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Updating a panel every second, minute and hour [duplicate]

Original question:
This method is supposed to change the image being displayed on a JFrame gradually into another image. However, without some way to slow it down, it just seems to change from one image to the new image. In order to slow it down, I put in a Thread.sleep(1000) so the changes wouldn't happen instantly. However, with this line in there, my program freezes completely. No error message, no nothing. Can anyone please help me out? Suggest a better method to slow it down, or how this can be fixed.
For clarification: int k is the number of gradual steps in the change. k = 1 would be an instant change. Anything greater would be gradual changes. int l meanwhile controls the ratio of how much of each image is displayed.
public void morphImg(int width, int height, BufferedImage morphImage, int k) {
//creates new image from two images of same size
BufferedImage image2 = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
for (int i = 0; i < width; i++) {
for (int j = 0; j < height; j++) {
//get color from original image
Color c = new Color(image.getRGB(i, j));
//get colors from morph image
Color c2 = new Color(morphImage.getRGB(i, j));
for (int l = 1; l <= k; l++) {
//gets colors at different stages
int r = ((k-l)*c.getRed()/k) + (l*c2.getRed()/k);
int g = ((k-l)*c.getGreen()/k) + (l*c2.getGreen()/k);
int b = ((k-l)*c.getBlue()/k) + (l*c2.getBlue()/k);
Color newColor = new Color(r, g, b);
//set colors of new image to average of the two images
image2.setRGB(i, j, newColor.getRGB());
//display new image
try {
imageLabel.setIcon(new ImageIcon(image2));
Thread.sleep(1000);
}
catch (InterruptedException e){
System.out.println("Exception caught.");
}
}
}
}
//sets modified image as "original" for further manipulation
setImage(image2);
}
UPDATED CODE: Using a Timer also causes the program to freeze...Am I not using it right?
public void morphImg(int width, int height, BufferedImage morphImage, int k) {
//creates new image from two images of same size
final BufferedImage image2 = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
for (int l = 1; l <= k; l++) {
for (int i = 0; i < width; i++) {
for (int j = 0; j < height; j++) {
//get color from original image
Color c = new Color(image.getRGB(i, j));
//get colors from morph image
Color c2 = new Color(morphImage.getRGB(i, j));
//gets colors at different stages
int r = ((k-l)*c.getRed()/k) + (l*c2.getRed()/k);
int g = ((k-l)*c.getGreen()/k) + (l*c2.getGreen()/k);
int b = ((k-l)*c.getBlue()/k) + (l*c2.getBlue()/k);
Color newColor = new Color(r, g, b);
//set colors of new image to average of the two images
image2.setRGB(i, j, newColor.getRGB());
//display new image
imageLabel.setIcon(new ImageIcon(image2));
final Timer t = new Timer(500,null);
t.setInitialDelay(500);
t.start();
}
}
}
//sets modified image as "original" for further manipulation
setImage(image2);
}

Never use Thread.sleep() when code is executing on the Event Dispatch Thread.
Instead you should use a Swing Timer to schedule your animation.
See the sections from the Swing tutorial on:
Concurrency in Swing
How to Use Timers
Or if you don't want to use a Timer, then you can use a SwingWorker (as described in the tutorial on concurrency) and then just publish() the image after you change it. Then you can use a Thread.sleep() since the SwingWorker doesn't execute on the EDT.
Simple Timer example:
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
import javax.swing.Timer;
public class TimerTime extends JPanel implements ActionListener
{
private JLabel timeLabel;
private int count = 0;
public TimerTime()
{
timeLabel = new JLabel( new Date().toString() );
add( timeLabel );
Timer timer = new Timer(1000, this);
timer.setInitialDelay(1);
timer.start();
}
#Override
public void actionPerformed(ActionEvent e)
{
// Update the time
timeLabel.setText( new Date().toString() );
count++;
// Stop after 10 events have been generated
if (count == 10)
{
Timer timer = (Timer)e.getSource();
timer.stop();
System.out.println( "Timer stopped" );
}
}
private static void createAndShowGUI()
{
JFrame frame = new JFrame("TimerTime");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add( new TimerTime() );
frame.setLocationByPlatform( true );
frame.pack();
frame.setVisible( true );
}
public static void main(String[] args)
{
EventQueue.invokeLater( () -> createAndShowGUI() );
}
}

The loop over k should be the outermost loop. Right now you are calling Thread.sleep k*width*height times.

