Calculate bounding box from region (react-native-maps#2615)

* Add helper method for getting bounding box from region

* Awaiting promise in async method, add typescript definition

* Fix eslint

Author: radeno

index.d.ts

@@ -237,6 +237,7 @@ declare module "react-native-maps" {
         fitToSuppliedMarkers(markers: string[], options?: { edgePadding?: EdgePadding, animated?: boolean }): void;
         fitToCoordinates(coordinates?: LatLng[], options?: { edgePadding?: EdgePadding, animated?: boolean }): void;
         setMapBoundaries(northEast: LatLng, southWest: LatLng): void;
+        getMapBoundaries(): {northEast: LatLng; southWest: LatLng};
         takeSnapshot(options?: SnapshotOptions): Promise<string>;
     }
 

lib/components/MapView.js

@@ -665,9 +665,9 @@ class MapView extends React.Component {
    */
   async getMapBoundaries() {
     if (Platform.OS === 'android') {
-      return NativeModules.AirMapModule.getMapBoundaries(this._getHandle());
+      return await NativeModules.AirMapModule.getMapBoundaries(this._getHandle());
     } else if (Platform.OS === 'ios') {
-      return this._runCommand('getMapBoundaries', []);
+      return await this._runCommand('getMapBoundaries', []);
     }
     return Promise.reject('getMapBoundaries not supported on this platform');
   }
@@ -791,6 +791,26 @@ class MapView extends React.Component {
     return Promise.reject('coordinateForPoint not supported on this platform');
   }
 
+  /**
+   * Get bounding box from region
+   *
+   * @param region Region
+   *
+   * @return Object Object bounding box ({ northEast: <LatLng>, southWest: <LatLng> })
+   */
+  boundingBoxForRegion(region) {
+    return {
+      northEast: {
+        latitude: region.latitude + (region.latitudeDelta / 2),
+        longitude: region.longitude + (region.longitudeDelta / 2),
+      },
+      southWest: {
+        latitude: region.latitude - (region.latitudeDelta / 2),
+        longitude: region.longitude - (region.longitudeDelta / 2),
+      },
+    };
+  }
+
   _uiManagerCommand(name) {
     return NativeModules.UIManager[getAirMapName(this.props.provider)].Commands[name];
   }

lib/ios/AirMaps/AIRMapManager.m

@@ -939,7 +939,7 @@ - (void)mapView:(AIRMap *)mapView regionDidChangeAnimated:(__unused BOOL)animate
 - (void)mapViewWillStartRenderingMap:(AIRMap *)mapView
 {
     if (!mapView.hasStartedRendering) {
-      mapView.onMapReady(@{}); 
+      mapView.onMapReady(@{});
       mapView.hasStartedRendering = YES;
     }
     [mapView beginLoading];