GameCanvasTest

import java.awt.Canvas;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics2D;
import java.awt.image.BufferStrategy;

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

/**
 * An example game canvas which renders using accelerated graphics and updates
 * with nanosecond precision.
 *
 * @author Ryan Greene
 *
 */
@SuppressWarnings("serial")
public final class GameCanvasTest extends Canvas {

    private static final long NANOSECONDS_PER_MILISECOND = 1000000;

    private static final long TICK_RATE = NANOSECONDS_PER_MILISECOND * 8;

    private final BufferStrategy strategy;

    public GameCanvasTest() {
        final JFrame container = new JFrame("Game");

        final JPanel panel = (JPanel) container.getContentPane();
        panel.setPreferredSize(new Dimension(800, 600));
        panel.setLayout(null);

        setBounds(0, 0, 800, 600);
        panel.add(this);

        setIgnoreRepaint(true);

        container.pack();
        container.setResizable(false);
        container.setVisible(true);

        container.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        requestFocus();

        createBufferStrategy(3);
        strategy = getBufferStrategy();
    }

    private double boxX = 0;

    private double boxY = 0;

    private double boxDX = .4;

    private double boxDY = .2;

    public void loop() {
        long lastTickTime = System.nanoTime();
        long delta;
        long sleepTime;
        Graphics2D g;
        while (true) {
            delta = System.nanoTime() - lastTickTime;
            lastTickTime = System.nanoTime();
            g = (Graphics2D) strategy.getDrawGraphics();

            // update
            boxX += (delta * boxDX) / NANOSECONDS_PER_MILISECOND;
            boxY += (delta * boxDY) / NANOSECONDS_PER_MILISECOND;

            // render
            g.setColor(Color.BLACK);
            g.fillRect(0, 0, 800, 600);
            g.setColor(Color.RED);
            g.drawRect((int) boxX, (int) boxY, 50, 50);

            g.dispose();
            strategy.show();

            sleepTime = TICK_RATE - (System.nanoTime() - lastTickTime);
            System.out.println("delta: " + delta + " sleep time: " + sleepTime + " (ms: " + sleepTime / NANOSECONDS_PER_MILISECOND + " ns: " + sleepTime % NANOSECONDS_PER_MILISECOND + ")");
            if (sleepTime > 0) {
                try {
                    Thread.sleep(sleepTime / NANOSECONDS_PER_MILISECOND, (int) (sleepTime % NANOSECONDS_PER_MILISECOND));
                } catch (final InterruptedException e) {
                    e.printStackTrace();
                }
            } else {
                System.out.println("[WARNING]: Load: " + (100 + Math.abs(sleepTime) / (TICK_RATE / 100)) + "%!");
            }
        }
    }

    public static void main(final String[] args) {
        new GameCanvasTest().loop();
    }
}