Oh, animated GIFs .
Image handling isn't simple in most cases, but animated GIFs are whole other level of pain ... I mean fun.
Normally, I prefer to use ImageIO.read, but ImageIO returns a BufferedImage and it's not (easily) possible to then render animated GIFs through it.
The "easy" route of displaying animated GIFs is by using Image or ImageIcon.
The first step is get your image "embedded" within your application context (assuming that you're not allowing the user to select the image). How this is done will depend on your IDE and build system (Eclipse and Netbeans allow you to simply include them in the src folder, when you're not using Maven).
Next, you want to use Class#getResource to obtain a URL reference to the embedded resource. In this case, you can use ImageIO.read, ImageIcon(URL) or Toolkit#getImage(URL) to load the image. But, as I've said, ImageIO.read isn't going to help you.
Next, you need a component which can render the image, lucky for us, Swing can do this pretty much auto magically for use, all we need to do is make sure the component is passed as the ImageObserver reference, for example...
public class BackgroundPane extends JPanel {
private Image image;
public BackgroundPane(Image image) {
this.image = image;
}
@Override
public Dimension getPreferredSize() {
Image image = getBackgroundImage();
return image == null ? super.getPreferredSize() : new Dimension(image.getWidth(this), image.getHeight(this));
}
public Image getBackgroundImage() {
return image;
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Image image = getBackgroundImage();
if (image == null) {
return;
}
int x = (getWidth() - image.getWidth(this)) / 2;
int y = (getHeight() - image.getHeight(this)) / 2;
g.drawImage(image, x, y, this);
}
}
Also, note, JLabel supports animated GIFs via it's icon property as well, but look at How to set a background picture in JPanel for reasons why you shouldn't use a JLabel as a background container.
Now, all we need to do is load the image, pass it to the background, add what ever content we need to the component and show it, easy, or at least it should be. ImageIcon and Toolkit#getImage both off load the reading of the image to a background thread, so inspecting the images dimensions before the image is loaded will return 0x0 , so, we need to wait for it to load (this is why I prefer ImageIO.read as it won't return until the image is loaded or an error occurs).
Something like...
Image image = Toolkit.getDefaultToolkit().getImage(getClass().getResource("/images/kitty.gif"));
BackgroundPane backgroundPane = new BackgroundPane(image);
// Did I mention I had this workflow, but ImageIO doesn't
// support animated images, without a lot of work
MediaTracker mt = new MediaTracker(backgroundPane);
mt.addImage(image, 0);
mt.waitForAll();
// The image is now loaded, hooray for us
Runnable example...
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.GridBagLayout;
import java.awt.Image;
import java.awt.MediaTracker;
import java.awt.Toolkit;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
public class Main {
public static void main(String[] args) {
new Main();
}
public Main() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
Image image = Toolkit.getDefaultToolkit().getImage(getClass().getResource("/images/kitty.gif"));
BackgroundPane backgroundPane = new BackgroundPane(image);
// Did I mention I had this workflow, but ImageIO doesn't
// support animated images, without a lot of work
MediaTracker mt = new MediaTracker(backgroundPane);
mt.addImage(image, 0);
mt.waitForAll();
backgroundPane.setLayout(new GridBagLayout());
JLabel label = new JLabel("All your kitty is belong to us");
label.setForeground(Color.WHITE);
backgroundPane.add(label);
JFrame frame = new JFrame();
frame.add(backgroundPane);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
} catch (InterruptedException ex) {
Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
}
}
});
}
public class BackgroundPane extends JPanel {
private Image image;
public BackgroundPane(Image image) {
this.image = image;
}
@Override
public Dimension getPreferredSize() {
Image image = getBackgroundImage();
return image == null ? super.getPreferredSize() : new Dimension(image.getWidth(this), image.getHeight(this));
}
public Image getBackgroundImage() {
return image;
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Image image = getBackgroundImage();
if (image == null) {
return;
}
int x = (getWidth() - image.getWidth(this)) / 2;
int y = (getHeight() - image.getHeight(this)) / 2;
g.drawImage(image, x, y, this);
}
}
}
Please note...
If you're not using an animated GIF, then you can just use ImageIO.read instead of Toolkit#getImage and you won't need to wait (as ImageIO.read works in the current thread), in which case the code would look more like...
try {
BackgroundPane backgroundPane = new BackgroundPane(ImageIO.read(getClass().getResource("/images/kitty.gif")));
backgroundPane.setLayout(new GridBagLayout());
JLabel label = new JLabel("All your kitty is belong to us");
label.setForeground(Color.WHITE);
backgroundPane.add(label);
JFrame frame = new JFrame();
frame.add(backgroundPane);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
} catch (IOException ex) {
Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
}
(the BackgroundPane code doesn't change)