If the intention is to show progressive animation of the morph effect, below is the test code I did without using Timer or Thread.sleep(), using the latest morph code given by OP:
import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import javax.imageio.ImageIO;
import javax.swing.JApplet;
import javax.swing.JFrame;
class MorphComponent extends Component {
/**
*
*/
private static final long serialVersionUID = 1L;
private BufferedImage bi;
private URL imageSrc1;
private URL imageSrc2;
public MorphComponent(URL imageSrc1, URL imageSrc2) {
this.imageSrc1 = imageSrc1;
this.imageSrc2 = imageSrc2;
try {
BufferedImage img1 = ImageIO.read(imageSrc1);
//BufferedImage img2 = ImageIO.read(imageSrc2);
int w = img1.getWidth(null);
int h = img1.getHeight(null);
bi = new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB);
Graphics g = bi.getGraphics();
g.drawImage(img1, 0, 0, null);
} catch (IOException e) {
System.out.println("Image could not be read");
System.exit(1);
}
}
public Dimension getPreferredSize() {
return new Dimension(bi.getWidth(null), bi.getHeight(null));
}
public void paint(Graphics g) {
Graphics2D g2d = (Graphics2D)g;
g2d.setColor(Color.white);
g2d.fillRect(0,0, getWidth(), getHeight());
try {
BufferedImage img1 = ImageIO.read(imageSrc1);
BufferedImage img2 = ImageIO.read(imageSrc2);
int w = img1.getWidth(null);
int h = img1.getHeight(null);
bi = morphImg(g, img1, img2, w, h, 10);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
private long start = System.currentTimeMillis();
public BufferedImage morphImg(Graphics gp, BufferedImage originalImage, BufferedImage morphImage, int width, int height, int k) {
//creates new image from two images of same size
final BufferedImage image2 = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
for (int l = 1; l <= k; l++) {
for (int i = 0; i < width; i++) {
for (int j = 0; j < height; j++) {
long elapsed = System.currentTimeMillis() - start;
//get color from original image
Color c = new Color(originalImage.getRGB(i, j));
//get colors from morph image
Color c2 = new Color(morphImage.getRGB(i, j));
//gets colors at different stages
int r = ((k-l)*c.getRed()/k) + (l*c2.getRed()/k);
int g = ((k-l)*c.getGreen()/k) + (l*c2.getGreen()/k);
int b = ((k-l)*c.getBlue()/k) + (l*c2.getBlue()/k);
Color newColor = new Color(r, g, b);
//set colors of new image to average of the two images
image2.setRGB(i, j, newColor.getRGB());
if( elapsed > 100 ) {
gp.drawImage(image2, 0, 0, null);
start = System.currentTimeMillis();
repaint();
}
}
}
}
return image2;
}
}
public class MorphImageApplet extends JApplet {
/**
*
*/
private static final long serialVersionUID = 1L;
static String imageFileName1 = "image_1.jpg";
static String imageFileName2 = "image_2.jpg";
private URL imageSrc1;
private URL imageSrc2;
public MorphImageApplet () {
}
public MorphImageApplet (URL imageSrc1, URL imageSrc2) {
this.imageSrc1 = imageSrc1;
this.imageSrc2 = imageSrc2;
}
public void init() {
try {
imageSrc1 = new URL(getCodeBase(), imageFileName1);
imageSrc2 = new URL(getCodeBase(), imageFileName2);
} catch (MalformedURLException e) {
}
buildUI();
}
public void buildUI() {
final MorphComponent st = new MorphComponent(imageSrc1, imageSrc2);
add("Center", st);
}
public static void main(String s[]) {
JFrame f = new JFrame("See Through Image");
f.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {System.exit(0);}
});
URL imageSrc1 = null;
URL imageSrc2 = null;
try {
imageSrc1 = ((new File(imageFileName1)).toURI()).toURL();
imageSrc2 = ((new File(imageFileName2)).toURI()).toURL();
} catch (MalformedURLException e) {
}
MorphImageApplet sta = new MorphImageApplet(imageSrc1, imageSrc2);
sta.buildUI();
f.add("Center", sta);
f.pack();
f.setVisible(true);
}
}

How do I implement Java swing GUI start screen for a game with drawString and drawImage?

I'm not sure how I would fix the errors in my program and how I would highlight the option the user is hovering on. I want it to highlight the code for each position, i.e position 1 would be highlighted(as a different color) to start game,etc. and up/down would change position and I would change the position with up ,down, left, right. This is what I have so far. At the moment its bugged and when compiled with my window it comes out as:
Which works for the main game and altered for this titleboard, what am I doing wrong and how do I fix it?
TitleBoard class
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import java.util.ArrayList;
//sound + file opening
import java.io.*;
import javax.sound.sampled.*;
public class TitleBoard extends JPanel implements ActionListener{
private ArrayList<String> OptionList;
private Image background;
private ImageIcon bgImageIcon;
private String cheatString;
private int position;
private Timer timer;
public TitleBoard(){
setFocusable(true);
addKeyListener(new TAdapter());
bgImageIcon = new ImageIcon("");
background = bgImageIcon.getImage();
String[] options = {"Start Game","Options","Quit"};
OptionList = new ArrayList<String>();
optionSetup(options);
position = 1;
timer = new Timer(8, this);
timer.start();
/*
1 mod 3 =>1 highlight on start
2 mod 3 =>2 highlight on options
3 mod 3 =>0 highlight on quit
*/
try{
Font numFont = Font.createFont(Font.TRUETYPE_FONT,new File("TwistedStallions.ttf"));
GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
ge.registerFont(numFont);
setFont(numFont.deriveFont(24f)); //adjusthislater
}catch(IOException|FontFormatException e){
e.printStackTrace();
}
}
private void optionSetup(String[] s){
for(int i=0; i<s.length;i++) {
OptionList.add(s[i]);
}
}
public void paint(Graphics g){
super.paint(g);
Graphics g2d = (Graphics2D)g;
g2d.drawImage(background,0,0,this);
for (int i=0;i<OptionList.size();i++){
g2d.drawString(OptionList.get(i),200,120+120*i);
}/*
g2d.drawString(OptionList.get(1),400,240);
g2d.drawString(OptionList.get(2),400,360);
//instructions on start screen maybe??
//800x500
//highlighting*/
Toolkit.getDefaultToolkit().sync();
g.dispose();
}
public void actionPerformed(ActionEvent e){
repaint();
}
public class TAdapter extends KeyAdapter {
public void keyPressed(KeyEvent e){
if(e.getKeyCode() == KeyEvent.VK_UP||
e.getKeyCode() == KeyEvent.VK_RIGHT){
position++;
}
if(e.getKeyCode() == KeyEvent.VK_DOWN||
e.getKeyCode() == KeyEvent.VK_LEFT){
position--;
}
}
}
}
Window Class
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Window extends JFrame{
public Window(){
int width = 800, height = 600;
//TO DO: make a panel in TITLE MODE
///////////////////////////////////
//panel in GAME MODE.
add(new TitleBoard());
//set default close
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setSize(width,height);
//centers window
setLocationRelativeTo(null);
setTitle("Title");
setResizable(false);
setVisible(true);
}
public static void main(String[] args){
new Window();
}
}

