Android Automotive OS: add driving direction to vehicle data

fixes #188

app/src/google/java/net/vonforst/evmap/auto/CarSensors.kt

@@ -0,0 +1,140 @@
+package net.vonforst.evmap.auto
+
+import android.content.Context
+import android.hardware.Sensor
+import android.hardware.SensorEvent
+import android.hardware.SensorEventListener
+import android.hardware.SensorManager
+import androidx.car.app.CarContext
+import androidx.car.app.hardware.CarHardwareManager
+import androidx.car.app.hardware.common.CarValue
+import androidx.car.app.hardware.common.OnCarDataAvailableListener
+import androidx.car.app.hardware.info.*
+import androidx.car.app.hardware.info.CarSensors.UpdateRate
+import net.vonforst.evmap.BuildConfig
+import java.util.concurrent.Executor
+
+/**
+ * CarSensors is not yet implemented for Android Automotive OS
+ * (see docs at https://developer.android.com/reference/androidx/car/app/hardware/info/CarSensors)
+ * so we provide our own implementation based on SensorManager APIs.
+ */
+val CarContext.patchedCarSensors: CarSensors
+    get() = if (BuildConfig.FLAVOR_automotive != "automotive") {
+        (this.getCarService(CarContext.HARDWARE_SERVICE) as CarHardwareManager).carSensors
+    } else {
+        CarSensorsWrapper(this)
+    }
+
+class CarSensorsWrapper(carContext: CarContext) :
+    CarSensors {
+    private val sensorManager = carContext.getSystemService(Context.SENSOR_SERVICE) as SensorManager
+    private val compassListeners: MutableMap<OnCarDataAvailableListener<Compass>, SensorEventListener> =
+        mutableMapOf()
+
+    override fun addAccelerometerListener(
+        rate: Int,
+        executor: Executor,
+        listener: OnCarDataAvailableListener<Accelerometer>
+    ) {
+        TODO("Not yet implemented")
+    }
+
+    override fun removeAccelerometerListener(listener: OnCarDataAvailableListener<Accelerometer>) {
+        TODO("Not yet implemented")
+    }
+
+    override fun addGyroscopeListener(
+        rate: Int,
+        executor: Executor,
+        listener: OnCarDataAvailableListener<Gyroscope>
+    ) {
+        TODO("Not yet implemented")
+    }
+
+    override fun removeGyroscopeListener(listener: OnCarDataAvailableListener<Gyroscope>) {
+        TODO("Not yet implemented")
+    }
+
+    override fun addCompassListener(
+        rate: Int,
+        executor: Executor,
+        listener: OnCarDataAvailableListener<Compass>
+    ) {
+        val magSensor = sensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD)
+        val accSensor = sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER)
+
+        if (magSensor == null) {
+            executor.execute {
+                listener.onCarDataAvailable(Compass(CarValue(null, 0, CarValue.STATUS_UNAVAILABLE)))
+            }
+            return
+        }
+        val sensorListener = object : SensorEventListener {
+            var magValues: FloatArray? = null
+
+            // AAOS cars may not provide an acceleration sensor, so we assume acceleration based on
+            // Earth's gravity. May not be correct when driving on other planets.
+            var accValues = floatArrayOf(0f, 0f, SensorManager.GRAVITY_EARTH)
+            val rotMatrix = FloatArray(9)
+            val orientation = FloatArray(3)
+
+            override fun onSensorChanged(event: SensorEvent) {
+                when (event.sensor) {
+                    magSensor -> magValues = event.values
+                    accSensor -> accValues = event.values
+                }
+                if (magValues == null) return
+
+                SensorManager.getRotationMatrix(rotMatrix, null, accValues, magValues)
+                SensorManager.getOrientation(rotMatrix, orientation)
+                val compassDegrees = orientation.map { Math.toDegrees(it.toDouble()).toFloat() }
+                executor.execute {
+                    listener.onCarDataAvailable(
+                        Compass(
+                            CarValue(
+                                compassDegrees,
+                                event.timestamp,
+                                CarValue.STATUS_SUCCESS
+                            )
+                        )
+                    )
+                }
+            }
+
+            override fun onAccuracyChanged(sensor: Sensor, accuracy: Int) {
+            }
+
+        }
+        compassListeners[listener] = sensorListener
+        sensorManager.registerListener(sensorListener, magSensor, mapRate(rate))
+        accSensor?.let { sensorManager.registerListener(sensorListener, it, mapRate(rate)) }
+    }
+
+    private fun mapRate(@UpdateRate rate: Int): Int {
+        return when (rate) {
+            CarSensors.UPDATE_RATE_NORMAL -> SensorManager.SENSOR_DELAY_NORMAL
+            CarSensors.UPDATE_RATE_UI -> SensorManager.SENSOR_DELAY_UI
+            CarSensors.UPDATE_RATE_FASTEST -> SensorManager.SENSOR_DELAY_FASTEST
+            else -> throw IllegalArgumentException()
+        }
+    }
+
+    override fun removeCompassListener(listener: OnCarDataAvailableListener<Compass>) {
+        compassListeners[listener]?.let {
+            sensorManager.unregisterListener(it)
+        }
+    }
+
+    override fun addCarHardwareLocationListener(
+        rate: Int,
+        executor: Executor,
+        listener: OnCarDataAvailableListener<CarHardwareLocation>
+    ) {
+        TODO("Not yet implemented")
+    }
+
+    override fun removeCarHardwareLocationListener(listener: OnCarDataAvailableListener<CarHardwareLocation>) {
+        TODO("Not yet implemented")
+    }
+}

