C#中实现拖动无边框窗体Form

 Point mouseOff;//鼠标移动位置变量
            bool leftFlag;//标签是否为左键
            private void Form1_MouseDown(object sender, MouseEventArgs e)
            {
                if (e.Button == MouseButtons.Left)
                {
                    mouseOff = new Point(-e.X, -e.Y); //得到变量的值
                    leftFlag = true;                  //点击左键按下时标注为true;
                }
            }

            private void Form1_MouseMove(object sender, MouseEventArgs e)
            {
                if (leftFlag)
                {
                    Point mouseSet = Control.MousePosition;
                    mouseSet.Offset(mouseOff.X, mouseOff.Y);  //设置移动后的位置
                    Location = mouseSet;
                }
            }

            private void Form1_MouseUp(object sender, MouseEventArgs e)
            {
                if (leftFlag)
                {
                    leftFlag = false;//释放鼠标后标注为false;
                }
            }