@Override
        public void onPreviewError(Exception e) {
            synchronized (LOCK) {
                if (running) {
                    // Post to our thread.
                    handler.obtainMessage(R.id.zxing_preview_failed).sendToTarget();
                }
            }
        }
Stop decoding.

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