Displaying a Map

Your environment is now fully configured, and you have the necessary Google Maps and MapsIndoors API keys. Next you will learn how to load a map with MapsIndoors and display it in a React Native app.

Selecting and Loading a Solution​

To start off, we set up a simple two screen navigation using the @react-navigation package. We will create a FrontScreen component that lets us chose the solution to open, and a MapScreen component that will display the actual map.

App.tsx

import {NavigationContainer} from "@react-navigation/native";
import {createNativeStackNavigator} from "@react-navigation/native-stack";
import FrontScreen from "./screens/FrontScreen";
import MapScreen from "./screens/MapScreen";

function App(): React.JSX.Element {
  const Stack = createNativeStackNavigator();

  return (
      <NavigationContainer>
        <Stack.Navigator>
          <Stack.Screen name={'Front'} component={FrontScreen}/>
          <Stack.Screen name={'Map'} component={MapScreen}/>
        </Stack.Navigator>
      </NavigationContainer>
  )
}

export default App;

The FrontScreen is defined as a functional component function FrontScreen(/*...*/) {/*...*/} that returns the View to be displayed. The property navigation gives us access to the navigator and lets us navigate to other screens.

We use a useState hook apiKeyString for storing the API key entered by the user and to pass it to the next screen when navigating.

As for what to actually render, we return a react fragment containing a button with a preset API key for a demo solution. And following that, a row containing an input box and a button for using the entered API key. In order to navigate to the MapScreen, we call navigation.navigate('Map', {apiKey: apiKeyString})} where 'Map' is the name we gave the screen in the navigator, and we pass the API key in the parameters, which will be available through route on the following screen.

The FrontScreen and app App are already implemented for you.

screens/FrontScreen.tsx

import {Button, TextInput, View} from "react-native";
import {Colors} from "react-native/Libraries/NewAppScreen";
import {useState} from "react";


export default function FrontScreen({navigation}) {
  const [apiKeyString, setApiKeyString] = useState(''); // The API key entered into the TextInput

  return (
      <>
        <Button title={'White House demo'} onPress={() => navigation.navigate('Map', {apiKey: 'd876ff0e60bb430b8fabb145'})}/>
        <View style={{flexDirection: 'row'}}>
          <TextInput placeholder={'Enter an API key for your solution'} placeholderTextColor={'#AAA'} onChangeText={setApiKeyString} style={{flex: 1, backgroundColor: Colors.white}}/>
          <Button title={'Go to map'} onPress={() => navigation.navigate('Map', {apiKey: apiKeyString})}/>
        </View>
      </>
  )
}

Showing the map​

For the MapScreen we create a functional component similarly to the above. Note the additional property route which contains parameters from the navigation stack, such as the API key we provided from the FrontScreen

From the basic example you are now left to implement the load function as well as the useEffect hook and adding the MapView to the returned view.

We store the reference to our MapControl in a useState hook, so that we can pass it to other components in the future. We define a load function, which gets the API key from route.params. We use it to load our solution data through MapsIndoors, create a MapControl that is used to control the displayed map, and navigate to the first venue in the solution by using MapControl. Be sure to await the asynchronous API calls to know when it has fully loaded.

We use a useEffect hook to load when entering the MapScreen.

Actually showing the Map is pretty simple, consisting of returning a MapView component, styled to set the appropriate size.

Currently there is a limitation that on some platforms the size of the MapView must be provided in actual dimensions, as opposed to percentages or flex. We can get the size of the screen using useWindowDimensions(), and use flex: 1 to reduce the size to fit.

Here is the first implementation of the MapScreen, with the logic described above.

import MapsIndoors, {
  MapControl,
  MapView,
  MPMapConfig,
} from "@mapsindoors/react-native-maps-indoors-google-maps";
import {NativeEventEmitter, useWindowDimensions} from "react-native";
import React, {useEffect, useState} from "react";


export default function MapScreen({navigation, route}) {

  const [mapControl, setMapControl] = useState<MapControl>()

  const load = async () => {
    try {
      const {apiKey} = route.params;

      console.log('Loading MapsIndoors...');
      await MapsIndoors.load(apiKey);

      console.log('Creating MapControl...');
      const mapControl = await MapControl.create(new MPMapConfig({useDefaultMapsIndoorsStyle: true}), NativeEventEmitter);
      setMapControl(mapControl)

      console.log('Moving to venue...');
      await mapControl.goTo((await MapsIndoors.getVenues()).getAll()[0]);

      console.log('Done!');

    } catch (e) {
      console.error('Error while loading MapsIndoors:', e);
      navigation.pop();
    }
  };

  // Load MapsIndoors when the app mounts, i.e. the MapView should be ready.
  useEffect(() => {
    load().catch((reason) => {console.error('MapsIndoors failed to load:', reason)});
  }, []); // NOTE: the second parameter deps: [] is important, otherwise it will load everytime the MapView changes

  const {width, height} = useWindowDimensions();

  return (
    <GestureHandlerRootView style={{flex:1, flexGrow:1}}>
      <MapView style={{
        width: width,
        height: height,
        flex: 1,
      }}/>
      <BottomSheet ref={bottomSheet} snapPoints={['15%', '60%']} index={-1} enablePanDownToClose={true}>
      </BottomSheet>
    </GestureHandlerRootView>
  );
}