Name: rm29839 Date: 05/28/98


Ever play that game called "Wack A Mole"? That's what I seem to be doing tonight...

If I load a JFIF JPEG into a BufferedImage via JPEGImageDecoder.getBufferedImage() and then call
BufferedImage.getScaledInstance( x, y, Image.SCALE_DEFAULT) to scale it I get an Image that when passed to a
Graphics2D.drawImage() causes a NullPointerException.

      file = new File(SourceDir.getPath()+File.separatorChar+files[i]);

      if ((file == null) || (!file.exists())) {
continue;
      }

is = new FileInputStream( file);

try {
input = new JPEGImageDecoder(is);
src = input.decodeBufferedImage();
} catch (Exception e) {
System.out.println( "Bad picture: "+files[i]);
continue;
}

scaled = src.getScaledInstance( tw, th, Image.SCALE_DEFAULT);
if (scaled != null) {
g2.drawImage( scaled, tx, ty, null);
}

Yeah, I know, the null looks pretty ugly in that drawImage call. But it works when you pass in a Image loaded via
Toolkit.getDefaultToolkit().getImage()... And works with a BufferedImage (except for the reported bug there...)

I get the follwing:
java.lang.NullPointerException:
        at java.awt.image.FilteredImageSource.startProduction(FilteredImageSourc
e.java:122)
        at sun.awt.image.ImageRepresentation.startProduction(ImageRepresentation
.java:563)
        at sun.awt.image.ImageRepresentation.drawToBufImage(ImageRepresentation.
java:633)
        at sun.awt.image.BufferedImageGraphics2D.drawImage(BufferedImageGraphics
2D.java:432)
        at medusa.main(medusa.java:156)

Hmm, that null does look bad doesn't it?

Well I just went and checked it with an ImageObserver passed in instead of a null. I get the exact same result.
So it isn't the null (and I hope that keeps working in future versions, I detest ImageObservers)

Hmm, just checked the FilteredImageSource.java:122 reference. Looks like this:
    public void startProduction(ImageConsumer ic) {
if (proxies == null) {
proxies = new Hashtable();
}
ImageFilter imgf = (ImageFilter) proxies.get(ic);
if (imgf == null) {
imgf = filter.getFilterInstance(ic);
proxies.put(ic, imgf);
}
src.startProduction(imgf);
    }

No one is checking that src is non-null. The constructor isn't checking either:
    /**
     * Constructs an ImageProducer object from an existing ImageProducer
     * and a filter object.
     * @see ImageFilter
     * @see java.awt.Component#createImage
     */
    public FilteredImageSource(ImageProducer orig, ImageFilter imgf) {
src = orig;
filter = imgf;
    }

This would be a good place for a coupla assert's to nail this sucker back where the real bug is...
(Review ID: 30526)
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