有没有从BoxShape获取三角形的方法？

import 'package:flutter/material.dart';

class TriangleContainer extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return CustomPaint(
      painter: TrianglePainter(),
      child: Container(
        width: 100,
        height: 100,
      ),
    );
  }
}

class TrianglePainter extends CustomPainter {
  @override
  void paint(Canvas canvas, Size size) {
    final paint = Paint()
      ..color = Colors.blue
      ..style = PaintingStyle.fill;

    final path = Path();
    path.moveTo(0, size.height);
    path.lineTo(size.width, size.height);
    path.lineTo(size.width / 2, 0);
    path.close();

    canvas.drawPath(path, paint);
  }

  @override
  bool shouldRepaint(covariant CustomPainter oldDelegate) {
    return false;
  }
}