In Flutter, you can use the CustomPaint and CustomPainter classes to draw to the canvas.

CustomPainter subclasses must implement the paint() and shouldRepaint() methods.

It’s should be passes to CustomPaint’s as a painter parameter.

import 'package:flutter/material.dart';

class MyCanvasPainter extends CustomPainter {
  const MyCanvasPainter();

  @override
  void paint(Canvas canvas, Size size) {
    final Paint paint = Paint()..color = Colors.amber;
    canvas.drawCircle(const Offset(100.0, 200.0), 40.0, paint);
    final Paint paintRect = Paint()..color = Colors.lightBlue;
    final Rect rect = Rect.fromPoints(
      const Offset(150.0, 300.0),
      const Offset(300.0, 400.0),
    );
    canvas.drawRect(rect, paintRect);
  }

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

class MyCanvasWidget extends StatelessWidget {
  const MyCanvasWidget({super.key});

  @override
  Widget build(BuildContext context) {
    return const Scaffold(
      body: CustomPaint(painter: MyCanvasPainter()),
    );
  }
}