import java.awt.*;					// Graphics
import java.awt.event.*;			// for Timer, ActionEvent
import javax.swing.*;				// JPanel, JFrame

public class Ch16_15
{
	public static void main(String[] args)
	{
		JFrame f=new JFrame("racing car");
		f.setSize(500,150);
		f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		RacePanel rp=new RacePanel();
		f.add(rp);
		f.setVisible(true);
	}
	
	public static class RacePanel extends JPanel implements ActionListener		// draw onto the JPanel and use the Timer
	{
		private int x,y;					// x,y coordinate of the lower left hand corner of the car
		public RacePanel()
		{
			Timer t=new Timer(10,this);		// create the Timer, set for 10 millisecond delay
			x=20;							// starting x coordinate of the car
			y=80;							// y coordinate of the bottom of the car, will not change
			t.start();						// start the Timer to animate the image
		}
		
		public void actionPerformed(ActionEvent e)		// called each time the Timer reaches the end of its delay
		{
			x++;							// move the car horizontally by 1 pixel, increase this to make the car move faster
			if(x>420) x=20;					// if it reaches the right border, start it over on the left
			repaint();						// now that we've moved the car, call paintComponent to redraw it at its new position
		}
		
		public void paintComponent(Graphics g)
		{
			super.paintComponent(g);		// blank the screen to start new
			int[] a={x+10,x+20,x+30,x+40};	// draw the canopy portion of the car as a polygon
			int[] b={y-20,y-30,y-30,y-20};
			g.setColor(Color.black);		// set color to black for the tires
			g.fillOval(x+10,y-10,10,10);	// back tire
			g.fillOval(x+30,y-10,10,10);	// front tire
			g.setColor(Color.gray);			// use grey for the body
			g.fillRect(x,y-20,50,10);		// the body of the car
			g.setColor(Color.green);		// use green for the canopy
			g.fillPolygon(a,b,4);			// draw the canopy
		}
	}
}