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Take a picture using the camera

Contents

Many apps require working with the device's cameras to take photos and videos. Flutter provides the camera plugin for this purpose. The camera plugin provides tools to get a list of the available cameras, display a preview coming from a specific camera, and take photos or videos.

This recipe demonstrates how to use the camera plugin to display a preview, take a photo, and display it using the following steps:

  1. Add the required dependencies.
  2. Get a list of the available cameras.
  3. Create and initialize the CameraController.
  4. Use a CameraPreview to display the camera's feed.
  5. Take a picture with the CameraController.
  6. Display the picture with an Image widget.

1. Add the required dependencies

#

To complete this recipe, you need to add three dependencies to your app:

camera
Provides tools to work with the cameras on the device.
path_provider
Finds the correct paths to store images.
path
Creates paths that work on any platform.

To add the packages as dependencies, run flutter pub add:

flutter pub add camera path_provider path

2. Get a list of the available cameras

#

Next, get a list of available cameras using the camera plugin.

dart
// Ensure that plugin services are initialized so that `availableCameras()`
// can be called before `runApp()`
WidgetsFlutterBinding.ensureInitialized();

// Obtain a list of the available cameras on the device.
final cameras = await availableCameras();

// Get a specific camera from the list of available cameras.
final firstCamera = cameras.first;

3. Create and initialize the CameraController

#

Once you have a camera, use the following steps to create and initialize a CameraController. This process establishes a connection to the device's camera that allows you to control the camera and display a preview of the camera's feed.

  1. Create a StatefulWidget with a companion State class.
  2. Add a variable to the State class to store the CameraController.
  3. Add a variable to the State class to store the Future returned from CameraController.initialize().
  4. Create and initialize the controller in the initState() method.
  5. Dispose of the controller in the dispose() method.
dart
// A screen that allows users to take a picture using a given camera.
class TakePictureScreen extends StatefulWidget {
  const TakePictureScreen({
    super.key,
    required this.camera,
  });

  final CameraDescription camera;

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

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

  @override
  void initState() {
    super.initState();
    // To display the current output from the Camera,
    // create a CameraController.
    _controller = CameraController(
      // Get a specific camera from the list of available cameras.
      widget.camera,
      // Define the resolution to use.
      ResolutionPreset.medium,
    );

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

  @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 Container();
  }
}

4. Use a CameraPreview to display the camera's feed

#

Next, use the CameraPreview widget from the camera package to display a preview of the camera's feed.

Use a FutureBuilder for exactly this purpose.

dart
// You must wait until the controller is initialized before displaying the
// camera preview. Use a FutureBuilder to display a loading spinner until the
// controller has finished initializing.
FutureBuilder<void>(
  future: _initializeControllerFuture,
  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());
    }
  },
)

5. Take a picture with the CameraController

#

You can use the CameraController to take pictures using the takePicture() method, which returns an XFile, a cross-platform, simplified File abstraction. On both Android and IOS, the new image is stored in their respective cache directories, and the path to that location is returned in the XFile.

In this example, create a FloatingActionButton that takes a picture using the CameraController when a user taps on the button.

Taking a picture requires 2 steps:

  1. Ensure that the camera is initialized.
  2. Use the controller to take a picture and ensure that it returns a Future<XFile>.

It is good practice to wrap these operations in a try / catch block in order to handle any errors that might occur.

dart
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 _initializeControllerFuture;

      // Attempt to take a picture and then get the location
      // where the image file is saved.
      final image = await _controller.takePicture();
    } catch (e) {
      // If an error occurs, log the error to the console.
      print(e);
    }
  },
  child: const Icon(Icons.camera_alt),
)

6. Display the picture with an Image widget

#

If you take the picture successfully, you can then display the saved picture using an Image widget. In this case, the picture is stored as a file on the device.

Therefore, you must provide a File to the Image.file constructor. You can create an instance of the File class by passing the path created in the previous step.

dart
Image.file(File('path/to/my/picture.png'));

Complete example

#
dart
import 'dart:async';
import 'dart:io';

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

Future<void> main() async {
  // Ensure that plugin services are initialized so that `availableCameras()`
  // can be called before `runApp()`
  WidgetsFlutterBinding.ensureInitialized();

  // Obtain a list of the available cameras on the device.
  final cameras = await availableCameras();

  // Get a specific camera from the list of available cameras.
  final firstCamera = cameras.first;

  runApp(
    MaterialApp(
      theme: ThemeData.dark(),
      home: TakePictureScreen(
        // Pass the appropriate camera to the TakePictureScreen widget.
        camera: firstCamera,
      ),
    ),
  );
}

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

  final CameraDescription camera;

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

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

  @override
  void initState() {
    super.initState();
    // To display the current output from the Camera,
    // create a CameraController.
    _controller = CameraController(
      // Get a specific camera from the list of available cameras.
      widget.camera,
      // Define the resolution to use.
      ResolutionPreset.medium,
    );

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

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

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Take a picture')),
      // You must wait until the controller is initialized before displaying the
      // camera preview. Use a FutureBuilder to display a loading spinner until the
      // controller has finished initializing.
      body: FutureBuilder<void>(
        future: _initializeControllerFuture,
        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());
          }
        },
      ),
      floatingActionButton: 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 _initializeControllerFuture;

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

            if (!context.mounted) return;

            // 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),
      ),
    );
  }
}

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

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

  @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)),
    );
  }
}

Unless stated otherwise, the documentation on this site reflects the latest stable version of Flutter. Page last updated on 2024-06-24. View source or report an issue.