Barcode Reader User Guide for Flutter

In this guide, we will explore the Barcode Reader module of the Dynamsoft Capture Vision library for Flutter.

Table of Contents

• System Requirements
• Installation
• Build Your Barcode Scanner App
  • Set up Development Environment
  • Initialize the Project
  • Include the Library
  • License Activation
  • Configure the Barcode Reader
  • Build the Widget
  • Configure Camera Permissions
  • Run the Project
• Customizing the Barcode Reader
  • Using the Settings Templates
  • Using the DBRRuntimeSettings Interface
  • Customizing the Scan Region
• Licensing

System Requirements

Flutter & Dart

• Flutter version: >=2.0.0
• Dart version: >=2.12.0 <3.0.0

Android

• Supported OS: Android 5.0 (API Level 21) or higher.
• Supported ABI: armeabi-v7a, arm64-v8a, x86 and x86_64.
• Development Environment: Android Studio 3.4+ (Android Studio 4.2+ recommended).
• JDK: 1.8+

iOS

• Supported OS: iOS 10.0 or higher.
• Supported ABI: arm64 and x86_64.
• Development Environment: Xcode 7.1 and above (Xcode 13.0+ recommended), CocoaPods 1.11.0+.

Installation

Run the following command:

flutter pub add dynamsoft_capture_vision_flutter

This will add a line like this to your package’s pubspec.yaml (and run an implicit flutter pub get):

dependencies:
   dynamsoft_capture_vision_flutter: ^1.0.0

Build Your Barcode Scanner App

Now you will learn how to create a simple barcode scanner using Dynamsoft Capture Vision Flutter SDK.

Note: You can get the full source code of a similar project: Barcode Reader Simple Sample

Set up Development Environment

If you are a beginner with Flutter, please follow the guide on the Flutter official website to set up the development environment.

Initialize the Project

Create a new Flutter project.

flutter create simple_barcode_scanner

Include the Library

View the installation section on how to add the library. In main.dart of your project, import the library.

import 'package:dynamsoft_capture_vision_flutter/dynamsoft_capture_vision_flutter.dart';

License Activation

The barcode reading module of Dynamsoft Capture Vision needs a valid license to work. Please refer to the Licensing section for more info on how to obtain a license. In the main() function, add the following code to activate the license:

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  // Put your Dynamsoft Barcode Reader license here.
  const String licenseKey = '';
  // Initialize the license so that you can use full feature of the Barcode Reader module.
  try {
    await DynamsoftBarcodeReader.initLicense(license: licenseKey);
  } catch (e) {
    print(e);
  }

  runApp(const MyApp());
}

Configure the Barcode Reader

In this section, we are going to work on the _MyHomePageState class in the newly created project to add the barcode decoding feature.

Add the following instance variables:

class _MyHomePageState extends State<MyHomePage> {
  late final DynamsoftBarcodeReader _barcodeReader;
  final DynamsoftCameraView _cameraView = DynamsoftCameraView();
  List<BarcodeResult> decodeResults = [];
}

• barcodeReader: The object that implements the barcode decoding feature. Users can configure barcode decoding settings via this object.
• cameraView: The camera view that displays the video stream (from a camera input).
• decodeResults: An object that will be used to receive and store barcode decoding results.

Add _configDBR method to initialize the barcode reader:

class _MyHomePageState extends State<MyHomePage> {
  ...
  @override
  void initState() {
    super.initState();
    _configDBR();
  }

  _configDBR() async {
    /// Create an instance of barcode reader.
    _barcodeReader = await DynamsoftBarcodeReader.createInstance();

    /// Receive the barcode decoding results and store the result in object decodeResults
    _barcodeReader.receiveResultStream().listen((List<BarcodeResult> res) {
      if (mounted) {
        setState(() {
          decodeResults = res;
        });
      }
    });

    /// Start barcode decoding when the widget is created.
    _barcodeReader.startScanning();

    /// When overlayVisible is set to true, the decoded barcodes will be highlighted with overlays.
    _cameraView.overlayVisible = true;
  }
}

