Accelerometer

[ligaz]

From @Alejonext on February 26, 2015 6:40

I really do not know where to place this issue... Well, the point is that I would like to access the accelerometer sensor. In the docs android and ios. As would be to implement? Do not know if an event ...

Copied from original issue: NativeScript/nativescript-cli#246

[ligaz]

From @brianchirls on March 24, 2015 14:32

Sensor access (accel, gyro, position, etc.) would definitely be useful.

I believe Android does it through event listeners, and that's probably the best way to do it. There are various settings that describe how often events get triggered, balancing needs of the application with energy consumption. It might make for an easier API to allow querying of sensor values on every frame, but I worry that it might encourage people to ignore those settings.

[ilyakam]

I just wanted to mention that thanks to this response in Google Groups, I was able to get the Android accelerometer to work correctly. The complete code is as follows:

var application = require('application');

function onAccuracyChanged(sensor, accuracy) {
  console.log('onAccuracyChanged:', accuracy);
}

function onSensorChanged(event) {
  var azimuth = event.values[0],
      pitch = event.values[1],
      roll = event.values[2];

  console.log('azimuth', azimuth);
  console.log('pitch', pitch);
  console.log('roll', roll);
}

function onPageLoaded(args) {
  var sensorManager = application.android.foregroundActivity.getSystemService(
        android.content.Context.SENSOR_SERVICE
      ),
      accelerometer,
      sensorActivity;

  sensorActivity = new android.hardware.SensorEventListener({
    onAccuracyChanged: onAccuracyChanged,
    onSensorChanged: onSensorChanged
  });

  accelerometer = sensorManager.getDefaultSensor(
    android.hardware.Sensor.TYPE_ACCELEROMETER
  );

  sensorManager.registerListener(
    sensorActivity,
    accelerometer,
    android.hardware.SensorManager.SENSOR_DELAY_NORMAL
  );
}

Having said that, does anybody know how to read the accelerometer data from an iOS device?

[jamlfy]

Well, i think to create a library for that

[valentinstoychev]

@Alejonext please let us know if you need help with the library.

[jamlfy]

OK!

[ilyakam]

After spending a few days messing with the iOS accelerometer, I am pleased to say that I've got it working on an iOS device! I've taken inspiration from @nikolay-diyanov's gists, specifically this one.

Here's the code to accomplish that:

var motionManager = new CMMotionManager();

function onTapStart() {
  if (!motionManager.accelerometerAvailable) {
    return;
  }

  motionManager.accelerometerUpdateInterval = 0.1;

  motionManager.startAccelerometerUpdatesToQueueWithHandler(
    NSOperationQueue.currentQueue(),
    function(accelerometerData, error) {
      var acceleration = accelerometerData.acceleration;

      console.log('x', acceleration.x);
      console.log('y', acceleration.y);
      console.log('z', acceleration.z);
    }
  );
}

function onTapStop() {
  motionManager.stopAccelerometerUpdates();

  NSOperationQueue.currentQueue().cancelAllOperations();
}

exports.onTapStart = onTapStart;
exports.onTapStop = onTapStop;

The biggest issue was that the accelerometer would only work for a few seconds if it was being called directly from the loaded's event listener. Therefore, we start logging only after onTapStart in this case.

---

Now that I've gotten both platforms to work, I tried writing a plugin, borrowing heavily from nativescript-flashdrive and the accompanying article. Since in both cases the accelerometer data is provided after some interval in a loop, I figured that an event-based architecture is most suitable.

The documentation outlining the creation of custom events isn't too helpful, and I haven't been able to find an example in JavaScript on how to use .notify and .on in a straightforward manner.

Can anyone on here please point me in the right direction…?

[enchev]

Hi @ilyakam,

I believe that you can use the approach from our connectivity module with a callback for the start method and additional stop method.