Circle

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;

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

        Random random = new Random();

        Color getRandomColor()
        {
            return Color.FromArgb(
                 random.Next(256),
                 random.Next(256),
                 random.Next(256));
        }

        protected override void OnPaint(PaintEventArgs e)
        {
            Graphics g = this.CreateGraphics();
            int x0 = this.Width / 2;
            int y0 = this.Height / 2;

            for (int r = 0; r < this.Height / 2; r++)
            {
                g.DrawEllipse(
                    new Pen(getRandomColor(), 1),
                    x0 - r,
                    y0 - r/2,
                    r * 2,
                    r * 2
                );
            }
            g.Dispose();
        }
    }
}