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.

        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 = false;
                    svc.Start(row);
                }
                return base.OnMouseDownLeft(e);
            }
        }

        //required to initiate drag and drop when grid is in bound mode
        private void svc_PreviewDragStart(object sender, PreviewDragStartEventArgs e)
        {
            e.CanStart = true;
        }

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

        private void svc_PreviewDragDrop(object sender, RadDropEventArgs e)
        {
            GridDataRowElement dragRowElement = e.DragInstance 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 != dragRowElement.GridViewElement.CurrentRow.Cells[dragRowElement.GridViewElement.CurrentColumn.Name])
                {
                    cell.Value = dragRowElement.GridViewElement.CurrentCell.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 = False
                svc.Start(row)
            End If

            Return MyBase.OnMouseDownLeft(e)
        End Function
    End Class

    Private Sub svc_PreviewDragStart(ByVal sender As Object, ByVal e As PreviewDragStartEventArgs)
        e.CanStart = True
    End Sub

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

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

            If targetCell IsNot Nothing AndAlso dragRowElement.GridControl.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 dragRowElement As GridDataRowElement = TryCast(e.DragInstance, 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(dragRowElement.GridViewElement.CurrentRow.Cells(dragRowElement.GridViewElement.CurrentColumn.Name)) Then
                cell.Value = dragRowElement.GridViewElement.CurrentCell.Value
            End If
        Next
    End Sub      

See Also

• RadDragDropService
• Copy, Paste, Cut