Re: Fading effect

lando wrote:


The way to do that is with AlphaComposite as Andrew Thompson said. It
is actually fairly simple to do the drawing. The complicated part is
the logic to flip through the images. If you don't like my images,
specify some of your own. They might not have anything different on
them depending on when you try this. They come from one of my webcams.
  You can play with the timing to get the transitions to happen as you
like them.

import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.io.*;
import java.net.*;
import javax.imageio.*;
import javax.swing.*;

public class Fader extends JPanel implements Runnable {
     final BufferedImage[] images = new BufferedImage[6];
     volatile BufferedImage first,next;
     volatile AlphaComposite comp1 =
      AlphaComposite.getInstance(AlphaComposite.SRC_OVER,1.0f);
     volatile AlphaComposite comp2 =
      AlphaComposite.getInstance(AlphaComposite.SRC_OVER,0.0f);

     public Fader() {
         try {
             for (int i=0; i<images.length; i++)
                 images[i] = ImageIO.read(
// new File(Integer.toString(i+1) + "0_min_ago.jpg"));
                  new URL("http://www.thealpacastore.com/alpacacam/" +
                   Integer.toString(i+1) + "0_min_ago.jpg"));
         } catch (IOException ioe) {
             ioe.printStackTrace();
         }
         setPreferredSize(new Dimension(
          images[0].getWidth(),images[0].getHeight()));
     }

     public void run() {
         while (true) {
             for (int i=0; i<images.length; i++) {
                 first = images[i];
                 if (i < images.length - 1)
                     next = images[i+1];
                 else
                     next = images[0];
                 for (int j=0; j<60; j++) {
                     comp1 = AlphaComposite.getInstance(
                      AlphaComposite.SRC_OVER,1.0f / (j + 1));
                     comp2 = AlphaComposite.getInstance(
                      AlphaComposite.SRC_OVER,(j + 1) / 60.0f);
                     repaint();
                     try {
                         Thread.sleep(50);
                     } catch (InterruptedException ie) { }
                 }
                 try {
                     Thread.sleep(1000);
                 } catch (InterruptedException ie) { }
             }
         }
     }

     public void paintComponent(Graphics g2D) {
         Graphics2D g = (Graphics2D)g2D;
         g.setComposite(comp1);
         g.drawImage(first,0,0,null);
         g.setComposite(comp2);
         g.drawImage(next,0,0,null);
     }

     public static void main(String[] args) {
         Runnable r = new Runnable() {
             public void run() {
                 JFrame frame = new JFrame();
                 frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                 Fader fader = new Fader();
                 frame.add(fader);
                 frame.pack();
                 frame.setVisible(true);
                 new Thread(fader).start();
             }
         };
         EventQueue.invokeLater(r);
     }
}

--

Knute Johnson
email s/nospam/knute/