex As Exception
        MessageBox.Show(String.Format("An error occurred during the update process:" & vbLf & "{0}", ex.Message))
    Finally
        If deletedChildRecords IsNot Nothing Then
            deletedChildRecords.Dispose()
        End If
        If newChildRecords IsNot Nothing Then
            newChildRecords.Dispose()
        End If
        If modifiedChildRecords IsNot Nothing Then
            modifiedChildRecords.Dispose()
        End If
    End Try
End Sub

Figure 1: Using RadDragDropService

As we remove the dragged appointment,it is necessary to save the performed changes in the data source.Please refer to Data Binding Walkthrough article.

Drag and Drop from RadListControl to RadScheduler Using the OLE Drag and Drop

1. Firstly, we should start the drag and drop operation using the RadListControl.MouseMove event when the left mouse button is pressed. Afterwards, allow dragging over the RadScheduler via the Effect argument of the DragEventArgs in the RadScheduler.DragEnter event handler:

C#

        
private Point mouseDownPosition;
private bool isDragging;
        
private void radListControl1_MouseMove(object sender, MouseEventArgs e)
{
    if (e.Button != MouseButtons.Left)
    {
        this.isDragging = false;
        return;
    }
    
    if (this.isDragging)
        return;
    
    Point currentPosition = e.Location;
    if ((Math.Abs((currentPosition.X - this.mouseDownPosition.X)) >= SystemInformation.DragSize.Width) ||
        (Math.Abs((currentPosition.Y - this.mouseDownPosition.Y)) >= SystemInformation.DragSize.Height))
    {
        this.isDragging = true;
        DragObject dragObject = new DragObject();
        RadListVisualItem draggedItem = this.radListControl1.ElementTree.GetElementAtPoint(currentPosition) as RadListVisualItem;
        if (draggedItem != null)
        {
            string itemText = draggedItem.Text; 
            
            if (itemText != string.Empty)
            {
                dragObject.Values.Add(AppointmentFields.Summary, itemText);
                dragObject.Status = AppointmentFields.Summary;
                //start the drag and drop operation
                (sender as RadListControl).DoDragDrop(dragObject, DragDropEffects.Copy);
            }
        }
    }
}
        
private void radScheduler1_DragEnter(object sender, DragEventArgs e)
{
    DragObject dragObject = e.Data.GetData(typeof(DragObject)) as DragObject;
    //allow dragging over the RadScheduler
    e.Effect = dragObject == null ? DragDropEffects.None : DragDropEffects.Copy;
}

VB.NET

Private mouseDownPosition As Point
Private isDragging As Boolean
Private Sub radListControl1_MouseMove(sender As Object, e As MouseEventArgs)
    If e.Button <> MouseButtons.Left Then
        Me.isDragging = False
        Return
    End If
    If Me.isDragging Then
        Return
    End If
    Dim currentPosition As Point = e.Location
    If (Math.Abs((currentPosition.X - Me.mouseDownPosition.X)) >= SystemInformation.DragSize.Width) OrElse (Math.Abs((currentPosition.Y - Me.mouseDownPosition.Y)) >= SystemInformation.DragSize.Height) Then
        Me.isDragging = True
        Dim dragObject As New DragObject()
        Dim draggedItem As RadListVisualItem = TryCast(Me.RadListControl1.ElementTree.GetElementAtPoint(currentPosition), RadListVisualItem)
        If draggedItem IsNot Nothing Then
            Dim itemText As String = draggedItem.Text
            If itemText <> String.Empty Then
                dragObject.Values.Add(AppointmentFields.Summary, itemText)
                dragObject.Status = AppointmentFields.Summary
                'start the drag and drop operation
                TryCast(sender, RadListControl).DoDragDrop(dragObject, DragDropEffects.Copy)
            End If
        End If
    End If
End Sub
Private Sub radScheduler1_DragEnter(sender As Object, e As DragEventArgs)
    Dim dragObject As DragObject = TryCast(e.Data.GetData(GetType(DragObject)), DragObject)
    'allow dragging over the RadScheduler
    e.Effect = If(dragObject Is Nothing, DragDropEffects.None, DragDropEffects.Copy)
End Sub

2. In the RadScheduler.DragDrop event you need to get the location of the mouse and convert it to a point that the scheduler can use to get the cell element underneath the mouse. This MonthCellElement is passed to a private method GetCellAppointment that we will write next:

C#

        
private void radScheduler1_DragDrop(object sender, DragEventArgs e)
{
    Point point = this.radScheduler1.PointToClient(new Point(e.X, e.Y));
    SchedulerCellElement schedulerCell = SchedulerUIHelper.GetCellAtPoint(point, this.radScheduler1);
    
    if (schedulerCell != null)
    {
        DragObject dragObject = e.Data.GetData(typeof(DragObject)) as DragObject;
        if (dragObject != null)
        {
            Appointment appointment = CreateAppointment(schedulerCell.Date, dragObject);
            this.radScheduler1.Appointments.Add(appointment);
            
            int indexToRemove = this.radListControl1.Items.IndexOf(appointment.Summary);
            if (indexToRemove > -1)
            {
                this.radListControl1.Items.RemoveAt(indexToRemove);
            }
        }
    }
    
    this.mouseDownPosition = Point.Empty;
    this.isDragging = false;
    //save changes to database
    SaveChanges();
}

