NativeScript Android orientation service

orientation.android.js

'use strict';

const application = require('application');

const observable = require('data/observable');

const events = require('~/common/events');

const params = require('~/common/params');

const debug = require('nativescript-debug')(__filename);

var sensorManager, listener, accelerometerSensor, magneticFieldSensor;

const service = new observable.Observable();

service.watching = false;

service.timestamp = null;

service.value = null;
service.accuracy = null;

service._accelerometerValue = null;
service._accelerometerAccuracy = null;

service._magneticFieldValue = null;
service._magneticFieldAccuracy = null;

service.startWatching = function startWatching() {
  if (this.watching) {
    return;
  }

  const Context = android.content.Context;
  const SensorManager = android.hardware.SensorManager;
  const Surface = android.view.Surface;

  sensorManager = application.android.context.getSystemService(Context.SENSOR_SERVICE);

  function onAccuracyChanged(sensor, accuracy) {
    debug('onAccuracyChanged:', sensor.getName(), accuracy);

    if (sensor.getName() === accelerometerSensor.getName()) {
      this._accelerometerAccuracy = accuracy;
    } else if (sensor.getName() === magneticFieldSensor.getName()) {
      this._magneticFieldAccuracy = accuracy;
    }

    if (this._accelerometerAccuracy !== null && this._magneticFieldAccuracy !== null) {
      this.accuracy = (this._accelerometerAccuracy + this._magneticFieldAccuracy) / 2;
    }

  }

  var FACTOR = 180 / Math.PI;

  function onSensorChanged(event) {

    // debug('onSensorChanged', event, event.sensor.getName(), event.values);

    var timestamp = new Date();

    if (this.timestamp && timestamp - this.timestamp < params.orientationDelay) {
      return;
    }

    if (event.sensor.getName() === accelerometerSensor.getName()) {
      this._accelerometerValue = event.values;
    } else if (event.sensor.getName() === magneticFieldSensor.getName()) {
      this._magneticFieldValue = event.values;
    }

    if (this._accelerometerValue !== null && this._magneticFieldValue !== null) {
      // debug('onSensorChanged', this._accelerometerValue, this._magneticFieldValue);

      // var rotationMatrix = Array.create('float', 16);
      var rotationMatrix = java.lang.reflect.Array.newInstance(java.lang.Float.class.getField("TYPE").get(null), 16);

      var result = SensorManager.getRotationMatrix(rotationMatrix, null, this._accelerometerValue, this._magneticFieldValue);

      if (!result) {
        return;
      }
      // debug('onSensorChanged', rotationMatrix);


      var windowManager = application.android.context.getSystemService(Context.WINDOW_SERVICE);

      var screenRotation = windowManager.getDefaultDisplay().getRotation();
      // debug('onSensorChanged', 'screenRotation', screenRotation);

      var axisX, axisY;
      if (screenRotation === Surface.ROTATION_0) {
        // debug('onSensorChanged', 'Surface.ROTATION_0');
        axisX = SensorManager.AXIS_X;
        axisY = SensorManager.AXIS_Y;
      } else if (screenRotation === Surface.ROTATION_90) {
        // debug('onSensorChanged', 'Surface.ROTATION_90');
        axisX = SensorManager.AXIS_Y;
        axisY = SensorManager.AXIS_MINUS_X;
      } else if (screenRotation === Surface.ROTATION_180) {
        // debug('onSensorChanged', 'Surface.ROTATION_180');
        axisX = SensorManager.AXIS_MINUS_X;
        axisY = SensorManager.AXIS_MINUS_Y;
      } else if (screenRotation === Surface.ROTATION_270) {
        // debug('onSensorChanged', 'Surface.ROTATION_270');
        axisX = SensorManager.AXIS_MINUS_Y;
        axisY = SensorManager.AXIS_X;
      }

      var remappedRotationMatrix = java.lang.reflect.Array.newInstance(java.lang.Float.class.getField("TYPE").get(null), 16);

      result = SensorManager.remapCoordinateSystem(rotationMatrix, axisX, axisY, remappedRotationMatrix);

      if (!result) {
        return;
      }
      // debug('onSensorChanged', rotationMatrix);

      // var orientation = Array.create('float', 4);
      var orientation = java.lang.reflect.Array.newInstance(java.lang.Float.class.getField("TYPE").get(null), 4);
      SensorManager.getOrientation(remappedRotationMatrix, orientation);
      // debug('onSensorChanged', orientation);

      var value = orientation[0] * FACTOR;

      // debug('onSensorChanged', 'value', value);

      if (typeof this.value === 'number' && Math.abs(value - this.value) < params.orientationMinimalChange) {
        return;
      }

      this.timestamp = timestamp;

      this.value = value;

      this.notify({
        eventName: 'update',
        object: {
          timestamp: timestamp,
          value: value,
          accuracy: this.accuracy,
        },
      });
    }

    return;

  }

  listener = new android.hardware.SensorEventListener({
    onAccuracyChanged: onAccuracyChanged.bind(this),
    onSensorChanged: onSensorChanged.bind(this)
  });

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

  sensorManager.registerListener(
    listener,
    accelerometerSensor,
    SensorManager.SENSOR_DELAY_UI
  );

  magneticFieldSensor = sensorManager.getDefaultSensor(
    android.hardware.Sensor.TYPE_MAGNETIC_FIELD
  );

  sensorManager.registerListener(
    listener,
    magneticFieldSensor,
    SensorManager.SENSOR_DELAY_UI
  );

  this.watching = true;
};

service.stopWatching = function stopWatching() {
  if (!this.watching) {
    return;
  }
  sensorManager.unregisterListener(listener, accelerometerSensor);
  sensorManager.unregisterListener(listener, magneticFieldSensor);
  this.watching = false;
};

module.exports = service;