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How to overwrite a BufferedImage drawn to JPanel outside PaintComponent() with getGraphics()

I am working on a simple 2D game. Each tick, I want to check an effects queue that will start a thread for a certain effect(fading transitions, audio fade in and out, etc). For example, pressing "Play" on the menu screen will add a "FadeOut" message to this queue, which will be processed and start a thread to draw a black rectangle with an increasing alpha value over my GamePanel.
I'm overriding paintComponent() and sending my Graphics object to my GameStateManager, which passes along the Graphics object to the current states' draw(). I currently don't have an effects state (which maybe I should) to route the paintComponent() graphics object to, but I do pass my gamepanel to my effects thread, where I can use getGraphics() to draw on it. Drawing a rectangle to the GamePanel directly just causes flickering, as the gameloop is still rendering the game.
I found I can draw a black rectangle with increasing alpha to a BufferedImage, set the composite to AlphaComposite.Src (which causes the new draw to replace the old) then draw the BufferedImage over the game panel. The problem is the BufferedImages drawn to the game panel don't get overridden each draw, so the fade out happens really quickly because these black BufferedImages of various alphas just stack on each other.
I wrote this short program to test composite settings and see what is getting overridden. All drawing is done in the draw(), which would be my run() in the effects thread.
import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class ScratchPad extends JPanel implements Runnable
{
private JFrame oFrame = null;
private Thread oGameThread = null;
private Graphics2D oPanelGraphics = null;
private Graphics2D oImageGraphics = null;
private BufferedImage oImage = null;
public static void main(String args[]) throws Exception
{
new ScratchPad();
}
public ScratchPad()
{
createFrame();
initPanel();
addAndShowComponents();
oGameThread = new Thread(this, "Game_Loop");
oGameThread.start();
}
private void addAndShowComponents()
{
oFrame.add(this);
oFrame.setVisible(true);
}
private void initPanel()
{
this.setOpaque(true);
this.setBackground(Color.cyan);
}
private void createFrame()
{
oFrame = new JFrame("Fade");
oFrame.setSize(700, 300);
oFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
oFrame.setLocationRelativeTo(null);
}
public void run()
{
oImage = new BufferedImage(200, 200, BufferedImage.TYPE_INT_ARGB);
while(true)
{
try
{
draw();
Thread.sleep(100);
}
catch(InterruptedException e)
{
}
}
}
private void draw()
{
oPanelGraphics = (Graphics2D)this.getGraphics();
oImageGraphics = oImage.createGraphics();
oImageGraphics.setComposite(AlphaComposite.Src);
oImageGraphics.setColor(new Color(0,0,0,90));
oImageGraphics.fillRect(0, 0, oImage.getWidth(), oImage.getHeight());
oPanelGraphics.drawImage(oImage, 10, 10, null);
oImageGraphics.setColor(new Color(0,0,0,60));
oImageGraphics.fillRect(0, 0, oImage.getWidth(), oImage.getHeight());
oPanelGraphics.drawImage(oImage, 220, 10, null);
oImageGraphics.setColor(new Color(0,0,0,30));
oImageGraphics.fillRect(0, 0, oImage.getWidth(), oImage.getHeight());
oPanelGraphics.drawImage(oImage, 430, 10, null);
// Drawing this image over location of first image, should overwrite first
// after setting composite to 'Src'
oPanelGraphics.setComposite(AlphaComposite.Src);
oImageGraphics.setColor(new Color(0,0,0,10));
oImageGraphics.fillRect(0, 0, oImage.getWidth(), oImage.getHeight());
oPanelGraphics.drawImage(oImage, 10, 10, null);
oImageGraphics.dispose();
oPanelGraphics.dispose();
}
} // end class
What's interesting is setting the composite on 'oPanelGraphics' causes any alpha to the BufferedImage to go away, resulting in a fully opaque black image being drawn over the image that was previously there. Even setting the color to something other than black doesn't have an effect.
What's also interesting is setting the composite for the BufferedImage to:
oImageGraphics.setComposite(AlphaComposite.SrcIn);
causes nothing to be shown. The Oracle documentation on compositing graphics in Java2D states this for 'SrcIn':
"If pixels in the source and the destination overlap, only the source pixels in the overlapping area are rendered."
So, I would expect this to have the same behavior I get with AlphaComposite.Src.
Maybe someone out there can shed some light on whats going on with these composites, and how I could achieve my desired effect.

