Add a point, line, and polygon | ArcGIS Maps SDK for Flutter

Learn how to display point, line, and polygon graphics in a map.

You typically use graphics to display geographic data that is not connected to a database and that is not persisted, like highlighting a route between two locations, displaying a search buffer around a selected point, or showing the location of map coordinates entered by the user. Graphics are composed of a geometry, symbol, and attributes.

In this tutorial, you display points, lines, and polygons on a map as graphics.

Prerequisites

Before starting this tutorial:

You need an ArcGIS Location Platform or ArcGIS Online account.
Your system meets the system requirements.
You need an IDE for Flutter - we recommend VS Code.

Develop or download

You have two options for completing this tutorial:

Option 1: Develop the code or
Option 2: Download the completed solution

Option 1: Develop the code

To start the tutorial, complete the Display a map tutorial. This creates a map to display the Santa Monica Mountains in California using the topographic basemap from the ArcGIS Basemap Styles service.

Open a Flutter project

Open the project you created by completing the Display a map tutorial.
Continue with the following instructions to display a point, line, and polygon in the map.

Add a graphics overlay

A graphics overlay is a container for graphics. It is used with a map view to display graphics on a map. You can add more than one graphics overlay to a map view. Graphics overlays are displayed on top of all the other layers.

Open lib\main.dart.

In onMapViewReady(), create a GraphicsOverlay and add it to the map view controller.

main.dart
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  void onMapViewReady() {

    final map = ArcGISMap.withBasemapStyle(BasemapStyle.arcGISTopographic);

    _mapViewController.arcGISMap = map;

    // Create a new graphics overlay object.
    final graphicsOverlay = GraphicsOverlay();

    // Add the graphics overlay to the map view controller.
    _mapViewController.graphicsOverlays.add(graphicsOverlay);

    _mapViewController.setViewpoint(
      Viewpoint.withLatLongScale(
        latitude: 34.02700,
        longitude: -118.80500,
        scale: 72000,
      ),
    );

  }

Add a point graphic

A point graphic is created using a point and a marker symbol. A point is defined with x and y coordinates, and a spatial reference. For latitude and longitude coordinates, the spatial reference is WGS84.

Create an ArcGISPoint and a SimpleMarkerSymbol. To create the ArcGISPoint, provide longitude (x) and latitude (y) coordinates, and a SpatialReference. Use the SpatialReference.wgs84 convenience property. Create and style a SimpleMarkerSymbol.

Point graphics support a number of symbol types such as SimpleMarkerSymbol, PictureMarkerSymbol and TextSymbol. Learn more about the Symbol class in the API documentation.

main.dart
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    _mapViewController.setViewpoint(
      Viewpoint.withLatLongScale(
        latitude: 34.02700,
        longitude: -118.80500,
        scale: 72000,
      ),
    );

    // Create an ArcGIS point with long and lat
    // and set the spatial reference.
    final point = ArcGISPoint(
      x: -118.80657463861,
      y: 34.0005930608889,
      spatialReference: SpatialReference.wgs84,
    );

    // Create a new orange circle with a solid blue outline symbol.
    final pointSymbol =
        SimpleMarkerSymbol(
            style: SimpleMarkerSymbolStyle.circle,
            color: Colors.orange,
            size: 10,
          )
          ..outline = SimpleLineSymbol(
            style: SimpleLineSymbolStyle.solid,
            color: Colors.blue,
            width: 2,
          );

Create a Graphic with the point and pointSymbol. Display the Graphic by adding it to the graphicOverlay's list of graphics.

main.dart
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    // Create an ArcGIS point with long and lat
    // and set the spatial reference.
    final point = ArcGISPoint(
      x: -118.80657463861,
      y: 34.0005930608889,
      spatialReference: SpatialReference.wgs84,
    );

    // Create a new orange circle with a solid blue outline symbol.
    final pointSymbol =
        SimpleMarkerSymbol(
            style: SimpleMarkerSymbolStyle.circle,
            color: Colors.orange,
            size: 10,
          )
          ..outline = SimpleLineSymbol(
            style: SimpleLineSymbolStyle.solid,
            color: Colors.blue,
            width: 2,
          );

    // Create a graphic using the point and point symbol defined earlier.
    final pointGraphic = Graphic(geometry: point, symbol: pointSymbol);

    // Add the graphic to the graphics overlay to display it.
    graphicsOverlay.graphics.add(pointGraphic);

Run the app

Make sure you have an Android emulator, iOS simulator or physical device configured and running.
In VS Code, select Run > Run Without Debugging.

