Real'sHowTo AddThis Feed Button
Custom Search

Fade an imageTag(s): AWT


This example display a GIF with a fade-in, fade-out effect.
import java.applet.*;
import java.awt.*;
import java.awt.image.*;
import java.net.*;

public class FadeImage extends Applet {
  Image   img, faded;
  int level, sign;
  MediaTracker tracker;
  AlphaFilter f;
  FilteredImageSource fis;

  public void init() {
    level = 0;
    sign =  15;
    tracker = new MediaTracker(this);
    try {
      img = getImage(new URL(getDocumentBase(), "../images/gumby.gif"));
      tracker.addImage(img,0);
      tracker.waitForID(0);
    }
    catch (Exception e) {
      e.printStackTrace();
    }
    f = new AlphaFilter();
    f.setLevel(level);
    fis = new FilteredImageSource(img.getSource(), f) ;

    FadeThread ft = new FadeThread();
    ft.delayedFading(this, 20);
    ft.start();
  }

  public void paint(Graphics g) {
    if (faded != null) {
       g.drawImage(faded,0,0,this);
    }
  }

  public void fadeIt() {
    Graphics g = this.getGraphics();
    level += sign;
    if (level < 0) {
       level=0;
       sign = sign * -1;
    }
    if (level > 255) {
       level=255;
       sign =  sign * -1;
     try {
       Thread.sleep(1000);
     }
     catch (Exception e) {}
    }
    f.setLevel(level);
    if (faded != null) faded.flush();
    faded = this.createImage(fis);
    tracker.addImage(faded,0);
    try {
      tracker.waitForID(0);
    }
    catch (Exception ex) {
      ex.printStackTrace();
    }
    repaint();
  }

  class FadeThread extends Thread {
    FadeImage fadeApplet;
    int delay;

    public void delayedFading(FadeImage f, int delay) {
      this.fadeApplet = f;
      this.delay = delay;
    }

    public void run() {
      while (true) {
        try {
          sleep(delay);
          fadeApplet.fadeIt();
        }
        catch (Exception e) {
          e.printStackTrace();
        }
      }
    }
  }

  class AlphaFilter extends RGBImageFilter {
    private int level;

    public AlphaFilter() {
      canFilterIndexColorModel = true;
    }

    public void setLevel(int lev) {
      level = lev;
    }

    public int filterRGB(int x, int y, int rgb) {
      int a = level * 0x01000000;
      return (rgb &   0x00ffffff) | a;
    }
  }
}
Try it here.
blog comments powered by Disqus


If you find this article useful, consider making a small donation
to show your support for this Web site and its content.

Written and compiled by Réal Gagnon ©1998-2014
[ home ]