I'm kinda new to programming and got a question on what is a good practice.

I created a class that represents a ball and it has a function Jump() that use 2 timers and get the ball up and down.

I know that in Winforms you got to call Invalidate() every time you want to repaint the screen, or part of it. I didn't find a good way to do that, so I reference the form in my class, and called Invalidate() inside my ball class every time I need to repaint to ball movement.

(this works but I got a feeling that this is not a good practice)

Here is the class I created:

public class Ball
{
    public Form1 parent;//----> here is the reference to the form
    public Rectangle ball;
    Size size;
    public  Point p;
    Timer timerBallGoUp  = new Timer();
    Timer timerBallGDown = new Timer();

    public  int ballY;

    public Ball(Size _size, Point _p)
    {
        size = _size;
        p = _p;
        ball = new Rectangle(p, size);
    }

    public void Jump()
    {
        ballY = p.Y;
        timerBallGDown.Elapsed += ballGoDown;
        timerBallGDown.Interval = 50;
        timerBallGoUp.Elapsed += ballGoUp;
        timerBallGoUp.Interval = 50;
        timerBallGoUp.Start();
    }

    private void ballGoUp(object obj,ElapsedEventArgs e)
    {
        p.Y++;
        ball.Location = new Point(ball.Location.X, p.Y);
        if (p.Y >= ballY + 50)
        {
            timerBallGoUp.Stop();
            timerBallGDown.Start();
        }

        parent.Invalidate(); // here i call parent.Invalidate() 1
    }

    private void ballGoDown(object obj, ElapsedEventArgs e)
    {
        p.Y--;
        ball.Location = new Point(ball.Location.X, p.Y);

        if (p.Y <= ballY)
        {
            timerBallGDown.Stop();
            timerBallGoUp.Start();
        }

        parent.Invalidate(); // here i call parent.Invalidate() 2
    }
}

I'm wondring if there is a better way to do that?

(sorry for my english)