Java tutorial
/* From http://java.sun.com/docs/books/tutorial/index.html */ /* * Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are met: * * -Redistribution of source code must retain the above copyright notice, this * list of conditions and the following disclaimer. * * -Redistribution in binary form must reproduce the above copyright notice, * this list of conditions and the following disclaimer in the documentation * and/or other materials provided with the distribution. * * Neither the name of Sun Microsystems, Inc. or the names of contributors may * be used to endorse or promote products derived from this software without * specific prior written permission. * * This software is provided "AS IS," without a warranty of any kind. ALL * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN") * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE * AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST * REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL, * INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY * OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE, * EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. * * You acknowledge that this software is not designed, licensed or intended * for use in the design, construction, operation or maintenance of any * nuclear facility. */ /* * TrackFocusDemo.java is a 1.4 example that requires the following files: * Picture.java images/Maya.jpg images/Anya.jpg images/Laine.jpg * images/Cosmo.jpg images/Adele.jpg images/Alexi.jpg */ import java.awt.BorderLayout; import java.awt.Color; import java.awt.Component; import java.awt.Dimension; import java.awt.Graphics; import java.awt.GridLayout; import java.awt.Image; import java.awt.KeyboardFocusManager; import java.awt.event.FocusEvent; import java.awt.event.FocusListener; import java.awt.event.MouseEvent; import java.awt.event.MouseListener; import java.beans.PropertyChangeEvent; import java.beans.PropertyChangeListener; import javax.accessibility.Accessible; import javax.swing.BorderFactory; import javax.swing.ImageIcon; import javax.swing.JComponent; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JPanel; public class TrackFocusDemo extends JPanel { Picture pic1, pic2, pic3, pic4, pic5, pic6; JLabel info; static String mayaString = "Maya"; static String anyaString = "Anya"; static String laineString = "Laine"; static String cosmoString = "Cosmo"; static String adeleString = "Adele"; static String alexiString = "Alexi"; String[] comments = { "Oops. What is this?", "This is Maya", "This is Anya", "This is Laine", "This is Cosmo", "This is Adele", "This is Alexi" }; public TrackFocusDemo() { super(new BorderLayout()); JPanel mugshots = new JPanel(new GridLayout(2, 3)); pic1 = new Picture(createImageIcon("images/" + mayaString + ".jpg", mayaString).getImage()); pic1.setName("1"); mugshots.add(pic1); pic2 = new Picture(createImageIcon("images/" + anyaString + ".jpg", anyaString).getImage()); pic2.setName("2"); mugshots.add(pic2); pic3 = new Picture(createImageIcon("images/" + laineString + ".jpg", laineString).getImage()); pic3.setName("3"); mugshots.add(pic3); pic4 = new Picture(createImageIcon("images/" + cosmoString + ".jpg", cosmoString).getImage()); pic4.setName("4"); mugshots.add(pic4); pic5 = new Picture(createImageIcon("images/" + adeleString + ".jpg", adeleString).getImage()); pic5.setName("5"); mugshots.add(pic5); pic6 = new Picture(createImageIcon("images/" + alexiString + ".jpg", alexiString).getImage()); pic6.setName("6"); mugshots.add(pic6); info = new JLabel("Nothing selected"); setPreferredSize(new Dimension(450, 350)); add(mugshots, BorderLayout.CENTER); add(info, BorderLayout.PAGE_END); setBorder(BorderFactory.createEmptyBorder(20, 20, 20, 20)); KeyboardFocusManager focusManager = KeyboardFocusManager.getCurrentKeyboardFocusManager(); focusManager.addPropertyChangeListener(new PropertyChangeListener() { public void propertyChange(PropertyChangeEvent e) { String prop = e.getPropertyName(); if (("focusOwner".equals(prop)) && (e.getNewValue() != null) && ((e.getNewValue()) instanceof Picture)) { Component comp = (Component) e.getNewValue(); String name = comp.getName(); Integer num = new Integer(name); int index = num.intValue(); if (index < 0 || index > comments.length) { index = 0; } info.setText(comments[index]); } } }); } /** Returns an ImageIcon, or null if the path was invalid. */ protected static ImageIcon createImageIcon(String path, String description) { java.net.URL imageURL = TrackFocusDemo.class.getResource(path); if (imageURL == null) { System.err.println("Resource not found: " + path); return null; } else { return new ImageIcon(imageURL, description); } } /** * Create the GUI and show it. For thread safety, this method should be * invoked from the event-dispatching thread. */ private static void createAndShowGUI() { //Make sure we have nice window decorations. JFrame.setDefaultLookAndFeelDecorated(true); //Create and set up the window. JFrame frame = new JFrame("TrackFocusDemo"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); JComponent newContentPane = new TrackFocusDemo(); newContentPane.setOpaque(true); //content panes must be opaque frame.setContentPane(newContentPane); //Display the window. frame.pack(); frame.setVisible(true); } public static void main(String[] args) { //Schedule a job for the event-dispatching thread: //creating and showing this application's GUI. javax.swing.SwingUtilities.invokeLater(new Runnable() { public void run() { createAndShowGUI(); } }); } } /* * Picture.java is used by the 1.4 TrackFocusDemo.java and DragPictureDemo.java * examples. */ class Picture extends JComponent implements MouseListener, FocusListener, Accessible { Image image; public Picture(Image image) { this.image = image; setFocusable(true); addMouseListener(this); addFocusListener(this); } public void mouseClicked(MouseEvent e) { //Since the user clicked on us, let's get focus! requestFocusInWindow(); } public void mouseEntered(MouseEvent e) { } public void mouseExited(MouseEvent e) { } public void mousePressed(MouseEvent e) { } public void mouseReleased(MouseEvent e) { } public void focusGained(FocusEvent e) { //Draw the component with a red border //indicating that it has focus. this.repaint(); } public void focusLost(FocusEvent e) { //Draw the component with a black border //indicating that it doesn't have focus. this.repaint(); } protected void paintComponent(Graphics graphics) { Graphics g = graphics.create(); //Draw in our entire space, even if isOpaque is false. g.setColor(Color.WHITE); g.fillRect(0, 0, image == null ? 125 : image.getWidth(this), image == null ? 125 : image.getHeight(this)); if (image != null) { //Draw image at its natural size of 125x125. g.drawImage(image, 0, 0, this); } //Add a border, red if picture currently has focus if (isFocusOwner()) { g.setColor(Color.RED); } else { g.setColor(Color.BLACK); } g.drawRect(0, 0, image == null ? 125 : image.getWidth(this), image == null ? 125 : image.getHeight(this)); g.dispose(); } }