SensorManager requestTriggerSensor返回false

Question

I am making a fitness app that uses step count to measure distance. I am trying to use the sensorManager.requestTriggerSensor() method to get the initial step count when the app is started. However, my code returns false, meaning sensor was not triggered. I have successfully implemented the SensorEventListener , which I use for continuing the step count. My code snippet is as follows, similar to the documentation

private SensorManager mSensorManager;
private Sensor sensorStepCounter;
private TriggerEventListener triggerEventListener;

@Override
protected void onCreate(Bundle savedInstanceState) {
    ...
    mSensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);

    triggerEventListener = new TriggerEventListener() {
        @Override
        public void onTrigger(TriggerEvent event) {

            float initialSteps = event.values[0];
            Log.d(TAG, "initial Steps: " + Arrays.toString(event.values));
        }
    };

    sensorStepCounter = mSensorManager.getDefaultSensor(Sensor.TYPE_STEP_COUNTER);
    ....
}

@Override
protected void onResume() {
    ...
    boolean triggered = mSensorManager.requestTriggerSensor(triggerEventListener, sensorStepCounter);
}

Or is there a different way to get the current sensor data, such as step count, when app is started?

Answer 1

I believe you want to use the Google Fit API for this, rather than accessing the raw sensor data. From the documentation :

    long total = 0;

    PendingResult<DailyTotalResult> result = Fitness.HistoryApi.readDailyTotal(mClient, DataType.TYPE_STEP_COUNT_DELTA);
    DailyTotalResult totalResult = result.await(30, TimeUnit.SECONDS);
    if (totalResult.getStatus().isSuccess()) {
        DataSet totalSet = totalResult.getTotal();
        total = totalSet.isEmpty()
                ? 0
                : totalSet.getDataPoints().get(0).getValue(Field.FIELD_STEPS).asInt();
    } else {
        Log.w(TAG, "There was a problem getting the step count.");
    }

Note that this code doesn't want to be run on the UI thread. You can either move it into another thread (as is shown on the page I linked) or use the PendingResult.setResultCallback method.

Answer 2

I have only assumption that triggering the step sensor is false beacause the sensor was already triggered. Yet, I propose a different solution.

1. You can listen to the Sensor.TYPE_STEP_COUNTER. Then value of steps you receive with first sensor event is your 'bias' so to detect how many steps user made since app launch you would need to substract the 'bias' from the newest sensor value.
2. On the other hand there is another sensor: Sensor.TYPE_STEP_COUNTER which is triggered with every step. You also might want to use this one.