Google's ML Kit Barcode Flutter Plugin

A Barcode Flutter plugin to use Google's standalone ML Kit for Android and iOS.

Requirements

iOS

• Minimum iOS Deployment Target: 10.0
• Xcode 12 or newer
• Swift 5
• ML Kit only supports 64-bit architectures (x86_64 and arm64). Check this list to see if your device has the required device capabilities.

Since ML Kit does not support 32-bit architectures (i386 and armv7) (Read mode), you need to exclude amrv7 architectures in Xcode in order to run flutter build ios or flutter build ipa.

Go to Project > Runner > Building Settings > Excluded Architectures > Any SDK > armv7

Then your Podfile should look like this:

# add this line:
$iOSVersion = '10.0'

post_install do |installer|
  # add these lines:
  installer.pods_project.build_configurations.each do |config|
    config.build_settings["EXCLUDED_ARCHS[sdk=*]"] = "armv7"
    config.build_settings['IPHONEOS_DEPLOYMENT_TARGET'] = $iOSVersion
  end
  
  installer.pods_project.targets.each do |target|
    flutter_additional_ios_build_settings(target)
    
    # add these lines:
    target.build_configurations.each do |config|
      if Gem::Version.new($iOSVersion) > Gem::Version.new(config.build_settings['IPHONEOS_DEPLOYMENT_TARGET'])
        config.build_settings['IPHONEOS_DEPLOYMENT_TARGET'] = $iOSVersion
      end
    end
    
  end
end

Notice that the minimum IPHONEOS_DEPLOYMENT_TARGET is 10.0, you can set it to something newer but not older.

Android

• minSdkVersion: 21
• targetSdkVersion: 29

Usage

Add this plugin as dependency in your pubspec.yaml.

• In your project-level build.gradle file, make sure to include Google's Maven repository in both your buildscript and allprojects sections(for all api's).

• Configure your application to download the model to your device automatically from play store by adding the following to your app's AndroidManifest.xml, if not configured the respective models will be downloaded when the API's are invoked for the first time.

  <meta-data
          android:name="com.google.mlkit.vision.DEPENDENCIES"
          android:value="ocr" />
  

1. Create an InputImage

From path:

final inputImage = InputImage.fromFilePath(filePath);

From file:

final inputImage = InputImage.fromFile(file);

From bytes:

final inputImage = InputImage.fromBytes(bytes: bytes, inputImageData: inputImageData);

From CameraImage (if you are using the camera plugin):

final camera; // your camera instance
final WriteBuffer allBytes = WriteBuffer();
for (Plane plane in cameraImage.planes) {
  allBytes.putUint8List(plane.bytes);
}
final bytes = allBytes.done().buffer.asUint8List();

final Size imageSize = Size(cameraImage.width.toDouble(), cameraImage.height.toDouble());

final InputImageRotation imageRotation =
    InputImageRotationMethods.fromRawValue(camera.sensorOrientation) ??
        InputImageRotation.Rotation_0deg;

final InputImageFormat inputImageFormat =
    InputImageFormatMethods.fromRawValue(cameraImage.format.raw) ??
        InputImageFormat.NV21;

final planeData = cameraImage.planes.map(
  (Plane plane) {
    return InputImagePlaneMetadata(
      bytesPerRow: plane.bytesPerRow,
      height: plane.height,
      width: plane.width,
    );
  },
).toList();

final inputImageData = InputImageData(
  size: imageSize,
  imageRotation: imageRotation,
  inputImageFormat: inputImageFormat,
  planeData: planeData,
);

final inputImage = InputImage.fromBytes(bytes: bytes, inputImageData: inputImageData);

2. Create an instance of detector

final barcodeScanner = GoogleMlKit.vision.barcodeScanner();

3. Call the corresponding method

final List<Barcode> barcodes = await barcodeScanner.processImage(inputImage);

4. Extract data from response.

for (Barcode barcode in barcodes) {
  final BarcodeType type = barcode.type;
  final Rect boundingBox = barcode.value.boundingBox;
  final String displayValue = barcode.value.displayValue;
  final String rawValue = barcode.value.rawValue;

  // See API reference for complete list of supported types
  switch (type) {
    case BarcodeType.wifi:
      BarcodeWifi barcodeWifi = barcode.value;
      break;
    case BarcodeValueType.url:
      BarcodeUrl barcodeUrl = barcode.value;
      break;
  }
}

5. Release resources with close().

barcodeScanner.close();

Contributing

Contributions are welcome. In case of any problems open an issue. Create a issue before opening a pull request for non trivial fixes. In case of trivial fixes open a pull request directly.

License

MIT