C# groupbox 改变颜色 paint事件

groupbox1改变边框颜色

 private void groupBox1_Paint(object sender, PaintEventArgs e)
        {
            GroupBox gBox = (GroupBox)sender;  //获取当前的groupbox

            e.Graphics.Clear(gBox.BackColor);  //清除当前groupbox的所有的颜色（字体和边框）
            e.Graphics.DrawString(gBox.Text, gBox.Font, Brushes.Red, 10, 1); //设置group的text颜色为红色
            var vSize = e.Graphics.MeasureString(gBox.Text, gBox.Font); //获取groupbox的大小
            e.Graphics.DrawLine(Pens.Black, 1, vSize.Height / 2, 8, vSize.Height / 2);//画出字体左边的边框。黑色
            e.Graphics.DrawLine(Pens.Red, vSize.Width + 8, vSize.Height / 2, gBox.Width - 2, vSize.Height / 2);//画出字体右边的边框。红色
            e.Graphics.DrawLine(Pens.Yellow, 1, vSize.Height / 2, 1, gBox.Height - 2);//画出左边边框。黄色
            e.Graphics.DrawLine(Pens.Blue, 1, gBox.Height - 2, gBox.Width - 2, gBox.Height - 2);//画出底部边框。蓝色
            e.Graphics.DrawLine(Pens.Green, gBox.Width - 2, vSize.Height / 2, gBox.Width - 2, gBox.Height - 2);//画出右边边框。绿色
        }