How to drag a cell and copy its content in multiple cells

Environment

Product Version	Product	Author
2019.2.618	RadGridView for WinForms	Desislava Yordanova

Description

This tutorial demonstrates how to drag a single cell in RadGridView in such a way that you can copy the content of one cell into multiple cells similar to MS Excel.

While performing the multiple selection in RadGridView and dragging and dropping the cell, it is necessary to keep the Ctrl key pressed. Thus, the multiple selection will be preserved.

Solution

You can enable the multiple cell selection in RadGridView by setting the MultiSelect property to true and the SelectionMode property to CellSelect. Then, in the PreviewDragDrop event of the RadDragDropService, you can adjust the value of the selected cells considering the value of the current cell.

• C#
• VB.NET

public RadForm1()
{
    InitializeComponent();

    this.radGridView1.MultiSelect = true;
    this.radGridView1.SelectionMode = GridViewSelectionMode.CellSelect;

    RadDragDropService svc =
        this.radGridView1.GridViewElement.GetService<RadDragDropService>();
    svc.PreviewDragStart += svc_PreviewDragStart;
    svc.PreviewDragDrop += svc_PreviewDragDrop;
    svc.PreviewDragOver += svc_PreviewDragOver;
    svc.PreviewDropTarget += svc_PreviewDropTarget;

    //register the custom row selection behavior
    var gridBehavior = this.radGridView1.GridBehavior as BaseGridBehavior;
    gridBehavior.UnregisterBehavior(typeof(GridViewDataRowInfo));
    gridBehavior.RegisterBehavior(typeof(GridViewDataRowInfo), new RowSelectionGridBehavior());
}

private void svc_PreviewDropTarget(object sender, PreviewDropTargetEventArgs e)
{
    e.DropTarget = e.HitTarget;
}

//initiates drag and drop service for clicked rows
public class RowSelectionGridBehavior : GridDataRowBehavior
{
    protected override bool OnMouseDownLeft(MouseEventArgs e)
    {
        GridDataRowElement row = this.GetRowAtPoint(e.Location) as GridDataRowElement;
        if (row != null)
        {
            RadGridViewDragDropService svc = this.GridViewElement.GetService<RadGridViewDragDropService>();
            svc.AllowAutoScrollColumnsWhileDragging = false;
            svc.AllowAutoScrollRowsWhileDragging = true;
            svc.Start(new SnapshotDragItem(row));
        }
        return base.OnMouseDownLeft(e);
    }
}
GridViewRowInfo draggedRow;
//required to initiate drag and drop when grid is in bound mode
private void svc_PreviewDragStart(object sender, PreviewDragStartEventArgs e)
{
    SnapshotDragItem draggedSnapShot = e.DragInstance as SnapshotDragItem;
    if (draggedSnapShot == null)
    {
        e.CanStart = false;
    }
    else
    {
        e.CanStart = true;
          GridDataRowElement dragRowElement = draggedSnapShot.Item as GridDataRowElement;
          draggedRow = dragRowElement.RowInfo;
    }
}

private void svc_PreviewDragOver(object sender, RadDragOverEventArgs e)
{
    SnapshotDragItem draggedSnapShot = e.DragInstance as SnapshotDragItem;
    if (draggedSnapShot == null)
    {
        return;
    }
    GridDataRowElement dragRowElement = draggedSnapShot.Item as GridDataRowElement;
    if (dragRowElement != null)
    {
        GridCellElement targetCell = e.HitTarget as GridCellElement;
        if (targetCell != null && draggedRow.ViewTemplate.CurrentColumn == targetCell.ColumnInfo)
        {
            e.CanDrop = true;
        }
        else
        {
            e.CanDrop = false;
        }
    }
}

private void svc_PreviewDragDrop(object sender, RadDropEventArgs e)
{
    SnapshotDragItem draggedSnapShot = e.DragInstance as SnapshotDragItem;
    if (draggedSnapShot==null)
    {
        return;
    }
    GridDataRowElement dragRowElement = draggedSnapShot.Item as GridDataRowElement;
    GridCellElement targetCell = e.HitTarget as GridCellElement;
    if (dragRowElement == null || targetCell == null)
    {
        return;
    }
    e.Handled = true;

    foreach (GridViewCellInfo cell in targetCell.GridControl.SelectedCells)
    {
        if (cell != draggedRow.ViewTemplate.MasterTemplate.CurrentRow.Cells[draggedRow.ViewTemplate.CurrentColumn.Name])
        {
             cell.Value = draggedRow.ViewTemplate.MasterTemplate.CurrentRow.Cells[draggedRow.ViewTemplate.CurrentColumn.Name].Value;
        }
    }
}