There are any number of ways you might achieve this, for example, you could use some kind of delegation model.
That is, rather then trying to mange of each element in a single method (or methods), you could devise a delegate which provide a simple interface method that the paint method would call and it would know how to do the rest.
For example, Swing uses this type of concept with it's cell renderers for JList, JTable and JTree.
For example...
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.swing.AbstractAction;
import javax.swing.ActionMap;
import javax.swing.InputMap;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class MyAwesomeMenu {
public static void main(String[] args) {
new MyAwesomeMenu();
}
public MyAwesomeMenu() {
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 List<String> menuItems;
private String selectMenuItem;
private String focusedItem;
private MenuItemPainter painter;
private Map<String, Rectangle> menuBounds;
public TestPane() {
setBackground(Color.BLACK);
painter = new SimpleMenuItemPainter();
menuItems = new ArrayList<>(25);
menuItems.add("Start Game");
menuItems.add("Options");
menuItems.add("Exit");
selectMenuItem = menuItems.get(0);
MouseAdapter ma = new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent e) {
String newItem = null;
for (String text : menuItems) {
Rectangle bounds = menuBounds.get(text);
if (bounds.contains(e.getPoint())) {
newItem = text;
break;
}
}
if (newItem != null && !newItem.equals(selectMenuItem)) {
selectMenuItem = newItem;
repaint();
}
}
#Override
public void mouseMoved(MouseEvent e) {
focusedItem = null;
for (String text : menuItems) {
Rectangle bounds = menuBounds.get(text);
if (bounds.contains(e.getPoint())) {
focusedItem = text;
repaint();
break;
}
}
}
};
addMouseListener(ma);
addMouseMotionListener(ma);
InputMap im = getInputMap(WHEN_IN_FOCUSED_WINDOW);
ActionMap am = getActionMap();
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_DOWN, 0), "arrowDown");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_UP, 0), "arrowUp");
am.put("arrowDown", new MenuAction(1));
am.put("arrowUp", new MenuAction(-1));
}
#Override
public void invalidate() {
menuBounds = null;
super.invalidate();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
if (menuBounds == null) {
menuBounds = new HashMap<>(menuItems.size());
int width = 0;
int height = 0;
for (String text : menuItems) {
Dimension dim = painter.getPreferredSize(g2d, text);
width = Math.max(width, dim.width);
height = Math.max(height, dim.height);
}
int x = (getWidth() - (width + 10)) / 2;
int totalHeight = (height + 10) * menuItems.size();
totalHeight += 5 * (menuItems.size() - 1);
int y = (getHeight() - totalHeight) / 2;
for (String text : menuItems) {
menuBounds.put(text, new Rectangle(x, y, width + 10, height + 10));
y += height + 10 + 5;
}
}
for (String text : menuItems) {
Rectangle bounds = menuBounds.get(text);
boolean isSelected = text.equals(selectMenuItem);
boolean isFocused = text.equals(focusedItem);
painter.paint(g2d, text, bounds, isSelected, isFocused);
}
g2d.dispose();
}
public class MenuAction extends AbstractAction {
private final int delta;
public MenuAction(int delta) {
this.delta = delta;
}
#Override
public void actionPerformed(ActionEvent e) {
int index = menuItems.indexOf(selectMenuItem);
if (index < 0) {
selectMenuItem = menuItems.get(0);
}
index += delta;
if (index < 0) {
selectMenuItem = menuItems.get(menuItems.size() - 1);
} else if (index >= menuItems.size()) {
selectMenuItem = menuItems.get(0);
} else {
selectMenuItem = menuItems.get(index);
}
repaint();
}
}
}
public interface MenuItemPainter {
public void paint(Graphics2D g2d, String text, Rectangle bounds, boolean isSelected, boolean isFocused);
public Dimension getPreferredSize(Graphics2D g2d, String text);
}
public class SimpleMenuItemPainter implements MenuItemPainter {
public Dimension getPreferredSize(Graphics2D g2d, String text) {
return g2d.getFontMetrics().getStringBounds(text, g2d).getBounds().getSize();
}
#Override
public void paint(Graphics2D g2d, String text, Rectangle bounds, boolean isSelected, boolean isFocused) {
FontMetrics fm = g2d.getFontMetrics();
if (isSelected) {
paintBackground(g2d, bounds, Color.BLUE, Color.WHITE);
} else if (isFocused) {
paintBackground(g2d, bounds, Color.MAGENTA, Color.BLACK);
} else {
paintBackground(g2d, bounds, Color.DARK_GRAY, Color.LIGHT_GRAY);
}
int x = bounds.x + ((bounds.width - fm.stringWidth(text)) / 2);
int y = bounds.y + ((bounds.height - fm.getHeight()) / 2) + fm.getAscent();
g2d.setColor(isSelected ? Color.WHITE : Color.LIGHT_GRAY);
g2d.drawString(text, x, y);
}
protected void paintBackground(Graphics2D g2d, Rectangle bounds, Color background, Color foreground) {
g2d.setColor(background);
g2d.fill(bounds);
g2d.setColor(foreground);
g2d.draw(bounds);
}
}
}
For here, you could add ActionListener

When a GUI needs a button, use a JButton! The JButton API allows the possibility to add icons for many different circumstances. This example shows different icons for the standard icon, the hover icon, and the pressed icon. Your GUI would obviously use icons with text on them for the required effect.
The icons are pulled directly (hot-linked) from Example images for code and mark-up Q&As.
Standard
Hover over triangle
Press triangle
Code
import java.awt.*;
import java.awt.image.BufferedImage;
import javax.imageio.ImageIO;
import javax.swing.*;
import javax.swing.border.EmptyBorder;
import java.net.URL;
public class IconHoverFocusIndication {
// the GUI as seen by the user (without frame)
// swap the 1 and 0 for single column
JPanel gui = new JPanel(new GridLayout(1,0,50,50));
public static final int GREEN = 0, YELLOW = 1, RED = 2;
String[][] urls = {
{
"http://i.stack.imgur.com/T5uTa.png",
"http://i.stack.imgur.com/IHARa.png",
"http://i.stack.imgur.com/wCF8S.png"
},
{
"http://i.stack.imgur.com/gYxHm.png",
"http://i.stack.imgur.com/8BGfi.png",
"http://i.stack.imgur.com/5v2TX.png"
},
{
"http://i.stack.imgur.com/1lgtq.png",
"http://i.stack.imgur.com/6ZXhi.png",
"http://i.stack.imgur.com/F0JHK.png"
}
};
IconHoverFocusIndication() throws Exception {
// adjust to requirement..
gui.setBorder(new EmptyBorder(15, 30, 15, 30));
gui.setBackground(Color.BLACK);
Insets zeroMargin = new Insets(0,0,0,0);
for (int ii = 0; ii < 3; ii++) {
JButton b = new JButton();
b.setBorderPainted(false);
b.setMargin(zeroMargin);
b.setContentAreaFilled(false);
gui.add(b);
URL url1 = new URL(urls[ii][GREEN]);
BufferedImage bi1 = ImageIO.read(url1);
b.setIcon(new ImageIcon(bi1));
URL url2 = new URL(urls[ii][YELLOW]);
BufferedImage bi2 = ImageIO.read(url2);
b.setRolloverIcon(new ImageIcon(bi2));
URL url3 = new URL(urls[ii][RED]);
BufferedImage bi3 = ImageIO.read(url3);
b.setPressedIcon(new ImageIcon(bi3));
}
}
public JComponent getGUI() {
return gui;
}
public static void main(String[] args) {
Runnable r = new Runnable() {
#Override
public void run() {
try {
IconHoverFocusIndication ihfi =
new IconHoverFocusIndication();
JFrame f = new JFrame("Button Icons");
f.add(ihfi.getGUI());
// Ensures JVM closes after frame(s) closed and
// all non-daemon threads are finished
f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
// See https://stackoverflow.com/a/7143398/418556 for demo.
f.setLocationByPlatform(true);
// ensures the frame is the minimum size it needs to be
// in order display the components within it
f.pack();
// should be done last, to avoid flickering, moving,
// resizing artifacts.
f.setVisible(true);
} catch (Exception ex) {
ex.printStackTrace();
}
}
};
// Swing GUIs should be created and updated on the EDT
// http://docs.oracle.com/javase/tutorial/uiswing/concurrency
SwingUtilities.invokeLater(r);
}
}

