Open source the Android Location module

Reviewed By: foghina

Differential Revision: D2658581

fb-gh-sync-id: e95b21c5c7c06f3332d2a7c9fab8be9a2e6441cb

Examples/UIExplorer/UIExplorerList.android.js

@@ -38,6 +38,7 @@ var COMPONENTS = [
 var APIS = [
   require('./AccessibilityAndroidExample.android'),
   require('./BorderExample'),
+  require('./GeolocationExample'),
   require('./IntentAndroidExample.android'),
   require('./LayoutEventsExample'),
   require('./LayoutExample'),

Libraries/Geolocation/Geolocation.js

@@ -29,12 +29,19 @@ type GeoOptions = {
 }
 
 /**
+ * The Geolocation API follows the web spec:
+ * https://developer.mozilla.org/en-US/docs/Web/API/Geolocation
+ *
+ * ### iOS
  * You need to include the `NSLocationWhenInUseUsageDescription` key
  * in Info.plist to enable geolocation. Geolocation is enabled by default
  * when you create a project with `react-native init`.
  *
- * Geolocation follows the MDN specification:
- * https://developer.mozilla.org/en-US/docs/Web/API/Geolocation
+ * ### Android
+ * To request access to location, you need to add the following line to your
+ * app's `AndroidManifest.xml`:
+ *
+ * `<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />`
  */
 var Geolocation = {
 

ReactAndroid/src/main/java/com/facebook/react/modules/location/LocationModule.java

