Extending Ensemble
External Screen

import { Callout } from 'nextra/components'

Embed Flutter screen in an Ensemble app

Ensemble allows you to navigate to a screen built with Flutter. This allows you to reuse any existing Flutter screen.

You can find the entire source code [here](https://github.com/EnsembleUI/starter/tree/external-screen).

How it works.

This is our beloved counter widget. Let's see how you can specify this widget and call it in your Ensemble App.

class CounterWidget extends StatefulWidget {
  const CounterWidget({
    super.key,
    this.message,
  });
 
  final String? message;
 
  @override
  State<CounterWidget> createState() => _CounterWidgetState();
}
 
class _CounterWidgetState extends State<CounterWidget> {
  int counter = 0;
 
  void _incrementCounter() {
    setState(() {
      counter++;
    });
  }
 
  @override
  void initState() {
    super.initState();
  }
 
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Theme.of(context).colorScheme.inversePrimary,
        title: const Text('Flutter Page'),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: const Icon(Icons.add),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              widget.message ?? 'You have pushed the button this many times:',
            ),
            Text(
              '$counter',
              style: Theme.of(context).textTheme.headlineMedium,
            ),
          ],
        ),
      ),
    );
  }
}

First we need to specify a map of name and builder widget. The builder has context and args as parameters. The args are basically passed using navigateScreen's inputs.

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  Ensemble().setExternalScreenWidgets({
    'counterScreen': (context, args) {
      final message = args?['message'];
      return CounterWidget(message: message);
    },
  });
  runApp(const EnsembleApp());
}

Now, the ensemble framework know about external screen named counterScreen. We can now navigate to external screen like following.

Button:
    label: Navigate external screen
    onTap:
        navigateScreen:
        name: counterScreen
        external: true
        inputs:
            message: Hello world
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