Cannot get image to display in Swing on OSX

Question

Hi chaps, I think I'm being a bit of an idiot, given that I haven't done Swing programming in a while, but I'm trying to draw a simple image to screen, and I'm not getting what I expected

public class ImageApp {

    public static void main(String[] args) throws MalformedURLException, IOException {
        final Image image = ImageIO.read(new File("/Library/WebServer/Documents/image.gif"));

        final JPanel component = new JPanel(){

            public void paint(final Graphics g) {
                System.out.println("Drawing image "+image.getWidth(null)+" "+image.getHeight(null));
                g.drawString("hello", 0,0);
                g.drawImage(image,this.getWidth()/2,this.getHeight()/2, 100, 100, Color.blue,this);
                super.paint(g);
            }
        };

        final JFrame frame = new JFrame();

        frame.add(component);
        frame.setSize(100, 100);

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

}

This renders a blank window which doesn't seem to be sized to 100,100. Is there some other step I need to perform to get the graphics to appear on screen, or the size to be respected?

I'm using JDK6 on OSX 10.6

Answer 1

In Swing, you should override paintComponent(), not paint().

Addendum: e.g., see below. In a comment, @eugener raises an excellent point about using a JLabel as an alternative image container.

import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Image;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class ImageApp {

    public static void main(String[] args) throws IOException {
        final Image image = ImageIO.read(new File("image.jpg"));
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                final JPanel component = new JPanel() {

                    @Override
                    public void paintComponent(final Graphics g) {
                        g.drawImage(image, 0, 0, null);
                    }

                    @Override
                    public Dimension getPreferredSize() {
                        return new Dimension(
                            image.getWidth(this), image.getHeight(this));
                    }
                };

                final JFrame frame = new JFrame();
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(component);
                frame.pack();
                frame.setVisible(true);
            }
        });
    }
}

Answer 2

Try this:

public class ImageApp {

    public static void main(String[] args) throws MalformedURLException, IOException {
        final Image image = ImageIO.read(new File("/Library/WebServer/Documents/image.gif"));

        final JPanel component = new JPanel() {

            @Override
            public void paintComponent(final Graphics g) {
                super.paintComponent(g);
                System.out.println("Drawing image " + image.getWidth(null) + " " + image.getHeight(null));
                g.drawString("hello", 0,10);
                g.drawImage(image, this.getWidth() / 2, this.getHeight() / 2, 100, 100, Color.blue, this);
            }
        };

        final JFrame frame = new JFrame();

        frame.add(component);
        frame.setSize(100, 100);

        frame.setVisible(true);
    }
}