camera_example.dart

import 'package:camera/camera.dart';
import 'package:flutter/material.dart';

Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();

  runApp(const App());
}

class App extends StatelessWidget {
  const App({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      routes: {
        '/': (context) => const HomeScreen(),
        '/camera': (context) {
          final camera =
              ModalRoute.of(context)?.settings.arguments as CameraDescription;

          return CameraScreen(camera: camera);
        },
      },
    );
  }
}

class HomeScreen extends StatefulWidget {
  const HomeScreen({Key? key}) : super(key: key);

  @override
  State<HomeScreen> createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen> {
  late Future<List<CameraDescription>> _cameras;

  @override
  void initState() {
    super.initState();
    _cameras = availableCameras();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Camera Demo'),
      ),
      body: FutureBuilder<List<CameraDescription>>(
        future: _cameras,
        builder: (context, snapshot) {
          switch (snapshot.connectionState) {
            case ConnectionState.none:
            case ConnectionState.waiting:
              return const Center(
                child: CircularProgressIndicator.adaptive(),
              );

            case ConnectionState.active:
            case ConnectionState.done:
              final error = snapshot.error;

              if (error != null) {
                return Center(
                  child: Padding(
                    padding: const EdgeInsets.all(24.0),
                    child: Text(error.toString()),
                  ),
                );
              }

              final data = snapshot.data as List<CameraDescription>;

              if (data.isEmpty) {
                return const Center(
                  child: Padding(
                    padding: EdgeInsets.all(24.0),
                    child: Text('This device does not have any camera'),
                  ),
                );
              }

              return ListView.builder(
                itemCount: data.length,
                itemBuilder: (context, index) {
                  final camera = data[index];

                  return Card(
                    child: InkWell(
                      onTap: () {
                        Navigator.of(context).pushNamed(
                          '/camera',
                          arguments: camera,
                        );
                      },
                      child: Padding(
                        padding: const EdgeInsets.all(8.0),
                        child: Column(
                          crossAxisAlignment: CrossAxisAlignment.stretch,
                          children: [
                            Text('Name: ${camera.name}'),
                            Text('Direction: ${camera.lensDirection}'),
                          ],
                        ),
                      ),
                    ),
                  );
                },
              );
          }
        },
      ),
    );
  }
}

class CameraScreen extends StatefulWidget {
  const CameraScreen({
    Key? key,
    required this.camera,
  }) : super(key: key);

  final CameraDescription camera;

  @override
  State<CameraScreen> createState() => _CameraScreenState();
}

class _CameraScreenState extends State<CameraScreen> {
  late CameraController _cameraController;
  late Future<void> _controllerInit;

  @override
  void initState() {
    super.initState();
    _cameraController = CameraController(widget.camera, ResolutionPreset.max);
    _controllerInit = _cameraController.initialize();
  }

  @override
  void didUpdateWidget(covariant CameraScreen oldWidget) {
    super.didUpdateWidget(oldWidget);
    if (oldWidget.camera != widget.camera) {
      _cameraController.dispose();
      _cameraController = CameraController(widget.camera, ResolutionPreset.max);
      _controllerInit = _cameraController.initialize();
    }
  }

  @override
  void dispose() {
    _cameraController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Camera Preview'),
      ),
      body: FutureBuilder<void>(
        future: _controllerInit,
        builder: (context, snapshot) {
          switch (snapshot.connectionState) {
            case ConnectionState.none:
            case ConnectionState.waiting:
              return const Center(
                child: CircularProgressIndicator.adaptive(),
              );

            case ConnectionState.active:
            case ConnectionState.done:
              final error = snapshot.error;

              if (error != null) {
                return Center(
                  child: Padding(
                    padding: const EdgeInsets.all(24.0),
                    child: Text(error.toString()),
                  ),
                );
              }

              return CameraPreview(_cameraController);
          }
        },
      ),
    );
  }
}