huixiang_app/lib/home/help_farmers/farmers_tab.dart

import 'package:flutter/cupertino.dart';
import 'package:flutter_screenutil/flutter_screenutil.dart';

class FarmersTab extends Decoration {
  @override
  BoxPainter createBoxPainter([VoidCallback? onChanged]) {
    return _CustomBoxPainter();
  }
}

class _CustomBoxPainter extends BoxPainter {
  @override
  void paint(Canvas canvas, Offset offset, ImageConfiguration configuration) {
    ///每个Tab的宽高
    Size tabSize = Size(32.w, 32.w);
    final Offset tabOffset = Offset(offset.dx + (((configuration.size?.width ?? 0) - 32.w) / 2), offset.dy);
    final Rect rect = tabOffset & tabSize;
    final Paint paint = Paint();
    paint.color = Color(0xFFFFFFFF);
    paint.style = PaintingStyle.stroke;
    paint.strokeCap = StrokeCap.round;
    paint.strokeWidth = 3;
    ///画Tab矩形
    canvas.drawArc(rect, 1, 1.2, false, paint);
  }
}