You should see a point graphic in Point Dume State Beach.

Add a line graphic

A line graphic is created using a polyline and a line symbol. A polyline is defined as a sequence of points.

Polylines have one or more distinct parts. Each part is a sequence of points. For a continuous line, you can use the Polyline constructor to create a polyline with just one part. To create a polyline with more than one part, use a PolylineBuilder.

Create a Polyline and a SimpleLineSymbol. To create the Polyline, call the addPointXY() method on PolylineBuilder for each (x, y) coordinate pair that defines a point along the polyline's path. Create and style a SimpleLineSymbol.

Line graphics support a number of symbol types such as SimpleLineSymbol and TextSymbol. Learn more about the Symbol class in the API documentation.

main.dart
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    // Add the graphic to the graphics overlay to display it.
    graphicsOverlay.graphics.add(pointGraphic);

    // Create a polyline builder and set its spatial reference.
    // Use the `addPointXY()` method to add (x,y) coordinates one at a time
    // that define the polyline's geometry.
    final polylineBuilder =
        PolylineBuilder(spatialReference: SpatialReference.wgs84)
          ..addPointXY(x: -118.82152, y: 34.01395)
          ..addPointXY(x: -118.81489, y: 34.00806)
          ..addPointXY(x: -118.80887, y: 34.00166);

    // Retrieve the polyline's geometry that the builder constructed.
    final polyline = polylineBuilder.toGeometry();

    // Create a solid blue line simple line symbol.
    final polylineSymbol = SimpleLineSymbol(
      style: SimpleLineSymbolStyle.solid,
      color: Colors.blue,
      width: 3,
    );

Create a Graphic with the polyline and polylineSymbol. Display the Graphic by adding it to the list of graphics.

main.dart
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    // Retrieve the polyline's geometry that the builder constructed.
    final polyline = polylineBuilder.toGeometry();

    // Create a solid blue line simple line symbol.
    final polylineSymbol = SimpleLineSymbol(
      style: SimpleLineSymbolStyle.solid,
      color: Colors.blue,
      width: 3,
    );

    // Create a graphic using the polyline and polyline symbol defined earlier.
    final polylineGraphic = Graphic(geometry: polyline, symbol: polylineSymbol);

    // Add the graphic to the graphics overlay to display it.
    graphicsOverlay.graphics.add(polylineGraphic);

Use Flutter's hot restart to load your code changes and restart the app.

You should see a point and line graphic along Westward Beach.

Add a polygon graphic

A polygon graphic is created using a polygon and a fill symbol. A polygon is defined as a sequence of points that describe a closed boundary.

Polygons have one or more distinct parts. Each part is a sequence of points describing a closed boundary. For a single area with no holes, you can use the Polygon constructor to create a polygon with just one part. To create a polygon with more than one part, use a PolygonBuilder.

Create a Polygon and a SimpleFillSymbol. To create the Polygon, call the addPointXY() method on PolygonBuilder for each (x,y) coordinate pair that defines a point on the closed boundary. Create and style a SimpleFillSymbol.

