public void start() {
        Util.validateMainThread();

        thread = new HandlerThread(TAG);
        thread.start();
        handler = new Handler(thread.getLooper(), callback);
        running = true;
        requestNextPreview();
    }
Start decoding.

This must be called from the UI thread.
zxing-android-embedded/src/com/journeyapps/barcodescanner/DecoderThread.java