DrawString with cell_painting

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C#

i use cell_painting event to paint group of cells(3 cells in the same row) in my dataGridView.
is it possible to DrawString in the middle of the painted cells ?

i tried use RectangleF but the String Appeared more then one time.

i have List of points that i keep there the painted cells, when i drag item from listbox to the DataGridView i want that in the middle of the painted cells it will be writen something for example "hello to everybody" but this string Appeares Three times, one on the another

private List<Point> GeneralCourseWithHours = new List<Point>();

private void dataGridView1_DragDrop(object sender, DragEventArgs e)
        {
            Point p = this.dataGridView1.PointToClient(new Point(e.X, e.Y));
            DataGridView.HitTestInfo info = this.dataGridView1.HitTest(p.X, p.Y);
            if (info.RowIndex != -1 && info.ColumnIndex != -1)
            {
                Object value = (Object)e.Data.GetData(typeof(string));

                this.dataGridView1.Rows[info.RowIndex].Cells[info.ColumnIndex].Value = value;
                GeneralCourseWithHours.Add(new Point(info.RowIndex, info.ColumnIndex));
                GeneralCourseWithHours.Add(new Point(info.RowIndex, info.ColumnIndex + 1));
                GeneralCourseWithHours.Add(new Point(info.RowIndex, info.ColumnIndex + 2));
            }
     }

protected void dataGridView1_CellPainting(object sender, DataGridViewCellPaintingEventArgs e)
        {
            if (GeneralCourseWithHours.Contains(new Point(e.RowIndex, e.ColumnIndex)))
            {
                e.Graphics.FillRectangle(Brushes.LightBlue, e.CellBounds);
                e.PaintContent(e.CellBounds);
                e.Handled = true;
                dataGridView1.Invalidate();

                RectangleF rectDest = RectangleF.Empty;
                StringFormat sf = new StringFormat();
                sf.Alignment = StringAlignment.Center;
                sf.LineAlignment = StringAlignment.Center;
                sf.Trimming = StringTrimming.EllipsisCharacter;
                string str;

                str = "hello to everybody";

                rectDest = new RectangleF(e.CellBounds.X, e.CellBounds.Y, e.CellBounds.Size.Width * 3, e.CellBounds.Height);
                e.Graphics.DrawString(str, new Font("Arial", 10, FontStyle.Regular), Brushes.Black, rectDest, sf);
            }
        }