public class RajzPanel : Panel
{
    public RajzPanel()
    {
        this.DoubleBuffered = true;
        this.ResizeRedraw = true;
    }

    public bool Pufferelt
    {
        get { return this.DoubleBuffered; }
        set { this.DoubleBuffered = value; }
    }
}

// Form1.cs
private float labdaX = 60, labdaY = 60, vx = 4, vy = 3;
private const int R = 20;
private int paintDb = 0;
private List<Point[]> vonalak = new List<Point[]>();
private Random veletlen = new Random();

private void Form1_Load(object sender, EventArgs e)
{
    tmrAnim.Interval = 20;
    tmrAnim.Start();
    chkPuffer.Checked = true;
    chkSima.Checked = true;
}

private void tmrAnim_Tick(object sender, EventArgs e)
{
    float seb = tbSebesseg.Value / 4f;

    labdaX += vx * seb;
    labdaY += vy * seb;

    if (labdaX - R < 0) { labdaX = R; vx = Math.Abs(vx); }
    if (labdaX + R > rp.Width) { labdaX = rp.Width - R; vx = -Math.Abs(vx); }
    if (labdaY - R < 0) { labdaY = R; vy = Math.Abs(vy); }
    if (labdaY + R > rp.Height) { labdaY = rp.Height - R; vy = -Math.Abs(vy); }

    if (chkRefresh.Checked) { rp.Refresh(); } else { rp.Invalidate(); }
}

private void rp_Paint(object sender, PaintEventArgs e)
{
    Graphics g = e.Graphics;
    paintDb++;

    g.SmoothingMode = chkSima.Checked ? SmoothingMode.AntiAlias : SmoothingMode.None;
    g.Clear(Color.White);

    using (Pen halvany = new Pen(Color.Gainsboro))
    {
        for (int x = 0; x < rp.Width; x += 40) { g.DrawLine(halvany, x, 0, x, rp.Height); }
        for (int y = 0; y < rp.Height; y += 40) { g.DrawLine(halvany, 0, y, rp.Width, y); }
    }

    using (Pen vonal = new Pen(Color.SteelBlue, 2))
    {
        foreach (Point[] v in vonalak) { g.DrawLine(vonal, v[0], v[1]); }   // a modellből
    }

    using (Brush labda = new SolidBrush(Color.FromArgb(104, 64, 165)))
    using (Pen perem = new Pen(Color.Black, 2))
    {
        g.FillEllipse(labda, labdaX - R, labdaY - R, 2 * R, 2 * R);
        g.DrawEllipse(perem, labdaX - R, labdaY - R, 2 * R, 2 * R);
    }

    // mosolygó arc a bal alsó sarokban
    int ax = 20, ay = rp.Height - 100;

    using (Brush sarga = new SolidBrush(Color.Gold))
    using (Pen toll = new Pen(Color.Black, 2))
    {
        g.FillEllipse(sarga, ax, ay, 80, 80);
        g.DrawEllipse(toll, ax, ay, 80, 80);
        g.FillEllipse(Brushes.Black, ax + 22, ay + 24, 10, 10);
        g.FillEllipse(Brushes.Black, ax + 48, ay + 24, 10, 10);
        g.DrawArc(toll, ax + 18, ay + 28, 44, 36, 20, 140);
    }

    using (Font betu = new Font("Segoe UI", 11))
    {
        g.DrawString("Paint hívások: " + paintDb + "   ClipRectangle: " + e.ClipRectangle.Width + " × " + e.ClipRectangle.Height, betu, Brushes.Black, 8, 8);
    }
}

private void chkPuffer_CheckedChanged(object sender, EventArgs e)
{
    rp.Pufferelt = chkPuffer.Checked;
}

private void btnCreateGraphics_Click(object sender, EventArgs e)
{
    using (Graphics g = rp.CreateGraphics())
    using (Pen toll = new Pen(Color.Red, 3))
    {
        g.DrawLine(toll, 0, 0, rp.Width, rp.Height);   // az animáció következő képkockája letörli
    }
}

private void btnModellVonal_Click(object sender, EventArgs e)
{
    vonalak.Add(new Point[] { new Point(veletlen.Next(rp.Width), veletlen.Next(rp.Height)), new Point(veletlen.Next(rp.Width), veletlen.Next(rp.Height)) });
    rp.Invalidate();
}

private void btnStart_Click(object sender, EventArgs e)
{
    tmrAnim.Enabled = !tmrAnim.Enabled;
}