Drawing Animation - Java Sample Program

//file: Hypnosis.java
import java.awt.*;
import java.awt.event.*;
import java.awt.geom.GeneralPath;
import javax.swing.*;

public class Hypnosis extends JComponent implements Runnable {

private int[] coordinates;
private int[] deltas;
private Paint paint;

public Hypnosis(int numberOfSegments) {

int numberOfCoordinates = numberOfSegments * 4 + 2;
coordinates = new int[numberOfCoordinates];
deltas = new int[numberOfCoordinates];

for (int i = 0 ; i < numberOfCoordinates; i++) {
coordinates[i] = (int)(Math.random() * 300);
deltas[i] = (int)(Math.random() * 4 + 3);

if (deltas[i] > 4) deltas[i] = -(deltas[i] - 3);
}

paint = new GradientPaint(0, 0, Color.BLUE, 20, 10, Color.RED, true);
Thread t = new Thread(this);
t.start();
}
public void run() {
try {
while (true) {
timeStep();
repaint();
Thread.sleep(1000 / 24);
}
}
catch (InterruptedException ie) {}
}

public void paint(Graphics g) {
Graphics2D g2 = (Graphics2D)g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,RenderingHints.VALUE_ANTIALIAS_ON);
Shape s = createShape();

g2.setPaint(paint);
g2.fill(s);
g2.setPaint(Color.WHITE);
g2.draw(s);
}
private void timeStep() {
Dimension d = getSize();

if (d.width == 0 || d.height == 0) return;

for (int i = 0; i < coordinates.length; i++) {
coordinates[i] += deltas[i];
int limit = (i % 2 == 0) ? d.width : d.height;

if (coordinates[i] < 0) {
coordinates[i] = 0;
deltas[i] = -deltas[i];
}
else if (coordinates[i] > limit) {
coordinates[i] = limit - 1;
deltas[i] = -deltas[i];
}
}
}

private Shape createShape() {
GeneralPath path = new GeneralPath();
path.moveTo(coordinates[0], coordinates[1]);
for (int i = 2; i < coordinates.length; i += 4)
path.quadTo(coordinates[i], coordinates[i + 1], coordinates[i + 2], coordinates[i + 3]);
path.closePath();
return path;
}

public static void main(String[] args) {
JFrame frame = new JFrame("Hypnosis");
frame.add( new Hypnosis(4) );
frame.setSize(300, 300);
frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
frame.setVisible(true);
}
}


Sample Output:

Media Tracker - Java Sample Program

//The following code snippet illustrates how to use a MediaTracker to wait while an image is prepared:
//file: StatusImage.java

import java.awt.*;
import javax.swing.*;

public class StatusImage extends JComponent
{
boolean loaded = false;
String message = "Loading...";
Image image;

public StatusImage( Image image ) { this.image = image; }

public void paint(Graphics g) {

if (loaded)
g.drawImage(image, 0, 0, this);
else {
g.drawRect(0, 0, getSize().width - 1, getSize().height - 1);
g.drawString(message, 20, 20);
}
}

public void loaded() {
loaded = true;
repaint();
}

public void setMessage( String msg ) {
message = msg;
repaint();
}

public static void main( String [] args ) {
JFrame frame = new JFrame("TrackImage");
Image image = Toolkit.getDefaultToolkit().getImage( args[0] );
StatusImage statusImage = new StatusImage( image );

frame.add( statusImage );
frame.setSize(300,300);
frame.setVisible(true);

MediaTracker tracker = new MediaTracker( statusImage );

int MAIN_IMAGE = 0;

tracker.addImage( image, MAIN_IMAGE );

try {
tracker.waitForID( MAIN_IMAGE ); }
catch (InterruptedException e) {}
if ( tracker.isErrorID( MAIN_IMAGE ) )
statusImage.setMessage( "Error" );
else
statusImage.loaded();
}
}