PreviewPane.java

package br.com.etyllica.awt.components.chooser;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.io.File;
import java.io.IOException;

import javax.imageio.ImageIO;
import javax.swing.BorderFactory;
import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JFileChooser;
import javax.swing.JLabel;
import javax.swing.JPanel;

/**
 * A JPanel with Image Preview
 * 
 * Code found at: http://www.javalobby.org/forums/thread.jspa?messageID=91844740
 */
public class PreviewPane extends JPanel implements PropertyChangeListener {

	private static final long serialVersionUID = 1L;

	private JLabel label;
	private int maxImgWidth;

	public PreviewPane() {
		setLayout(new BorderLayout(5,5));
		setBorder(BorderFactory.createEmptyBorder(5,5,5,5));
		add(new JLabel("Preview:"), BorderLayout.NORTH);
		label = new JLabel();
		label.setBackground(Color.WHITE);
		label.setOpaque(true);
		label.setPreferredSize(new Dimension(200, 200));
		maxImgWidth = 195;
		label.setBorder(BorderFactory.createEtchedBorder());
		add(label, BorderLayout.CENTER);
	}

	public void propertyChange(PropertyChangeEvent evt) {
		Icon icon = null;
		if(JFileChooser.SELECTED_FILE_CHANGED_PROPERTY.equals(evt
				.getPropertyName())) {
			File newFile = (File) evt.getNewValue();
			if(newFile != null) {
				String path = newFile.getAbsolutePath();
				if(isCompatibleImage(path)) {
					try {
						BufferedImage img = ImageIO.read(newFile);
						float width = img.getWidth();
						float height = img.getHeight();
						float scale = height / width;
						width = maxImgWidth;
						height = (width * scale); // height should be scaled from new width							
						icon = new ImageIcon(img.getScaledInstance(Math.max(1, (int)width), Math.max(1, (int)height), Image.SCALE_SMOOTH));
					}
					catch(IOException e) {
						// couldn't read image.
					}
				}
			}

			label.setIcon(icon);
			this.repaint();
		}
	}

	private boolean isCompatibleImage(String path) {
		return path.endsWith(".gif") || path.endsWith(".jpg") || path.endsWith(".png") || path.endsWith(".bmp");
	}
}