fast_barcode_scanner 2.0.0-dev.1

A fast barcode scanner using MLKit on Android and AVFoundation on iOS.

fast_barcode_scanner

A fast barcode scanner using MLKit (and CameraX) on Android and AVFoundation on iOS. This package leaves the UI up to the user, but rather gives an access to a camera preview.

Note: If you have any issues, ideas or recommendendations, don't hesitate to create an issue or pull request on github. I am using this plugin in production myself and will actively develop and maintain it going forward.

This plugin required iOS 10.0 and Android sdk version 23 or higher.

Installation

Add the following line to your pubspec.yaml:

fast_barcode_scanner: ^2.0.0

iOS

Add the NSCameraUsageDescription key to your ios/Runner/Info.plist, like so:

<key>NSCameraUsageDescription</key>
<string>This app requires access to your phone’s camera solely for scanning barcodes</string>

Android

Change the minimum Android sdk version to 23 (or higher) in your android/app/build.gradle file.

minSdkVersion 23

Usage

The barcode scanner consists of two main classes CameraController and BarcodeCamera, which are further described below. Have a look at the example app to find out how to control and interact with the plugin. A (almost) minimal example looks like this:

import 'package:fast_barcode_scanner/fast_barcode_scanner.dart';

class MyScannerScreen extends StatelessWidget {
    @override
    Widget build(BuildContext context) {
        return Scaffold(
            appBar: AppBar(title: Text('Barcode Scanner')),
            body: BarcodeCamera(
                types: const [
                    BarcodeType.ean8,
                    BarcodeType.ean13,
                    BarcodeType.code128
                ],
                resolution: Resolution.hd720,
                framerate: Framerate.fps30,
                mode: DetectionMode.pauseVideo,
                onScan: (code) => print(code),
                children: [
                    MaterialPreviewOverlay(animateDetection: false),
                    BlurPreviewOverlay(),
                    Positioned(
                      child: ElevatedButton(
                        onPressed: () =>
                            CameraController.instance.resumeDetector(),
                        child: Text('Resume'),
                      ),
                    )
                ],
            )
        )
    }
}

You don' have to provide all settings yourself, as sensible defaults are set already. As you can see, there are two overlays in the childrens list. These two are included in the package. MaterialPreviewOverlay mimics the official material barcode scanning example. BlurPreviewOverlay blurs the screen when a barcode is detected and unblurs it on resuming. These are normal widget, which are shown above the camera preview (inside a Stack widget). If you want to code your own overlay, look at the source code, to find out how to react to events from the barcode scanner.

CameraController

The CameraController-singleton manages the camera. It handles all the low level stuff like communicating with native code. It is implemented as a singleton to guarantee that there is always one and the same controller managing the camera. You can access the controller via the CameraController.instance attribute. These are the accessible methods:

method	Description
initialize	Initializes the scanner with the provided config
pauseDetector	Actively pauses the scanner
resumeDetector	Resumes the scanner from the paused state
toggleTorch	toggles the torch on and off
dispose	Stops and resets the camera on platform level

You do not have to call initialize yourself, if you use the BarcodeCamera widget. Calling these methods are throwing. For possible error codes have a look at ScannerError.swift or ScannerError.kt.

CameraState

CameraController.instance.state contains the current state of the scanner. Use it to build your own overlay. The following information can be accessed:

Attribute	Description
isInitialized	Indicated whether the camera is currently initialized
previewConfig	A PreviewConfiguration that is currently used
scannerConfig	A ScannerConfiguration that is currently used
eventNotifier	A event notifier to react to init or detecting codes
torchState	The current state of the torch (on/off)
hasError	Indicates whether error is null or not
error	Access the error produced last

A PreviewConfiguration contains informations about the the dimensions and rotation of the preview and ScannerConfiguration holds the settings about how the camera was setup.

BarcodeCamera

The BarcodeCamera is a widget showing a preview of the camera feed. It calls the CameraController in the background for initialization and configuration of the barcode camera.

It allows to configurate the scanner. A ScannerConfiguration is then generated and passed to native code, which in turn produces a PreviewConfiguration. You can find both in the CameraController.instance.state attribute. A full overview of all parameters that can be passed to BarcodeCamera:

Attribute	Description
types	See code types to scan (see BarcodeType)
resolution	The resolution of the camera feed
framerate	The framerate of the camera feed
position	Choose between back and front camera
mode	Whether to pause the camera on detection
onScan	The callback when a barcode is scanned
children	Widgets to display on top of the preview