TiltService.kt

TiltService.kt

package com.github.cdflynn.tilt.service

import android.app.Activity
import android.content.Context
import android.hardware.Sensor
import android.hardware.SensorEvent
import android.hardware.SensorEventListener
import android.hardware.SensorManager
import com.github.cdflynn.tilt.model.Tilt
import com.jakewharton.rxrelay2.PublishRelay
import com.jakewharton.rxrelay2.Relay
import io.reactivex.Observable

class TiltService(context: Context) {

    private val sensorManager = context.getSystemService(Activity.SENSOR_SERVICE) as SensorManager
    private val rotationSensor: Sensor = sensorManager.getDefaultSensor(Sensor.TYPE_ROTATION_VECTOR)
    private val tiltStream: PublishRelay<Tilt> = PublishRelay.create()

    fun observeTilt(): Observable<Tilt> {
        if (tiltStream.hasObservers()) {
            return tiltStream.hide()
        }

        val rotationListener = RotationListener(tiltStream)

        return tiltStream
            .doOnSubscribe {
                sensorManager.registerListener(
                    rotationListener,
                    rotationSensor,
                    SENSOR_INTERVAL_MICROSECONDS
                )
            }
            .doOnDispose { sensorManager.unregisterListener(rotationListener) }

    }

    companion object {
        const val SENSOR_INTERVAL_MICROSECONDS = 16 * 1000
    }

}

class RotationListener(private val relay: Relay<Tilt>) : SensorEventListener {
    private val rotationMatrix = FloatArray(9)
    private val orientation = FloatArray(3)

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

    override fun onSensorChanged(event: SensorEvent) {
        val tilt = rotationVectorToTiltInternal(event.values)
        relay.accept(tilt)
    }

    private fun rotationVectorToTiltInternal(vector: FloatArray): Tilt {
        SensorManager.getRotationMatrixFromVector(rotationMatrix, vector)
        SensorManager.getOrientation(rotationMatrix, orientation)
        return Tilt(orientation[0], orientation[1], orientation[2])
    }
}

data class Tilt(val yaw: Float, val pitch: Float, val roll: Float)