package com.knutejohnson.demos;

import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.net.*;
import javax.swing.*;

public class ImageObserverExample extends JPanel {
    private Image image;
    private volatile boolean appFlag;

    public ImageObserverExample(URL url) {
        try {
            // use createImage instead of getImage to avoid caching
            image = getToolkit().createImage(url);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public ImageObserverExample(String fname) {
        try {
            image = getToolkit().createImage(fname);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public void paintComponent(Graphics g) {
        g.drawImage(image,0,0,this);
    }

    public boolean imageUpdate(Image img, int infoflags, int x, int y,
     int width, int height) {
        // if this is an application and not an applet
        // check the status of the width and height info
        // if both values are available, set the preferred size of our
        // component and call pack on the our top level container
        if (appFlag && (infoflags & ImageObserver.WIDTH) > 0 &&
         (infoflags & ImageObserver.HEIGHT) > 0) {
            setPreferredSize(new Dimension(width,height));
            ((Window)getTopLevelAncestor()).pack();
        }
        return super.imageUpdate(img,infoflags,x,y,width,height);
    }

    public static void main(final String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                JFrame f = new JFrame("ImageObserverExample");
                f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                ImageObserverExample ioe = new ImageObserverExample(args[0]);
                ioe.appFlag = true;
                f.getContentPane().add(ioe,BorderLayout.CENTER);
                f.pack();
                f.setVisible(true);
            }
        });
    }
}