public void quitSynchronously() {
    state = State.DONE;
    cameraManager.stopPreview();
    Message quit = Message.obtain(decodeThread.getHandler(), Constants.ID_QUIT);
    quit.sendToTarget();
    try {
      // Wait at most half a second; should be enough time, and onPause() will timeout quickly
      decodeThread.join(500L);
    } catch (InterruptedException e) {
      // continue
    }

    // Be absolutely sure we don't send any queued up messages
    removeMessages(Constants.ID_DECODE_SUCCESS);
    removeMessages(Constants.ID_DECODE_FAILED);
  }
 @Override
 public void handleMessage(Message message) {
   switch (message.what) {
     case Constants.ID_RESTART_PREVIEW:
       restartPreviewAndDecode();
       break;
     case Constants.ID_DECODE_SUCCESS:
       state = State.SUCCESS;
       activity.handleDecode((String) message.obj, message.getData());
       break;
     case Constants.ID_DECODE_FAILED:
       // We're decoding as fast as possible, so when one decode fails, start another.
       state = State.PREVIEW;
       cameraManager.requestPreviewFrame(decodeThread.getHandler(), Constants.ID_DECODE);
       break;
   }
 }
 private void restartPreviewAndDecode() {
   if (state == State.SUCCESS) {
     state = State.PREVIEW;
     cameraManager.requestPreviewFrame(decodeThread.getHandler(), Constants.ID_DECODE);
   }
 }