Draw a graph (similar to GeoGebra)

GraphDrawer.java

import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.LayoutManager;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.LayoutStyle;

import java.awt.BorderLayout;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;

import javax.swing.JLabel;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.geom.AffineTransform;


public class GraphDrawer extends JFrame {
	
	private JPanel pnlGraph;
	/**
	 * Launch the application.
	 */
	public static void main(String[] args) {
		EventQueue.invokeLater(new Runnable() {
			public void run() {
				try {
					GraphDrawer frame = new GraphDrawer();
					frame.setVisible(true);
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		});
	}

	/**
	 * Create the frame.
	 */
	public GraphDrawer() {
		setBounds(100, 100, 800, 600);
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		
		pnlGraph = new GraphPanel();
		pnlGraph.addMouseMotionListener((MouseMotionListener) pnlGraph);
		getContentPane().add(pnlGraph, BorderLayout.CENTER);

	}

}
class GraphPanel extends JPanel implements MouseMotionListener{
	private int mousex,mousey;
	private JLabel lblCoords;
	
	public GraphPanel(){
		
		setLayout(new BorderLayout(0,0));
		lblCoords=new JLabel("Coords: 0, 0");
		add(lblCoords,BorderLayout.SOUTH);
		
	}
	
	protected void paintComponent(Graphics g) {
		super.paintComponent(g);
		
		Graphics2D g2 = (Graphics2D)g;
        AffineTransform at = g2.getTransform(),atOrig=g2.getTransform();
        at.translate(getWidth()/2, getHeight()/2);
        at.scale(1, -1);
        at.translate(0, 0);
        g2.setTransform(at);
        
		for(int i=-200;i<200;++i)
			g.drawLine(i, (int)(0.0001*f(i)), i+1, (int)(0.0001*f(i + 1)));

        g2.setTransform(atOrig);
		lblCoords.setText("Coords: " + String.valueOf(mousex-getWidth()/2) + ", " + String.valueOf(mousey-getHeight()/2));
	}
	
	private double f(double x){
		return 2*x*x*x + 9*x*x + 3*x + 8;
	}

	public void mouseDragged(MouseEvent arg0) {
	}

	public void mouseMoved(MouseEvent arg0) {
		mousex=arg0.getPoint().x;
		mousey=arg0.getPoint().y;
		this.repaint();
	}

}