java swing background image

Solution 1:

It sounds as though you are talking about tiling vs. stretching, though it's not clear which behaviour you want.

This program has examples of both:

import java.awt.BorderLayout;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.io.IOException;
import java.net.URL;

import javax.imageio.ImageIO;
import javax.swing.AbstractAction;
import javax.swing.JCheckBox;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class Main {
    public static void main(String[] args) throws IOException {
        final Image image = ImageIO.read(new URL("http://sstatic.net/so/img/logo.png"));
        final JFrame frame = new JFrame();
        frame.add(new ImagePanel(image));
        frame.setSize(800, 600);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
    }
}

@SuppressWarnings("serial")
class ImagePanel extends JPanel {
    private Image image;
    private boolean tile;

    ImagePanel(Image image) {
        this.image = image;
        this.tile = false;
        final JCheckBox checkBox = new JCheckBox();
        checkBox.setAction(new AbstractAction("Tile") {
            public void actionPerformed(ActionEvent e) {
                tile = checkBox.isSelected();
                repaint();
            }
        });
        add(checkBox, BorderLayout.SOUTH);
    };

    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        if (tile) {
            int iw = image.getWidth(this);
            int ih = image.getHeight(this);
            if (iw > 0 && ih > 0) {
                for (int x = 0; x < getWidth(); x += iw) {
                    for (int y = 0; y < getHeight(); y += ih) {
                        g.drawImage(image, x, y, iw, ih, this);
                    }
                }
            }
        } else {
            g.drawImage(image, 0, 0, getWidth(), getHeight(), this);
        }
    }
}

Solution 2:

You want something like the background image of the windows desktop, when using the background image multiple times instead of resizing it or just display it centered?

You only have to keep the image once and just paint it multiple times in the paintComponent method.