C#窗体控件GroupBox修改边框色

https://www.cnblogs.com/CUIT-DX037/p/7246231.html

public partial class TestForm : Form
    {

        public TestForm()
        {
            InitializeComponent();

            this.groupBox1.Paint += groupBox_Paint;
            this.groupBox2.Paint += groupBox_Paint;
        }

        void groupBox_Paint(object sender, PaintEventArgs e)
        {
            GroupBox gBox = (GroupBox)sender;

            e.Graphics.Clear(gBox.BackColor);
            e.Graphics.DrawString(gBox.Text, gBox.Font, Brushes.Red, 10, 1);
            var vSize = e.Graphics.MeasureString(gBox.Text, gBox.Font);
            e.Graphics.DrawLine(Pens.Red, 1, vSize.Height / 2, 8, vSize.Height / 2);
            e.Graphics.DrawLine(Pens.Red, vSize.Width + 8, vSize.Height / 2, gBox.Width - 2, vSize.Height / 2);
            e.Graphics.DrawLine(Pens.Red, 1, vSize.Height / 2, 1, gBox.Height - 2);
            e.Graphics.DrawLine(Pens.Red, 1, gBox.Height - 2, gBox.Width - 2, gBox.Height - 2);
            e.Graphics.DrawLine(Pens.Red, gBox.Width - 2, vSize.Height / 2, gBox.Width - 2, gBox.Height - 2);
        }

        private void TestForm_Load(object sender, EventArgs e)
        {

        }
    }