Polygon graphics support a number of symbol types such as SimpleFillSymbol, PictureFillSymbol, SimpleMarkerSymbol and TextSymbol. Learn more about the Symbol class in the API documentation.

main.dart
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    // Add the graphic to the graphics overlay to display it.
    graphicsOverlay.graphics.add(polylineGraphic);

    // Create a polygon builder and set its spatial reference.
    // Use the `addPointXY()` method to add (x,y) coordinates one at a time
    // that define the polygon's geometry.
    final polygonBuilder =
        PolygonBuilder(spatialReference: SpatialReference.wgs84)
          ..addPointXY(x: -118.81898, y: 34.01375)
          ..addPointXY(x: -118.80679, y: 34.02158)
          ..addPointXY(x: -118.79143, y: 34.01638)
          ..addPointXY(x: -118.79596, y: 34.00856)
          ..addPointXY(x: -118.80855, y: 34.00350);

    // Retrieve the polygon's geometry that the builder constructed.
    final polygon = polygonBuilder.toGeometry();

    // Create an orange fill with solid blue line outline simple fill symbol.
    final polygonSymbol = SimpleFillSymbol(
      style: SimpleFillSymbolStyle.solid,
      color: Colors.orange,
      outline: SimpleLineSymbol(
        style: SimpleLineSymbolStyle.solid,
        color: Colors.blue,
        width: 2,
      ),
    );

Create a Graphic with the polygon and polygonSymbol. Display the Graphic by adding it to the list of graphics.

main.dart
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    // Retrieve the polygon's geometry that the builder constructed.
    final polygon = polygonBuilder.toGeometry();

    // Create an orange fill with solid blue line outline simple fill symbol.
    final polygonSymbol = SimpleFillSymbol(
      style: SimpleFillSymbolStyle.solid,
      color: Colors.orange,
      outline: SimpleLineSymbol(
        style: SimpleLineSymbolStyle.solid,
        color: Colors.blue,
        width: 2,
      ),
    );

    // Create a graphic using the polygon and polygon symbol defined earlier.
    final polygonGraphic = Graphic(geometry: polygon, symbol: polygonSymbol);

    // Add the graphic to the graphics overlay to display it.
    graphicsOverlay.graphics.add(polygonGraphic);

Hot restart your app.

You should see a point, line, and polygon graphic around Mahou Riviera in the Santa Monica Mountains.

Alternatively, you can download the tutorial solution, as follows.

Option 2: Download the solution

Click the Download solution link under Solution and unzip the file to a location on your machine.
Open the project in VS code.

Since the downloaded solution does not contain authentication code, you must first set up authentication to create credentials, then add authentication code and set the developer credentials to the solution.

Set up authentication

To access the secure ArcGIS location services used in this tutorial, you must implement API key authentication or user authentication using an ArcGIS Location Platform or an ArcGIS Online account.

You can implement API key authentication or user authentication in this tutorial. Compare the differences below:

API key authentication

Users are not required to sign in.
Requires creating an API key credential with the correct privileges.
API keys are long-lived access tokens.
Service usage is billed to the API key owner/developer.
Simplest authentication method to implement.
Recommended approach for new ArcGIS developers.

Learn more in API key authentication.

User authentication

Users are required to sign in with an ArcGIS account.
User accounts must have privilege to access the ArcGIS services used in application.
Requires creating OAuth credentials.
Application uses a redirect URL and client ID.
Service usage is billed to the organization of the user signed into the application.

Learn more in User authentication.

To complete this tutorial, click on the tab in the switcher below for your authentication type of choice, either API key authentication or User authentication.

Create a new API key access token with privileges to access the secure resources used in this tutorial.

Complete the Create an API key tutorial and create an API key with the following privilege(s):
- Privileges
  - Location services > Basemaps
Copy and paste the API key access token into a safe location. It will be used in a later step.

Create new OAuth credentials to access the secure resources used in this tutorial.

Complete the Create OAuth credentials for user authentication tutorial to obtain a Client ID and Redirect URL.

A Client ID uniquely identifies your app on the authenticating server. If the server cannot find an app with the provided Client ID, it will not proceed with authentication.
The Redirect URL (also referred to as a callback url) is used to identify a response from the authenticating server when the system returns control back to your app after an OAuth login. Since it does not necessarily represent a valid endpoint that a user could navigate to, the redirect URL can use a custom scheme, such as my-app://auth. It is important to make sure the redirect URL used in your app's code matches a redirect URL configured on the authenticating server.
Copy and paste the Client ID and Redirect URL into a safe location. They will be used in a later step.

