face_anti_spoofing_detector 0.0.3

Flutter plugin that provides passive liveness detection for facial recognition systems — ensuring that the detected face belongs to a live person rather than a photo, video.

example/lib/main.dart

import 'package:face_anti_spoofing_detector/face_anti_spoofing_detector.dart';
import 'package:face_contour_detector/face_contour_detector.dart';
import 'package:flutter/material.dart';
import 'dart:async';

import 'package:flutter/services.dart';
import 'package:image/image.dart' as img;
import 'package:liveness_detector_example/camera_view.dart';


void main() {
  runApp(const MaterialApp(
    home: LivenessScreen(),
  ));
}

class LivenessScreen extends StatefulWidget {
  const LivenessScreen({super.key});

  @override
  State<LivenessScreen> createState() => _LivenessScreenState();
}

class _LivenessScreenState extends State<LivenessScreen> {
  
  double? _confidenceScore;
  bool _initializeModelStatus = false;

  @override
  void initState() {
    super.initState();
    _initializeDetector();
  }

  @override
  void dispose() {
    super.dispose();
    FaceAntiSpoofingDetector.destroy();
    FaceContourDetector.destroy();
  }

  Future<void> _initializeDetector() async {
    final livenessDetectorStatus = await FaceAntiSpoofingDetector.initialize();
    final faceContourDetectorStatus = await FaceContourDetector.initialize();
    if(livenessDetectorStatus && faceContourDetectorStatus){
      setState(() {
        _initializeModelStatus = true;
      });
    }
  }

  void handleCameraStream(Uint8List yuvBytes,Size cameraViewSize) async {
    try {
      final startAt = DateTime.now();
      final faceContourList = await FaceContourDetector.detectFromYuv(
        yuvBytes: yuvBytes,
        width: cameraViewSize.width.toInt(),
        height: cameraViewSize.height.toInt()
      );
      if(faceContourList.isEmpty){
        _confidenceScore = null;
      }else {
        final faceContour = faceContourList[0];
        _confidenceScore = await FaceAntiSpoofingDetector.detect(
          yuvBytes: yuvBytes,
          previewWidth: cameraViewSize.width.toInt(),
          previewHeight: cameraViewSize.height.toInt(),
          orientation: 7,
          faceContour : faceContour,
        );
        print("Confidence Score = $_confidenceScore");
      }
      print("Detect duration = ${DateTime.now().difference(startAt).inMilliseconds} ms");
    } catch (e) {
      print(e);
      _confidenceScore = null;
    }finally {
      setState(() {});
    }
    

  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Liveness Detector')),
      body: Padding(
        padding: const EdgeInsets.all(20.0),
        child: _initializeModelStatus ? Column(
          mainAxisAlignment: MainAxisAlignment.start,
          children: [
            const SizedBox(height: 20),
            CameraView(
              customPaint: null, 
              onImage: handleCameraStream ,
              // cameraStreamProcessDelay: Duration(milliseconds: 500),
            ),
            SizedBox(height: 40),
            _confidenceScore == null ?
              Text(
                "No face detected",
                style: TextStyle(
                  color: Colors.redAccent
                ),
              ) :
              Text(
                "${(_confidenceScore! > .8 ? "Real" : "Fake")}\n Score : $_confidenceScore",
                style: TextStyle(
                  color: _confidenceScore! > .8 ? Colors.lightGreen : Colors.red,
                ), 
                textAlign: TextAlign.center,
              )
          ],
        ) :
        Text(
          "Failed to initialize detector!."
        )
      ),
    );
  }
}


Uint8List convertBytesImageToYuv(Uint8List imageBytes) {
  // Decode the image from bytes
  final image = img.decodeImage(imageBytes);
  if (image == null) {
    throw Exception('Failed to decode image');
  }

  // Resize image to match the preview dimensions (640x480)
  final resized = img.copyResize(image, width: 640, height: 480);
  
  final width = resized.width;
  final height = resized.height;
  
  // Calculate buffer sizes for YUV420 format (NV21)
  final ySize = width * height;
  final uvSize = (width ~/ 2) * (height ~/ 2);
  final totalSize = ySize + uvSize * 2;
  
  final yuv = Uint8List(totalSize);
  
  int yIndex = 0;
  int uvIndex = ySize;
  
  // Convert RGB to YUV
  for (int y = 0; y < height; y++) {
    for (int x = 0; x < width; x++) {
      final pixel = resized.getPixel(x, y);
      final r = pixel.r.toInt();
      final g = pixel.g.toInt();
      final b = pixel.b.toInt();
      
      // Convert to Y (luminance)
      final yValue = ((66 * r + 129 * g + 25 * b + 128) >> 8) + 16;
      yuv[yIndex++] = yValue.clamp(0, 255);
      
      // Sample U and V at every other pixel (for YUV420)
      if (y % 2 == 0 && x % 2 == 0) {
        final uValue = ((-38 * r - 74 * g + 112 * b + 128) >> 8) + 128;
        final vValue = ((112 * r - 94 * g - 18 * b + 128) >> 8) + 128;
        
        yuv[uvIndex++] = vValue.clamp(0, 255); // V (NV21 format)
        yuv[uvIndex++] = uValue.clamp(0, 255); // U
      }
    }
  }
  
  return yuv;
}

class FaceBoxPainter extends CustomPainter {
  final List<FaceModel> faces;
  final Size imageSize;

  FaceBoxPainter(this.faces, this.imageSize);

  @override
  void paint(Canvas canvas, Size size) {
    final paint = Paint()
      ..color = Colors.green
      ..style = PaintingStyle.stroke
      ..strokeWidth = 4.0;

    for (var face in faces) {
      
      // Draw rectangle
      canvas.drawRect(face.faceContour, paint);
      
      // Draw text at top-left corner
      final textSpan = TextSpan(
        text: "Real : ${face.score}",
        style: TextStyle(
          color: Colors.green,
          fontSize: 16,
          fontWeight: FontWeight.bold,
          backgroundColor: Colors.black.withOpacity(0.7),
        ),
      );
      
      final textPainter = TextPainter(
        text: textSpan,
        textDirection: TextDirection.ltr,
      );
      
      textPainter.layout();
      
      // Position text at top-left corner with small offset
      final offset = Offset(
        face.faceContour.left + 5,
        face.faceContour.top - textPainter.height - 5,
      );
      
      // Draw background rectangle for better readability
      final backgroundRect = Rect.fromLTWH(
        offset.dx - 2,
        offset.dy - 2,
        textPainter.width + 4,
        textPainter.height + 4,
      );
      
      canvas.drawRect(
        backgroundRect,
        Paint()..color = Colors.black.withOpacity(0.7),
      );
      
      // Draw text
      textPainter.paint(canvas, offset);
    }
  }

  @override
  bool shouldRepaint(covariant FaceBoxPainter oldDelegate) {
    return faces != oldDelegate.faces || imageSize != oldDelegate.imageSize;
  }
}

class FaceModel{

  double? score;
  Rect faceContour;

  FaceModel({
    this.score, 
    required this.faceContour
  });
  
}