Java problems with gif in label

Question

A gif that I tried to put into a JPanel isn't showing up after clicking the button that triggers it until I resize the window. When it does show up, it does not fit the JPanel and is not animated. I looked at several posts that dealt with this but I don't understand how to use them in my case.

/*
 * Author: Raymo111
 * Date: 13/04/2018
 * Description: Wishes happy birthday to a special someone
 */

//Imports java GUI classes
import javax.imageio.ImageIO;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

// Main class with JFrame and ActionListener enabled
public class Happy_Birthday_GUI extends JFrame implements ActionListener {

    // Class variables
    private static JButton startButton = new JButton("CLICK TO START");
    private static JPanel startPanel = new JPanel(), gifPanel = new JPanel();
    private static Color blue = new Color(126, 192, 238), pink = new Color(255, 192, 203);
    private static GridLayout grid1 = new GridLayout(1, 1);

    // Constructor
    public Happy_Birthday_GUI() {

        // Initial screen
        startButton.addActionListener(this);
        startButton.setFont(new Font("Comic Sans MS", Font.PLAIN, 50));
        startPanel.setLayout(grid1);
        startPanel.add(startButton);
        startPanel.setBorder(BorderFactory.createLineBorder(blue, 100));
        startButton.setBackground(pink);
        getContentPane().add(startPanel);

        // Sets title, size, layout (grid 1x1), and location of GUI window (center)
        setTitle("Happy Birthday from Dolphin");
        setSize(840, 840);
        setLayout(grid1);
        setLocationRelativeTo(null);
        setVisible(true);

    }

    // Main method
    public static void main(String[] args) {
        new Happy_Birthday_GUI();
    }

    // Action Performed method
    public void actionPerformed(ActionEvent event) {

        // Proceed to gif and song
        if (startButton == event.getSource()) {
            getContentPane().removeAll();
            BufferedImage dolphin;
            gifPanel.setLayout(grid1);
            gifPanel.setBorder(BorderFactory.createLineBorder(pink, 100));
            try {
                dolphin = ImageIO.read(new File("C:\\Users\\raymo\\Pictures\\dolphin.gif"));
                JLabel gifLabel = new JLabel(new ImageIcon(dolphin));
                gifPanel.add(gifLabel);
            } catch (IOException e) {
                e.printStackTrace();
            }
            getContentPane().add(gifPanel);
        }
    }

}

---

Here is dolphin.gif. It's cute.

---

How do I get it to show up immediately after clicking the start button as an animated gif that fits the JPanel? Thanks in advance.

Answer 1

I ended up doing:

gifPanel.add(new TestPane());
getContentPane().add(gifPanel);
revalidate();
repaint();

using camickr's revalidate and repaint, and MadProgrammer's TestPane class, which worked very well to get the gif to animate, resize correctly and display immediately.

Answer 2

BufferedImage doesn't support painting animated Gifs, instead, you'll need to make use of Image (or preferably, ImageIcon).

This could then be applied directly to a JLabel, which will perform the animation operation itself.

animated gif that fits he JPanel?

Okay, that's a much more complex problem. One approach would be to convert the Gif to the required size, but needless to say, that's very, very complex.

A simpler solution might be to use a AffineTransform and scale the image to meet the requirements of the component itself. This would require a custom component, capable of calculating the scale and painting each frame of the image.

Luckily for you, JPanel is an ImageObserver, this means it's capable of painting the gif animation

import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.AffineTransform;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JPanel;
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 ImageIcon image;

        public TestPane() {
            image = new ImageIcon("/Users/swhitehead/Downloads/NbENe.gif");
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(600, 600);
        }

        @Override
        protected void paintComponent(Graphics g) {
            int imageWidth = image.getIconWidth();
            int imageHeight = image.getIconHeight();

            if (imageWidth == 0 || imageHeight == 0) {
                return;
            }
            double widthScale = (double)getWidth() / (double)imageWidth;
            double heightScale = (double)getHeight() / (double)imageHeight;
            Graphics2D g2d = (Graphics2D) g.create();
            g2d.drawImage(image.getImage(), AffineTransform.getScaleInstance(widthScale, heightScale), this);
            g2d.dispose();
        }

    }

}

Answer 3

I tried to put into a JPanel isn't showing up after clicking the button

When you add (or remove) components from a visible GUI the basic code is:

panel.add(...);
panel.revalidate();
panel.repaint();

The revalidate() is need to invoke the layout manager so the component is given a size.

is not animated.

Use a JLabel with an ImageIcon to display images. A JLabel will animated the gif.

When it does show up, it does not fit the JPanel and

You can try the Stretch Icon which is designed to fill the space available to the label.