There are a number issues with what you "seem" to be trying to do
Don't call getGraphics on a component. This can return null and only returns a snapshot of what was last painted during a Swing paint cycle. Anything you paint to it will be erased on the next paint cycle
You should also never dispose of Graphics context you did not create, doing so could effect other components that are painted by Swing
Painting is compounding, this means that painting to the same Graphics context (or BufferedImage) over and over again, will continue to apply those changes over the top of what was previously painted
You also don't seem to have a concept of how animation should work. Instead of trying to paint your fade effect in a single pass, where the results can't be applied to the screen, you need to apply a phase on each cycle and allow that to be updated to the screen before the next pass runs.
The following is a really basic example of what I'm talking about. It takes a "base" image (this could be the "base" state of the game, but I've used a static image) and the paints effects over the top.
import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private Engine engine;
private Image frame;
public TestPane() {
engine = new Engine();
engine.setEngineListener(new EngineListener() {
#Override
public void updateDidOccur(Image img) {
frame = img;
repaint();
}
});
engine.start();
addMouseListener(new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent e) {
engine.addEffect(new FadeOutEffect(Color.BLACK));
}
});
}
#Override
public Dimension getPreferredSize() {
return engine.getSize();
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (frame != null) {
Graphics2D g2d = (Graphics2D) g.create();
g2d.drawImage(frame, 0, 0, null);
g2d.dispose();
}
}
}
public interface EngineListener {
public void updateDidOccur(Image img);
}
public class Engine {
// This is the "base" image, without effects
private BufferedImage base;
private Timer timer;
private EngineListener listener;
private List<Effect> effects = new ArrayList<Effect>(25);
public Engine() {
try {
base = ImageIO.read(new File("/Volumes/Big Fat Extension/Dropbox/MegaTokyo/megatokyo_omnibus_1_3_cover_by_fredrin-d4oupef 50%.jpg"));
} catch (IOException ex) {
ex.printStackTrace();
}
timer = new Timer(10, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
int width = base.getWidth();
int height = base.getHeight();
BufferedImage frame = new BufferedImage(width, height, base.getType());
Graphics2D g2d = frame.createGraphics();
g2d.drawImage(base, 0, 0, null);
Iterator<Effect> it = effects.iterator();
while (it.hasNext()) {
Effect effect = it.next();
if (!effect.applyEffect(g2d, width, height)) {
it.remove();
}
}
g2d.dispose();
if (listener != null) {
listener.updateDidOccur(frame);
}
}
});
}
public void start() {
timer.start();
}
public void stop() {
timer.stop();
}
public void addEffect(Effect effect) {
effects.add(effect);
}
public void setEngineListener(EngineListener listener) {
this.listener = listener;
}
public Dimension getSize() {
return base == null ? new Dimension(200, 200) : new Dimension(base.getWidth(), base.getHeight());
}
}
public interface Effect {
public boolean applyEffect(Graphics2D context, int width, int height);
}
public class FadeOutEffect implements Effect {
private int tick = 0;
private Color fadeToColor;
public FadeOutEffect(Color fadeToColor) {
this.fadeToColor = fadeToColor;
}
#Override
public boolean applyEffect(Graphics2D context, int width, int height) {
tick++;
float alpha = (float) tick / 100.0f;
if (alpha > 1.0) {
return false;
}
Graphics2D g2d = (Graphics2D) context.create();
g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, alpha));
g2d.setColor(fadeToColor);
g2d.fillRect(0, 0, width, height);
g2d.dispose();
return true;
}
}
}
Remember, every effect or change should be applied within the same "main loop", this means you shouldn't have multiple threads, in fact, since Swing is not thread safe, you should avoid having any additional threads if possible. This example make use of a Swing Timer to act as the "main loop" because the ActionListers actionPerformed method is called within the context of the EDT, making it safe to update the UI from. It also provides a simple synchronisation method, as the UI can't be painted while the actionPerformed method is been called

