how to dynamically resize the background image of a JPanel as the size of window changes

[aity myles]

i have just successfully added a background image to a JPanel by overriding the paintComponent method, however i realized that each time i maximize the window containing the JPanel, the image doesnt re-adjust to completely fill up the the window. The size of the background image remains static irrespective of the size of the window. i want the background image to dynamically fill up the the JPanel each time the window is resized.
Thanks in advance for your assistance

[Michael Dunn]

is it the panel, or the image, that is not resizing?

if the panel, use a correct layout manager.

if the image, use the correct parameters
i.e. panel has getWidth() and getHeight()

[Volodymyr Levytskyi]

At first simply run it and browser is after you!

package its;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Cursor;
import java.awt.Dialog.ModalityType;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.RenderingHints;
import java.awt.Toolkit;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionAdapter;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.net.URL;

import javax.imageio.ImageIO;
import javax.swing.JDialog;
import javax.swing.JEditorPane;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;

public class ResizeImage extends JPanel {

	private static final long serialVersionUID = 7210857306625744220L;
	private Image mainImage = null;
	private Image scaledImage = null;
	private URL path = null;
	private JDialog browser = null;

	public ResizeImage(int width, int height) {
		this.setBackground(Color.lightGray);
		this.setPreferredSize(new Dimension(width, height));
		this.setCursor(Cursor.getPredefinedCursor(Cursor.HAND_CURSOR));

		browser = new JDialog((JFrame) this.getParent(), "My future robot");
		browser.setModalityType(ModalityType.APPLICATION_MODAL);
		JEditorPane pane = null;
		try {
			pane = new JEditorPane(
					"http://www.robotshop.com/blog/international-robotics-robots-dancing-with-humans-573");
		} catch (IOException e1) {
			e1.printStackTrace();
		}
		browser.add(new JScrollPane(pane), BorderLayout.CENTER);
		Toolkit toolkit = Toolkit.getDefaultToolkit();
		browser.setSize(toolkit.getScreenSize());

		try {
			path = new URL(
					"http://www.robotshop.com/blog/images/International-Robotics.jpg");
			mainImage = ImageIO.read(path);
			mainImage = mainImage.getScaledInstance(
					this.getPreferredSize().width,
					this.getPreferredSize().height, Image.SCALE_REPLICATE);
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}

		addComponentListener(new ComponentAdapter() {
			public void componentResized(ComponentEvent e) {
				scaledImage = mainImage.getScaledInstance(
						ResizeImage.this.getWidth(),
						ResizeImage.this.getHeight(), Image.SCALE_REPLICATE);
				ResizeImage.this.repaint();
				super.componentResized(e);
			}
		});

		addMouseMotionListener(new MouseMotionAdapter() {

			public void mouseMoved(MouseEvent e) {
				if (e.getY() == 0) {
					setMyCursor(Cursor.N_RESIZE_CURSOR);
				} else if (e.getX() == 0) {
					setMyCursor(Cursor.W_RESIZE_CURSOR);
				} else if (e.getX() == ResizeImage.this.getWidth()) {
					setMyCursor(Cursor.E_RESIZE_CURSOR);
				} else if (e.getY() == ResizeImage.this.getHeight()) {
					setMyCursor(Cursor.S_RESIZE_CURSOR);
				}
			}
		});

		addMouseListener(new MouseAdapter() {
			public void mouseClicked(MouseEvent e) {
				if (e.getClickCount() == 2) {
					browser.setVisible(true);
				}
			}
		});
	}

	public void paintComponent(Graphics g) {
		super.paintComponent(g);
		Graphics2D g2d = (Graphics2D) g;
		// to prevent this method to apply g2d features from preceding methods
		g2d = (Graphics2D) g2d.create();
		// g2d.setRenderingHint(RenderingHints.KEY_RENDERING,
		// RenderingHints.VALUE_RENDER_QUALITY);
		// g2d.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
		// RenderingHints.VALUE_INTERPOLATION_BILINEAR);
		g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
				RenderingHints.VALUE_ANTIALIAS_ON);
		if (scaledImage == null)
			//this way is not possible if you use MVC where your image is represented by your own class in model
//			g2d.drawImage(mainImage, 0, 0, this.getWidth(), this.getHeight(),
//					Color.white, this);
			g2d.drawImage(mainImage, 0, 0, this);
		else {
			g2d.drawImage(scaledImage, 0, 0, this);
//			g2d.drawImage(scaledImage, 0, 0, this.getWidth(), this.getHeight(),
//					Color.white, this);
		}
		// to prevent next methods of g2d to use features set to g2d here
		g2d.dispose();
	}

	public void setMyCursor(int cursor) {
		setCursor(Cursor.getPredefinedCursor(Cursor.HAND_CURSOR));
	}

	public static void main(String[] args) {
		JFrame frame = new JFrame();
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.getContentPane().add(new ResizeImage(600, 600));
		frame.pack();
		frame.setVisible(true);

	}
}

I got rid of jagged edges because of scaledImage!!!

[aity myles]

Thanks for the valuable contributions, i got it figure out through your assistance.