A refactored camera widget based on the "Take a Picture Using the Camera" cookbook found on flutter.dev. For full walkthru see: https://www.kinmanlam.com/2021/08/flutter-framework-refractored-camera.html

camera.dart

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

// A screen that allows users to take a picture using a given camera.
class TakePictureScreen extends StatefulWidget {
  const TakePictureScreen({
    Key? key,
  }) : super(key: key);

  @override
  TakePictureScreenState createState() => TakePictureScreenState();
}

class TakePictureScreenState extends State<TakePictureScreen> {
  late CameraController _controller;

  @override
  void dispose() {
    // Dispose of the controller when the widget is disposed.
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    // Fill this out in the next steps.
    return Column(
      mainAxisAlignment: MainAxisAlignment.spaceBetween,
      children: [
        FutureBuilder<void>(
          future: initCamera(),
          builder: (context, snapshot) {
            if (snapshot.connectionState == ConnectionState.done) {
              // If the Future is complete, display the preview.
              return CameraPreview(_controller);
            } else {
              // Otherwise, display a loading indicator.
              return const Center(child: CircularProgressIndicator());
            }
          },
        ),
        Expanded(
          child: FloatingActionButton(
            // Provide an onPressed callback.
            onPressed: () async {
              // Take the Picture in a try / catch block. If anything goes wrong,
              // catch the error.
              try {
                // Ensure that the camera is initialized.
                await initCamera();

                // Attempt to take a picture and get the file `image`
                // where it was saved.
                final image = await _controller.takePicture();

                // If the picture was taken, display it on a new screen.
                await Navigator.of(context).push(
                  MaterialPageRoute(
                    builder: (context) => DisplayPictureScreen(
                      // Pass the automatically generated path to
                      // the DisplayPictureScreen widget.
                      imagePath: image.path,
                    ),
                  ),
                );
              } catch (e) {
                // If an error occurs, log the error to the console.
                print(e);
              }
            },
            child: const Icon(Icons.camera_alt),
          ),
        ),
      ],
    );
  }

  Future<void> initCamera() async {
    final cameras = await availableCameras();
    // Get a specific camera from the list of available cameras.
    final firstCamera = cameras.first;
    // To display the current output from the Camera,
    // create a CameraController.
    _controller = CameraController(
      // Get a specific camera from the list of available cameras.
      firstCamera,
      // Define the resolution to use.
      ResolutionPreset.medium,
    );

    // Next, initialize the controller. This returns a Future.
    await _controller.initialize();
  }
}

// A widget that displays the picture taken by the user.
class DisplayPictureScreen extends StatelessWidget {
  final String imagePath;

  const DisplayPictureScreen({Key? key, required this.imagePath})
      : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Display the Picture')),
      // The image is stored as a file on the device. Use the `Image.file`
      // constructor with the given path to display the image.
      body: Image.file(File(imagePath)),
    );
  }
}