dynamically update JPanel background does't work

After reading image from JFilechooser, I am trying to read pixel of an image one by one and display it to JPanel after some delay in sequential manner. can't update the background of JPanel.
public class ImageMain extends JFrame implements ActionListener {
/**
*
*/
private static final long serialVersionUID = 2916361361443483318L;
private JFileChooser fc = null;
private JMenuItem item1, item2;
private BufferedImage image = null;
private JPanel panel = null;
private int width = 0;
private int height = 0;
private BorderLayout card;
private Container contentPane;
//private int loopcount = 0;
//private int counter = 0;
public ImageMain() {
JFrame frame = new JFrame("Image Extraction Tool");
frame.setExtendedState(Frame.MAXIMIZED_BOTH);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
contentPane = frame.getContentPane();
panel = new JPanel();
card = new BorderLayout();
panel.setLayout(card);
panel.setBackground(Color.white);
JMenuBar menuBar = new JMenuBar();
JMenu menu = new JMenu("Menu");
menuBar.add(menu);
item1 = new JMenuItem("Browse an image");
item2 = new JMenuItem("Exit");
item1.addActionListener(this);
item2.addActionListener(this);
menu.add(item1);
menu.add(item2);
frame.setJMenuBar(menuBar);
contentPane.add(panel);
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
try {
SwingUtilities.invokeAndWait(new Runnable() {
#Override
public void run() {
ImageMain img = new ImageMain();
}
});
} catch (InvocationTargetException | InterruptedException e) {
e.printStackTrace();
}
}
#Override
public void actionPerformed(ActionEvent e) {
if (e.getSource() == item1) {
if (fc == null)
fc = new JFileChooser();
int retVal = fc.showOpenDialog(null);
if (retVal == JFileChooser.APPROVE_OPTION) {
File file = fc.getSelectedFile();
try {
image = ImageIO.read(file);
height = image.getHeight();
width = image.getWidth();
// final int[][] pixelData = new int[height * width][3];
// int[] rgb;
for (int i = 0; i < height; i++) {
for (int j = 0; j < width; j++) {
System.out.println(i + " " + j);
Color c = new Color(image.getRGB(j, i));
panel.setBackground(c);
panel.invalidate();
panel.validate();
panel.repaint();
}
}
} catch (IOException e1) {
System.out.println("IO::" + e1.getMessage());
} catch (Exception e1) {
System.out.println("Exception::" + e1.getMessage());
}
}
}
if (e.getSource() == item2) {
System.exit(0);
}
}}
Inside ActionPerformed, I got Color object by reading RGB values and then I am stuck at displaying them to JApplet. Suggestion are welcome if there is a better way to achieve this.
Thanks in advance.