Add configurations to parse and display the barcode decoding results:

class _MyHomePageState extends State<MyHomePage> {
  ...
  /// Get listItem
  Widget listItem(BuildContext context, int index) {
    BarcodeResult res = decodeResults[index];

    return ListTileTheme(
        textColor: Colors.white,
        // tileColor: Colors.green,
        child: ListTile(
          title: Text(res.barcodeFormatString),
          subtitle: Text(res.barcodeText),
        ));
  }
}

Build the Widget

Modify the build method to display the decode barcode results on the widget.

class _MyHomePageState extends State<MyHomePage> {
  ...
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('HelloWorld'),
      ),
      body: Stack(
        children: [
          Container(
            child: _cameraView,
          ),
          Container(
            height: 200,
            child: ListView.builder(
              itemBuilder: listItem,
              itemCount: decodeResults.length,
            ),
          ),
        ],
      ));
  }
}

Configure Camera Permissions

Before you run the project on iOS devices, you need to add the camera permission first.

In the project folder, go to file ios/Runner/info.plist, add the following code for requesting camera permission:

<plist version="1.0">
<dict>
  ...
  <key>NSCameraUsageDescription</key>
  <string>Request your authorization.</string>
  ...
</dict>

Run the Project

Run Android on Windows

Go to the file build.gradle(app), update the minSdkVersion to 21.

android {
   defaultConfig {
      ...
      minSdkVersion 21
      ...
   }
}

In the root of your project run the following command to build and install the app:

flutter run

Run iOS on macOS

Go to the Podfile in ios folder and add the following code at the top of the file:

platform:ios, '10.0'

In the root of your project run the following command to build and install the app:

flutter run

Note: You can get the full source code of a similar project: Barcode Reader Simple Sample

Customizing the Barcode Reader

Using the Settings Templates

DBR offers several preset templates for different popular scenarios. For example, to prioritize speed over accuracy, you can use one of the speed templates and choose the corresponding template for images or video, and vice versa if you’re looking to prioritize read rate and accuracy over speed. For the full set of templates, please refer to EnumPresetTemplate. Here is a quick example:

await _barcodeReader.updateRuntimeSettingsFromTemplate(template: EnumDBRPresetTemplate.VIDEO_READ_RATE_FIRST );

Using the DBRRuntimeSettings Interface

The SDK also supports a more granular control over the individual runtime settings rather than using a preset template. The main settings that you can control via this interface are which barcode formats to read, the expected number of barcodes to be read in a single image or frame, and the timeout. For more info on each, please refer to DBRRuntimeSettings. Here is a quick example:

DBRRuntimeSettings currentSettings = await _barcodeReader.getRuntimeSettings();
currentSettings.barcodeFormatIds = EnumBarcodeFormat.BF_ONED;
currentSettings.expectedBarcodeCount = 10;
currentSettings.timeout = 500;
try {
   await _barcodeReader.updateRuntimeSettings(settings: currentSettings);
} catch (e) {
   print('error = $e');
}

Customizing the Scan Region

You can also limit the scan region of the SDK so that it doesn’t exhaust resources trying to read from the entire image or frame. In order to do this, we will need to use the Region interface as well as the DynamsoftCameraView component.

First, let’s define the DynamsoftCameraView object. Next, we will define the region using the Region interface. In this example, we define a rectangular Region whose dimensions are measured as a percentage of the total dimensions. It is then assigned to the scanRegion parameter of the DynamsoftCameraView component:

final DynamsoftCameraView _cameraView = DynamsoftCameraView();
Region scanRegion = Region(regionTop: 20, regionBottom: 80, regionLeft: 20, regionRight: 80, regionMeasuredByPercentage: true);
_cameraView.scanRegion = scanRegion;

Licensing

• The BarcodeReader module of Dynamsoft Capture Vision needs a valid license to work.
• A one-day trial license is available by default for every new device to try Dynamsoft Capture Vision.
• You can request a 30-day free trial license via Dynamsoft customer portal for further evaluation.
• Contact us to purchase a full license.