drawOval的异常行为

Question

I'm facing problem with drawOval function. I use it to draw circle but the result doesn't look like a circle. I think this behavior happened after certain height for Jpanel. Scroll down till the end and you can get the result as shown in the attached image below. Could anyone offer an explanation for this?

Result after Execute the sample program

import java.awt.*;
import java.awt.geom.*;
import javax.swing.*;

public class TestMain
{
    public static void main(String[] args)
    {
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JScrollPane jsp = new JScrollPane();
        jsp.setViewportView(new TestPanel());
        f.getContentPane().add(jsp);
        f.setSize(500,400);
        f.setLocation(200,200);
        f.setVisible(true);
    }
}

class TestPanel extends JPanel
{
    public TestPanel()
    {
        setPreferredSize(new Dimension(1960 , 77660240));
        setBackground(Color.white);
    }

    protected void paintComponent(Graphics g)
    {
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D)g;
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                            RenderingHints.VALUE_ANTIALIAS_ON);
        g2.drawRect(30, 77660141, 100, 20);
        g2.drawOval(15, 77660141, 10, 10);
        g2.draw(new Ellipse2D.Double(140, 77660141,
                             10,
                             10));
        g2.draw(new Ellipse2D.Double(160, 77660141,
                             10,
                             10));
        g2.draw(new Ellipse2D.Double(180, 77660141,
                             10,
                             10));
        g2.draw(new Ellipse2D.Double(200, 77660141,
                             30,
                             30));
    }
}

Answer 1

将面板的尺寸更改为更合理的尺寸，例如：1000，它将可以正常工作。