• Graphics is complicated considerably by "windowing"
• As a result, the performance of graphical systems is hampered by "windowing"
• One way around this problem is for a single graphical application to take control of the entire screen

• Environment:
  • A description of the overall capabilities of the system. In Java, an environment is encapsulated by the GraphicsEnvironment class
• Device:
  • A display device (usually a monitor, printer, or plotter). In Java, a device is encapsulated by the GraphicsDevice class.
• Configuration:
  • The settings for a particular device (e.g., resolution, color depth). In Java, a configuration is encapsulated by the GraphicsConfiguration class.

• Display Mode:
  • It is not always possible to change the display mode on the fly, and this makes full-screen graphics cumbersome
  • If the display mode is the same color depth as the screen then the colors will not have to be dithered, and this is usually much more efficient
• Page Flipping:
  • The screen has a video pointer and there are two (or more in the case of a multi-buffered system) images
  • This group of images is sometimes called a flip chain

• Image Acceleration:
  • In some system, an image can be accelerated in a variety of ways including including pixmaps, Video RAM (VRAM), and Accelerated Graphics Port (AGP)
• Volatility of Images:
  • A "volatile image" (which is encapsulated in Java by the VolatileImage class) is subject to losing its contents at any time in ways that are beyond the control of the application (e.g., situations caused by the operating system or by other applications).
  • Volatile images are required by some kinds of acceleration.

javaexamples/fullscreen/ShowCapabilities.java

        import java.awt.*;
import javax.swing.*;

/**
 * A utility that displays  full-screen exclusive 
 * mode graphics capabilities
 *
 * @author  Prof. David Bernstein, James Madison University
 * @version 1.0
 */
public class ShowCapabilities
{

    public static void main(String[] args)
    {
        BufferCapabilities       bcaps;
        DisplayMode[]            modes;
        GraphicsConfiguration[]  configs;
        GraphicsDevice[]         devices;
        GraphicsEnvironment      env;
        ImageCapabilities        icaps;
        int                      aram, i, j, k;


        env     = GraphicsEnvironment.getLocalGraphicsEnvironment();
        devices = env.getScreenDevices();

        System.out.println("Screen Devices: ");
        for (i=0; i < devices.length; i++) {

            System.out.println(i+"\t"+devices[i]);

            if (devices[i].isDisplayChangeSupported())
                System.out.println("\tDisplay Changes Supported");

            if (devices[i].isFullScreenSupported())
                System.out.println("\tFull-Screen Supported");

            aram = devices[i].getAvailableAcceleratedMemory();
            System.out.println("\tAccelerated RAM: "+aram/1024+" Kb");

            configs = devices[i].getConfigurations();
            for (j=0; j < configs.length; j++) {

                System.out.println("\t\tGraphicsConfiguraion "+j);
                icaps = configs[i].getImageCapabilities();
                if (icaps.isAccelerated()) 
                    System.out.println("\t\t\tAccelerated");
                if (icaps.isTrueVolatile()) 
                    System.out.println("\t\t\tTrue Volatile");
                bcaps = configs[i].getBufferCapabilities();
                if (bcaps.isMultiBufferAvailable())
                    System.out.println("\t\t\tMulti Buffer");
                if (bcaps.isPageFlipping())
                    System.out.println("\t\t\tPage Flipping");
            }


            modes = devices[i].getDisplayModes();
            for (j=0; j < modes.length; j++) {

                System.out.println("\t\t"+modes[j].getWidth()+"x"+
                                          modes[j].getHeight()+"x"+
                                          modes[j].getBitDepth());
            }


        }
    }
}
        

• Up until now, the "rendering" loop was under the control of the OS.
• With full-screen exclusive mode graphics, it is completely controlled by the application.

Without a Buffer Strategy

  Graphics g = getPaintGraphics();

  while (!done) 
  {

    // Rendering using g

  }

  g.dispose();

With a Buffer Strategy

    BufferStrategy       strategy;
    Window               window;
    
    // Construct the Window

    // Create the BufferStrategy
    window.createBufferStrategy(2);
    strategy = window.getBufferStrategy();

    Graphics g = strategy.getDrawGraphics();

    while (!done)
    {
        // Rendering using g
        strategy.show();
    }

    g.dispose();

The Stage Revisited

javaexamples/fullscreen/FullScreenStage.java

        import java.applet.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.awt.geom.*;
import java.net.*;
import javax.swing.*;
import java.util.Enumeration;
import java.util.Hashtable;

import visual.dynamic.described.Sprite;
import visual.statik.sampled.ImageFactory;

/**
 * A Stage that uses full-screen exclusive mode
 *
 * @version 1.0
 * @author  Prof. David Bernstein, James Madison University
 *
 */
public class FullScreenStage implements ActionListener, KeyListener
{
    private boolean          shouldRestart;
    private BufferStrategy   bufferStrategy;
    private Graphics         g;
    private Hashtable        sprites;
    private int              frameTime, height, restartTime, time, width;
    private JFrame           frame;
    private Rectangle        bounds;
    private TexturePaint     texture;
    private Timer            timer;



