using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace Kulka
{
    public partial class Form1 : Form
    {
        int x = 0, y = 0;
        int vX = 20, vY = 20;


        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Paint(object sender, PaintEventArgs e)
        {
            Graphics g = e.Graphics;
            SolidBrush b = new SolidBrush(Color.Blue);
            g.FillEllipse(b, x, y, 80, 80);
        }

        private void timer1_Tick(object sender, EventArgs e)
        {
            x += vX;
            y += vY;


            if (y + 80 >= this.ClientRectangle.Height)
            {
                vY = -vY;
            }
            if (y <= 0)
            {
                vY = 20;
            }
            else if (x + 80 >= this.ClientRectangle.Width)
            {
                vX = -vX;
            }
            if (x <= 0)
            {
                vX = 20;
            }

            this.Invalidate();
        }
    }
}