Full Screen Active Rendering

To change the above windowed example into a full screen application requires a few changes. The first thing that needs to be done is removing the JFrame border and title bar. Doing this, however, will leave no way for the user to exit the application. A simple key handler and a static boolean variable does the trick...

public class SimpleFullScreenGame {

static boolean running;

public static void main( String[] args ) {
  
  // Create game window...
  JFrame app = new JFrame();
  app.setIgnoreRepaint( true );
  app.setUndecorated( true );
  
  // Add ESC listener to quit...
  app.addKeyListener( new KeyAdapter() {
    public void keyPressed( KeyEvent e ) {
      if( e.getKeyCode() == KeyEvent.VK_ESCAPE )
        running = false;
      }
  });

// Get graphics configuration...
GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
GraphicsDevice gd = ge.getDefaultScreenDevice();
GraphicsConfiguration gc = gd.getDefaultConfiguration();

// Change to full screen, 640 x 480, 32 bit color
gd.setFullScreenWindow( app );
if( gd.isDisplayChangeSupported() ) {
  gd.setDisplayMode( 
    new DisplayMode( 640, 480, 32, DisplayMode.REFRESH_RATE_UNKNOWN )
  );
}

running = true;
while( running ) {
  // do game stuff here!
}

gd.setFullScreenWindow( null );
System.exit(0);

import java.awt.*;
import java.util.Random;
import javax.swing.JFrame;

public class SimpleFullScreenGame {
	
  static boolean running;
	
  public static void main( String[] args ) {
		
    // Create game window...
    JFrame app = new JFrame();
    app.setIgnoreRepaint( true );
    app.setUndecorated( true );
		
    // Add ESC listener to quit...
    app.addKeyListener( new KeyAdapter() {
      public void keyPressed( KeyEvent e ) {
        if( e.getKeyCode() == KeyEvent.VK_ESCAPE )
	    running = false;
	  }
    });
		
    // Get graphics configuration...
    GraphicsEnvironment ge = 
        GraphicsEnvironment.getLocalGraphicsEnvironment();
    GraphicsDevice gd = ge.getDefaultScreenDevice();
    GraphicsConfiguration gc = gd.getDefaultConfiguration();

    // Change to full screen
    gd.setFullScreenWindow( app );
    if( gd.isDisplayChangeSupported() ) {
      gd.setDisplayMode( 
        new DisplayMode( 640, 480, 32, DisplayMode.REFRESH_RATE_UNKNOWN )
      );
    }
		
    // Create BackBuffer...
    app.createBufferStrategy( 2 );
    BufferStrategy buffer = app.getBufferStrategy();
		
    // Create off-screen drawing surface
    BufferedImage bi = gc.createCompatibleImage( 640, 480 );

    // Objects needed for rendering...
    Graphics graphics = null;
    Graphics2D g2d = null;
    Color background = Color.BLACK;
    Random rand = new Random();
		
    // Variables for counting frames per seconds
    int fps = 0;
    int frames = 0;
    long totalTime = 0;
    long curTime = System.currentTimeMillis();
    long lastTime = curTime;
		
    running = true;
    while( running ) {
      try {
        // count Frames per second...
        lastTime = curTime;
        curTime = System.currentTimeMillis();
        totalTime += curTime - lastTime;
        if( totalTime > 1000 ) {
          totalTime -= 1000;
          fps = frames;
          frames = 0;
        } 
        ++frames;

        // clear back buffer...
        g2d = bi.createGraphics();
        g2d.setColor( background );
        g2d.fillRect( 0, 0, 639, 479 );
				
        // draw some rectangles...
        for( int i = 0; i < 20; ++i ) {
          int r = rand.nextInt(256);
          int g = rand.nextInt(256);
          int b = rand.nextInt(256);
          g2d.setColor( new Color(r,g,b) );
          int x = rand.nextInt( 640/2 );
          int y = rand.nextInt( 480/2 );
          int w = rand.nextInt( 640/2 );
          int h = rand.nextInt( 480/2 );
          g2d.fillRect( x, y, w, h );
        }
				
        // display frames per second...
        g2d.setFont( new Font( "Courier New", Font.PLAIN, 12 ) );
        g2d.setColor( Color.GREEN );
        g2d.drawString( String.format( "FPS: %s", fps ), 20, 20 );
				
        // Blit image and flip...
        graphics = buffer.getDrawGraphics();
        graphics.drawImage( bi, 0, 0, null );
				
        if( !buffer.contentsLost() )
          buffer.show();
				
      } finally {
        // release resources
        if( graphics != null ) 
          graphics.dispose();
        if( g2d != null ) 
          g2d.dispose();
      }
    }
		
    gd.setFullScreenWindow( null );
    System.exit(0);
  }
}

Now What?

WOW! That covered a lot of material in a short amount of time. Active rendering makes it possible to learn the fundamentals of 2D game programming while using Java. While there are still many things that need to be handled to make a complete game, such as input polling, image loading, and sound, this should be enough to get those creative juices flowing. Stay tuned for more articles covering Java games!

References

• Full-Screen Exclusive Mode API by Michael Martak - Article about the basics of Full Screen Exclusive mode
• Avoid Common Pitfalls when Programming 2D Graphics in Java by Alexandre Denault and Jörg Kienzle - Article about the lessons learned while programming the minueto game library
• Killer Game Programming in Java by Andrew Davison - Great book with lots of source code to download

_{Article written by Tim Wright
Copyright© 2007 - All rights reserved}