C#只有底边框的Textbox

自定义控件实现，效果如下

代码如下

public partial class LineTextBox : TextBox
    {
        public LineTextBox()
        {
            this.Width = 100;
            this.BorderStyle = BorderStyle.None;
        }
        private Color _linecolor = Color.Black;
        /// <summary>
        /// 线条颜色
        /// </summary>
        public Color LineColor
        {
            get
            {
                return this._linecolor;
            }
            set
            {
                this._linecolor = value;
                this.Invalidate();
            }
        }
        private const int WM_PAINT = 0xF;
        protected override void WndProc(ref Message m)
        {
            base.WndProc(ref m);
            if (m.Msg == WM_PAINT)
            {
                DrawLine();
            }
        }
        //只画底边
        private void DrawLine()
        {
            Graphics g = this.CreateGraphics();
            using (Pen p = new Pen(this._linecolor))
            {
                g.DrawLine(p, 0, this.Height - 1, this.Width, this.Height - 1);
            }
        }
    }