Public Sub New()
    InitializeComponent()
    Me.RadGridView1.MultiSelect = True
    Me.RadGridView1.SelectionMode = GridViewSelectionMode.CellSelect
    Dim svc As RadDragDropService = Me.RadGridView1.GridViewElement.GetService(Of RadDragDropService)()
    AddHandler svc.PreviewDragStart, AddressOf svc_PreviewDragStart
    AddHandler svc.PreviewDragDrop, AddressOf svc_PreviewDragDrop
    AddHandler svc.PreviewDragOver, AddressOf svc_PreviewDragOver
    AddHandler svc.PreviewDropTarget, AddressOf svc_PreviewDropTarget
    Dim gridBehavior = TryCast(Me.RadGridView1.GridBehavior, BaseGridBehavior)
    gridBehavior.UnregisterBehavior(GetType(GridViewDataRowInfo))
    gridBehavior.RegisterBehavior(GetType(GridViewDataRowInfo), New RowSelectionGridBehavior())
End Sub

Private Sub svc_PreviewDropTarget(ByVal sender As Object, ByVal e As PreviewDropTargetEventArgs)
    e.DropTarget = e.HitTarget
End Sub

Public Class RowSelectionGridBehavior
        Inherits GridDataRowBehavior

        Protected Overrides Function OnMouseDownLeft(ByVal e As MouseEventArgs) As Boolean
            Dim row As GridDataRowElement = TryCast(Me.GetRowAtPoint(e.Location), GridDataRowElement)

            If row IsNot Nothing Then
                Dim svc As RadGridViewDragDropService = Me.GridViewElement.GetService(Of RadGridViewDragDropService)()
                svc.AllowAutoScrollColumnsWhileDragging = False
                svc.AllowAutoScrollRowsWhileDragging = True
                svc.Start(New SnapshotDragItem(row))
            End If

            Return MyBase.OnMouseDownLeft(e)
        End Function
    End Class

Private draggedRow As GridViewRowInfo

Private Sub svc_PreviewDragStart(ByVal sender As Object, ByVal e As PreviewDragStartEventArgs)
    Dim draggedSnapShot As SnapshotDragItem = TryCast(e.DragInstance, SnapshotDragItem)

    If draggedSnapShot Is Nothing Then
        e.CanStart = False
    Else
        e.CanStart = True
        Dim dragRowElement As GridDataRowElement = TryCast(draggedSnapShot.Item, GridDataRowElement)
        draggedRow = dragRowElement.RowInfo
    End If
End Sub

Private Sub svc_PreviewDragOver(ByVal sender As Object, ByVal e As RadDragOverEventArgs)
    Dim draggedSnapShot As SnapshotDragItem = TryCast(e.DragInstance, SnapshotDragItem)

    If draggedSnapShot Is Nothing Then
        Return
    End If

    Dim dragRowElement As GridDataRowElement = TryCast(draggedSnapShot.Item, GridDataRowElement)

    If dragRowElement IsNot Nothing Then
        Dim targetCell As GridCellElement = TryCast(e.HitTarget, GridCellElement)

        If targetCell IsNot Nothing AndAlso draggedRow.ViewTemplate.CurrentColumn.Equals(targetCell.ColumnInfo) Then
            e.CanDrop = True
        Else
            e.CanDrop = False
        End If
    End If
End Sub

Private Sub svc_PreviewDragDrop(ByVal sender As Object, ByVal e As RadDropEventArgs)
    Dim draggedSnapShot As SnapshotDragItem = TryCast(e.DragInstance, SnapshotDragItem)

    If draggedSnapShot Is Nothing Then
        Return
    End If

    Dim dragRowElement As GridDataRowElement = TryCast(draggedSnapShot.Item, GridDataRowElement)
    Dim targetCell As GridCellElement = TryCast(e.HitTarget, GridCellElement)

    If dragRowElement Is Nothing OrElse targetCell Is Nothing Then
        Return
    End If

    e.Handled = True

    For Each cell As GridViewCellInfo In targetCell.GridControl.SelectedCells

        If Not cell.Equals(draggedRow.ViewTemplate.MasterTemplate.CurrentRow.Cells(draggedRow.ViewTemplate.CurrentColumn.Name)) Then
            cell.Value = draggedRow.ViewTemplate.MasterTemplate.CurrentRow.Cells(draggedRow.ViewTemplate.CurrentColumn.Name).Value
        End If
    Next
End Sub