Flutter WebView: How to Keep Microphone and Camera Active When App is in Background?

The Problem: Default Behavior of Flutter WebView

By default, Flutter WebView is designed to release system resources, including the microphone and camera, when the app is running in the background. This is done to conserve battery life and prevent memory leaks. While this approach is beneficial for many applications, it can be detrimental to apps that rely heavily on these features.

The Solution: Using Platform Channels

One solution to keep the microphone and camera active is to use Platform Channels, a feature in Flutter that enables communication between the Flutter app and the native platform (iOS or Android). By using Platform Channels, we can create a native module that will maintain access to the microphone and camera, even when the app is in the background.

// iOS Platform Channel
#import <Flutter/Flutter.h>

@interface BACKGROUND_SERVICE : NSObject <FlutterPlugin>

@end

@implementation BACKGROUND_SERVICE

+ (void)registerWithRegistrar:(NSObject<FlutterPluginRegistrar>*)registrar {
  FlutterMethodChannel* channel = [FlutterMethodChannel
      methodChannelWithName:@"BACKGROUND_SERVICE"
            binaryMessenger:[registrar messenger]];
  [channel setMethodCallHandler:^(FlutterMethodCall* call, FlutterResult result) {
    // Handle method calls from Flutter
  }];
}

@end

// Android Platform Channel
import io.flutter.embedding.android.FlutterActivity;
import io.flutter.embedding.engine.plugins.FlutterPlugin;
import io.flutter.plugin.common.MethodChannel;
import io.flutter.plugin.common.MethodChannel.MethodCallHandler;
import io.flutter.plugin.common.MethodChannel.Result;
import io.flutter.plugin.common.PluginRegistry.Registrar;

public class BackgroundServicePlugin implements FlutterPlugin, MethodCallHandler {
  private MethodChannel channel;

  public static void registerWith(Registrar registrar) {
    final MethodChannel channel = new MethodChannel(registrar.messenger(), "BACKGROUND_SERVICE");
    channel.setMethodCallHandler(new BackgroundServicePlugin());
  }

  @Override
  public void onMethodCall(MethodCall call, Result result) {
    // Handle method calls from Flutter
  }
}

Registering the Platform Channel

Once we’ve created the native module, we need to register it in our Flutter app. This can be done using the following code:

// Registering the Platform Channel
import 'package:flutter/services.dart';

class _MyAppState extends State<MyApp> {
  static const platform = const MethodChannel('BACKGROUND_SERVICE');

  @override
  void initState() {
    super.initState();
    _initPlatformState();
  }

  _initPlatformState() async {
    await platform.invokeMethod('INIT_BACKGROUND_SERVICE');
  }
}

Maintaining Access to Microphone and Camera

Now that we’ve registered the Platform Channel, we need to maintain access to the microphone and camera. This can be achieved by using native modules to request permission and keep the device’s camera and microphone active.

// iOS Native Module
#import <AVFoundation/AVFoundation.h>

@implementation BACKGROUND_SERVICE

+ (void)initBackgroundService {
  // Request camera permission
  [AVCaptureDevice requestAccessForMediaType:AVMediaTypeVideo completionHandler:^(BOOL granted) {
    if (granted) {
      // Start camera capture
      [[AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo] start Running];
    }
  }];

  // Request microphone permission
  [AVCaptureDevice requestAccessForMediaType:AVMediaTypeAudio completionHandler:^(BOOL granted) {
    if (granted) {
      // Start microphone capture
      [[AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeAudio] start Running];
    }
  }];
}

@end

// Android Native Module
import android.hardware.Camera;
import android.media.MediaRecorder;

public class BackgroundService {
  private Camera camera;
  private MediaRecorder mediaRecorder;

  public void initBackgroundService() {
    // Request camera permission
    camera = Camera.open();
    camera.startPreview();

    // Request microphone permission
    mediaRecorder = new MediaRecorder();
    mediaRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
    mediaRecorder.start();
  }
}

The Power of Foreground Services

In addition to using Platform Channels, we can also utilize Android’s Foreground Services to maintain access to the microphone and camera. A Foreground Service is a service that is considered to be something the user is actively aware of, such as an audio app that continues to play music even when the user switches to another app.

// Android Foreground Service
import android.content.Intent;
import android.os.Bundle;
import android.os.IBinder;
import android.app.Service;
import android.content.Context;

public class BackgroundService extends Service {
  private Camera camera;
  private MediaRecorder mediaRecorder;

  @Override
  public IBinder onBind(Intent intent) {
    return null;
  }

  @Override
  public void onCreate() {
    super.onCreate();

    // Request camera permission
    camera = Camera.open();
    camera.startPreview();

    // Request microphone permission
    mediaRecorder = new MediaRecorder();
    mediaRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
    mediaRecorder.start();
  }

  @Override
  public int onStartCommand(Intent intent, int flags, int startId) {
    return START_STICKY;
  }
}

Starting the Foreground Service

To start the Foreground Service, we need to create an Intent and start the service using the `startForegroundService` method:

// Starting the Foreground Service
import 'package:flutter/services.dart';

class _MyAppState extends State<MyApp> {
  @override
  void initState() {
    super.initState();
    _startForegroundService();
  }

  _startForegroundService() async {
    final Intent intent = Intent("com.example.BackgroundService");
    await Platform.isAndroid ? await AndroidIntent.action("startForegroundService") : await Fluttertoast.showToast(msg: "Not supported on iOS");
  }
}

Conclusion

In this comprehensive guide, we’ve explored the challenges of maintaining access to the microphone and camera in a Flutter WebView app when it’s running in the background. We’ve discussed the importance of keeping these features active and provided solutions using Platform Channels and Foreground Services.

By implementing these solutions, you’ll be able to create seamless experiences for your users, even when your app is running in the background. Remember to always prioritize user experience and maintain transparency when requesting permission for device resources.

Now, go ahead and give your users the seamless experience they deserve!

Frequently Asked Question

Got stuck with keeping your microphone and camera active when your Flutter app is in the background? Don’t worry, we’ve got you covered!