Develop Reference

How to make ImageIcon on JLabel update faster with less latency

I am trying to update an ImageIcon on a JLabel which sits on a JLayeredPane, but there is a lot of latency between when the setting thread sends the proper state to the JLabel object and when the GUI displays the ImageIcon of the proper state. The following code is an example of the issue, look for the difference in time between the print of the button being on/off and when the displayed icon gets lighter/darker.
The setting thread:
new Thread(new Runnable() { // setting thread
#Override
public void run() {
// TODO Auto-generated method stub
try {
while(true) {
System.out.println("testButton on"); // print that the button is on
testButton.updateState(1); // set button state to on
Thread.sleep(70 + random.nextInt(500)); //sleep between 70 and 570 milliseconds
System.out.println("testButton off");// print that the button is off
testButton.updateState(0); // set button state to off
Thread.sleep(70 + random.nextInt(500)); // sleep between 70 and 570 milliseconds
}
} catch(Exception e) {
e.printStackTrace();
}
}
}).start();
The button object:
class Button extends JLabel {
ImageIcon released;
ImageIcon pressed;
String text;
public Button(int x, int y, String text) {
released = new ImageIcon("src/components/images/button.png");
pressed = new ImageIcon("src/components/images/buttonDown.png");
setBounds(x,y, 100, 100);
this.text = text;
setIcon(released);
}
public void updateState(int data) {
if (data == 1) {
setIcon(pressed);
}
else {
setIcon(released);
}
}
}
The ImageIcons are only 325 bytes, so what might be causing the latency? I looked up about the Event Dispatcher Thread and many people say it should be instantaneous for an image to get painted.
End goal: Have many button objects on screen with the setting thread calling them to update based on randomly occurring actions. The displayed icon for a specific button object should change immediately as it is set in the function. The setting thread will not be constantly looping, instead loop once for every action sent (it is twice here just to show the issue).
Any suggestions or things to try I will test as soon as I can.
Edit: In the end the thread that gets the information will call to a device driver in Linux where it will wait for a response and only when it gets a response will it need to update the window. From what I know timer is used to update something at regular intervals, but I am likely wrong.

As explained in the comments running long processes on the The Event Dispatch Thread blocks it, so it does not respond to changes.
Also you are not suppose to update Swing components from other (not EDT) threads.
You need to use Swing tools like SwingWorker or Timer.
The following mcve demonstrates a simple slide-show using Timer:
import java.awt.BorderLayout;
import java.io.IOException;
import java.net.URL;
import java.util.Random;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingConstants;
import javax.swing.Timer;
public class ChangeButtonIcon extends JPanel{
private final URL[] urls = {
new URL("https://findicons.com/files/icons/345/summer/128/cake.png"),
new URL("http://icons.iconarchive.com/icons/atyourservice/service-categories/128/Sweets-icon.png"),
new URL("https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcS_FkBgG3_ux0kCbfG8mcRHvdk1dYbZYsm2SFMS01YvA6B_zfH_kg"),
};
private int iconNumber = 0;
private final JButton button;
private boolean stop = true;
private final Random random;
private static final int MIN_DELAY = 70, DELAY = 500;
private Timer timer;
public ChangeButtonIcon() throws IOException {
random = new Random();
button = new JButton();
button.setIcon(new ImageIcon(urls[iconNumber]));
button.setHorizontalTextPosition(SwingConstants.CENTER);
button.addActionListener(e -> startStopSlideShow());
add(button);
}
private void startStopSlideShow(){
stop = ! stop;
if(stop){
timer.stop();
return;
}
timer = new Timer( MIN_DELAY+ random.nextInt(DELAY), (e)->swapIcon());
timer.start();
}
private void swapIcon() {
iconNumber = iconNumber >= urls.length -1 ? 0 : iconNumber+1;
button.setIcon(new ImageIcon(urls[iconNumber]));
}
public static void main(String[] args) throws IOException{
JFrame window = new JFrame();
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.add(new ChangeButtonIcon());
window.add(new JLabel("Click image to start / stop"), BorderLayout.PAGE_END);
window.pack();
window.setVisible(true);
}
}