app/src/google/java/net/vonforst/evmap/auto/VehicleDataScreen.kt

@@ -21,7 +21,9 @@ import kotlin.math.min
 import kotlin.math.roundToInt
 
 class VehicleDataScreen(ctx: CarContext) : Screen(ctx), LifecycleObserver {
-    private val hardwareMan = ctx.getCarService(CarContext.HARDWARE_SERVICE) as CarHardwareManager
+    private val carInfo =
+        (ctx.getCarService(CarContext.HARDWARE_SERVICE) as CarHardwareManager).carInfo
+    private val carSensors = carContext.patchedCarSensors
     private var model: Model? = null
     private var energyLevel: EnergyLevel? = null
     private var speed: Speed? = null
@@ -232,15 +234,15 @@ class VehicleDataScreen(ctx: CarContext) : Screen(ctx), LifecycleObserver {
         println("Setting up energy level listener")
 
         val exec = ContextCompat.getMainExecutor(carContext)
-        hardwareMan.carInfo.addEnergyLevelListener(exec, ::onEnergyLevelUpdated)
-        hardwareMan.carInfo.addSpeedListener(exec, ::onSpeedUpdated)
-        hardwareMan.carSensors.addCompassListener(
+        carInfo.addEnergyLevelListener(exec, ::onEnergyLevelUpdated)
+        carInfo.addSpeedListener(exec, ::onSpeedUpdated)
+        carSensors.addCompassListener(
             CarSensors.UPDATE_RATE_NORMAL,
             exec,
             ::onCompassUpdated
         )
 
-        hardwareMan.carInfo.fetchModel(exec) {
+        carInfo.fetchModel(exec) {
             this.model = it
             invalidate()
         }
@@ -249,9 +251,9 @@ class VehicleDataScreen(ctx: CarContext) : Screen(ctx), LifecycleObserver {
     @OnLifecycleEvent(Lifecycle.Event.ON_PAUSE)
     private fun removeListeners() {
         println("Removing energy level listener")
-        hardwareMan.carInfo.removeEnergyLevelListener(::onEnergyLevelUpdated)
-        hardwareMan.carInfo.removeSpeedListener(::onSpeedUpdated)
-        hardwareMan.carSensors.removeCompassListener(::onCompassUpdated)
+        carInfo.removeEnergyLevelListener(::onEnergyLevelUpdated)
+        carInfo.removeSpeedListener(::onSpeedUpdated)
+        carSensors.removeCompassListener(::onCompassUpdated)
     }
 
     private fun permissionsGranted(): Boolean =