@@ -0,0 +1,285 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+package com.facebook.react.modules.location;
+
+import javax.annotation.Nullable;
+
+import android.content.Context;
+import android.location.Location;
+import android.location.LocationListener;
+import android.location.LocationManager;
+import android.location.LocationProvider;
+import android.os.Bundle;
+import android.os.Handler;
+
+import com.facebook.react.bridge.Callback;
+import com.facebook.react.bridge.Arguments;
+import com.facebook.react.bridge.ReactApplicationContext;
+import com.facebook.react.bridge.ReactContext;
+import com.facebook.react.bridge.ReactContextBaseJavaModule;
+import com.facebook.react.bridge.ReactMethod;
+import com.facebook.react.bridge.ReadableMap;
+import com.facebook.react.bridge.WritableMap;
+import com.facebook.react.common.SystemClock;
+import com.facebook.react.modules.core.DeviceEventManagerModule.RCTDeviceEventEmitter;
+
+/**
+ * Native module that exposes Geolocation to JS.
+ */
+public class LocationModule extends ReactContextBaseJavaModule {
+
+  private @Nullable String mWatchedProvider;
+
+  private final LocationListener mLocationListener = new LocationListener() {
+    @Override
+    public void onLocationChanged(Location location) {
+      getReactApplicationContext().getJSModule(RCTDeviceEventEmitter.class)
+          .emit("geolocationDidChange", locationToMap(location));
+    }
+
+    @Override
+    public void onStatusChanged(String provider, int status, Bundle extras) {
+      if (status == LocationProvider.OUT_OF_SERVICE) {
+        emitError("Provider " + provider + " is out of service.");
+      } else if (status == LocationProvider.TEMPORARILY_UNAVAILABLE) {
+        emitError("Provider " + provider + " is temporarily unavailable.");
+      }
+    }
+
+    @Override
+    public void onProviderEnabled(String provider) { }
+
+    @Override
+    public void onProviderDisabled(String provider) { }
+  };
+
+  public LocationModule(ReactApplicationContext reactContext) {
+    super(reactContext);
+  }
+
+  @Override
+  public String getName() {
+    return "LocationObserver";
+  }
+
+  private static class LocationOptions {
+    private final long timeout;
+    private final double maximumAge;
+    private final boolean highAccuracy;
+
+    private LocationOptions(long timeout, double maximumAge, boolean highAccuracy) {
+      this.timeout = timeout;
+      this.maximumAge = maximumAge;
+      this.highAccuracy = highAccuracy;
+    }
+
+    private static LocationOptions fromReactMap(ReadableMap map) {
+      // precision might be dropped on timeout (double -> int conversion), but that's OK
+      long timeout =
+          map.hasKey("timeout") ? (long) map.getDouble("timeout") : Long.MAX_VALUE;
+      double maximumAge =
+          map.hasKey("maximumAge") ? map.getDouble("maximumAge") : Double.POSITIVE_INFINITY;
+      boolean highAccuracy =
+          map.hasKey("enableHighAccuracy") && map.getBoolean("enableHighAccuracy");
+
+      return new LocationOptions(timeout, maximumAge, highAccuracy);
+    }
+  }
+
+  /**
+   * Get the current position. This can return almost immediately if the location is cached or
+   * request an update, which might take a while.
+   *
+   * @param options map containing optional arguments: timeout (millis), maximumAge (millis) and
+   *        highAccuracy (boolean)
+   */
+  @ReactMethod
+  public void getCurrentPosition(
+      ReadableMap options,
+      final Callback success,
+      Callback error) {
+    LocationOptions locationOptions = LocationOptions.fromReactMap(options);
+
+    LocationManager locationManager =
+        (LocationManager) getReactApplicationContext().getSystemService(Context.LOCATION_SERVICE);
+    String provider = getValidProvider(locationManager, locationOptions.highAccuracy);
+    if (provider == null) {
+      error.invoke("No available location provider.");
+      return;
+    }
+
+    Location location = null;
+    try {
+      location = locationManager.getLastKnownLocation(provider);
+    } catch (SecurityException e) {
+      throwLocationPermissionMissing(e);
+    }
+    if (location != null &&
+        SystemClock.currentTimeMillis() - location.getTime() < locationOptions.maximumAge) {
+      success.invoke(locationToMap(location));
+      return;
+    }
+
+    new SingleUpdateRequest(locationManager, provider, locationOptions.timeout, success, error)
+        .invoke();
+  }
+
+  /**
+   * Start listening for location updates. These will be emitted via the
+   * {@link RCTDeviceEventEmitter} as {@code geolocationDidChange} events.
+   *
+   * @param options map containing optional arguments: highAccuracy (boolean)
+   */
+  @ReactMethod
+  public void startObserving(ReadableMap options) {
+    if (LocationManager.GPS_PROVIDER.equals(mWatchedProvider)) {
+      return;
+    }
+    LocationOptions locationOptions = LocationOptions.fromReactMap(options);
+    LocationManager locationManager =
+        (LocationManager) getReactApplicationContext().getSystemService(Context.LOCATION_SERVICE);
+    String provider = getValidProvider(locationManager, locationOptions.highAccuracy);
+    if (provider == null) {
+      emitError("No location provider available.");
+      return;
+    }
+
+    try {
+      if (!provider.equals(mWatchedProvider)) {
+        locationManager.removeUpdates(mLocationListener);
