Dim xc As Single = e.X + e.Width/2 '中心点
Dim yc As Single = e.Y + e.Height/2
Dim r As Single '半径
If e.Height > e.Width Then
r = e.Width/2 - 1
Else
r = e.Height/2 - 1
End If
Dim points(5) As PointF
points(0) = New PointF(xc , yc - r) '第一点 上
points(1) = New PointF(xc + r * Math.Cos(18) ,yc - r * Math.Sin(18) + 1) '右上
points(2) = New PointF(xc + r * Math.Cos(54),yc + r * Math.Sin(54)) '右下
points(3) = New PointF(xc - r * Math.Cos(54),yc + r * Math.Sin(54)) '左下
points(4) = New PointF(xc - r *Math.Cos(18),yc - r * Math.Sin(18) + 1) '左上
points(5) = New PointF(xc , yc - r)
e.Graphics.DrawLines(Pens.Green, points)
还是找个图片吧,省事。