Multiview Map

In this guide, you will learn how to display multiple interactive maps in one viewport.

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 multiview_map 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.

Run: flutter pub get

Configure the native parts:

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:

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    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 project pathname

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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
        }
    }
}

iOS

In the ios/Podfile configuration file, at the top, set the minimum ios platform version to 14 like this:

platform :ios, '14.0'

We recommend you to run these commands after you copy the gem_kit into your project: |flutter clean |flutter pub get |and |cd ios |pod install

Then run the project:

flutter run --debug

or

flutter run --release

App entry and initialization

const projectApiToken = String.fromEnvironment('GEM_TOKEN');

void main() {
  runApp(const MyApp());
}

This code initializes the projectApiToken with the required authorization token and launches the app.

How It Works

Creating the Grid of Maps

// Arrange MapViews in a grid with fixed number of elements on row
body: GridView.builder(
    physics: const NeverScrollableScrollPhysics(),
    gridDelegate: const SliverGridDelegateWithFixedCrossAxisCount(crossAxisCount: 2),
    itemCount: _mapViewsCount,
    itemBuilder: (context, index) {
      return Container(
          clipBehavior: Clip.hardEdge,
          decoration: BoxDecoration(
              border: Border.all(color: Colors.black, width: 1),
              borderRadius: BorderRadius.circular(10),
              boxShadow: const [
                BoxShadow(color: Colors.grey, offset: Offset(0, -2), spreadRadius: 1, blurRadius: 2)
              ]),
          margin: const EdgeInsets.all(5),
          child: const GemMap());
    }));

A GridView is used to create a grid with a maximum of 2 map views per row. Each map view is created by GemMap() and enclosed in a Container as a grid element.

Managing the Number of Map Views

void _addViewButtonPressed() => setState(() {
    if (_mapViewsCount < 4) {
      _mapViewsCount += 1;
    }
  });

void _removeViewButtonPressed() => setState(() {
    if (_mapViewsCount > 0) {
      _mapViewsCount -= 1;
    }
  });

The number of interactive map views (initially zero) to display is stored in _mapViewsCount and can be increased or decreased interactively by the user using the functions shown above.

Each map is a separate view and can be panned/zoomed independently of the others.

Flutter Examples

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