c# GDI region

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using System.Windows.Forms;

using System.Drawing.Drawing2D;

namespace irregular

{

    public partial class Form1 : Form

    {

        public Form1()

        {

            InitializeComponent();

            timer1.Start();

        }

        private float f=0f;

        private void Form1_Paint(object sender, PaintEventArgs e)

        {

            GraphicsPath gp = new GraphicsPath();

            gp.AddEllipse(20, 20, 110, 110);

            Rectangle a = new Rectangle(110, 110, 220, 220);

            gp.AddRectangle(a);

            Matrix rotation = new Matrix(1, 0, 0, 1, 1, 1);

            PointF rotationpoint = new PointF(110f, 110f);

            rotation.RotateAt(f, rotationpoint);

            gp.Transform(rotation);

            e.Graphics.DrawPath(Pens.Red, gp);

            f += 1;

            this.Region = new Region(gp);

        }

        private void timer1_Tick(object sender, EventArgs e)

        {

            this.Refresh();

        }

    }

}