convertsCameraImage method

InputImage? convertsCameraImage(CameraImage image)

Sends captured image to be converted from CameraImage type into InputImage type.

The converted imaged is received by listenBarcodes method.

Implementation

InputImage? convertsCameraImage(CameraImage image) {
  if (cameraController == null) return null;

  // get image rotation
  // it is used in android to convert the InputImage from Dart to Java: https://github.com/flutter-ml/google_ml_kit_flutter/blob/master/packages/google_mlkit_commons/android/src/main/java/com/google_mlkit_commons/InputImageConverter.java
  // `rotation` is not used in iOS to convert the InputImage from Dart to Obj-C: https://github.com/flutter-ml/google_ml_kit_flutter/blob/master/packages/google_mlkit_commons/ios/Classes/MLKVisionImage%2BFlutterPlugin.m
  // in both platforms `rotation` and `camera.lensDirection` can be used to compensate `x` and `y` coordinates on a canvas: https://github.com/flutter-ml/google_ml_kit_flutter/blob/master/packages/example/lib/vision_detector_views/painters/coordinates_translator.dart
  final camera = cameras[_cameraIndex ?? 0];
  final sensorOrientation = camera.sensorOrientation;
  // print(
  //     'lensDirection: ${camera.lensDirection}, sensorOrientation: $sensorOrientation, ${_controller?.value.deviceOrientation} ${_controller?.value.lockedCaptureOrientation} ${_controller?.value.isCaptureOrientationLocked}');
  InputImageRotation? rotation;
  if (Platform.isIOS) {
    rotation = InputImageRotationValue.fromRawValue(sensorOrientation);
  } else if (Platform.isAndroid) {
    var rotationCompensation =
        _orientations[cameraController!.value.deviceOrientation];
    if (rotationCompensation == null) return null;
    if (camera.lensDirection == CameraLensDirection.front) {
      // front-facing
      rotationCompensation = (sensorOrientation + rotationCompensation) % 360;
    } else {
      // back-facing
      rotationCompensation =
          (sensorOrientation - rotationCompensation + 360) % 360;
    }
    rotation = InputImageRotationValue.fromRawValue(rotationCompensation);
    // print('rotationCompensation: $rotationCompensation');
  }
  if (rotation == null) return null;
  // print('final rotation: $rotation');

  // get image format
  final format = InputImageFormatValue.fromRawValue(image.format.raw);
  // validate format depending on platform
  // only supported formats:
  // * nv21 for Android
  // * bgra8888 for iOS
  if (format == null ||
      (Platform.isAndroid && format != InputImageFormat.nv21) ||
      (Platform.isIOS && format != InputImageFormat.bgra8888)) return null;

  // since format is constraint to nv21 or bgra8888, both only have one plane
  if (image.planes.length != 1) return null;
  final plane = image.planes.first;

  // compose InputImage using bytes
  return InputImage.fromBytes(
    bytes: plane.bytes,
    metadata: InputImageMetadata(
      size: Size(image.width.toDouble(), image.height.toDouble()),
      rotation: rotation, // used only in Android
      format: format, // used only in iOS
      bytesPerRow: plane.bytesPerRow, // used only in iOS
    ),
  );
}