C# VS2017 WPF : fail to create draw movement on form

Question

Hi

I am tryintg to draw a moving rectangle and circle on a form using the paint method.

A button should start the process. 2nd pres should end the program.

The once variable is a global boolean set to True on start.

X1 is a global int, set to 10 on start.

Up is a global boolean, set to true on start. 

 

Each iteeration the X1 variable is increased until 100, going down to 10, endlessly. 

 

Two problems:

1- No movement of the drawing on the form

2- No control on the form once the program starts.

 

 

private void Form1_Paint(object sender, PaintEventArgs e)
{

    Pen red = new Pen(Color.Red,3);
    Rectangle rect = new Rectangle(x1, x1, x1, x1);
    Rectangle circle = new Rectangle(x1+10, x1 + 10, x1 + 50, x1 + 50);

    //Graphics g = e.Graphics;
    Graphics g = CreateGraphics();
    g.DrawRectangle(red,rect);
    g.DrawEllipse(red, circle);

    red.Dispose();
    g.Dispose();
}

private void button2_Click(object sender, EventArgs e)
{
    if (once)
        once = false;
    else
        Environment.Exit(0);

    while (true)
    {
        if (up )
        {
            x1 += 10;
            if (x1 > 100)
                up = false;
        }
        else
        {
            x1 -= 10;
            if (x1 <= 10)
                up = true;
        }
        this.Invalidate();
        Thread.Sleep(500);
    }
}