VB.NET

Private Sub radScheduler1_DragDrop(sender As Object, e As DragEventArgs)
    Dim point__1 As Point = Me.RadScheduler1.PointToClient(New Point(e.X, e.Y))
    Dim schedulerCell As SchedulerCellElement = SchedulerUIHelper.GetCellAtPoint(point__1, Me.RadScheduler1)
    If schedulerCell IsNot Nothing Then
        Dim dragObject As DragObject = TryCast(e.Data.GetData(GetType(DragObject)), DragObject)
        If dragObject IsNot Nothing Then
            Dim appointment As Appointment = CreateAppointment(schedulerCell.[Date], dragObject)
            Me.RadScheduler1.Appointments.Add(appointment)
            Dim indexToRemove As Integer = Me.RadListControl1.Items.IndexOf(appointment.Summary)
            If indexToRemove > -1 Then
                Me.RadListControl1.Items.RemoveAt(indexToRemove)
            End If
        End If
    End If
    Me.mouseDownPosition = Point.Empty
    Me.isDragging = False
    'save changes to database
    SaveChanges()
End Sub

3. The helper method CreateAppointment() creates an appointment, starting at the cell where the RadListControl item is dropped. This appointment gets its data from the dragged item.

C#

    
private Appointment CreateAppointment(DateTime currentDate, DragObject dragObject)
{
    Appointment appointment = new Appointment();
    DateTime startDate = currentDate;
    DateTime endDate = currentDate.AddHours(1);
    switch (dragObject.Status)
    {
        case AppointmentFields.Summary:
            appointment.Summary = dragObject.Values[dragObject.Status] as string;
            break;
        case AppointmentFields.Row:
            appointment.Summary = dragObject.Values[AppointmentFields.Summary] as string;
            appointment.Description = dragObject.Values[AppointmentFields.Description] as string;
            appointment.BackgroundId = (int)dragObject.Values[AppointmentFields.Background];
            appointment.StatusId = (int)dragObject.Values[AppointmentFields.Status];
            appointment.Location = dragObject.Values[AppointmentFields.Location] as string;
            
            startDate = (DateTime)dragObject.Values[AppointmentFields.Start];
            endDate = (DateTime)dragObject.Values[AppointmentFields.End];
            
            TimeSpan range = endDate - startDate;
            endDate = currentDate + range;
            startDate = currentDate;
    
            break;
    }
    appointment.Start = startDate;
    appointment.End = endDate;
    return appointment;
}
    
private enum AppointmentFields
{
    Row,
    Summary,
    Location,
    Description,
    Start,
    End,
    Background,
    Status
}
    
private class DragObject
{
    private AppointmentFields status;
    private Dictionary<AppointmentFields, object> values = new Dictionary<AppointmentFields, object>();
        
    public AppointmentFields Status
    {
        get
        {
            return this.status;
        }
        set
        {
            this.status = value;
        }
    }
        
    public Dictionary<AppointmentFields, object> Values
    {
        get
        {
            return this.values;
        }
    }
}

VB.NET

Private Function CreateAppointment(currentDate As DateTime, dragObject As DragObject) As Appointment
    Dim appointment As New Appointment()
    Dim startDate As DateTime = currentDate
    Dim endDate As DateTime = currentDate.AddHours(1)
    Select Case dragObject.Status
        Case AppointmentFields.Summary
            appointment.Summary = TryCast(dragObject.Values(dragObject.Status), String)
            Exit Select
        Case AppointmentFields.Row
            appointment.Summary = TryCast(dragObject.Values(AppointmentFields.Summary), String)
            appointment.Description = TryCast(dragObject.Values(AppointmentFields.Description), String)
            appointment.BackgroundId = CInt(dragObject.Values(AppointmentFields.Background))
            appointment.StatusId = CInt(dragObject.Values(AppointmentFields.Status))
            appointment.Location = TryCast(dragObject.Values(AppointmentFields.Location), String)
            startDate = DirectCast(dragObject.Values(AppointmentFields.Start), DateTime)
            endDate = DirectCast(dragObject.Values(AppointmentFields.[End]), DateTime)
            Dim range As TimeSpan = endDate - startDate
            endDate = currentDate + range
            startDate = currentDate
            Exit Select
    End Select
    appointment.Start = startDate
    appointment.[End] = endDate
    Return appointment
End Function
Private Enum AppointmentFields
    Row
    Summary
    Location
    Description
    Start
    [End]
    Background
    Status
End Enum
Private Class DragObject
    Private m_status As AppointmentFields
    Private m_values As New Dictionary(Of AppointmentFields, Object)()
    Public Property Status() As AppointmentFields
        Get
            Return Me.m_status
        End Get
        Set(value As AppointmentFields)
            Me.m_status = value
        End Set
    End Property
    Public ReadOnly Property Values() As Dictionary(Of AppointmentFields, Object)
        Get
            Return Me.m_values
        End Get
    End Property
End Class

Figure 2: OLE Drag and Drop

See Also

• Views
• Working with Appointments
• Formatting Appointments
• Scheduler Element Provider