StubBackgroundSegmenter class

Stub implementation of BackgroundSegmenter for platforms without ML Kit.

This class serves as a reference implementation. To enable real segmentation on mobile:

  1. Add google_mlkit_selfie_segmentation: ^0.6.0 to pubspec.yaml
  2. Create a class extending BackgroundSegmenter that uses ML Kit
  3. Set it on VirtualBackgroundProcessor.segmenter

Example implementation with ML Kit:

import 'package:google_mlkit_selfie_segmentation/google_mlkit_selfie_segmentation.dart';

class MLKitSegmenter implements BackgroundSegmenter {
  late SelfieSegmenter _segmenter;
  bool _isReady = false;

  @override
  Future<void> initialize() async {
    _segmenter = SelfieSegmenter(
      mode: SegmenterMode.stream, // Use stream mode for video
      enableRawSizeMask: true,
    );
    _isReady = true;
  }

  @override
  Future<SegmentationResult> processFrame(
    Uint8List frameData, {
    required int width,
    required int height,
  }) async {
    // Convert frame to InputImage
    final inputImage = InputImage.fromBytes(
      bytes: frameData,
      metadata: InputImageMetadata(
        size: Size(width.toDouble(), height.toDouble()),
        rotation: InputImageRotation.rotation0deg,
        format: InputImageFormat.nv21, // or bgra8888 on iOS
        bytesPerRow: width,
      ),
    );

    // Process with ML Kit
    final mask = await _segmenter.processImage(inputImage);
    if (mask == null) {
      return SegmentationResult.error('Segmentation failed');
    }

    // Convert mask to Uint8List
    final maskBytes = _convertMaskToBytes(mask, width, height);

    return SegmentationResult(
      processedFrame: frameData,
      mask: maskBytes,
      processingTimeMs: 0,
    );
  }

  Uint8List _convertMaskToBytes(SegmentationMask mask, int width, int height) {
    final bytes = Uint8List(width * height);
    for (int i = 0; i < mask.confidences.length; i++) {
      // Convert confidence (0.0-1.0) to grayscale (0-255)
      bytes[i] = (mask.confidences[i] * 255).round().clamp(0, 255);
    }
    return bytes;
  }

  @override
  Future<void> dispose() async {
    await _segmenter.close();
    _isReady = false;
  }

  @override
  bool get isReady => _isReady;
}
Implemented types

Constructors

StubBackgroundSegmenter()

Properties

hashCode → int
The hash code for this object.
no setterinherited
isReady → bool
Check if the segmenter is ready
no setteroverride
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited

Methods

dispose() → Future<void>
Dispose of resources
override
initialize() → Future<void>
Initialize the segmenter
override
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
processFrame(Uint8List frameData, {required int width, required int height}) → Future<SegmentationResult>
Process a frame and return the segmented result
override
toString() → String
A string representation of this object.
inherited

Operators

operator ==(Object other) → bool
The equality operator.
inherited