Text search

In this guide you will learn how to do a text search and select a result to be displayed on an interactive map.

Setup

First, get an API key token, see the Getting Started guide.

Prerequisites

Make sure you completed the Environment Setup - Flutter Examples guide before starting this guide.

Build and run

Go to the text_search directory, within the flutter examples directory - that is the name of this example project.

Note - the gem_kit directory containing the Maps SDK for Flutter should be in the plugins directory of the example, e.g. example_pathname/plugins/gem_kit - see the environment setup guide above. Replace example_pathname with the actual example path name, such as address_search

Download project dependencies:

flutter upgrade

run the following terminal commands in the project directory, where the pubspec.yaml file is located:

flutter clean

flutter pub get

Run the example:

Android

First, verify that the ANDROID_SDK_ROOT environment variable is set to the root path of your android SDK.

In android/build.gradle add the maven {} block as shown, within the allprojects {} block, for both debug and release builds, without the line numbers, those are for reference:

allprojects {
    repositories {
        google()
        mavenCentral()
        maven {
           url "${rootDir}/../plugins/gem_kit/android/build"
        }
    }
}

in android/app/build.gradle within the android {} block, in the defaultConfig {} block, the android SDK version minSdk must be set as shown below.

Additionally, for release builds, in android/app/build.gradle, within the android {} block, add the buildTypes {} block as shown:

Replace example_pathname with the actual example pathname, such as center_coordinates

android {
    defaultConfig {
        applicationId "com.magiclane.gem_kit.examples.example_pathname"
        minSdk 21
        targetSdk flutter.targetSdk
        versionCode flutterVersionCode.toInteger()
        versionName flutterVersionName
    }
    buildTypes {
        release {
            minifyEnabled false
            shrinkResources false

            // TODO: Add your own signing config for the release build.
            // Signing with the debug keys for now, so `flutter run --release` works.
            signingConfig signingConfigs.debug
        }
    }
}

Then run the project:

flutter run --debug

or

flutter run --release

iOS

In the ios/Podfile configuration text file, at the top, set the minimum ios platform to 13 like this:

platform :ios, '13.0'

Then run the project:

flutter run --debug

or

flutter run --release

How it works

import 'package:gem_kit/core.dart';
import 'package:gem_kit/landmark_store.dart';
import 'package:gem_kit/map.dart';
import 'search_page.dart';
import 'package:flutter/material.dart';

Note that the source file search_page.dart also includes:

import 'package:gem_kit/search.dart';
import 'dart:async';

The dart material package is imported, as well as the required gem_kit packages.

void onMapCreated(GemMapController controller) {
  _mapController = controller;
}

This callback function is called when the interactive map is initialized and ready to use.

// Custom method for navigating to search screen
void _onSearchButtonPressed(BuildContext context) async {
// Taking the coordinates at the center of the screen as reference coordinates for search.
 final x = MediaQuery.of(context).size.width / 2;
 final y = MediaQuery.of(context).size.height / 2;
 final mapCoords = _mapController.transformScreenToWgs(XyType(x: x.toInt(), y: y.toInt()));

// Navigating to search screen. The result will be the selected search result(Landmark)
 final result = await Navigator.of(context).push(MaterialPageRoute<dynamic>(
   builder: (context) => SearchPage(coordinates: mapCoords!),
 ));

 if (result is Landmark) {
   // Retrieves the LandmarkStore with the given name.
   var historyStore = LandmarkStoreService.getLandmarkStoreByName("History");

   // If there is no LandmarkStore with this name, then create it.
   historyStore ??= LandmarkStoreService.createLandmarkStore("History");

   // Add the landmark to the store.
   historyStore.addLandmark(result);

   // Activating the highlight
   _mapController.activateHighlight([result], renderSettings: RenderSettings());

   // Centering the map on the desired coordinates
   _mapController.centerOnCoordinates(result.coordinates);
 }
}

This is the method to navigate to the search screen, defined in the SearchPage() widget, in search_page.dart

void _onSearchSubmitted(String text) {
  SearchPreferences preferences = SearchPreferences(maxMatches: 40, allowFuzzyResults: true);

  search(text, widget.coordinates, preferences: preferences);
}

As text is typed in the text field by the user, the _onSearchSubmitted() function is called, which creates a preferences instance and then the search() function is called.

The coordinates of the current location displayed on the map widget.coordinates are used for comparison, to compute the distance to the positions of the search results.

// Search method. Text and coordinates parameters are mandatory, preferences are optional.
Future<void> search(String text, Coordinates coordinates, {SearchPreferences? preferences}) async {
  Completer<List<Landmark>> completer = Completer<List<Landmark>>();

// Calling the search method from the sdk.
// (err, results) - is a callback function that calls when the computing is done.
// err is an error code, results is a list of landmarks
  SearchService.search(text, coordinates, preferences: preferences, (err, results) async {
    // If there is an error or there aren't any results, the method will return an empty list.
    if (err != GemError.success || results == null) {
      completer.complete([]);
      return;
    }
    if (!completer.isCompleted) completer.complete(results);
  });
  final result = await completer.future;
  setState(() {
    landmarks = result;
  });
}

The search() function calls the SearchService.search(), obtains a list of landmarks in results, which are then displayed as a text list. Tapping on a result causes the map to be centered on the position of that search result.

This is done in the method that calls SearchPage() above.

The result landmark tapped by the user is selected:

_mapController.activateHighlight([result], renderSettings: RenderSettings());

Then the map is centered on the coordinates of that result landmark:

_mapController.centerOnCoordinates(result.coordinates);

Flutter Examples

Maps SDK for Flutter Examples can be downloaded or cloned with Git