更改 Windows 窗体中的文本框边框样式 - C#

private void Form1_Load(object sender, EventArgs e)
{
    textBox1.BorderStyle = BorderStyle.FixedSingle;
}

public class CustomTextBox : TextBox
{
    public CustomTextBox()
    {
        SetStyle(ControlStyles.UserPaint, true);
    }

    protected override void OnPaint(PaintEventArgs e)
    {
        base.OnPaint(e);

        // 在这里绘制自定义边框样式
        using (Pen pen = new Pen(Color.Red, 1))
        {
            e.Graphics.DrawRectangle(pen, new Rectangle(0, 0, Width - 1, Height - 1));
        }
    }
}

private void Form1_Load(object sender, EventArgs e)
{
    customTextBox1.BorderStyle = BorderStyle.None;
}