tabcontrol的alignment属性设置成Right时，tabPage的text内容怎么显示成竖着的字体

privateRectangletabArea;
privateRectangleFtabTextArea;
privatevoidfrmopen_Load(objectsender,System.EventArgse)
{
this.tabControl1.DrawMode=TabDrawMode.OwnerDrawFixed;
}
privatevoidtabControl1_DrawItem(objectsender,System.Windows.Forms.DrawItemEventArgse)
{
tabArea=tabControl1.GetTabRect(e.Index);
tabTextArea=RectangleF.op_Implicit(tabControl1.GetTabRect(e.Index));
Graphicsg=e.Graphics;
StringFormatsf=newStringFormat();
sf.LineAlignment=StringAlignment.Center;
sf.Alignment=StringAlignment.Center;
Fontfont=this.tabControl1.Font;
SolidBrushbrush=newSolidBrush(Color.Black);
g.DrawString(((TabControl)(sender)).TabPages[e.Index].Text,font,brush,tabTextArea,sf);
}