import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image; // Used to create an image buffer
import java.awt.event.ActionEvent; // Needed by the Timer
import java.awt.event.ActionListener; // Needed by the Timer
import java.awt.Graphics2D; // Used for anti-aliasing
import java.awt.RenderingHints; // Used for anti-aliasing

import javax.swing.JFrame;
import javax.swing.Timer;

public class GraphicsMoveObjectsWithTimerAndJFrame extends JFrame implements ActionListener
{
	Timer timer;
	Image image;
	Graphics graphics;
	int width = 400, height = 250;
	int dotSize = 25, dotBlueX = 150, dotBlueY = 70, dotMagentaX = 230, dotMagentaY = 190;
	int directionBlue = 1, speedBlue = 2, directionMagenta = 1, speedMagenta = 4;

	public static void main(String[] args)
	{
		// Create an instance of the 'GraphicsMoveObjectsWithTimerAndJFrame'
		//  class and set the frame background color
		GraphicsMoveObjectsWithTimerAndJFrame frame = new GraphicsMoveObjectsWithTimerAndJFrame();
		frame.setBackground(Color.WHITE);
	}

	// Constructor
	public GraphicsMoveObjectsWithTimerAndJFrame()
	{
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		setSize(width, height);
		setTitle("Object Movement with a Timer on a JFrame");
		setLocationRelativeTo(null);
		setResizable(false);
		setVisible(true);

		// Set and start a new Swing timer to fire every 10/1000 milliseconds
		//  (after an initial delay of 500/1000 milliseconds); this timer,
		//  along with the distance (number of pixels) that the blue dots
		//  move with each cycle, controls how fast the dots move on the frame
		timer = new Timer(10, this);
		timer.setInitialDelay(500);
		timer.start();
	}

	// This method is called automatically by the timer
	public void actionPerformed(ActionEvent e)
	{
		// Update the position/direction of the blue dot 
		dotBlueX += speedBlue * directionBlue;
		if (dotBlueX < 16 || dotBlueX > width - 18)
			directionBlue = -directionBlue;

		// Update the position/direction of the magenta dot
		dotMagentaX += speedMagenta * directionMagenta;
		if (dotMagentaX < 16 || dotMagentaX > width - 18)
			directionMagenta = -directionMagenta;

		repaint();
	}

	public void paint(Graphics g)
	{
		// Prepare to create the image on a separate 'Image' instance; this
		//  should prevent flickering by using a "buffer" on which the frame
		//  image will first be drawn before it is displayed to the user
		image = createImage(width, height);
		graphics = image.getGraphics();

		// This line causes graphics and text to be rendered with anti-aliasing
		//  turned on, making the overall display look smoother and cleaner
		((Graphics2D) graphics).setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

		// Draw/Redraw the blue dot
		graphics.setColor(Color.BLUE);
		graphics.fillOval(dotBlueX - dotSize / 2, dotBlueY - dotSize / 2, dotSize, dotSize);

		// Draw/Redraw the magenta dot
		graphics.setColor(Color.MAGENTA);
		graphics.fillOval(dotMagentaX - dotSize / 2, dotMagentaY - dotSize / 2, dotSize, dotSize);

		// Display (Draw) the buffered image on the frame
		g.drawImage(image, 0, 0, null);
	}
}