PB: PixelGrabber, offscreen Image, Windows 98, ie5

Question

Hello,
I've got a problem with a bug that occurs under Windows 98, and ie5.
This is the code of a little applet that works fine under Windows NT, but not under Windows 98:
This applet draws 3 colors in a square, and use the grabPixel method for catching the pixels of the image and create another image with those pixels.(the image should be the same)
The problem is that the grabPixel method changes the colors of the pixels. It occurs only with an offscreen Image (that means an Image created with the createImage(w, h) method). there is no problem with a MemoryImageSource, for example.
I just notice that the ColorModel of an offscreen Image is not the same as the default ColorModel:
colorModel: java.awt.image.DirectColorModel = {...}
red_mask: int = 0xf800 (instead of 0x00ff0000 )
green_mask: int = 0x7e0 (instead of 0x0000ff00 )
blue_mask: int = 0x1f (instead of 0x000000ff)
alpha_mask: int = 0x0 (instead of 0xff000000)
red_offset: int = 0xb
green_offset: int = 0x5
blue_offset: int = 0x0
alpha_offset: int = 0x0
red_scale: int = 0x1f
green_scale: int = 0x3f
blue_scale: int = 0x1f
alpha_scale: int = 0x0
But i don't know how to solve the bug.
Here is the code :
import java.awt.*;
import java.awt.image.*;
import java.applet.*;
public class AppletFlush extends Applet implements Runnable{
Thread anim;
Image memimg;
boolean bool;
Image offImage;
Graphics offGraphics;
     public void init() {
     public void start() {
     anim = new Thread(this);
     anim.start();
bool = true;
offImage = this.createImage(100, 100);
offGraphics = offImage.getGraphics();
     public synchronized void stop() {
     anim = null;
     notify();
     public synchronized void run() {
     while (Thread.currentThread() == anim) {
int[] pixels = new int[100 * 100];
int color = 0;
//set the pixels of a squared image that contains 3 colors (this is my reference image)
if (bool)
bool = false;
for (int i=0; i<100; i++)
if (i<33)
color = 0xffff0000;
else if (i<66)
color = 0xff00ff00;
else
color = 0xff0000ff;
for (int j=0; j<100; j++)
pixels[i*100 + j] = color;
else
//grab the pixels of the offscreen image(here is the problem)
PixelGrabber pg = new PixelGrabber(offImage, 0, 0, 100, 100, pixels, 0, 100);
try
pg.grabPixels();
catch (InterruptedException ex)
System.out.println("erreur pendant gragPixels !!!");
//create the new image with the pixels
MemoryImageSource imgsrc = new MemoryImageSource(100, 100, pixels, 0, 100);
memimg = createImage(imgsrc);
//draw the image in the offscreen image
offGraphics.drawImage(memimg, 0, 0, null);
          repaint();
          try {wait(1000);} catch (InterruptedException e) {return;}
     public void paint(Graphics g) {
     // display the offscreen image
     g.drawImage(offImage, 0, 0, this);
PLEASE HELP !
YaYa

Answer 1

try
public void paint(Graphics g )
if((_offScreen != null)&&(offScreenImage != null))
// put your stuff here
else
update(g);
g.dispose();
g.finalize();
return;
public void update(Graphics g)
if( offScreenImage == null)
offScreenImage = this.createImage( width, height );
if( _offScreen == null)
_offScreen = offScreenImage .getGraphics();
paint(g);
}