Image Slideshow using JFrame

I have a problem with a task that seemed to be pretty easy. I have to create a program that will show images (.jpg,.png and .gif) consecutively. Images have to be the contents of some files, that is given as an argument to the program. When I have to load the images separately, it works, but the issue occurs when I load them one after another with a sleep between them.
Here is my code:
import javax.swing.SwingUtilities;
public class Main {
public static void main(String[] args)
{
SwingUtilities.invokeLater(new Runnable()
{
#Override
public void run()
{
new MyFrame(args[0],Integer.parseInt(args[1]));
//First argument is path to file with images, second - amount of time (in seconds) which every image has to stay on the screen until the next one appears
}
});
}
}
import java.io.File;
import javax.swing.*;
public class MyFrame extends JFrame{
public MyFrame(String path, int time){
super("Obrazki");
this.setDefaultCloseOperation(EXIT_ON_CLOSE);
this.setVisible(true);
MyPanel panel = new MyPanel();
panel.setVisible(true);
this.add(panel);
pack();
File file = new File(path);
String[] tabs = file.list();
for(int i=0; i<tabs.length; i++)
{
panel.loadImage(path+"\\"+tabs[i]);
this.repaint();
try {
Thread.sleep(time*1000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.MediaTracker;
import java.awt.Toolkit;
import javax.swing.JPanel;
public class MyPanel extends JPanel
{
Image img;
public void loadImage(String s)
{
img = Toolkit.getDefaultToolkit().getImage(s);
MediaTracker tracker = new MediaTracker(this);
tracker.addImage(img, 1);
while(!tracker.checkID(1)) {
try {
tracker.waitForID(1);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
this.repaint();
}
#Override
public void paintComponent(Graphics g)
{
super.paintComponent(g);
Graphics2D g2 = (Graphics2D)g;
g2.drawImage(this.img, 0, 0, this.getSize().width, this.getSize().height, this);
}
}

but the issue is when i load them one after another with sleep time between them.
You are causing the Event Dispatch Thread (EDT) to sleep, which means the GUI can't respond to events or repaint itself. Read the section from the Swing tutorial on Concurrency for more information.
Don't use Thread.sleep() when code is executing on the EDT.
For animation you can:
use a SwingWorker (with Thread.sleep())and publish the Icon you want to paint, or
use a Swing Timer. The tutorial also has a section on How to Use Swing Timers.

Stopping a window from displaying till it is fully drawn?

I am working on a Java program that takes in a large amount of files (3000 max) with an associated array of 1/0's. Currently I have a visualization of the array where there is a grid where each box is filled black for 1 or white for 0. When drawn it runs well but takes around a minute to fully load (and potentially locks the computer up in the meantime.) Is there a way I can: 1, not display the window till it is done
(i.e JFrame create,
//draw window
frame.setVisible(true))
and 2, track the progress of the process so that I can use a progress bar with it?
edit: Can I run a thread to draw it and then simply make a while loop to only display it once the thread is completed?

In the example below, a SwingWorker sets pixels in a BufferedImage based on the data read from a random file. Note that Thread.sleep() is used to simulate latency; it is otherwise not required. You can add a JProgressBar as shown here.
Is there a better way to get simple colored boxes?
Yes. In the example below, each pixel represents one cell. For larger boxes, return a multiple of the image size, e.g.
#Override
public Dimension getPreferredSize() {
return new Dimension(2 * N, 2 * N);
}
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.BufferedInputStream;
import java.io.DataInputStream;
import java.io.FileInputStream;
import java.util.List;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingWorker;
/**
* #see https://stackoverflow.com/a/25043676/230513
*/
public class WorkerTest {
private static final int N = 256;
private final BooleanPanel panel = new BooleanPanel();
private class BooleanPanel extends JPanel {
private BufferedImage image;
public void setImage(BufferedImage bi) {
this.image = bi;
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
g2d.drawImage(image, 0, 0, getWidth(), getHeight(), null);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(N, N);
}
}
private class BufferedImageWorker extends SwingWorker<BufferedImage, BufferedImage> {
#Override
protected BufferedImage doInBackground() throws Exception {
BufferedImage image = new BufferedImage(N, N, BufferedImage.TYPE_INT_ARGB);
try (DataInputStream dis = new DataInputStream(
new BufferedInputStream(new FileInputStream("/dev/random")))) {
for (int row = 0; row < N; row++) {
for (int col = 0; col < N; col++) {
image.setRGB(col, row, dis.readByte() < 0 ? 0xffffffff : 0xff000000);
}
Thread.sleep(40); // ~25 Hz
publish(image);
}
return image;
}
}
#Override
protected void process(List<BufferedImage> list) {
for (BufferedImage bi : list) {
panel.setImage(bi);
panel.repaint();
}
}
}
private void display() {
JFrame f = new JFrame("WorkerTest");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(panel);
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
new BufferedImageWorker().execute();
}
public static void main(String[] args) {
EventQueue.invokeLater(() -> {
new WorkerTest().display();
});
}
}

