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Description:

flutter fgbg

Flutter Foreground/Background Event Notifier #
Flutter plugin to detect when app(not Flutter container) goes to background or foreground.
Why #
Flutter has WidgetsBindingObserver to get notified when app changes its state from active to inactive states and back. But it actually includes the state changes of the embedding Activity/ViewController as well. So if you have a plugin that opens a new activity/view controller or in iOS if you start a FaceID prompt then WidgetsBindingObserver will report as the app is inactive/resumed.
This plugin on the other hand reports the events only at app level. Since most apps need only background/foreground events this plugin is implemented with just those events. In iOS, plugin reports didEnterBackgroundNotification and willEnterForegroundNotification notifications and in Android, plugin reports these using androidx.lifecycle:lifecycle-process package. In other platforms plugin fallbacks to AppLifecycleListener API for signals.
Checkout example/ project to see the differences in action.
Getting Started #
Add to your pubpsec:
flutter pub add flutter_fgbg
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Do a clean build to integrate the plugin native code to app. Otherwise you might encounter MissingPluginException.
Use the built in Widget:
FGBGNotifier(
onEvent: (event) {
print(event); // FGBGType.foreground or FGBGType.background
},
child: ...,
)
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Or consume the event stream directly:
import 'package:flutter_fgbg/flutter_fgbg.dart';

StreamSubscription<FGBGType> subscription;

...
// in initState
subscription = FGBGEvents.instance.stream.listen((event) {
print(event); // FGBGType.foreground or FGBGType.background
});

// in dispose
subscription.cancel();
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Caveats #
In newer Android versions and image_picker library, picking an image will open a different app this will make Flutter app switch to background/foreground and flutter_fgbg will report this. At the moment there is no solution to this since the API is working as intented. Tracking the issue here.
As a work around you can use FGBGEvents.ignoreWhile API like this:
FGBGEvents.ignoreWhile(() async {
await picker.pickImage(source: ImageSource.gallery);
// or do something else that can put app to background but don't want to be handled by flutter_fgbg
});
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