Graphics2D drawImage won't send correctly to printer

My issue is, i'm trying to print using Java and it seems to give a random result each time(Look at the pictures and you will understand). The first time I run it the Image prints fine, but the second time there is a black box covering half of the screen. Here is the First Run
and the Second run
Here is the code:
package test;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.ImageObserver;
import javax.swing.*;
import java.awt.print.*;
import java.net.URL;
public class HelloWorldPrinter implements Printable, ActionListener {
private Image ix = null;
public int print(Graphics g, PageFormat pf, int page) throws PrinterException {
if (page > 0) { /* We have only one page, and 'page' is zero-based */
return NO_SUCH_PAGE;
}
/*
* User (0,0) is typically outside the imageable area, so we must
* translate by the X and Y values in the PageFormat to avoid clipping
*/
Graphics2D g2d = (Graphics2D) g;
g2d.translate(pf.getImageableX(), pf.getImageableY());
ix = getImage("Capture.JPG");
g.drawImage(ix, 1, 1, null);
return PAGE_EXISTS;
}
public void actionPerformed(ActionEvent e) {
PrinterJob job = PrinterJob.getPrinterJob();
job.setPrintable(this);
boolean ok = job.printDialog();
if (ok) {
try {
job.print();
} catch (PrinterException ex) {
/* The job did not successfully complete */
}
}
}
public static void main(String args[]) {
UIManager.put("swing.boldMetal", Boolean.FALSE);
JFrame f = new JFrame("Hello World Printer");
f.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
JButton printButton = new JButton("Print Hello World");
printButton.addActionListener(new HelloWorldPrinter());
f.add("Center", printButton);
f.pack();
f.setVisible(true);
}
public Image getImage(String path) {
Image tempImage = null;
try {
URL imageURL = HelloWorldPrinter.class.getResource(path);
imageURL = HelloWorldPrinter.class.getResource(path);
tempImage = Toolkit.getDefaultToolkit().getImage(imageURL);
} catch (Exception e) {
System.out.println(e);
}
return tempImage;
}
}
Thanks for taking the time to read this and I hope you have a solution.
EDIT: I'm using Microsoft Print To PDF so I can view the print. I don't know if it's relevant but I would add it anyways.

MadProgrammer's solution worked.
Don't use Toolkit#getImage, this could using a thread to load the image an or caching the results in unexpected ways, consider using ImageIO.read instead, it will block until the image is fully realised. It's also possible that your getImage method is triggering an exception and is returning a blank image, but since you ignore the exception result, it's hard to know – MadProgrammer

How do I make this an 'interactive image' [JAVA]

I, basically, want to make an image a 'map'. Kind of like google maps, but with my own image. Here are a few of the issues I run into:
1.) Image is too large to fit into applet screen (Solution: click and drag to pan?)
2.) I have no clue how to make it so I can zoom in and out.
3.) I'd like to make it so when a person 'hovers' their mouse over a location, a text box shows up telling them about the area, but disappears when not 'hovering'
Here is my current code:
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.io.*;
import javax.imageio.*;
public class MapRender extends JApplet {
BufferedImage img;
public void paint(Graphics g) {
g.drawImage(img, 0, 0, null);
}
public MapRender() {
try {
img = ImageIO.read(new File("Mapv1Resize.PNG"));
} catch (IOException e) {
}
}
public Dimension getPreferredSize() {
if (img == null) {
return new Dimension(100,100);
} else {
return new Dimension(img.getWidth(null), img.getHeight(null));
}
}
public static void main(String[] args) {
JFrame f = new JFrame("Load Image Sample");
f.addWindowListener(new WindowAdapter(){
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
f.add(new MapRender());
f.pack();
f.setVisible(true);
}
}
This code is part of a sample provided by another area, I just changed it to an applet.
Note: I understand whoever helps me can't run the program without the picture, but you can substitute any 2k*2k resolution picture for this.

