设置lable在图片上透明显示

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Data;
using System.Text;
using System.Windows.Forms;

namespace usercontrol_touming
{
    public partial class UserControl1 : UserControl
    {
        public UserControl1()
        {
            InitializeComponent();
            this.BackColor = Color.Transparent;
          
            //panel1.Controls.Add(pictureBox1);
       }
        public class TransparentLabel : System.Windows.Forms.PictureBox
        {
            //Fields
            private Point _Location = new Point(0, 0);
            //Properties
            public Point TextLocation
            {
                get
                {
                    return this._Location;
                }
                set
                {
                    this._Location = value;
                }
            }
            [Browsable(true)]
            new public string Text
            {
                get { return base.Text; }
                set { base.Text = value; }
            }
            [Browsable(true)]
            new public Font Font
            {
                get { return base.Font; }
                set { base.Font = value; }
            }
            //
            public TransparentLabel()
            {
              
            }

            protected override void OnPaint(PaintEventArgs e)
            {
                base.OnPaint(e);
                SizeF m_size = e.Graphics.MeasureString(this.Text, this.Font);
                e.Graphics.DrawString(this.Text, this.Font, Brushes.Black, new RectangleF(this._Location, m_size));
            }
        }

        private void UserControl1_Load(object sender, EventArgs e)
        {
            label1.Text = "2013-08-05";        }       
    }
}