twonly-app/lib/src/views/camera/painters/barcode_detector_painter.dart

import 'dart:io';
import 'dart:ui';
import 'dart:ui' as ui;

import 'package:camera/camera.dart';
import 'package:flutter/material.dart';
import 'package:google_mlkit_barcode_scanning/google_mlkit_barcode_scanning.dart';

import 'coordinates_translator.dart';

class BarcodeDetectorPainter extends CustomPainter {
  BarcodeDetectorPainter(
    this.barcodes,
    this.imageSize,
    this.rotation,
    this.cameraLensDirection,
  );

  final List<Barcode> barcodes;
  final Size imageSize;
  final InputImageRotation rotation;
  final CameraLensDirection cameraLensDirection;

  @override
  void paint(Canvas canvas, Size size) {
    final Paint paint = Paint()
      ..style = PaintingStyle.stroke
      ..strokeWidth = 3.0
      ..color = Colors.lightGreenAccent;

    final Paint background = Paint()..color = Color(0x99000000);

    for (final Barcode barcode in barcodes) {
      final ParagraphBuilder builder = ParagraphBuilder(
        ParagraphStyle(
            textAlign: TextAlign.left,
            fontSize: 16,
            textDirection: TextDirection.ltr),
      );
      builder.pushStyle(
          ui.TextStyle(color: Colors.lightGreenAccent, background: background));
      builder.addText('${barcode.displayValue}');
      builder.pop();

      final left = translateX(
        barcode.boundingBox.left,
        size,
        imageSize,
        rotation,
        cameraLensDirection,
      );
      final top = translateY(
        barcode.boundingBox.top,
        size,
        imageSize,
        rotation,
        cameraLensDirection,
      );
      final right = translateX(
        barcode.boundingBox.right,
        size,
        imageSize,
        rotation,
        cameraLensDirection,
      );
      // final bottom = translateY(
      //   barcode.boundingBox.bottom,
      //   size,
      //   imageSize,
      //   rotation,
      //   cameraLensDirection,
      // );
      //
      // // Draw a bounding rectangle around the barcode
      // canvas.drawRect(
      //   Rect.fromLTRB(left, top, right, bottom),
      //   paint,
      // );

      final List<Offset> cornerPoints = <Offset>[];
      for (final point in barcode.cornerPoints) {
        final double x = translateX(
          point.x.toDouble(),
          size,
          imageSize,
          rotation,
          cameraLensDirection,
        );
        final double y = translateY(
          point.y.toDouble(),
          size,
          imageSize,
          rotation,
          cameraLensDirection,
        );

        cornerPoints.add(Offset(x, y));
      }

      // Add the first point to close the polygon
      cornerPoints.add(cornerPoints.first);
      canvas.drawPoints(PointMode.polygon, cornerPoints, paint);

      canvas.drawParagraph(
        builder.build()
          ..layout(ParagraphConstraints(
            width: (right - left).abs(),
          )),
        Offset(
            Platform.isAndroid &&
                    cameraLensDirection == CameraLensDirection.front
                ? right
                : left,
            top),
      );
    }
  }

  @override
  bool shouldRepaint(BarcodeDetectorPainter oldDelegate) {
    return oldDelegate.imageSize != imageSize ||
        oldDelegate.barcodes != barcodes;
  }
}