react-native-maps/examples/DisplayLatLng.js

React Native Mapview component for iOS + Android

var React = require('react-native');
var {
  StyleSheet,
  PropTypes,
  View,
  Text,
  Dimensions,
  TouchableOpacity,
} = React;

var MapView = require('../components/MapView');

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

const ASPECT_RATIO = width / height;
const LATITUDE = 37.78825;
const LONGITUDE = -122.4324;
const LATITUDE_DELTA = 0.0922;
const LONGITUDE_DELTA = LATITUDE_DELTA * ASPECT_RATIO;

var DisplayLatLng = React.createClass({
  getInitialState() {
    return {
      region: {
        latitude: LATITUDE,
        longitude: LONGITUDE,
        latitudeDelta: LATITUDE_DELTA,
        longitudeDelta: LONGITUDE_DELTA,
      },
    };
  },

  onRegionChange(region) {
    this.setState({ region });
  },

  jumpRandom() {
    this.setState({ region: this.randomRegion() });
  },

  animateRandom() {
    this.refs.map.animateToRegion(this.randomRegion());
  },

  randomRegion() {
    var { region } = this.state;
    return {
      ...this.state.region,
      latitude: region.latitude + (Math.random() - 0.5) * region.latitudeDelta / 2,
      longitude: region.longitude + (Math.random() - 0.5) * region.longitudeDelta / 2,
    };
  },

  render() {
    return (
      <View style={styles.container}>
        <MapView
          ref="map"
          style={styles.map}
          region={this.state.region}
          onRegionChange={this.onRegionChange}
        >
        </MapView>
        <View style={[styles.bubble, styles.latlng]}>
          <Text style={{ textAlign: 'center'}}>
            {`${this.state.region.latitude.toPrecision(7)}, ${this.state.region.longitude.toPrecision(7)}`}
          </Text>
        </View>
        <View style={styles.buttonContainer}>
          <TouchableOpacity onPress={this.jumpRandom} style={[styles.bubble, styles.button]}>
            <Text>Jump</Text>
          </TouchableOpacity>
          <TouchableOpacity onPress={this.animateRandom} style={[styles.bubble, styles.button]}>
            <Text>Animate</Text>
          </TouchableOpacity>
        </View>
      </View>
    );
  },
});

var styles = StyleSheet.create({
  container: {
    position: 'absolute',
    top: 0,
    left: 0,
    right: 0,
    bottom: 0,
    justifyContent: 'flex-end',
    alignItems: 'center',
  },
  map: {
    position: 'absolute',
    top: 0,
    left: 0,
    right: 0,
    bottom: 0,
  },
  bubble: {
    backgroundColor: 'rgba(255,255,255,0.7)',
    paddingHorizontal: 18,
    paddingVertical: 12,
    borderRadius: 20,
  },
  latlng: {
    width: 200,
    alignItems: 'stretch',
  },
  button: {
    width: 80,
    paddingHorizontal: 12,
    alignItems: 'center',
    marginHorizontal: 10,
  },
  buttonContainer: {
    flexDirection: 'row',
    marginVertical: 20,
    backgroundColor: 'transparent',
  },
});

module.exports = DisplayLatLng;