The main problem is your performing a long running task within the context of the Event Dispatching Thread, which is responsible for, amongst other things, processing repaint requests.
#Override
public void actionPerformed(ActionEvent e) {
//...
// Nothing will be updated until after the
// actionPerformed method exists
for (int i = 0; i < height; i++) {
for (int j = 0; j < width; j++) {
System.out.println(i + " " + j);
Color c = new Color(image.getRGB(j, i));
panel.setBackground(c);
panel.invalidate();
panel.validate();
panel.repaint();
}
}
The other problem you have is that you are required to only modify the state of the UI from within the context of the EDT
Depending on your exact needs, you could use a SwingWorker, which would allow you to process the pixels in the background while updating the UI from within the context of the EDT, however, because SwingWorker consolidates it's updates, you could miss color changes.
A better solution might be to use a java.swing.Timer which would allow you to trigger updates at a specified period, which are triggered within the context of the EDT.
See Concurrency in Swing for more details...
Updated with example
In order to draw pixels, you need something to draw them on. Now, you could simply add each pixel you want to paint to an array and loop that array each time you need to repaint the component, but that's kind of expensive...
Instead, it would be simpler to have a backing buffer of some kind, onto which you paint the pixels and then paint that buffer to the component, which should be faster.
Basically, the allows you to supply the height and width of the expected image and then supply each pixel as you need..
public class ImagePane extends JPanel {
private BufferedImage img;
public ImagePane() {
}
public void reset(int width, int height) {
img = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
revalidate();
}
public void reset() {
img = null;
revalidate();
}
public void setPixelAt(int x, int y, int pixel) {
img.setRGB(x, y, pixel);
}
#Override
public Dimension getPreferredSize() {
return img == null ? new Dimension(200, 200) : new Dimension(img.getWidth(), img.getHeight());
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
if (img != null) {
int x = (getWidth() - img.getWidth()) / 2;
int y = (getHeight() - img.getHeight()) / 2;
g2d.drawImage(img, x, y, this);
}
g2d.dispose();
}
}
Take a look at Performing Custom Painting for more details...
Then you need some way to process the original image and update the image panel...Now, based on the updated requirements, I would use a SwingWorker, the reason for this, is that the SwingWorker can cache what is passed back to the EDT, this allows the background thread to continue processing and caching the output until the EDT (and system) is ready to process it...
public class PixelExposerWorker extends SwingWorker<Void, Pixel> {
private final BufferedImage img;
private final ImagePane imagePane;
private final List<Point> points;
public PixelExposerWorker(BufferedImage img, ImagePane imagePane) {
this.img = img;
this.imagePane = imagePane;
points = new ArrayList<>(img.getWidth() * img.getHeight());
for (int x = 0; x < img.getWidth(); x++) {
for (int y = 0; y < img.getHeight(); y++) {
points.add(new Point(x, y));
}
}
}
#Override
protected void process(List<Pixel> chunks) {
System.out.println("Publish " + chunks.size());
for (Pixel pixel : chunks) {
imagePane.setPixelAt(pixel.getX(), pixel.getY(), pixel.getColor());
}
imagePane.repaint();
}
#Override
protected Void doInBackground() throws Exception {
int pixelCount = (int) (points.size() * 0.005);
while (!points.isEmpty()) {
for (int count = 0; count < pixelCount && !points.isEmpty(); count++) {
int index = (int) (Math.random() * (points.size() - 1));
Point p = points.remove(index);
Pixel pixel = new Pixel(p.x, p.y, img.getRGB(p.x, p.y));
publish(pixel);
}
Thread.yield();
}
return null;
}
}
Basically, this SwingWorker builds a List of "pixel points", it uses the list to randomly remove points from the list, generate a virtual Pixel and publish back to the EDT for processing. The worker will process around 0.5% of the pixels at a time, meaning that the work is always trying to send a "bunch" of pixels back to the EDT, rather the one at a time.
Finally, it will yield to allow other threads to run (and the hopefully for the EDT to update it self)
An image of 650x975 takes roughly 1m and 10s to fully renderer
And the full code...
import core.util.StopWatch;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
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.lang.reflect.InvocationTargetException;
import java.util.ArrayList;
import java.util.List;
import javax.imageio.ImageIO;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.SwingWorker;
import javax.swing.Timer;
public class PixelShower implements ActionListener {
private static final long serialVersionUID = 2916361361443483318L;
private JFileChooser fc = null;
private JMenuItem item1, item2;
private BufferedImage image = null;
private ImagePane panel = null;
private int width = 0;
private int height = 0;
private BorderLayout card;
private Container contentPane;
public PixelShower() {
JFrame frame = new JFrame("Image Extraction Tool");
frame.setExtendedState(Frame.MAXIMIZED_BOTH);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
contentPane = frame.getContentPane();
panel = new ImagePane();
card = new BorderLayout();
panel.setLayout(card);
panel.setBackground(Color.white);
JMenuBar menuBar = new JMenuBar();
JMenu menu = new JMenu("Menu");
menuBar.add(menu);
item1 = new JMenuItem("Browse an image");
item2 = new JMenuItem("Exit");
item1.addActionListener(this);
item2.addActionListener(this);
menu.add(item1);
menu.add(item2);
frame.setJMenuBar(menuBar);
contentPane.add(panel);
frame.setVisible(true);
}
public static void main(String[] args) {
try {
SwingUtilities.invokeAndWait(new Runnable() {
#Override
public void run() {
PixelShower img = new PixelShower();
}
});
} catch (InvocationTargetException | InterruptedException e) {
e.printStackTrace();
}
}
#Override
public void actionPerformed(ActionEvent e) {
if (e.getSource() == item1) {
if (fc == null) {
fc = new JFileChooser();
}
int retVal = fc.showOpenDialog(null);
if (retVal == JFileChooser.APPROVE_OPTION) {
File file = fc.getSelectedFile();
try {
image = ImageIO.read(file);
panel.reset(image.getWidth(), image.getHeight());
PixelExposerWorker worker = new PixelExposerWorker(image, panel);
worker.execute();
} catch (IOException e1) {
e1.printStackTrace();
} catch (Exception e1) {
e1.printStackTrace();
}
}
}
if (e.getSource() == item2) {
System.exit(0);
}
}
public class ImagePane extends JPanel {
private BufferedImage img;
public ImagePane() {
}
public void reset(int width, int height) {
img = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
revalidate();
}
public void reset() {
img = null;
revalidate();
}
public void setPixelAt(int x, int y, int pixel) {
img.setRGB(x, y, pixel);
}
#Override
public Dimension getPreferredSize() {
return img == null ? new Dimension(200, 200) : new Dimension(img.getWidth(), img.getHeight());
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
if (img != null) {
int x = (getWidth() - img.getWidth()) / 2;
int y = (getHeight() - img.getHeight()) / 2;
g2d.drawImage(img, x, y, this);
}
g2d.dispose();
}
}
public class Pixel {
private int x;
private int y;
private int color;
public Pixel(int x, int y, int color) {
this.x = x;
this.y = y;
this.color = color;
}
public int getColor() {
return color;
}
public int getX() {
return x;
}
public int getY() {
return y;
}
}
public class PixelExposerWorker extends SwingWorker<Void, Pixel> {
private final BufferedImage img;
private final ImagePane imagePane;
private final List<Point> points;
public PixelExposerWorker(BufferedImage img, ImagePane imagePane) {
this.img = img;
this.imagePane = imagePane;
points = new ArrayList<>(img.getWidth() * img.getHeight());
for (int x = 0; x < img.getWidth(); x++) {
for (int y = 0; y < img.getHeight(); y++) {
points.add(new Point(x, y));
}
}
}
#Override
protected void process(List<Pixel> chunks) {
System.out.println("Publish " + chunks.size());
for (Pixel pixel : chunks) {
imagePane.setPixelAt(pixel.getX(), pixel.getY(), pixel.getColor());
}
imagePane.repaint();
}
#Override
protected Void doInBackground() throws Exception {
StopWatch sw = StopWatch.newInstance().start();
int pixelCount = (int) (points.size() * 0.005);
System.out.println("pixelCount = " + pixelCount + "; " + points.size());
while (!points.isEmpty()) {
StopWatch sw1 = StopWatch.newInstance().start();
for (int count = 0; count < pixelCount && !points.isEmpty(); count++) {
int index = (int) (Math.random() * (points.size() - 1));
Point p = points.remove(index);
Pixel pixel = new Pixel(p.x, p.y, img.getRGB(p.x, p.y));
publish(pixel);
}
Thread.yield();
}
System.out.println("Took " + sw.stop());
return null;
}
}
}

SwingWorker, Thread.sleep(), or javax.swing.timer? I need to "insert a pause"

