Name: jk109818 Date: 05/23/2002


FULL PRODUCT VERSION :
java version "1.4.0"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.0-b92)
Java HotSpot(TM) Client VM (build 1.4.0-b92, mixed mode)


FULL OPERATING SYSTEM VERSION :Windows 98 [Version
4.10.2222]



ADDITIONAL OPERATING SYSTEMS : Windows 2000



A DESCRIPTION OF THE PROBLEM :
When I display a monochrome JAI image in a
ScrollPane that contains the image
sink for the image, the image is "smeared"
when I scroll in small increments. i.e.,
moving the scrollbar a little bit to the right
or left, or using the little arrow, small vertical
lines look like wide lines, and text is a few pixels
wide when it should be one or two pixels wide. This
seems to happen for monochrome images but not for color
ones.

BTW, I have also noticed problems with
repaint(int, int, int, int) redrawing pixels at a location
one or two pixels to the left or right of where
they should be. I think this might be another
symptom of the same problem.


STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. Run the enclosed program, using a large monochrome TIFF
image for input. I can supply you with a sample
image if necessary.
2. Scroll using the arrows, especially looking at
well-defined edges in the image.
3.

EXPECTED VERSUS ACTUAL BEHAVIOR :
The image shouldn't be displayed differently depending
on whether I do fast or slow scrolling.


ERROR MESSAGES/STACK TRACES THAT OCCUR :
No trace information appeared.


This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.awt.Component;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.ScrollPane;
import java.awt.geom.AffineTransform;
import java.awt.image.RenderedImage;
import javax.media.jai.JAI;
import javax.swing.JFrame;

public class JAIScroller {
    ScrollPane scrollPane;
    JAIScrollCanvas canvas;

    public JAIScroller (RenderedImage sourceImage) {
scrollPane = new ScrollPane ();
canvas = new JAIScrollCanvas (sourceImage);
scrollPane.add (canvas);
    }
    public ScrollPane getScrollPane() { return scrollPane; }
    public static void main (String[] argv) {
if (argv.length == 0) {
System.out.println ("usage: java JAIScroller <imagefilename>");
return;
}
String filename = argv[0];
System.out.println ("Loading image file: " + filename);
RenderedImage image = JAI.create ("fileload", filename);
JFrame jframe = new JFrame ("JAIScroller Test");
JAIScroller js = new JAIScroller (image);
jframe.getContentPane().add (js.getScrollPane());
jframe.setSize (400, 400);
jframe.invalidate();
jframe.setVisible (true);
    }

    class JAIScrollCanvas extends Component {
RenderedImage localSourceImage;
AffineTransform identityTransform = new AffineTransform();

public JAIScrollCanvas (RenderedImage localSourceImage) {
set (localSourceImage);
}

public void set (RenderedImage localSourceImage) {
if (localSourceImage == null) return;
this.localSourceImage = localSourceImage;
setSize (localSourceImage.getWidth(),
localSourceImage.getHeight());
scrollPane.invalidate();
scrollPane.repaint();
}
public Dimension getPreferredSize() {
if (localSourceImage == null) return null;
return new Dimension
((int)(localSourceImage.getWidth()),
(int)(localSourceImage.getHeight()));
}
public void update(Graphics g) { paint(g); }
public void paint (Graphics g) {
if (localSourceImage == null) return;
Graphics2D g2d = (Graphics2D)g;
g2d.drawRenderedImage (localSourceImage,
identityTransform);
}
    }
}

---------- END SOURCE ----------

CUSTOMER WORKAROUND :
I haven't found a workaround yet. My client is
screaming for one. Let me know if you have any
bright ideas.
(Review ID: 146448)
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