Hi Roger,

Thank you for your reply and detailed explanation! I can understand your
question now.

Firstly, to custom draw a DataGridView, we need to handle its CellPainting
event.

Secondly, to draw a vertical oriented text, we could call the
Graphics.DrawString(string,Brush,RectangleF,StringFormat) method passing an
instance of StringFormat with a DirectionVertical format flag to this
method. For example:

System.Drawing.StringFormat drawFormat = new System.Drawing.StringFormat();
drawFormat.FormatFlags = StringFormatFlags.DirectionVertical;
// g is a Graphics object. The text "hello" will be drawn in vertical
orientation
g.DrawString("hello", this.Font, Brushes.Orange, new PointF(0,
0),drawFormat);

Unfortunately, the reading direction of the text "hello" would be from top
to bottom using the above method, which doesn't meet your requirement.

A solution is to call the Graphics.TranslateTransform and RotateTransform
methods to get what you want. The following is a sample.

void dataGridView1_CellPainting(object sender,
DataGridViewCellPaintingEventArgs e)
   {
           if (e.RowIndex == -1 && e.ColumnIndex >= 0)
           {
               e.PaintBackground(e.ClipBounds, true);
               Rectangle rect =
this.dataGridView1.GetColumnDisplayRectangle(e.ColumnIndex, true);
               Size titleSize =
TextRenderer.MeasureText(e.Value.ToString(), e.CellStyle.Font);
               if (this.dataGridView1.ColumnHeadersHeight <
titleSize.Width)
                   this.dataGridView1.ColumnHeadersHeight =
titleSize.Width;

               e.Graphics.TranslateTransform(0, titleSize.Width);
               e.Graphics.RotateTransform(-90.0F);
             
               e.Graphics.DrawString(e.Value.ToString(), this.Font,
Brushes.Orange, new PointF(rect.Y, rect.X));

               e.Graphics.RotateTransform(90.0F);
               e.Graphics.TranslateTransform(0, -titleSize.Width);
               e.Handled = true;
           }
  }

In addition, you could set the AutoSizeColumnsMode property of the
DataGridView to AllCellsExceptHeader in order to make the DataGridView
compact.

Hope this helps.
If you have any question, please feel free to let me know.

Sincerely,
Linda Liu
Microsoft Online Community Support