Java full screen image viewer

abstract

This article contains a source code of a simple Java program which draws image(from file or http:// URL) at the center of full-screen window. It uses AWT Toolkit to load image (from the file or http URL) and Swing JFrame to display it.

compatible

Sun Java 1.4 or higher

This program consist of single class Test1, which extends standard Swing JFrame class. Majority of the code is in the class constructor: there are two simple event listeners there (mouse listener to exit program on click and window listener which will end program when the window is closed), full screen switching code and image loading.

Full screen switching code is quote simple:

this.setUndecorated(true);
this.setVisible(true);
GraphicsEnvironment.getLocalGraphicsEnvironment().getDefaultScreenDevice().setFullScreenWindow(this);

We remove window borders and menus (setUndecorated method), make sure that the window is visible(setVisible) and call setFullScreenWindow. You can read more about advanced full-screen API at sun.com.

Program will try to load and draw image specified as a command line argument. If argument starts with "http://" substring, we create URL object. Otherwise, argument is treated like a file name and passed directly to AWT Toolkit getImage method.

Toolkit.getDefaultToolkit().getImage() method can load GIF, JPEG and PNG files. It accepts either string argument (file name) or URL object.

import java.awt.Graphics;
import java.awt.GraphicsEnvironment;
import java.awt.Image;
import java.awt.Toolkit;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.net.MalformedURLException;
import java.net.URL;
 
import javax.swing.JFrame;
 
public class Test1 extends JFrame {
 
    // this line is needed to avoid serialization warnings 
    private static final long serialVersionUID = 1L;
 
 
    Image screenImage; // downloaded image 
    int w, h; // Display height and width
 
 
    // Program entry
    public static void main(String[] args) throws Exception {
        if (args.length < 1) // by default program will load AnyExample logo
            new Test1("http://www.anyexample.com/i/logo.gif"); 
        else
            new Test1(args[0]); // or first command-line argument
    }
 
    // Class constructor 
    Test1(String source) throws MalformedURLException {
 
        // Exiting program on window close
        addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });
 
        // Exitig program on mouse click
        addMouseListener(new MouseListener() {
            public void mouseClicked(MouseEvent e) { System.exit(0); }
            public void mousePressed(MouseEvent e) {}
            public void mouseReleased(MouseEvent e) {}
            public void mouseEntered(MouseEvent e) {}
            public void mouseExited(MouseEvent e) {}
        }
        );
 
        // remove window frame 
        this.setUndecorated(true);
 
        // window should be visible
        this.setVisible(true);
 
        // switching to fullscreen mode
        GraphicsEnvironment.getLocalGraphicsEnvironment().
        getDefaultScreenDevice().setFullScreenWindow(this);
 
        // getting display resolution: width and height
        w = this.getWidth();
        h = this.getHeight();
        System.out.println("Display resolution: " + String.valueOf(w) + "x" + String.valueOf(h));
 
        // loading image 
        if (source.startsWith("http://")) // http:// URL was specified
            screenImage = Toolkit.getDefaultToolkit().getImage(new URL(source));
        else
            screenImage = Toolkit.getDefaultToolkit().getImage(source); // otherwise - file
    }
 
    public void paint (Graphics g) {
        if (screenImage != null) // if screenImage is not null (image loaded and ready)
            g.drawImage(screenImage, // draw it 
                        w/2 - screenImage.getWidth(this) / 2, // at the center 
                        h/2 - screenImage.getHeight(this) / 2, // of screen
                        this);
            // to draw image at the center of screen
            // we calculate X position as a half of screen width minus half of image width
            // Y position as a half of screen height minus half of image height
    }
 
 
}

warning

This program will display nothing if the image was not loaded.

tested by AnyExample.com on 2007-01-23

JDK 1.5

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