I'm working on a memory game and I want to set it up so I click the first "card", then the second and if they are not the same the second card shows for a few seconds then they return to the "non-flipped" position.
I tried using SwingWorker, Thread.sleep and SwingTimer but I cant get it to work. With Thread.sleep the second card wont "flip" if it's a duplicate it waits the amount of sleep time and disappears. If its not a match it waits "face down" and after the sleep timer the first card does flip back. This happens regardless of where I place the Thread.sleep.
With Swing Timer it only appears to "change the timer" while I'm interacting with the cards so I end up flipping 8 cards before it activates.
I've had no luck with SwingWorker and I'm not even sure it will work for what I'm looking for.
This is the code I have:
class ButtonListener implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
for(int index = 0; index < arraySize; index++)
{
if(button[index] == e.getSource())
{
button[index].setText(String.valueOf(cards.get(index)));
button[index].setEnabled(false);
number[counter]=cards.get(index);
if (counter == 0)
{
counter++;
}
else if (counter == 1)
{
if (number[0] == number[1])
{
for(int i = 0; i < arraySize; i++)
{
if(!button[i].isEnabled())
{
button[i].setVisible(false);
}
}
}
else
{
for(int i = 0; i < arraySize; i++)
{
if(!button[i].isEnabled())
{
button[i].setEnabled(true);
button[i].setText("Card");
}
}
}
counter = 0;
}
}
}
}
}
Basically what I need is for this code to execute when the counter == 1, and the card is not a match:
button[index].setText(String.valueOf(cards.get(index)));
button[index].setEnabled(false);
Then a pause so the card is revealed for that time, and finally it resumes to returning the card to its face down position.
This is what I tried with Thread.sleep():
class ButtonListener implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
for(int index = 0; index < arraySize; index++)
{
if(button[index] == e.getSource())
{
button[index].setText(String.valueOf(cards.get(index)));
button[index].setEnabled(false);
number[counter]=cards.get(index);
if (counter == 0)
{
counter++;
}
else if (counter == 1)
{
if (number[0] == number[1])
{
for(int i = 0; i < arraySize; i++)
{
if(!button[i].isEnabled())
{
button[i].setVisible(false);
}
}
}
else
{
try
{
Thread.sleep(800);
}
catch (InterruptedException e1)
{
e1.printStackTrace();
}
for(int i = 0; i < arraySize; i++)
{
if(!button[i].isEnabled())
{
button[i].setEnabled(true);
button[i].setText("Card");
}
}
}
counter = 0;
}
}
}
}
}
Thanks in advance for any advice

Use javax.swing.Timer to schedule a future event to trigger. This will allow you to make changes to the UI safely, as the timer is triggered within the context of the Event Dispatching Thread.
The problem with been able to flip multiple cards simultaneously has more to do with you not setting up a state that prevents the user from flipping cards then the use of timers.
The following example basically only allows one card to be flipped per group at a time.
Once a card has been flipped in both groups, the timer is started. When it is triggered, the cards are reset.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.LinearGradientPaint;
import java.awt.Point;
import java.awt.Rectangle;
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.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.io.File;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.border.LineBorder;
public class FlipCards {
public static void main(String[] args) {
new FlipCards();
}
public FlipCards() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class Card extends JPanel {
private BufferedImage image;
private boolean flipped = false;
private Dimension prefSize;
public Card(BufferedImage image, Dimension prefSize) {
setBorder(new LineBorder(Color.DARK_GRAY));
this.image = image;
this.prefSize = prefSize;
}
#Override
public Dimension getPreferredSize() {
return prefSize;
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
LinearGradientPaint lgp = new LinearGradientPaint(
new Point(0, 0),
new Point(0, getHeight()),
new float[]{0f, 1f},
new Color[]{Color.WHITE, Color.GRAY});
g2d.setPaint(lgp);
g2d.fill(new Rectangle(0, 0, getWidth(), getHeight()));
if (flipped && image != null) {
int x = (getWidth() - image.getWidth()) / 2;
int y = (getHeight() - image.getHeight()) / 2;
g2d.drawImage(image, x, y, this);
}
g2d.dispose();
}
public void setFlipped(boolean flipped) {
this.flipped = flipped;
repaint();
}
}
public class CardsPane extends JPanel {
private Card flippedCard = null;
public CardsPane(List<BufferedImage> images, Dimension prefSize) {
setLayout(new GridBagLayout());
MouseAdapter mouseHandler = new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent e) {
if (flippedCard == null) {
Card card = (Card) e.getComponent();
card.setFlipped(true);
flippedCard = card;
firePropertyChange("flippedCard", null, card);
}
}
};
GridBagConstraints gbc = new GridBagConstraints();
gbc.insets = new Insets(4, 4, 4, 4);
gbc.fill = GridBagConstraints.BOTH;
gbc.weightx = 0.25f;
for (BufferedImage img : images) {
Card card = new Card(img, prefSize);
card.addMouseListener(mouseHandler);
add(card, gbc);
}
}
public Card getFlippedCard() {
return flippedCard;
}
public void reset() {
if (flippedCard != null) {
flippedCard.setFlipped(false);
flippedCard = null;
}
}
}
public class TestPane extends JPanel {
private CardsPane topCards;
private CardsPane bottomCards;
private Timer resetTimer;
public TestPane() {
resetTimer = new Timer(1000, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
topCards.reset();
bottomCards.reset();
}
});
resetTimer.setRepeats(false);
resetTimer.setCoalesce(true);
PropertyChangeListener propertyChangeHandler = new PropertyChangeListener() {
#Override
public void propertyChange(PropertyChangeEvent evt) {
Card top = topCards.getFlippedCard();
Card bottom = bottomCards.getFlippedCard();
if (top != null && bottom != null) {
resetTimer.start();
}
}
};
BufferedImage[] images = new BufferedImage[4];
try {
images[0] = ImageIO.read(new File("./Card01.png"));
images[1] = ImageIO.read(new File("./Card02.jpg"));
images[2] = ImageIO.read(new File("./Card03.jpg"));
images[3] = ImageIO.read(new File("./Card04.png"));
Dimension prefSize = getMaxBounds(images);
List<BufferedImage> topImages = new ArrayList<>(Arrays.asList(images));
Random rnd = new Random(System.currentTimeMillis());
int rotate = (int) Math.round((rnd.nextFloat() * 200) - 50);
Collections.rotate(topImages, rotate);
topCards = new CardsPane(topImages, prefSize);
topCards.addPropertyChangeListener("flippedCard", propertyChangeHandler);
List<BufferedImage> botImages = new ArrayList<>(Arrays.asList(images));
int botRotate = (int) Math.round((rnd.nextFloat() * 200) - 50);
Collections.rotate(botImages, botRotate);
bottomCards = new CardsPane(botImages, prefSize);
bottomCards.addPropertyChangeListener("flippedCard", propertyChangeHandler);
setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.insets = new Insets(4, 4, 4, 4);
gbc.gridwidth = GridBagConstraints.REMAINDER;
add(topCards, gbc);
add(bottomCards, gbc);
} catch (Exception e) {
e.printStackTrace();
}
}
protected Dimension getMaxBounds(BufferedImage[] images) {
int width = 0;
int height = 0;
for (BufferedImage img : images) {
width = Math.max(width, img.getWidth());
height = Math.max(height, img.getHeight());
}
return new Dimension(width, height);
}
}
}

