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);
}
};
worker.start();
}
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;
}
}
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