Problems in Using JLabel to Display a Chosen Image File

I encountered a problem while I am trying to display an image after I clicked a button and chose image file within the "Choose File Dialog".
Initially, I was managed to display the chosen image in JLabel, but later I created a separate ActionListener, I think it started to go wrong since then. Whatever image I choose, the JLabel won't display it.
I debugged it, and sure that the file chooser does pass the image to ImageIcon, JLabel does get the value from ImageIcon, but it doesn't display the image even after revalidate() and repaint().
Here I attached my code for your kind reference!
(I trimmed the code for a clean look, so there might be some brackets left not useful)
package com.xxx.LoyalCardManager;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.sql.SQLException;
import java.util.ArrayList;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JSeparator;
import javax.swing.JTextField;
import javax.swing.filechooser.FileFilter;
public class LoyalCardManagerMain implements ActionListener{
private JFrame frame;
private DatabaseHandler db = new DatabaseHandler();
private JLabel labelPic;
private JButton buttonPic;
private File picFile = new File("");
private BufferedImage image;
/**
* Launch the application.
* #throws SQLException
* #throws ClassNotFoundException
*/
public static void main(String[] args) throws SQLException, ClassNotFoundException {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
LoyalCardManagerMain window = new LoyalCardManagerMain();
window.frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
}
/**
* Create the application.
*/
public LoyalCardManagerMain() {
// Database initialisation
initDatabase();
// Draw GUI
frame = new JFrame();
frame.setBounds(100, 100, 619, 487);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().setLayout(null);
buttonPic = new JButton("Click to Choose Pic");
buttonPic.setBounds(415, 252, 166, 29);
frame.getContentPane().add(buttonPic);
buttonPic.setEnabled(false);
buttonPic.setActionCommand("ChoosePic");
buttonPic.addActionListener(this);
labelPic = new JLabel();
labelPic.setBounds(415, 30, 167, 210);
frame.getContentPane().add(labelPic);
}
public void actionPerformed(ActionEvent event) {
String command = event.getActionCommand();
if (command.equals("ChoosePic")) {
//TODO Label now cannot display images.
JFileChooser chooser = new JFileChooser();
chooser.setFileSelectionMode(JFileChooser.FILES_AND_DIRECTORIES);
chooser.setAcceptAllFileFilterUsed(false);
chooser.setFileFilter(new FileFilter() {
public boolean accept (File f) {
String extension = Utils.getExtension(f);
if(extension != null) {
if (extension.equals(Utils.gif) ||
extension.equals(Utils.jpeg) ||
extension.equals(Utils.jpg) ||
extension.equals(Utils.png) ||
extension.equals(Utils.tif) ||
extension.equals(Utils.tiff)) {
return true;
}else{
return false;
}
}
return false;
}
public String getDescription() {
return "Image File (*.gif, *.jpeg, *.jpg, *.png, *.tif, *.tiff)";
}
});
int retVal = chooser.showOpenDialog(frame);
if (retVal == JFileChooser.APPROVE_OPTION) {
picFile = chooser.getSelectedFile();
try {
image = ImageIO.read(picFile);
} catch (IOException e) {
e.printStackTrace();
}
// Calculate the pic's ratio and do re-scale
double ratio = (double) labelPic.getWidth() / (double) labelPic.getHeight();
// Do image scale, scaledW is the new Width, and LabelPic.getHeight is the new Height.
int scaledW = (int) (image.getHeight() * ratio);
image = new BufferedImage(scaledW, labelPic.getHeight(), BufferedImage.SCALE_FAST);
ImageIcon icon = new ImageIcon(image);
labelPic.setVisible(true);
labelPic.setIcon(icon);
labelPic.revalidate();
labelPic.repaint();
}
}
}
}
I also referenced other similar questions:
image loading using a JFileChooser into a JFrame
Image won't display in JLabel
Updating an image contained in a JLabel - problems
External Site: JFIleChooser opening image to JLabel
As well as Java Tutorial Docs
How to Use Buttons, Check Boxes, and Radio Buttons
But I still can't figure it out why the JLabel not display the chosen image.
Thanks for your kind help mates!

Ok, I finally figured out what's wrong with the code:
If I intend to use BufferedImage to resize (sorry, in my question I mis-understanding the method scale with resize), I need to use drawImage method to "redraw" the image. Otherwise the image will not be shown.
I made modification here:
double ratio = (double) labelPic.getWidth() / (double) labelPic.getHeight();
// Do image scale, scaledW is the new Width, and LabelPic.getHeight is the new Height.
int scaledW = (int) (image.getHeight() * ratio);
image = new BufferedImage(scaledW, labelPic.getHeight(), BufferedImage.SCALE_FAST);// Edit here
ImageIcon icon = new ImageIcon(image);
labelPic.setVisible(true);
labelPic.setIcon(icon);
labelPic.revalidate();
labelPic.repaint();
From the "Edit Here" mark, I use the following code:
BufferedImage imageTemp = new BufferedImage(resizedW, resizedH, BufferedImage.TYPE_INT_RGB);
imageTemp.getGraphics().drawImage(image,0,0, scaledW, scaledH, null);
image = imageTemp;
And there's difference between first pass the value to imageTemp then pass to image and directly pass the value to image. If I pass the new BufferedImage directly to image, it will display a pure black colour instead of the image you choose.

Try using this to display the image:
JfileChooser getImage = new JFileChooser();
..........
ImageIcon imagePath= new ImageIcon(getImage.getPath());
JLabel imageLabel= new JLabel() {
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(imagePath.getImage(), 0, 0, width, height, null);
}
};
imageLabel.setLocation(10, 40);
imageLabel.setBorder(viewAnimalPanelBorder);
imageLabel.setSize(200, newHeight);
panel.add(imageLabel);
Let me know if you require more assistance.
Also, try displaying the picture without using the JFileChooser, maybe hard code the path for a test.

