GamePanel.java

package al.artofsoul.batbatgame.main;

import al.artofsoul.batbatgame.gamestate.GameStateManager;
import al.artofsoul.batbatgame.handlers.Keys;
import al.artofsoul.batbatgame.handlers.LoggingHelper;

import javax.swing.*;
import java.awt.*;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.image.BufferedImage;
import java.util.logging.Level;

public class GamePanel extends JPanel implements Runnable, KeyListener {

    // dimensions
    public static final int WIDTH = 320;
    public static final int HEIGHT = 240;
    public static final int SCALE = 2;
    /**
     *
     */
    private static final long serialVersionUID = 1275876853084636658L;
    // game thread
    private transient Thread thread;
    private boolean running;
    private int fps = 60;
    private long targetTime = 1000 / fps;

    // image
    private transient BufferedImage image;
    private transient Graphics2D g;

    // game state manager
    private transient GameStateManager gsm;

    // other
    private boolean recording = false;
    private int recordingCount = 0;
    private boolean screenshot;

    public GamePanel() {
        super();
        setPreferredSize(new Dimension(WIDTH * SCALE, HEIGHT * SCALE));
        setFocusable(true);
        requestFocus();
    }

    @Override
    public void addNotify() {
        super.addNotify();
        if (thread == null) {
            thread = new Thread(this);
            addKeyListener(this);
            thread.start();
        }
    }

    private void init() {

        image = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);
        g = (Graphics2D) image.getGraphics();

        running = true;

        gsm = new GameStateManager();

    }

    @Override
    public void run() {
        init();

        long start;
        long elapsed;
        long wait;

        // game loop
        while (running) {

            start = System.nanoTime();

            update();
            draw();
            drawToScreen();

            elapsed = System.nanoTime() - start;

            wait = targetTime - elapsed / 1000000;
            if (wait < 0)
                wait = 5;

            try {
                Thread.sleep(wait);
            } catch (Exception e) {
                LoggingHelper.LOGGER.log(Level.SEVERE, e.getMessage());
            }

        }

    }

    private void update() {
        gsm.update();
        Keys.update();
    }

    private void draw() {
        gsm.draw(g);
    }

    private void drawToScreen() {
        Graphics g2 = getGraphics();
        g2.drawImage(image, 0, 0, WIDTH * SCALE, HEIGHT * SCALE, null);
        g2.dispose();
        if (screenshot) {
            screenshot = false;
            try {
                java.io.File out = new java.io.File("screenshot " + System.nanoTime() + ".gif");
                javax.imageio.ImageIO.write(image, "gif", out);
            } catch (Exception e) {
                LoggingHelper.LOGGER.log(Level.SEVERE, e.getMessage());
            }
        }
        if (!recording)
            return;
        try {
            java.io.File out = new java.io.File("C:\\out\\frame" + recordingCount + ".gif");
            javax.imageio.ImageIO.write(image, "gif", out);
            recordingCount++;
        } catch (Exception e) {
            LoggingHelper.LOGGER.log(Level.SEVERE, e.getMessage());
        }
    }

    @Override
    public void keyPressed(KeyEvent key) {
        if (key.isControlDown()) {
            if (key.getKeyCode() == KeyEvent.VK_R) {
                recording = !recording;
                return;
            }
            if (key.getKeyCode() == KeyEvent.VK_S) {
                screenshot = true;
                return;
            }
        }
        Keys.keySet(key.getKeyCode(), true);
    }

    @Override
    public void keyReleased(KeyEvent key) {
        Keys.keySet(key.getKeyCode(), false);
    }

    @Override
    public void keyTyped(KeyEvent e) {
        // Not necessary

    }

}