c# 鼠标在控件上拖动 移动窗体 移动窗口

        #region 移动窗体 移动窗口
        private Point _mousePoint;
        private int topA(Control cc)
        {
            if (cc == null || cc == this) return 0;
            if (cc.Parent == null || cc.Parent == this)
                return cc.Top;
            else
                return topA(cc.Parent) + cc.Top;
        }
        private int leftA(Control cc)
        {
            if (cc == null || cc == this) return 0;
            if (cc.Parent == null || cc.Parent == this)
                return cc.Left;
            else
                return leftA(cc.Parent) + cc.Left;
        }
        private void labTitle_MouseDown(object sender, MouseEventArgs e)
        {
            Control cc = (Control)sender;
            if (e.Button == MouseButtons.Left)
            {
                _mousePoint.X = e.X + leftA(cc);
                _mousePoint.Y = e.Y + topA(cc);
            }
        }
        private void labTitle_MouseMove(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                Top = MousePosition.Y - _mousePoint.Y;
                Left = MousePosition.X - _mousePoint.X;
            }
        }
        #endregion