I would definitely use a SwingWorker in this case. Basically, maybe something along these lines (I'm not sure what type of object your 'visualization' is, so for simplicity, I'll just say it's an Image). You can add this at the bottom of your class. You'll obviously have to edit it to make it work for you.
protected class DrawGridTask extends SwingWorker<Image, Object> {
ObjectToPutImageOn imageObject;
public DrawGridTask(ObjectToPutImageOn obj) {
this.imageObject = obj;
}
protected Image doInBackground() {
// generate your Image or graphic or whatever here
return Image;
}
protected void done() {
imageObject.drawThisCompletedImage(get());
}
}
To call this method, you would run (new DrawGridTask(objectToPutImageOn)).execute();
All the code in doInBackground() will run on it's own worker thread. Done() runs on the event dispatch thread, and gets the reference doInBackground() returns when it calls get().
There is more information here, including how to do progress updates at: http://docs.oracle.com/javase/tutorial/uiswing/concurrency/worker.html
Since I mentioned Images, if you do work with them, you might also want to take a look at the MediaTracker class, this can be very useful for blocking until an image is ready.

Problems with actionPerformed and ActionListener [duplicate]

This question already exists:
Cannot repeat action with Java Swing [closed]
Closed 9 years ago.
I have started programming using Java and I have one problem with Swing. I would like to repeat oval animation after click on my button przycisk. So that's why I create RamkaAnimacjaKola mojeGUI= new RamkaAnimacjaKola(); in my ActionPerformed. So what should I change ?.
I call Thread.sleap because that was an example in my book. It works when i try to run my code only once. That means without action listener and button przycisk Source is below:
package Kurs;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class RamkaAnimacjaKola implements ActionListener {
JFrame ramka;
Panel mojPanel;
int x=40;
int y=40;
public void zacznijAnimacje(){
mojPanel = new Panel();
ramka= new JFrame();
JButton przycisk= new JButton("repeat");
ramka.getContentPane().add(BorderLayout.SOUTH, przycisk);
przycisk.addActionListener(this);
ramka.getContentPane().add(BorderLayout.CENTER, mojPanel);
ramka.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
ramka.setSize(300, 300);
ramka.setVisible(true);
for (int i=0 ; i <40 ;i++){
x++;
ramka.repaint();
try{
Thread.sleep(50);
} catch (Exception ex){ }
}
for (int i=0 ; i <40 ;i++){
y++;
ramka.repaint();
try{
Thread.sleep(50);
} catch (Exception ex){ }
}
for (int i=0 ; i <40 ;i++){
x--;
ramka.repaint();
try{
Thread.sleep(50);
} catch (Exception ex){ }
}
for (int i=0 ; i <40 ;i++){
y--;
ramka.repaint();
try{
Thread.sleep(50);
} catch (Exception ex){ }
}
}
public void actionPerformed(ActionEvent zdarzenie) {
RamkaAnimacjaKola mojeGUI= new RamkaAnimacjaKola();
mojeGUI.zacznijAnimacje();
}
class Panel extends JPanel {
public void paintComponent(Graphics g){
g.setColor(Color.green);
g.fillOval(x, y, 40, 40);
}
}
}
I start this code using my test class:
package Kurs;
public class UruchomGUI {
/**
* #param args
*/
public static void main(String[] args) {
RamkaAnimacjaKola mojeGUI = new RamkaAnimacjaKola();
mojeGUI.zacznijAnimacje();
}
}
Can you explain me why it doesn't work?

