在react native中从viewport获取latitudedelta和longitudedelta

const { width, height } = Dimensions.get('window');

const ASPECT_RATIO = width / height;
const LATITUDE_DELTA = 0.0922;

const lat = details.geometry.location.lat;
const lng = details.geometry.location.lng;
const latDelta = details.geometry.viewport.northeast.lat - details.geometry.viewport.southwest.lat;
const lngDelta = latDelta * ASPECT_RATIO;

let coordinate = {
    latitude: lat,
    longitude: lng,
    latitudeDelta: latDelta,
    longitudeDelta: lngDelta
};