如何在flutter中创建三角形UI

import 'package:flutter/material.dart';

class TriangleWidget extends StatelessWidget {
  final Color color;
  final double size;

  TriangleWidget({this.color = Colors.black, this.size = 100.0});

  @override
  Widget build(BuildContext context) {
    return CustomPaint(
      size: Size(size, size),
      painter: TrianglePainter(color),
    );
  }
}

class TrianglePainter extends CustomPainter {
  final Color color;

  TrianglePainter(this.color);

  @override
  void paint(Canvas canvas, Size size) {
    final paint = Paint()
      ..color = color
      ..style = PaintingStyle.fill;

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

    canvas.drawPath(path, paint);
  }

  @override
  bool shouldRepaint(TrianglePainter oldDelegate) {
    return oldDelegate.color != color;
  }
}

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Triangle Example',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: Scaffold(
        appBar: AppBar(
          title: Text('Triangle Example'),
        ),
        body: Center(
          child: TriangleWidget(
            color: Colors.red,
            size: 200.0,
          ),
        ),
      ),
    );
  }
}