    /**
     * Explicit Value Constructor
     *
     * @param frameTime    Milliseconds between exitFrame events
     */
    public FullScreenStage(int frameTime)
    {
       BufferedImage         image;
       GraphicsConfiguration graphicsConfiguration;
       GraphicsDevice        graphicsDevice;
       GraphicsEnvironment   graphicsEnvironment;
       Rectangle2D.Float     r;
       
       
       
       sprites        = new Hashtable();
       
       this.frameTime = frameTime;
       time           = -frameTime;
       shouldRestart  = false;
       restartTime    = -1;
       
       
       
       // Configure graphics-related objects
       graphicsEnvironment =
          GraphicsEnvironment.getLocalGraphicsEnvironment();
       graphicsDevice =
          graphicsEnvironment.getDefaultScreenDevice();
       graphicsConfiguration = graphicsDevice.getDefaultConfiguration();
       
       // Configure the JFrame
       frame = new JFrame(graphicsConfiguration);
       frame.setUndecorated(true);
       frame.setIgnoreRepaint(true);
       frame.setResizable(false);
       frame.addKeyListener(this);
       
       // Set full-screen exclusive mode (if supported)
       if (graphicsDevice.isFullScreenSupported())
          graphicsDevice.setFullScreenWindow(frame);
       
       
       // Configure the BufferStrategy
       frame.createBufferStrategy(2);
       bufferStrategy = frame.getBufferStrategy();
       
       
       // Get the rendering engine
       g = bufferStrategy.getDrawGraphics();
       
       // Get the bounds 
       bounds = frame.getBounds();
       
       image = ImageFactory.createBufferedImage("sky.jpeg");
       r = new Rectangle2D.Float(0.0f,0.0f,        
                                 (float)(image.getWidth()), 
                                 (float)(image.getHeight()));
       texture = new TexturePaint(image, r);
       
       // Create a Timer in a separate Thread
       timer = new Timer(frameTime, this);
    }




    /**
     * Part of being an ActionListener (for the Timer)
     *
     * @param ae   The ActionEvent to handle
     */
    public void actionPerformed(ActionEvent ae)
    {        
       if (ae.getSource() == timer)
       {
          time += frameTime;
          if ((shouldRestart) && (time >= restartTime)) time = 0;
          fireExitFrame();
          render();  // Instead of repaint()
       }
    }



    /**
     * Add a MouseMotionListener
     */
    public void addMouseMotionListener(MouseMotionListener mml)
    {
       frame.addMouseMotionListener(mml);
    }
    



    /**
     * Add a Sprite to the Stage
     *
     * @param s   The Sprite to add
     */
    public void addSprite(Sprite s)
    {
        sprites.put(s, s);
    }



    /**
     * Draw (i.e., render) the Stage
     *
     * @param g  The Graphics context to paint on
     */
    public void draw(Graphics g)
    {
        Enumeration e;
        Graphics2D  g2;
        Sprite      s;

        g2 = (Graphics2D)g;

        // Paint the background
        g2.setPaint(texture);
        g2.fillRect(0,0,bounds.width,bounds.height);

        // Have each Sprite render itself
        //
        e = sprites.elements();

        while (e.hasMoreElements()) {

            s = (Sprite)e.nextElement();
            s.render(g2);
        }
    }




    /**
     * Fire an exitFrame event to every Sprite
     */
    public void fireExitFrame()
    {
        Enumeration       e;
        Sprite s;


        e = sprites.elements();

        while (e.hasMoreElements()) {

            s = (Sprite)e.nextElement();
            s.exitFrame(time);
        }
    }



    /**
     * Handle key Pressedevents (required by KeyListener)
     *
     * @param evt   The KeyEvent
     */
    public void keyPressed(KeyEvent evt)
    {
        if (evt.getKeyCode() == KeyEvent.VK_Q) stop(); 
    }


    /**
     * Handle keyReleased events (required by KeyListener)
     *
     * @param evt   The KeyEvent
     */
    public void keyReleased(KeyEvent evt)
    {
    }


    /**
     * Handle keyTyped events (required by KeyListener)
     *
     * @param evt   The KeyEvent
     */
    public void keyTyped(KeyEvent evt)
    {
    }



    /**
     * Render the stage (in lieu of repaint)
     */
    public void render()
    {
        draw(g);
        bufferStrategy.show();
    }



    /**
     * Remove a Sprite from the Stage
     *
     * @param s   The Sprite to add
     */
    public void removeSprite(Sprite s)
    {
        sprites.remove(s);
    }



    /**
     * Start the Stage
     */
    public void start()
    {
        timer.start();
    }
    
    

    /**
     * Stop the Stage
     */
    public void stop()
    {
        timer.stop();
        g.dispose();
        System.exit(0);
    }
}