JOptionPane.showMessageDialog() shows but without any message?

In the following code, I call JOptionPane.showMessageDialog, inside a try/catch block. But when the error is caught, my JOptionPane is visible but without any message !!! Does someone knows why and how I can correct the problem ?
Regards
MyBoardJPannel.java
package experimentations.gui;
import java.awt.Graphics;
import java.awt.Image;
import java.io.InputStream;
import javax.imageio.ImageIO;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
public class MyBoardPannel extends JPanel {
#Override
public void paint(Graphics grahics) {
if (imageToShow == null)
imageToShow = loadImage("sampleImage");
}
/**
* In fact, there are not any image in project => will go to catch clause.
* #param imageName
*/
private void loadImage(String imageName) {
InputStream imageStream = getClass().getResourceAsStream("/"+imageName+".png");
try {
imageToShow = ImageIO.read(imageStream);
}
catch (Exception e) {
String errorMessage = "Failed to load image "+imageName;
System.err.println(errorMessage);
JOptionPane.showMessageDialog(this, errorMessage,
"Image loading error", JOptionPane.ERROR_MESSAGE);
imageToShow = null;
System.exit(1);
}
}
private Image imageToShow;
}
JOptionPaneErrorShowing.java
package experimentations.gui;
import javax.swing.JFrame;
public class JOptionPaneErrorShowing extends JFrame {
public JOptionPaneErrorShowing(){
setTitle("JOptionPane experimentation");
setSize(300, 300);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLocationRelativeTo(null);
add(new MyBoardPannel());
}
/**
* #param args
*/
public static void main(String[] args) {
new JOptionPaneErrorShowing().setVisible(true);
}
}

It's likely a Swing concurrency issue. But more importantly, you should never load an image from within a paint or paintComponent method, ever. Read it in the constructor or elsewhere but paint/paintComponent need to be lean and blazingly fast.
To solve your issue, consider reading in the image in SwingWorker object. If you call a JOptionPane from within the SwingWorker's doInBackground method though, be sure to call it on the Swing event thread, the EDT, using SwingUtilities.invokeLater(Runnable).
Also, you will hardly ever want to draw in a JPanel's paint method unless you are taking care of painting borders and children. Instead paint in a paintComponent method, and don't forget to call the super.paintComponent(g) method in that paintComponent override. You'll want to read the Swing graphics tutorials as this is all spelled out there.
For example:
import java.awt.Graphics;
import java.awt.Image;
import java.io.InputStream;
import java.util.concurrent.ExecutionException;
import javax.imageio.ImageIO;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.SwingWorker;
public class MyBoardPannel extends JPanel {
protected static final String SAMPLE_IMAGE = "sampleImage";
Image imageToShow = null;
public MyBoardPannel() {
SwingWorker<Image, Void> mySW = new SwingWorker<Image, Void>() {
#Override
protected Image doInBackground() throws Exception {
return loadImage(SAMPLE_IMAGE);
}
#Override
protected void done() {
try {
imageToShow = get();
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
}
};
mySW.execute();
}
#Override
public void paintComponent(Graphics grahics) {
super.paintComponent(grahics);
if (imageToShow != null) {
grahics.drawImage(imageToShow, 0, 0, null);
}
}
private Image loadImage(String imageName) {
InputStream imageStream = getClass().getResourceAsStream(
"/" + imageName + ".png");
try {
return ImageIO.read(imageStream);
} catch (Exception e) {
final String errorMessage = "Failed to load image " + imageName;
System.err.println(errorMessage);
SwingUtilities.invokeLater(new Runnable() {
public void run() {
JOptionPane.showMessageDialog(MyBoardPannel.this, errorMessage,
"Image loading error", JOptionPane.ERROR_MESSAGE);
System.exit(1);
}
});
}
return null;
}
}

I don't really know, but maybe your panel you use as parent of the JOptionPane (by passing this) is invisible or there is something else wrong. Try adding pack(); at the end of your JOptionPaneErrorShowing constructor.
What I know is that I had this problem when I was using an old Ubuntu and old Nvidia driver for my GPU, when the desktop effects were turned on (the Compiz Fusion of today. I don't know if it was already called Compiz, that long ago).
Aha! I found it, you are displaying the error inside the repaint method. Never do that! Load your image inside the constructor of the MyBoardPanel class and show error messages over there.