public partial class tspControl : UserControl

    {

        public tspControl()

        {

            InitializeComponent();

            SetStyle(ControlStyles.SupportsTransparentBackColor

              | ControlStyles.UserPaint

              | ControlStyles.AllPaintingInWmPaint

              | ControlStyles.Opaque, true);

            this.BackColor = Color.Transparent;

        }

        private Image img;

        public Image Image

        {

            get

            {

                return img;

            }

            set

            {

                img = value;

            }

        }

        protected override void OnLocationChanged(EventArgs e)

        {

            //base.OnLocationChanged(e);

            Visible = false;

            Visible = true;

        }

        protected override CreateParams CreateParams

        {

            get

            {

                //return base.CreateParams;

                CreateParams cp = base.CreateParams;

                cp.ExStyle |= 0x00000020; //WS_EX_TRANSPARENT

                return cp;

            }

        }

        protected override void OnPaint(PaintEventArgs pe)

        {

            if (img != null)

            {

                base.OnPaint(pe);

                pe.Graphics.DrawImage(img, 0, 0);

            }

            else

            {

            }

        }

    }

//注：如果是手动改变图片，最好在刷新一下界面(this.Refresh()；)，记着图片要是透明的才能实现透明