+        locationManager.requestLocationUpdates(provider, 1000, 0, mLocationListener);
+      }
+    } catch (SecurityException e) {
+      throwLocationPermissionMissing(e);
+    }
+
+    mWatchedProvider = provider;
+  }
+
+  /**
+   * Stop listening for location updates.
+   *
+   * NB: this is not balanced with {@link #startObserving}: any number of calls to that method will
+   * be canceled by just one call to this one.
+   */
+  @ReactMethod
+  public void stopObserving() {
+    LocationManager locationManager =
+        (LocationManager) getReactApplicationContext().getSystemService(Context.LOCATION_SERVICE);
+    locationManager.removeUpdates(mLocationListener);
+    mWatchedProvider = null;
+  }
+
+  @Nullable
+  private static String getValidProvider(LocationManager locationManager, boolean highAccuracy) {
+    String provider =
+        highAccuracy ? LocationManager.GPS_PROVIDER : LocationManager.NETWORK_PROVIDER;
+    if (!locationManager.isProviderEnabled(provider)) {
+      provider = provider.equals(LocationManager.GPS_PROVIDER)
+          ? LocationManager.NETWORK_PROVIDER
+          : LocationManager.GPS_PROVIDER;
+      if (!locationManager.isProviderEnabled(provider)) {
+        return null;
+      }
+    }
+    return provider;
+  }
+
+  private static WritableMap locationToMap(Location location) {
+    WritableMap map = Arguments.createMap();
+    WritableMap coords = Arguments.createMap();
+    coords.putDouble("latitude", location.getLatitude());
+    coords.putDouble("longitude", location.getLongitude());
+    coords.putDouble("altitude", location.getAltitude());
+    coords.putDouble("accuracy", location.getAccuracy());
+    coords.putDouble("heading", location.getBearing());
+    coords.putDouble("speed", location.getSpeed());
+    map.putMap("coords", coords);
+    map.putDouble("timestamp", location.getTime());
+    return map;
+  }
+
+  private void emitError(String error) {
+    getReactApplicationContext().getJSModule(RCTDeviceEventEmitter.class)
+        .emit("geolocationError", error);
+  }
+
+  /**
+   * Provides a clearer exception message than the default one.
+   */
+  private static void throwLocationPermissionMissing(SecurityException e) {
+    throw new SecurityException(
+      "Looks like the app doesn't have the permission to access location.\n" +
+      "Add the following line to your app's AndroidManifest.xml:\n" +
+      "<uses-permission android:name=\"android.permission.ACCESS_FINE_LOCATION\" />", e);
+  }
+
+  private static class SingleUpdateRequest {
+
+    private final Callback mSuccess;
+    private final Callback mError;
+    private final LocationManager mLocationManager;
+    private final String mProvider;
+    private final long mTimeout;
+    private final Handler mHandler = new Handler();
+    private final Runnable mTimeoutRunnable = new Runnable() {
+      @Override
+      public void run() {
+        synchronized (SingleUpdateRequest.this) {
+          if (!mTriggered) {
+            mError.invoke("Location request timed out");
+            mLocationManager.removeUpdates(mLocationListener);
+            mTriggered = true;
+          }
+        }
+      }
+    };
+    private final LocationListener mLocationListener = new LocationListener() {
+      @Override
+      public void onLocationChanged(Location location) {
+        synchronized (SingleUpdateRequest.this) {
+          if (!mTriggered) {
+            mSuccess.invoke(locationToMap(location));
+            mHandler.removeCallbacks(mTimeoutRunnable);
+            mTriggered = true;
+          }
+        }
+      }
+
+      @Override
+      public void onStatusChanged(String provider, int status, Bundle extras) {}
+
+      @Override
+      public void onProviderEnabled(String provider) {}
+
+      @Override
+      public void onProviderDisabled(String provider) {}
+    };
+    private boolean mTriggered;
+
+    private SingleUpdateRequest(
+        LocationManager locationManager,
+        String provider,
+        long timeout,
+        Callback success,
+        Callback error) {
+      mLocationManager = locationManager;
+      mProvider = provider;
+      mTimeout = timeout;
+      mSuccess = success;
+      mError = error;
+    }
+
+    public void invoke() {
+      mLocationManager.requestSingleUpdate(mProvider, mLocationListener, null);
+      mHandler.postDelayed(mTimeoutRunnable, SystemClock.currentTimeMillis() + mTimeout);
+    }
+  }
+}

ReactAndroid/src/main/java/com/facebook/react/shell/MainReactPackage.java

@@ -19,6 +19,7 @@
 import com.facebook.react.bridge.ReactApplicationContext;
 import com.facebook.react.modules.fresco.FrescoModule;
 import com.facebook.react.modules.intent.IntentModule;
+import com.facebook.react.modules.location.LocationModule;
 import com.facebook.react.modules.network.NetworkingModule;
 import com.facebook.react.modules.storage.AsyncStorageModule;
 import com.facebook.react.modules.toast.ToastModule;
@@ -50,6 +51,7 @@ public List<NativeModule> createNativeModules(ReactApplicationContext reactConte
       new AsyncStorageModule(reactContext),
       new FrescoModule(reactContext),
       new IntentModule(reactContext),
+      new LocationModule(reactContext),
       new NetworkingModule(reactContext),
       new WebSocketModule(reactContext),
       new ToastModule(reactContext));