protected override void OnMouseDown(MouseEventArgs e)
 {
     base.OnMouseDown(e);
     if (SearchBtnRectangle.Contains(e.Location))
     {
         ControlState = ControlState.Pressed;
     }
     else
     {
         ControlState = ControlState.Normal;
     }
     Invalidate();
 }
 protected override void OnMouseMove(MouseEventArgs e)
 {
     base.OnMouseMove(e);
     if (SearchBtnRectangle.Contains(e.Location))
     {
         ControlState = ControlState.Hover;
         Cursor       = Cursors.Hand;
     }
     else
     {
         ControlState = ControlState.Normal;
         Cursor       = _oldCursor;
     }
     Invalidate();
 }
        protected override void OnMouseUp(MouseEventArgs e)
        {
            base.OnMouseUp(e);
            if (e.Button == MouseButtons.Left)
            {
                if (SearchBtnRectangle.Contains(e.Location))
                {
                    ControlState = ControlState.Hover;


                    //触发搜索按钮事件
                    if (SearchBtnClick != null)
                    {
                        SearchBtnClick(this, new EventArgs());
                    }
                }
                else
                {
                    ControlState = ControlState.Normal;
                }
            }
            Invalidate();
        }