EDT violation in a thread created by Display.getInstance().startThread()

[Jeff Crump]

Simulator Issue

I have a successful 1D barcode decoder that I've used in a previous CN1 application that works by scanning an image created by capturePhoto(). I'm revisiting it on further implementation for another application. But on the simulator I received a EDT violation on a thread spawned by Display.getInstance().startThread(). The problem appears during the ImageIO.save(); I didn't think that a task running in a "startThread" could incur an EDT violation.

I've only tried this today on HTC Thunderbolt and LG Intuition, but worked fine on both and came back with a result in less than a second.

    @Override
    protected boolean perform() {
        Capture.capturePhoto(new ActionListener() {
            public void actionPerformed(ActionEvent evt) {
                final String snapshot = (String) evt.getSource();
                if (snapshot != null) {
                    Display.getInstance().startThread(new Runnable() {
                        public void run() {
                            try {
                                ByteArrayOutputStream output = new ByteArrayOutputStream();
                                ImageIO.getImageIO().save(snapshot, output, ImageIO.FORMAT_JPEG, xDimension, yDimension, quality);
                                Image image = EncodedImage.create(output.toByteArray());
                                if (image != null) {
                                    Image scannedImage = ImageDecoder.FormatImage(image);
                                    int[] picture = scannedImage.getRGB();
                                    int[] decoders = assignDecoders();
                                    ImageDecoder decoder = new ImageDecoder(decoders);
                                    final Result result = decoder.doDecode(picture, scannedImage.getWidth(), scannedImage.getHeight());
                                    setResult(result);
                                }
                                FileSystemStorage.getInstance().delete(snapshot);
                            } catch (IOException ex) {
                                logException("UITaskScanner", ex);
                            }
                        }
                    }, "decoder").start();
                }
            }
        });
        return true;
    }

Rendering frame took too long 265 milliseconds
EDT violation detected!
com.codename1.impl.javase.JavaSEPort$EDTViolation: EDT Violation Stack!
 at com.codename1.impl.javase.JavaSEPort.checkEDT(JavaSEPort.java:384)
EDT violation detected!
EDT violation detected!
EDT violation detected!
EDT violation detected!
EDT violation detected!
 at com.codename1.impl.javase.JavaSEPort.scale(JavaSEPort.java:3234)
 at com.codename1.ui.Image.scale(Image.java:961)
 at com.codename1.ui.Image.scaledImpl(Image.java:931)
 at com.codename1.ui.Image.scaled(Image.java:896)
 at com.codename1.impl.javase.JavaSEPort$53.save(JavaSEPort.java:6170)
 at com.codename1.ui.util.ImageIO.save(ImageIO.java:95)
 at com.crumptech.mobile.crump.ui.tasks.UITaskScanner$2$1.run(UITaskScanner.java:120)

[Shai Almog]

That seems like a false positive. We prefer to err on the side of safety when it comes to violation detection. In this particular usage you should be OK.

[Jeff Crump]

Thanks. CN1 is a very impressive product/service.