Infinite background for game

I am working on a Java project to simulate the flight of a helicopter in a frame. The helicopter moves on the screen using the arrow keys. I want the helicopter to be able to move infinitely, that is, when the helicopter reaches the edge of the frame, the background should move in the opposite direction to have the effect of endless terrain.
Here is the code I have so far:
import java.awt.Graphics;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.awt.image.BufferedImage;
import java.net.URL;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.*;
public class MainFrame extends JFrame
{
private static int FRAME_WIDTH = 800;
private static int FRAME_HEIGHT = 500;
public MainFrame()
{
add(new AnotherBackground(FRAME_WIDTH, FRAME_HEIGHT));
setTitle("Helicopter Background Test");
setSize(FRAME_WIDTH,FRAME_HEIGHT);
setLocationRelativeTo(null);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setVisible(true);
}
public static void main(String[] args)
{
new MainFrame();
}
}
class AnotherBackground extends JPanel
{
private BufferedImage heliImage = null;
private BufferedImage backImage = null;
private int heliX = 0;
private int heliY = 0;
private int backX = 0;
private int backY = 0;
private int frameWidth = 0;
private int frameHeight = 0;
private int backWidth = 0;
private int backHeight = 0;
public AnotherBackground(int fWidth, int fHeight)
{
frameWidth = fWidth;
frameHeight = fHeight;
this.setFocusable(true);
this.addKeyListener(new HeliListener());
try
{
heliImage = ImageIO.read(new URL("http://imageshack.us/a/img7/2133/helicopter2f.png"));
// 2.7 Meg Crap that is a humungous image! Substitute dummy.
backImage = new BufferedImage(1918,1200,BufferedImage.TYPE_INT_RGB);
}
catch(IOException ex)
{
System.out.println("Problem durinng loading heli image");
}
backWidth = backImage.getWidth();
backHeight = backImage.getHeight();
HeliPainter l = new HeliPainter();
new Thread(l).start();
}
#Override
protected void paintComponent(Graphics g)
{
super.paintComponent(g);
g.drawImage(backImage, backX, backY, null);
g.drawImage(heliImage, heliX, heliY, null);
}
class HeliListener extends KeyAdapter
{
#Override
public void keyPressed(KeyEvent e)
{
System.out.println(heliX + " " + heliY + " " + backX + " " + backY);
if (e.getKeyCode() == KeyEvent.VK_LEFT)
{
if(heliX > 0)
{
heliX -= 5;
}
else
{
backX += 5;
}
}
else if (e.getKeyCode() == KeyEvent.VK_RIGHT)
{
if(heliX < frameWidth)
{
heliX += 5;
}
else
{
backX -= 5;
}
}
else if (e.getKeyCode() == KeyEvent.VK_UP)
{
if(heliY > 0)
{
heliY -= 5;
}
else
{
backY += 5;
}
}
else if (e.getKeyCode() == KeyEvent.VK_DOWN)
{
if(heliY < frameHeight)
{
heliY += 5;
}
else
{
backY -= 5;
}
}
}
}
class HeliPainter implements Runnable
{
#Override
public void run()
{
try
{
while(true)
{
SwingUtilities.invokeLater(new Runnable()
{
#Override
public void run()
{
repaint();
}
});
Thread.sleep(1);
}
}
catch(InterruptedException ex)
{
System.out.println("Problem putting thread to sleep");
}
}
}
}
Now there's two images in the code. One is that of a small helicopter, and the other is a large (2.7 meg) background. They are here:
background
helicopter http://imageshack.us/a/img7/2133/helicopter2f.png
How to show the BG continuously?

