camera_screen.dart

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

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

  ///
  ///
  ///
  @override
  _CameraScreenState createState() => _CameraScreenState();
}

///
///
///
class _CameraScreenState extends State<CameraScreen> with WidgetsBindingObserver {
  late final CameraScreenController _controller = CameraScreenController(context: context);

  ///
  ///
  ///
  @override
  Widget build(BuildContext context) {
    return FutureBuilder<void>(
      future: _controller.initializeCamera(),
      builder: (BuildContext context, AsyncSnapshot<void> snapshot) {
        if (snapshot.connectionState != ConnectionState.done) {
          return const Scaffold(
            body: Text('Loading camera'),
          );
        }
        if (snapshot.hasError) {
          return Scaffold(
            appBar: AppBar(
              title: const Text('Gravação'),
            ),
            body: const Center(
              child: Text(
                'Failed to load camera.',
                textAlign: TextAlign.center,
              ),
            ),
          );
        }
        return Scaffold(
          backgroundColor: Colors.black,
          body: Stack(
            alignment: Alignment.bottomCenter,
            children: <Widget>[
              ValueListenableBuilder<CameraLensDirection>(
                valueListenable: _controller.activeCamera,
                builder: (
                  BuildContext context,
                  CameraLensDirection value,
                  Widget? child,
                ) {
                  return CameraPreview(_controller.cameraController!);
                },
              ),
              Container(
                padding: const EdgeInsets.all(16),
                color: Colors.black38,
                child: Column(
                  mainAxisSize: MainAxisSize.min,
                  mainAxisAlignment: MainAxisAlignment.center,
                  children: <Widget>[
                    Row(
                      mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                      children: <Widget>[
                        _toggleFlash(),
                        _startStopRecordButton(),
                        _toggleCameraButton(),
                      ],
                    ),
                  ],
                ),
              ),
            ],
          ),
        );
      },
    );
  }

  ///
  ///
  ///
  Widget _toggleFlash() {
    return InkWell(
      onTap: _controller.toggleFlash,
      child: Card(
        shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.circular(50),
        ),
        color: Colors.white,
        child: Container(
          height: 65,
          width: 65,
          child: ValueListenableBuilder<FlashMode>(
            valueListenable: _controller.flashMode,
            builder: (
              BuildContext context,
              FlashMode flashMode,
              Widget? child,
            ) {
              return Icon(
                flashMode == FlashMode.off ? Icons.flash_off : Icons.flash_on,
                size: 35,
              );
            },
          ),
        ),
      ),
    );
  }

  ///
  ///
  ///
  Widget _toggleCameraButton() {
    return InkWell(
      onTap: _controller.toggleCamera,
      child: Card(
        shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.circular(50),
        ),
        color: Colors.white,
        child: Container(
          height: 65,
          width: 65,
          child: const Icon(
            Icons.switch_camera,
            size: 35,
          ),
        ),
      ),
    );
  }

  ///
  ///
  ///
  Widget _startStopRecordButton() {
    return InkWell(
      onTap: _controller.startStopRecord,
      child: ValueListenableBuilder<bool>(
        valueListenable: _controller.recording,
        builder: (BuildContext context, bool value, Widget? child) {
          return Card(
            shape: RoundedRectangleBorder(
              borderRadius: BorderRadius.circular(50),
            ),
            color: value ? Colors.white : Colors.red,
            child: Container(
              height: 95,
              width: 95,
              child: Icon(
                value ? Icons.stop : Icons.play_arrow,
                color: value ? Colors.black : Colors.white,
              ),
            ),
          );
        },
      ),
    );
  }

  ///
  ///
  ///
  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  ///
  ///
  ///
  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    CameraController cameraController = _controller.cameraController!;

    if (!cameraController.value.isInitialized) {
      return;
    }
    if (state == AppLifecycleState.inactive) {
      cameraController.dispose();
    } else if (state == AppLifecycleState.resumed) {
      _controller.initializeCamera(cameraDescription: cameraController.description);
    }
  }
}

camera_screen_controller.dart

import 'dart:async';

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

///
///
///
class CameraScreenController {
  final BuildContext context;
  CameraController? cameraController;
  List<CameraDescription>? _availableCameras;
  final ValueNotifier<CameraLensDirection> activeCamera = ValueNotifier<CameraLensDirection>(CameraLensDirection.back);
  final ValueNotifier<Duration> recordDuration = ValueNotifier<Duration>(Duration.zero);
  final ValueNotifier<bool> recording = ValueNotifier<bool>(false);
  Timer? _timerGravacao;
  final ValueNotifier<FlashMode> flashMode = ValueNotifier<FlashMode>(FlashMode.off);

  ///
  ///
  ///
  CameraScreenController({
    required this.context,
  });

  ///
  ///
  ///
  Future<void> initializeCamera({CameraDescription? cameraDescription}) async {
    _availableCameras ??= await availableCameras();
    cameraController = CameraController(
      cameraDescription ?? _availableCameras!.first,
      ResolutionPreset.medium,
      imageFormatGroup: ImageFormatGroup.jpeg,
    );

    await cameraController!.initialize();
    if (!kIsWeb) {
      await cameraController!.setFlashMode(FlashMode.off);
    }
    cameraController!.addListener(() {
      recording.value = cameraController!.value.isRecordingVideo;
    });
  }

  ///
  ///
  ///
  Future<void> toggleFlash() async {
    if (cameraController!.value.flashMode == FlashMode.always) {
      await cameraController!.setFlashMode(FlashMode.off);
    } else {
      await cameraController!.setFlashMode(FlashMode.always);
    }
    flashMode.value = cameraController!.value.flashMode;
  }

  ///
  ///
  ///
  Future<void> toggleCamera() async {
    if (!recording.value) {
      CameraLensDirection camera = activeCamera.value;
      if (activeCamera.value == CameraLensDirection.back) {
        await initializeCamera(cameraDescription: _availableCameras!.last);
        camera = _availableCameras!.last.lensDirection;
      } else {
        await initializeCamera(cameraDescription: _availableCameras!.first);
        camera = _availableCameras!.first.lensDirection;
      }
      activeCamera.value = camera;
    }
  }

  ///
  ///
  ///
  Future<void> startStopRecord() async {
    recording.value = cameraController!.value.isRecordingVideo;
    if (recording.value) {
      XFile xfile = await cameraController!.stopVideoRecording();
      _timerGravacao?.cancel();
      Navigator.of(context).pop(xfile);
    } else {
      await cameraController!.startVideoRecording();
      int miliSegundos = 0;
      _timerGravacao = Timer.periodic(const Duration(milliseconds: 100), (Timer timer) {
        miliSegundos += 100;
        recordDuration.value = Duration(milliseconds: miliSegundos);
      });
    }
  }

  ///
  ///
  ///
  void dispose() {
    cameraController?.dispose();
    _timerGravacao?.cancel();
    recording.dispose();
    recordDuration.dispose();
    flashMode.dispose();
  }
}