All users that access this application need account privileges to access the ArcGIS Basemap Styles service.

Add authentication code and set developer credentials

To allow your app users to access ArcGIS location services, you will add authentication code and use the developer credentials that you created in the Set up authentication step to authenticate requests for resources.

Open lib/main.dart.

In the main() function, set the ArcGISEnvironment.apiKey value to your access token.

main.dart
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void main () {

  ArcGISEnvironment.apiKey = 'YOUR_ACCESS_TOKEN';

  runApp(

    const MaterialApp(home: MainApp())

  );
}

Best Practice: The access token is stored directly in the code as a convenience for this tutorial. Do not store credentials directly in source code in a production environment.

Add the Authenticator toolkit component to manage your OAuth credentials.

Add the ArcGIS Maps SDK for Flutter Toolkit package to your app by following these instructions

Add the following code to main.dart:

Define a final class member inside _MainAppState class, _oAuthUserConfiguration, and initialize it with OAuthUserConfiguration passing in the portalUri, clientId, and redirectUri values.
Add code to revoke all tokens, Authenticator.revokeOAuthTokens(), and clear all credentials, Authenticator.clearCredentials(), from the authenticator's credential store during application sign-out.
Add the Authenticator widget as a parent of the ArcGISMapView widget in the existing widget tree found in the build(). Set the value of the named parameter, oAuthUserConfigurations to a list containing the new member variable _oAuthUserConfiguration.

main.dart
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class _MainAppState extends State<MainApp> {

  final _mapViewController = ArcGISMapView.createController();

  final _oAuthUserConfiguration = OAuthUserConfiguration(
    portalUri: Uri.parse('https://www.arcgis.com'),
    clientId: 'YOUR_CLIENT_ID',
    redirectUri: Uri.parse('YOUR_REDIRECT_URL'),
  );

  @override
  void dispose() {
    Authenticator.revokeOAuthTokens().whenComplete(
      Authenticator.clearCredentials,
    );

    super.dispose();
  }

  @override
  Widget build(BuildContext context) {

    return Scaffold(
      body: Column(
        children: [
          Expanded(
            child: Authenticator(
              oAuthUserConfigurations: [_oAuthUserConfiguration],
              child: ArcGISMapView(
                controllerProvider: () => _mapViewController,
                onMapViewReady: onMapViewReady,
              ),
            ),
          ),
        ],
      ),
    );

  }
}

Best Practice: The OAuth credentials are stored directly in the code as a convenience for this tutorial. Do not store credentials directly in source code in a production environment.

For Android only, a system browser is required for user authentication. Add the following activity to the Android manifest in your project:

android/app/src/main/AndroidManifest.xml
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        <!-- ... -->

        <activity
            android:name="com.linusu.flutter_web_auth_2.CallbackActivity"
            android:exported="true">
            <intent-filter android:label="flutter_web_auth_2">
                <action android:name="android.intent.action.VIEW" />
                <category android:name="android.intent.category.DEFAULT" />
                <category android:name="android.intent.category.BROWSABLE" />
                <data android:scheme="YOUR_CALLBACK_URL_SCHEME_HERE" />
            </intent-filter>
        </activity>

        <!-- ... -->

Replace YOUR_CALLBACK_URL_SCHEME_HERE with the scheme of the redirect URL used when you set up authentication earlier. This is necessary so that the browser can communicate back to your app after the login workflow completes.

For example, if you have a redirect URL, such as: my-app://auth, the value of the scheme would be: my-app. This value would replace YOUR_CALLBACK_URL_SCHEME_HERE in the activity.

Run the application

Follow these steps to run the application.

In VS Code's terminal, run:
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```
1
flutter pub upgrade
```
Run:
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```
1
dart run arcgis_maps install
```
Make sure you have an Android emulator, iOS simulator or physical device configured and running.
In VS Code, select Run > Run Without Debugging.

You should see a point, line, and polygon graphic around Mahou Riviera in the Santa Monica Mountains.