主要代码

public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Paint(object sender, PaintEventArgs e)
        {
            Type(this, 25, 0.1);
        }

        private void Type(Control sender, int p_1, double p_2)
        {
            GraphicsPath oPath = new GraphicsPath();
            oPath.AddClosedCurve(new Point[] {
                new Point(0, sender.Height / p_1),
                new Point(sender.Width / p_1, 0),
                new Point(sender.Width - sender.Width / p_1, 0),
                new Point(sender.Width, sender.Height / p_1),
                new Point(sender.Width, sender.Height - sender.Height / p_1),
                new Point(sender.Width - sender.Width / p_1, sender.Height),
                new Point(sender.Width / p_1, sender.Height),
                new Point(0, sender.Height - sender.Height / p_1) },
                (float)p_2); sender.Region = new Region(oPath);
        }

        private void Form1_Resize(object sender, EventArgs e)
        {
            Type(this, 25, 0.1);
        }

        Point _Location;
        Boolean _Down = false;
        private void Form1_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                _Location = new Point(e.X, e.Y);
                _Down = true;
            }
        }

        private void Form1_MouseMove(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left && _Down == true)
            {
                this.Left += e.X - _Location.X;
                this.Top += e.Y - _Location.Y;
            }
        }

        private void Form1_MouseUp(object sender, MouseEventArgs e)
        {
            _Down = false;
        }
    }