获得子控件在父控件的坐标

        private Point GetPointAsParent(Control ctrl,Control parentCtrl)
        {
            int x, y;
            x=ctrl.Location.X;
            y=ctrl.Location.Y;
            while (ctrl.Parent!=null && !ctrl.Parent.GetType().Equals(parentCtrl.GetType()))
            {
                x += ctrl.Parent.Location.X;
                y += ctrl.Parent.Location.Y;
                ctrl = ctrl.Parent;
            }
            return new Point(x, y);
        }