Unlock the Power of Camera Functionality in Your Flutter App

App Overview

Before diving into the code, let’s take a look at the app we’re going to build. Our final app will feature:

• Capture quality selector
• Zoom control
• Exposure control
• Flash mode selector
• Button for flipping camera (rear cam to front cam, and vice versa)
• Button for capturing image
• Toggle for shifting from image mode to video mode
• Video mode controls (start, pause, resume, stop)
• Last captured image or video preview
• Retrieve image/video files

Getting Started

Create a new Flutter project using the following command:

flutter create my_camera_app

Open the project using your favorite IDE, and add the following dependencies to your pubspec.yaml file:

dependencies:
  camera: ^0.8.1+7
  video_player: ^2.1.14
  path_provider: ^2.0.2

Retrieve Available Cameras

In the main.dart file, define a global variable called cameras where we’ll store the list of available cameras. This will help us easily reference them later.

Initializing the Camera

Create a new file called camera_screen.dart and define the CameraScreen stateful widget inside it. Define a controller for the camera and a value for the isCameraInitialized Boolean variable.

class CameraScreen extends StatefulWidget {
  @override
  _CameraScreenState createState() => _CameraScreenState();
}

class _CameraScreenState extends State<CameraScreen> with WidgetsBindingObserver {
  CameraController _cameraController;
  bool _isCameraInitialized = false;

  //...
}

Handling Camera Lifecycle States

Running the camera on any device is a memory-hungry task, so how you handle freeing up the memory resources and when that occurs is important. We’ll use the WidgetsBindingObserver mixin and manage the lifecycle changes by overriding the didChangeAppLifecycleState() method.

@override
void didChangeAppLifecycleState(AppLifecycleState state) {
  if (state == AppLifecycleState.inactive) {
    _cameraController.dispose();
  } else if (state == AppLifecycleState.resumed) {
    _initCamera();
  }
}

Adding a Camera Preview

Now that we’ve finished initializing and managing the camera state, we can define a basic user interface for previewing the camera output. We’ll use the buildPreview() method from the Flutter camera plugin to display the camera output.

Widget _buildPreview() {
  return CameraPreview(_cameraController);
}

Adding Functionalities

Let’s add some functionalities to our camera app:

Capture Quality Selector

TODO: implement capture quality selector

Zoom Control

TODO: implement zoom control

Exposure Control

TODO: implement exposure control

Flash Mode Selector

TODO: implement flash mode selector

Flip Camera Toggle

TODO: implement flip camera toggle

Capturing Images

TODO: implement capturing images

Toggle between Image and Video Mode

TODO: implement toggle between image and video mode

Video Recording

TODO: implement video recording

Common Problems and Questions

While implementing the camera inside your app, you may face certain issues. We’ll cover some common problems and questions, such as:

• Solving stretched camera preview
• Adding an overlay to the camera
• Checking camera permission status
• Setting camera focus