Node drag and drop between RadTreeView and RadGridView

Product Version	Product	Author	Last modified
Q2 2012	RadTreeView for WinForms	Svetlin Ralchev	May 11, 2012

PROBLEM

RadTreeView allows drag and drop between two different instances of RadTreeView out of the box. However, it does not support out of the box drag and drop of a node to a data cell in RadGridView and this is what we will look at in this article.

SOLUTION

In order to implement this feature, we need to handle the PreviewDragOver and PreviewDragDrop events of the TreeViewDragDropService. The steps below demonstrates how you can achieve the desired scenario:

1. You should set the AllowDragDrop property of RadTreeView to true.
   
2. Then you should subscribe to the CellFormatting event of RadGridView where you can allow a drop operation over a data cell:
   

• C#
• VB.NET

private void radGridView1_CellFormatting(object sender, CellFormattingEventArgs e)
{
    e.CellElement.AllowDrop = true;
}

Private Sub radGridView1_CellFormatting(ByVal sender As Object, ByVal e As CellFormattingEventArgs)
    e.CellElement.AllowDrop = True
End Sub

3.Then you should handle the PreviewDragOver event of the TreeViewDragDropService in the following way:

• C#
• VB.NET

private void OnPreviewDragOver(object sender, Telerik.WinControls.RadDragOverEventArgs e)
{
    GridDataCellElement dataCell = e.HitTarget as GridDataCellElement;

    if (dataCell != null)
    {
        TreeNodeElement element = e.DragInstance as TreeNodeElement;

        object value = null;
        e.CanDrop = RadDataConverter.Instance.TryParse(dataCell as IDataConversionInfoProvider,
element.Data.Name, out value) == null;
    }
}

Private Sub OnPreviewDragOver(ByVal sender As Object, ByVal e As Telerik.WinControls.RadDragOverEventArgs)
    Dim dataCell As GridDataCellElement = TryCast(e.HitTarget, GridDataCellElement)

    If dataCell IsNot Nothing Then
        Dim element As TreeNodeElement = TryCast(e.DragInstance, TreeNodeElement)
        Dim value As Object = Nothing
        e.CanDrop = RadDataConverter.Instance.TryParse(TryCast(dataCell, IDataConversionInfoProvider), element.Data.Name, value) Is Nothing
    End If
End Sub

1. Finally, you should subscribe for the PreviewDragDrop event of the TreeViewDragDropService:
   

• C#
• VB.NET

private void OnPreviewDragDrop(object sender, Telerik.WinControls.RadDropEventArgs e)
{
    GridDataCellElement dataCell = e.HitTarget as GridDataCellElement;
    if (dataCell != null)
    {
        TreeNodeElement element = e.DragInstance as TreeNodeElement;
        dataCell.Value = element.Data.Name;
        e.Handled = true;
    }
}

Private Sub OnPreviewDragDrop(ByVal sender As Object, ByVal e As Telerik.WinControls.RadDropEventArgs)
    Dim dataCell As GridDataCellElement = TryCast(e.HitTarget, GridDataCellElement)

    If dataCell IsNot Nothing Then
        Dim element As TreeNodeElement = TryCast(e.DragInstance, TreeNodeElement)
        dataCell.Value = element.Data.Name
        e.Handled = True
    End If
End Sub

You can download a complete VB and C# project from the following link.