Hi everyone. I meet issue. how to detect when the user is not wearing their WearOS device?

# compose-wear

[lam bui]

Hi everyone. I meet issue.
how to detect when the user is not wearing their WearOS device?

[lam bui]

i research some solution: https://developer.samsung.com/sdp/blog/en/2023/06/14/detect-when-a-galaxy-watch-is-being-worn

[louiscad]

I think you can look into the sensors that sensorManager will give you (through code, some sensors are not documented)

[lam bui]

class WearDetectionService : Service(), SensorEventListener {

    private lateinit var sensorManager: SensorManager
    private var heartRateSensor: Sensor? = null
    private var job: Job? = null

    companion object {
        val isWorn = MutableLiveData(true)
    }

    override fun onCreate() {
        super.onCreate()
        sensorManager = getSystemService(Context.SENSOR_SERVICE) as SensorManager
        heartRateSensor = sensorManager.getDefaultSensor(Sensor.TYPE_HEART_RATE)
        sensorManager.registerListener(this, heartRateSensor, SensorManager.SENSOR_DELAY_NORMAL)
    }

    override fun onDestroy() {
        super.onDestroy()
        sensorManager.unregisterListener(this)
        job?.cancel()
    }

    override fun onBind(intent: Intent?): IBinder? {
        return null
    }

    override fun onAccuracyChanged(sensor: Sensor?, accuracy: Int) {}

    override fun onSensorChanged(event: SensorEvent?) {
        if (event?.sensor?.type == Sensor.TYPE_HEART_RATE) {
            job?.cancel()
            isWorn.postValue(true)
            job = CoroutineScope(Dispatchers.Default).launch {
                delay(10000) // 10 seconds without heart rate data
                isWorn.postValue(false)
            }
        }
    }
}

[lam bui]

i will try it, but not working for me.

[louiscad]

Don't use a Service

[louiscad]

The sensor is not heart_rate BTW

[louiscad]

It's another type. Just look into getSensors(TYPE_ALL), log/print it, and there should be one specific to the "worn/not-worn".

[louiscad]

What's your use case BTW? You don't need it to work while in the background, do you?

[lam bui]

currently app is running background

[louiscad]

What's your use case?

[lam bui]

I am developing a wear app, and record heart rate from wear, then send to phone. I want to detect when user takes off wear? to automatically close the app.

[louiscad]

Do you want to record the heart rate non-stop, or only for a limited duration, after the user starts an action?

[lam bui]

I have a workout maybe 10-20 minutes or 2-3 hours. We will record heart rate.

[louiscad]

Did you find the sensor that detects the on_body status?

[lam bui]

i will double check it. Thank you.

[amoledwatchfaces]

@lam bui Maybe what you need is Health Services API?

https://developer.android.com/health-and-fitness/guides/health-services

https://developer.android.com/health-and-fitness/guides/health-services/monitor-background

[lam bui]

currently, i use api health, I use solution, check heart rate = 0 in 10 seconds, I will count as not wearing watch.
It work ok, but I want to check if the sensor support is 100%?

[Ashley Ingram]

The sensor is the offbody detector. The constant in the SDK is TYPE_LOW_LATENCY_OFFBODY_DETECT (or TYPE_STRING_LOW_LATENCY_OFFBODY_DETECT).

[Ashley Ingram]

Samsung have a developer blog post on it here which looks correcgt

[Ashley Ingram]

https://developer.samsung.com/sdp/blog/en/2023/06/14/detect-when-a-galaxy-watch-is-being-worn

[Ashley Ingram]

The latency should be around 3 seconds max

[lam bui]

oh, i fixed issue, thank you all.