luojigou_thinking_core/example/lib/demo/demo4.dart

import 'dart:math';

import 'package:flutter/material.dart';
import 'package:luojigou_thinking_core/luojigou_thinking_core.dart';

class Demo4 extends StatefulWidget {
  const Demo4({Key? key}) : super(key: key);

  @override
  State<Demo4> createState() => _Demo4State();
}

class _Demo4State extends State<Demo4> {
  @override
  Widget build(BuildContext context) {
    return Center(
      child: SizedBox(
        width: MediaQuery.of(context).size.width,
        height: MediaQuery.of(context).size.width,
        child: CustomPaint(
          painter: _Painter(),
        ),
      ),
    );
  }
}

class _Painter extends CustomPainter {
  @override
  void paint(Canvas canvas, Size size) {
    Paint paint = Paint()
      ..color = Colors.deepPurple
      ..style = PaintingStyle.stroke
      ..strokeWidth = 0.5;

    final Offset o = Offset(50, 50);
    final Offset o1 = Offset(200, 400);
    final Offset o2 = Offset(400, 200);

    final path = Path();
    path.moveTo(o1.dx, o1.dy);
    path.lineTo(o.dx, o.dy);
    path.lineTo(o2.dx, o2.dy);

    canvas.drawPath(path, paint);
    canvas.drawCircle(PlaneGeometryUtils.origin(o, o1, o2, 40), 40, paint);
  }

  @override
  bool shouldRepaint(covariant CustomPainter oldDelegate) => false;
}