import java.awt.AWTEvent;
import java.awt.Canvas;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GraphicsConfiguration;
import java.awt.GraphicsEnvironment;
import java.awt.Transparency;
import java.awt.event.KeyEvent;
import java.awt.image.BufferStrategy;
import java.awt.image.BufferedImage;

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

public class Example extends Canvas {
	static final int KEYS = 65536;

	int font_height = 10;
	int width_in_chars = 80;
	int height_in_chars = 40;

	BufferStrategy strategy;
	BufferedImage buffer;
	boolean keys[];

	public Example() {
		Font font = new Font(Font.MONOSPACED, Font.PLAIN, font_height);
		keys = new boolean[KEYS];

		int win_width = width_in_chars * getFontMetrics(font).charWidth(' ');
		int win_height = height_in_chars * font_height;

		JFrame f = new JFrame();
		JPanel p = (JPanel) f.getContentPane();

		p.setPreferredSize(new Dimension(win_width, win_width));
		p.setLayout(null);

		setBounds(0, 0, win_width, win_height);
		p.add(this);

		f.pack();
		f.setResizable(false);
		f.setTitle("Example Project");
		f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		f.setVisible(true);
		f.setFont(font);
		f.setLocationRelativeTo(null);

		createBufferStrategy(2);
		strategy = getBufferStrategy();

		GraphicsConfiguration gc = GraphicsEnvironment
				.getLocalGraphicsEnvironment().getDefaultScreenDevice()
				.getDefaultConfiguration();
		buffer = gc.createCompatibleImage(win_width, win_height,
				Transparency.OPAQUE);

		setIgnoreRepaint(true);
		enableEvents(AWTEvent.KEY_EVENT_MASK);
	}

	void mainLoop() {
		while (!keys[KeyEvent.VK_ESCAPE]) {
			try {
				Thread.sleep(10);
			} catch (InterruptedException e) { }

			// draw on buffer
			buffer.getGraphics().drawLine(0, 0, 100, 100);

			// blit buffer to screen
			Graphics2D g = (Graphics2D) strategy.getDrawGraphics();
			paint(g);
			g.dispose();
			strategy.show();
		}
	}

	@Override
	public void paint(Graphics g) {
		g.drawImage(buffer, 0, 0, this);
	}

	@Override
	public void processKeyEvent(KeyEvent e) {
		keys[e.getKeyCode()] = e.getID() == KeyEvent.KEY_PRESSED;
	}

	public static void main(String[] args) {
		new Example().mainLoop();
	}
}