You should do nothing in the Event Dispatching Thread that would block it.
The EDT is responsible for, amongst other things, process repaint requests. Anything you do that prevents the EDT from processing these events (like Thread.sleep) will make it appear as your application has frozen. There are a number of excellent examples on SO.
Take a look at Multiple bouncing balls thread issue and Java Bouncing Ball and the images are not loading for some examples...
You might also like to have a read through Concurrency in Swing

Multiple instances of the same animated GIF in a Canvas (Java)

So I'm making a game where you can put bombs on the location of your character. Each bomb is associated with a GIF image when the bomb is displayed and eventually go BOOM (think about Bomberman).
The problem was, when i tried to paint more than one bomb on the screen, it was painted from the last frame of the GIF. Investigating, I found the method image.flush() to reset the GIF cicle but now the problem is that every time I paint a second bomb on the screen, the GIF cycle is reset for all previously bombs on screen.
Here is my constructor for each bomb:
public Tnt(int x, int y){
this.x = x;
this.y = y;
ImageIcon ii = new ImageIcon("src/main/resources/modelObjects/tnt.gif");
image = ii.getImage();
image.flush();
}
Every bomb i create enters an ArrayList (listTnt) and is removed after 6 secs, so i only paint the bombs already active.
Here is my method for drawing:
public void draw(Graphics2D g2d, JPanel board){
for(Tnt tnt: listTnt){
g2d.drawImage(tnt.getImage(), tnt.getX(), tnt.getY(), board);
}
}
EDIT: Seems that the problem was ImageIcon, since it reuses the image using Toolkit.getImage. Instead, Toolkit.createImage create a not reusable image.
Here is my new constructor for Tnt that worked perfectly:
public Tnt(int x, int y){
this.x = x;
this.y = y;
Toolkit t = Toolkit.getDefaultToolkit ();
image = t.createImage("src/main/resources/modelObjects/tnt.gif");
}
I dont even need image.flush() now. Thank you all.

The underlying Image is being reused amongst each ImageIcon.
Judging by the OpenJDK source code, it appears to be due to the fact that each simply requests the Image via Toolkit.getImage.
This method has a nifty caveat, however, which explains the issue at hand:
The underlying toolkit attempts to resolve multiple requests with the same filename to the same returned Image.
Instead, you should skip the ImageIcon step completely (since it's inappropriate to be using a Swing class unnecessarily in the first place), and instead call Toolkit.createImage, which states in the documentation:
The returned Image is a new object which will not be shared with any other caller of this method or its getImage variant.
Good luck.

As I did not know how to solve this, I tried #super_ solution and it works quite nicely. I share the code for anyone who wants an example. +1 to him
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.net.MalformedURLException;
import java.net.URL;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
public class TestAnimatedGif {
private static final int IMAGE_COUNT = 9;
protected void initUI() {
JFrame frame = new JFrame(TestAnimatedGif.class.getSimpleName());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
final JPanel panel = new JPanel();
frame.add(panel);
frame.setSize(600, 400);
frame.setVisible(true);
final Timer t = new Timer(1000, null);
t.addActionListener(new ActionListener() {
int count = 0;
#Override
public void actionPerformed(ActionEvent e) {
if (count < IMAGE_COUNT) {
try {
JLabel image = new JLabel(new ImageIcon(Toolkit.getDefaultToolkit().createImage(
new URL("http://www.sitevip.net/gifs/bomba/BOMB-B_animado.gif"))));
panel.add(image);
count++;
panel.revalidate();
panel.repaint();
System.err.println("image added");
} catch (MalformedURLException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
} else {
t.stop();
}
}
});
t.start();
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new TestAnimatedGif().initUI();
}
});
}
}