How to draw GIF with Image and drawImage

Question

I need to draw a GIF, I have the following code:

public BasicBlock(String path, String name, int id, boolean gif){
    this.path = path;
    this.name = name;
    this.id = id;   

    File img = new File(path);
    try {
        image = ImageIO.read(img);
    } catch (IOException e) {}
}

public static BufferedImage getBlockById(int id){
    return blocks[id].getImage();
}

g.drawImage(Blocks.getBlockById(id), x, y, null);

Answer 1

Despite ImageIO be used to upload images, and a gif also be an image, the problem of using this class for gifs is that it will only load the first frame.

To properly load the gif, you need to create a ImageIcon, retrieve a guy Image and move on to the method drawImage() in the paintComponent() of the panel or other component where you will draw the gif.

In addition, you also need to set an image observer to the drawImage, it is he who will take care of the animation.

I made an example for you to see in practice:

import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Image;
import java.net.MalformedURLException;
import java.net.URL;

import javax.swing.ImageIcon;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;

public class DrawGiFTest extends JComponent {

    public void createAndShowGUI() {

        JFrame window = new JFrame();

        window.getContentPane().add(new GifPanel(loadImage("http://introcs.cs.princeton.edu/java/15inout/duke.gif")));
        window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        window.setPreferredSize(new Dimension(300, 300));

        window.pack();
        window.setVisible(true);
    }

    //Este método recebe uma string com a url da imagem e
    //cria um ImageIcon e retorna um tipo Image, com o 
    //gif já carregador corretamente
    private Image loadImage(String url){

        ImageIcon icon;

        try {
            icon = new ImageIcon(new URL(url)); 
            Image img = icon.getImage();
            return img;
        } catch (MalformedURLException e) {
            e.printStackTrace();
            return null;
        }
    }

    class GifPanel extends JComponent{

        Image image;

        public GifPanel(Image image) {
            this.image = image;
        }

        @Override
        protected void paintComponent(Graphics g) {

            super.paintComponent(g);
            g.drawImage(image, 50, 50, this);
        }

    }


    public static void main(String[] a) {

        SwingUtilities.invokeLater(() -> {
            new DrawGiFTest().createAndShowGUI();
        });
    }
}

The result:

In this case, I passed the this, for the JComponent implements a ImageObserver. If drawing on any other component (such as a JPanel, Jbutton, etc...), you can pass the this also, because all swing components(except the top-level containers) inherit from JComponent directly or indirectly.

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References:

• Java Draw to GIF
• Show an Animated BG in Swing
• Why gif Animation doesn’t Animate when using it in paintComponent()?