C#运行时拖动label

bool isdown;//鼠标左键是否按下
        Point mousepos;//鼠标位置
        private void label1_MouseDown(object sender, MouseEventArgs e)
        {
            
            if (e.Button == MouseButtons.Left)
            {
               isdown = true;//鼠标按下
            }
        }

        private void label1_MouseMove(object sender, MouseEventArgs e)
        {
        
            if (isdown)
            {
                mousepos.Offset(e.X , e.Y);
                this.label1.Location = mousepos;//label控件的位置
            }

        }

        private void label1_MouseUp(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
                isdown = false;//释放鼠标左键
        }