import javax.swing.*; import java.awt.*; import java.awt.event.*; import java.net.URL; import java.util.Vector; import java.util.StringTokenizer; public class IconDemoApplet extends JApplet implements ActionListener { Vector pictures; JButton previousButton; JButton nextButton; JLabel photographLabel; JLabel captionLabel; JLabel numberLabel; int current = 0; int widthOfWidest = 0; int heightOfTallest = 0; String imagedir = null; public void init() { //Parse the applet parameters pictures = parseParameters(); //If the applet tag doesn't provide an "IMAGE0" parameter, //display an error message. if (pictures.size() == 0) { captionLabel = new JLabel("No images listed in applet tag."); captionLabel.setHorizontalAlignment(JLabel.CENTER); getContentPane().add(captionLabel); return; } //NOW CREATE THE GUI COMPONENTS //A label to identify XX of XX. numberLabel = new JLabel("Picture " + (current+1) + " of " + pictures.size()); numberLabel.setHorizontalAlignment(JLabel.LEFT); numberLabel.setBorder(BorderFactory.createEmptyBorder(5, 0, 5, 5)); //A label for the caption. final Photo first = (Photo)pictures.firstElement(); captionLabel = new JLabel(first.caption); captionLabel.setHorizontalAlignment(JLabel.CENTER); captionLabel.setBorder(BorderFactory.createEmptyBorder(5, 0, 5, 0)); //A label for displaying the photographs. photographLabel = new JLabel("Loading first image..."); photographLabel.setHorizontalAlignment(JLabel.CENTER); photographLabel.setVerticalAlignment(JLabel.CENTER); photographLabel.setVerticalTextPosition(JLabel.CENTER); photographLabel.setHorizontalTextPosition(JLabel.CENTER); photographLabel.setBorder(BorderFactory.createCompoundBorder( BorderFactory.createLoweredBevelBorder(), BorderFactory.createEmptyBorder(5, 5, 5, 5) )); photographLabel.setBorder(BorderFactory.createCompoundBorder( BorderFactory.createEmptyBorder(0, 0, 10, 0), photographLabel.getBorder() )); //Set the preferred size for the picture, //with room for the borders. Insets i = photographLabel.getInsets(); photographLabel.setPreferredSize(new Dimension( widthOfWidest+i.left+i.right, heightOfTallest+i.bottom+i.top)); //Create the next and previous buttons. ImageIcon nextIcon = new ImageIcon( getURL(imagedir + "right.gif")); ImageIcon dimmedNextIcon = new ImageIcon( getURL(imagedir + "dimmedRight.gif")); ImageIcon previousIcon = new ImageIcon( getURL(imagedir + "left.gif")); ImageIcon dimmedPreviousIcon = new ImageIcon( getURL(imagedir + "dimmedLeft.gif")); previousButton = new JButton("Previous Picture", previousIcon); previousButton.setDisabledIcon(dimmedPreviousIcon); previousButton.setVerticalTextPosition(AbstractButton.CENTER); previousButton.setHorizontalTextPosition(AbstractButton.RIGHT); previousButton.setMnemonic(KeyEvent.VK_P); previousButton.setActionCommand("previous"); previousButton.addActionListener(this); previousButton.setEnabled(false); nextButton = new JButton("Next Picture", nextIcon); nextButton.setDisabledIcon(dimmedNextIcon); nextButton.setVerticalTextPosition(AbstractButton.CENTER); nextButton.setHorizontalTextPosition(AbstractButton.LEFT); nextButton.setMnemonic(KeyEvent.VK_N); nextButton.setActionCommand("next"); nextButton.addActionListener(this); //Lay out the GUI. GridBagLayout layout = new GridBagLayout(); GridBagConstraints c = new GridBagConstraints(); Container contentPane = getContentPane(); contentPane.setLayout(layout); c.gridwidth = GridBagConstraints.REMAINDER; c.fill = GridBagConstraints.HORIZONTAL; layout.setConstraints(numberLabel, c); contentPane.add(numberLabel); layout.setConstraints(captionLabel, c); contentPane.add(captionLabel); c.gridwidth = GridBagConstraints.REMAINDER; c.fill = GridBagConstraints.BOTH; layout.setConstraints(photographLabel, c); contentPane.add(photographLabel); c.gridwidth = GridBagConstraints.RELATIVE; c.fill = GridBagConstraints.HORIZONTAL; layout.setConstraints(previousButton, c); contentPane.add(previousButton); c.gridwidth = GridBagConstraints.REMAINDER; layout.setConstraints(nextButton, c); contentPane.add(nextButton); //Start loading the image for the first photograph now. //The loadImage method uses a SwingWorker //to load the image in a separate thread. loadImage(imagedir + first.filename, current); } //User clicked either the next or the previous button. public void actionPerformed(ActionEvent e) { //Show loading message. photographLabel.setIcon(null); photographLabel.setText("Loading image..."); //Compute index of photograph to view. if (e.getActionCommand().equals("next")) { current += 1; if (!previousButton.isEnabled()) previousButton.setEnabled(true); if (current == pictures.size() - 1) nextButton.setEnabled(false); } else { current -= 1; if (!nextButton.isEnabled()) nextButton.setEnabled(true); if (current == 0) previousButton.setEnabled(false); } //Get the photo object. Photo pic = (Photo)pictures.elementAt(current); //Update the caption and number labels. captionLabel.setText(pic.caption); numberLabel.setText("Picture " + (current+1) + " of " + pictures.size()); //Update the photograph. ImageIcon icon = pic.getIcon(); if (icon == null) { //haven't viewed this photo before loadImage(imagedir + pic.filename, current); } else { updatePhotograph(current, pic); } } //Must be invoked from the event-dispatching thread. private void updatePhotograph(int index, Photo pic) { ImageIcon icon = pic.getIcon(); photographLabel.setToolTipText(pic.filename + ": " + icon.getIconWidth() + " X " + icon.getIconHeight()); photographLabel.setIcon(icon); photographLabel.setText(""); } //Load an image in a separate thread. private void loadImage(final String imagePath, final int index) { final SwingWorker worker = new SwingWorker() { ImageIcon icon = null; public Object construct() { icon = new ImageIcon(getURL(imagePath)); return icon; //return value not used by this program } //Runs on the event-dispatching thread. public void finished() { Photo pic = (Photo)pictures.elementAt(index); pic.setIcon(icon); if (index == current) updatePhotograph(index, pic); } }; } protected URL getURL(String filename) { URL codeBase = this.getCodeBase(); URL url = null; try { url = new URL(codeBase, filename); } catch (java.net.MalformedURLException e) { System.out.println("Couldn't create image: " + "badly specified URL"); return null; } return url; } protected Vector parseParameters() { Vector pix = new Vector(10); //start with 10, grows if necessary int i = 0; //parameters index must start at 0 String paramName = "IMAGE" + i; String paramValue; while ((paramValue = getParameter(paramName)) != null) { Photo pic = new Photo(paramValue, getCaption(i), getWidth(i), getHeight(i)); pix.addElement(pic); i++; paramName = "IMAGE" + i; } //Get the name of the directory that contains the image files. imagedir = getParameter("IMAGEDIR"); if (imagedir != null) imagedir = imagedir + "/"; return pix; } protected String getCaption(int i) { return getParameter("CAPTION"+i); } protected int getWidth(int i) { int width = 0; String widthString = getParameter("WIDTH"+i); if (widthString != null) { try { width = Integer.parseInt(widthString); } catch (NumberFormatException e) { width = 0; } } else { width = 0; } if (width > widthOfWidest) widthOfWidest = width; return width; } protected int getHeight(int i) { int height = 0; String heightString = getParameter("HEIGHT"+i); if (heightString != null) { try { height = Integer.parseInt(heightString); } catch (NumberFormatException e) { height = 0; } } else { height = 0; } if (height > heightOfTallest) heightOfTallest = height; return height; } public String[][] getParameterInfo() { String[][] info = { {"IMAGEDIR", "string", "directory containing image files" }, {"IMAGEN", "string", "filename" }, {"CAPTIONN", "string", "caption" }, {"WIDTHN", "integer", "width of image" }, {"HEIGHTN", "integer", "height of image" }, }; return info; } }