Image Buffering
import java.awt.BorderLayout;
import java.awt.Canvas;
import java.awt.Color;
import java.awt.Container;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridLayout;
import java.awt.Image;
import java.awt.MediaTracker;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.awt.image.BufferedImage;
import javax.swing.ButtonGroup;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JRadioButton;
import javax.swing.border.TitledBorder;
public class SimpleBufferedImageDemo extends JFrame {
DisplayCanvas canvas;
JRadioButton buffButton, nonBuffButton;
JButton displayButton, clearButton;
public SimpleBufferedImageDemo() {
super();
Container container = getContentPane();
canvas = new DisplayCanvas();
container.add(canvas);
JPanel panel = new JPanel();
panel.setLayout(new GridLayout(2, 2));
panel.setBorder(new TitledBorder(
"Select an Option and Display Image..."));
buffButton = new JRadioButton("Buffered");
buffButton.addActionListener(new ButtonListener());
nonBuffButton = new JRadioButton("Non-Buffered", true);
nonBuffButton.addActionListener(new ButtonListener());
ButtonGroup group = new ButtonGroup();
group.add(buffButton);
group.add(nonBuffButton);
displayButton = new JButton("Display");
displayButton.addActionListener(new ButtonListener());
clearButton = new JButton("Clear");
clearButton.addActionListener(new ButtonListener());
panel.add(nonBuffButton);
panel.add(buffButton);
panel.add(displayButton);
panel.add(clearButton);
container.add(BorderLayout.SOUTH, panel);
addWindowListener(new WindowEventHandler());
pack();
setVisible(true);
}
class WindowEventHandler extends WindowAdapter {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
}
public static void main(String arg[]) {
new SimpleBufferedImageDemo();
}
class ButtonListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
Object obj = e.getSource();
if (obj instanceof JRadioButton) {
JRadioButton button = (JRadioButton) obj;
if (button.equals(buffButton)) {
canvas.buffered = true;
} else if (button.equals(nonBuffButton)) {
canvas.buffered = false;
}
}
if (obj instanceof JButton) {
JButton button = (JButton) obj;
if (button.equals(displayButton)) {
canvas.display = true;
canvas.repaint();
} else if (button.equals(clearButton)) {
canvas.clear = true;
canvas.repaint();
}
}
}
}
}
class DisplayCanvas extends Canvas {
boolean display = false;
boolean clear = false;
boolean buffered = false;
Image displayImage;
DisplayCanvas() {
displayImage = Toolkit.getDefaultToolkit().getImage("largeJava2sLogo.jpg");
MediaTracker mt = new MediaTracker(this);
mt.addImage(displayImage, 1);
try {
mt.waitForAll();
} catch (Exception e) {
System.out.println("Exception while loading.");
}
if (displayImage.getWidth(this) == -1) {
System.out.println("No *.jpg file");
System.exit(0);
}
setBackground(Color.white);
setSize(400, 225);
}
public void paint(Graphics g) {
Graphics2D g2D = (Graphics2D) g;
if (display) {
if (buffered) {
BufferedImage bi = (BufferedImage) createImage(getWidth(),
getHeight());
// Draw into the memory buffer.
for (int i = 0; i < getWidth(); i = i
+ displayImage.getWidth(this)) {
for (int j = 0; j < getHeight(); j = j
+ displayImage.getHeight(this)) {
bi.createGraphics().drawImage(displayImage, i, j, this);
}
}
// Draw the buffered Image on to the screen
g2D.drawImage(bi, 0, 0, this);
}
// This block of code draws the texture directly onto the screen.
else if (!buffered) {
for (int i = 0; i < getWidth(); i = i
+ displayImage.getWidth(this)) {
for (int j = 0; j < getHeight(); j = j
+ displayImage.getHeight(this)) {
g2D.drawImage(displayImage, i, j, this);
}
}
}
display = false;
}else if (clear) {
g2D.setColor(Color.white);
g2D.clearRect(0, 0, getWidth(), getHeight());
clear = false;
}
}
}
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