Have a look through this source which behaves in a more predictable manner, and also includes a nice tweak to the chopper image (animated). ;)
import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import java.awt.image.BufferedImage;
import java.net.URL;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.*;
public class MainFrame
{
public MainFrame()
{
JFrame f = new JFrame("Helicopter Background Test");
f.add(new AnotherBackground());
//setTitle("Helicopter Background Test"); Redundant..
// Set a preferred size for the content area and pack() the frame instead!
// setSize(FRAME_WIDTH,FRAME_HEIGHT);
// setLocationRelativeTo(null); Better to..
f.setLocationByPlatform(true);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.pack(); // Size the GUI - VERY MPORTANT!
f.setVisible(true);
}
public static void main(String[] args)
{
new MainFrame();
}
}
class AnotherBackground extends JPanel
{
private static int PREFERRED_WIDTH = 400;
private static int PREFERRED_HEIGHT = 200;
private BufferedImage heliImage = null;
private BufferedImage heliLeftImage = null;
private BufferedImage heliRightImage = null;
private BufferedImage backImage = null; //getFlippedImage(
private int heliX = 0;
private int heliY = 0;
private int backX = 0;
private int backY = 0;
private int frameWidth = 0;
private int frameHeight = 0;
private int backWidth = 0;
private int backHeight = 0;
public AnotherBackground()
{
frameWidth = PREFERRED_WIDTH;
frameHeight = PREFERRED_HEIGHT;
this.setFocusable(true);
this.addKeyListener(new HeliListener());
try
{
heliLeftImage = ImageIO.read(
new URL("http://imageshack.us/a/img7/2133/helicopter2f.png"));
heliRightImage = getFlippedImage(heliLeftImage);
heliImage = heliLeftImage;
// 2.7 Meg Crap that is an humungous image! Substitute dummy.
backImage = getTileImage(250);
//ImageIO.read(
// new URL("http://i.stack.imgur.com/T5uTa.png"));
backWidth = backImage.getWidth();
backHeight = backImage.getHeight();
//HeliPainter l = new HeliPainter(); // see mention of repaint()
//new Thread(l).start();
} catch(IOException ex) {
// THERE IS NO POINT CONTINUING AFTER THIS POINT!
// unless it is to pop an option pane error message..
System.err.println("Problem during loading heli image");
ex.printStackTrace();
}
}
#Override
public Dimension getPreferredSize() {
return new Dimension(PREFERRED_WIDTH, PREFERRED_HEIGHT);
}
#Override
protected void paintComponent(Graphics g)
{
super.paintComponent(g);
int normalizeX = (heliRealX-heliX)%backImage.getWidth();
int normalizeY = (heliRealY-heliY)%backImage.getHeight();
int timesRepeatX = (getWidth()/backImage.getWidth())+2;
int timesRepeatY = (getHeight()/backImage.getHeight())+2;
for (int xx=-1; xx<timesRepeatX; xx++) {
for (int yy=-1; yy<timesRepeatY; yy++) {
g.drawImage(
backImage,
(xx*backImage.getWidth())-normalizeX,
(yy*backImage.getHeight())-normalizeY,
this); // A JPanel IS AN ImageObserver!
g.drawImage(heliImage, heliX, heliY, this);
}
}
g.setColor(Color.BLACK);
}
private int heliRealX = 0;
private int heliRealY = 0;
class HeliListener extends KeyAdapter
{
#Override
public void keyPressed(KeyEvent e)
{
int pad = 5;
if (e.getKeyCode() == KeyEvent.VK_LEFT)
{
if(heliX > 0)
{
heliX -= 5;
}
else
{
backX += 5;
}
heliRealX-=5;
heliImage = heliLeftImage;
}
else if (e.getKeyCode() == KeyEvent.VK_RIGHT)
{
// correct for image size + padding
if(heliX+heliImage.getWidth()+pad < getWidth())
{
heliX += 5;
}
else
{
backX -= 5;
}
heliRealX+=5;
heliImage = heliRightImage;
}
else if (e.getKeyCode() == KeyEvent.VK_UP)
{
if(heliY > 0)
{
heliY -= 5;
}
else
{
backY += 5;
}
heliRealY-=5;
}
else if (e.getKeyCode() == KeyEvent.VK_DOWN)
{
// correct for image size + padding
if(heliY+heliImage.getHeight()+pad < getHeight())
{
heliY += 5;
}
else
{
backY -= 5;
}
heliRealY+=5;
}
repaint(); // Replaces need for threads for this simple demo!
}
}
public BufferedImage getFlippedImage(BufferedImage original) {
BufferedImage bi = new BufferedImage(
original.getWidth(),
original.getHeight(),
BufferedImage.TYPE_INT_ARGB);
Graphics2D g = bi.createGraphics();
AffineTransform at = AffineTransform.getTranslateInstance(bi.getWidth(),1d);
at.concatenate(AffineTransform.getScaleInstance(-1d,1d));
g.setTransform(at);
g.drawImage(original,0,0,this);
g.dispose();
return bi;
}
public BufferedImage getTileImage(int s) {
BufferedImage bi = new BufferedImage(s,s,BufferedImage.TYPE_INT_ARGB);
Graphics2D g = bi.createGraphics();
GradientPaint gp1 = new GradientPaint(
(float)0,(float)s/4, Color.YELLOW,
(float)s/4,0f, Color.GREEN,
true);
g.setPaint(gp1);
g.fillRect(0,0,s,s);
int trans = 165;
GradientPaint gp2 = new GradientPaint(
(float)s/2,(float)s/2, new Color(255,0,0,trans),
0f,(float)s/2, new Color(255,255,255,trans),
true);
g.setPaint(gp2);
g.fillRect(0,0,s,s);
g.dispose();
return bi;
}
}

This is a really simple example (you can only move in a single direction). The basic idea is that there is a prepareView method that is responsible for generating a view of the world based on the available viewable area. If the view is trying to view an area off the map, the map is titled to make up for it.
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.imageio.ImageIO;
import javax.swing.AbstractAction;
import javax.swing.ActionMap;
import javax.swing.InputMap;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class InfiniteBackground {
public static void main(String[] args) {
new InfiniteBackground();
}
public InfiniteBackground() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public static class TestPane extends JPanel {
protected static final int DELTA = 5;
private BufferedImage terrian;
private BufferedImage heli;
private Point pov;
private Point heliPoint;
private BufferedImage view;
public TestPane() {
pov = new Point();
heliPoint = new Point();
try {
terrian = ImageIO.read(getClass().getResource("/terrain_map.jpg"));
heli = ImageIO.read(getClass().getResource("/helicopter2f.png"));
pov.x = terrian.getWidth() - getPreferredSize().width;
pov.y = ((terrian.getHeight() - getPreferredSize().height) / 2);
heliPoint.x = getPreferredSize().width / 2;
heliPoint.y = getPreferredSize().height / 2;
prepareView();
InputMap im = getInputMap(WHEN_IN_FOCUSED_WINDOW);
ActionMap am = getActionMap();
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_LEFT, 0), "goLeft");
am.put("goLeft", new AbstractAction() {
#Override
public void actionPerformed(ActionEvent e) {
heliPoint.x -= DELTA;
if (heliPoint.x - (heli.getWidth() / 2) < 0) {
heliPoint.x = (heli.getWidth() / 2);
prepareView();
pov.x -= DELTA;
}
repaint();
}
});
} catch (IOException ex) {
ex.printStackTrace();
}
}
#Override
public Dimension getPreferredSize() {
return new Dimension(400, 200);
}
protected void prepareView() {
if (getWidth() > 0 && getHeight() > 0) {
view = new BufferedImage(getWidth(), getHeight(), BufferedImage.TYPE_INT_RGB);
Graphics2D g2d = view.createGraphics();
if (pov.x < 0) {
pov.x = terrian.getWidth();
}
g2d.drawImage(terrian, -pov.x, -pov.y, this);
if (pov.x + getWidth() > terrian.getWidth()) {
g2d.drawImage(terrian, -pov.x + terrian.getWidth(), -pov.y, this);
}
g2d.dispose();
}
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (terrian != null) {
Graphics2D g2d = (Graphics2D) g.create();
if (view == null) {
prepareView();
}
g2d.drawImage(view, 0, 0, this);
g2d.drawImage(heli, heliPoint.x - (heli.getWidth() / 2), heliPoint.y - (heli.getHeight() / 2), this);
g2d.dispose();
}
}
}
}