Draw human shape.

main.dart

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Drawing',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key}) : super(key: key);

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("Flutter Drawing"),
      ),
      body: Center(
        child: Row(mainAxisAlignment: MainAxisAlignment.center,
          children: [
            CustomPaint(
              size: Size(200,300),
              painter: MyHumanPainter(),
            ),
          ],
        ),
      ),
    );
  }
}


class MyHumanPainter extends CustomPainter {
  MyHumanPainter();

  @override
  void paint(Canvas canvas, Size size) {
    double W = size.width;
    double H = size.height;


    // draw a head.
    Paint paintHeader = Paint()..color = Colors.blue[300];
    Offset offset = Offset(W / 2, H / 6);
    double radius = W / 4;
    canvas.drawCircle(offset, radius, paintHeader);

    // draw a body
    Paint paintBody = Paint()..color = Colors.green[300];
    Offset pBody1 = Offset(3 * (W / 8), (H / 3));
    Offset pBody2 = Offset(5 * (W / 8), 2 * (H / 3));
    Rect body = Rect.fromPoints(pBody1, pBody2);
    canvas.drawRect(body, paintBody);

    // draw a left arm.
    Paint paintLeftArm = Paint()
      ..color = Colors.green[300]
      ..strokeWidth = W / 30;
    Offset pLeftArm1 = Offset(4 * (W / 10), (H / 3));
    Offset pLeftArm2 = Offset(2 * (W / 10), 2 * (H / 3));
    canvas.drawLine(pLeftArm1, pLeftArm2, paintLeftArm);

    // draw a right arm.
    Paint paintRightArm = Paint()
      ..color = Colors.green[300]
      ..strokeWidth = W / 30;
    Offset pRightArm1 = Offset(6 * (W / 10), (H / 3));
    Offset pRightArm2 = Offset(8 * (W / 10), 2 * (H / 3));
    canvas.drawLine(pRightArm1, pRightArm2, paintRightArm);

    // draw a left leg.
    Paint paintLeftLeg = Paint()
      ..color = Colors.orange[300]
      ..strokeWidth = W / 25;
    Offset pLeftLeg1 = Offset(3 * (W / 8) + (W / 16), 2 * (H / 3));
    Offset pLeftLeg2 = Offset(3 * (W / 8) + (W / 16), H);
    canvas.drawLine(pLeftLeg1, pLeftLeg2, paintLeftLeg);

    // draw a left foot
    Paint paintLeftFoot = Paint()
      ..color = Colors.orange[300]
      ..strokeWidth = W / 25;
    Offset pLeftFoot1 = Offset(2 * (W / 8) + (W / 16), H);
    Offset pLeftFoot2 = Offset(3 * (W / 8) + (W / 16), H);
    canvas.drawLine(pLeftFoot1, pLeftFoot2, paintLeftFoot);

    // draw a right leg.
    Paint paintRightLeg = Paint()
      ..color = Colors.orange[300]
      ..strokeWidth = W / 25;
    Offset pRightLeg1 = Offset(4 * (W / 8) + (W / 16), 2 * (H / 3));
    Offset pRightLeg2 = Offset(4 * (W / 8) + (W / 16), H);
    canvas.drawLine(pRightLeg1, pRightLeg2, paintRightLeg);

    // draw a right foot
    Paint paintRightFoot = Paint()
      ..color = Colors.orange[300]
      ..strokeWidth = W / 25;
    Offset pRightFoot1 = Offset(4 * (W / 8) + (W / 16), H);
    Offset pRightFoot2 = Offset(5 * (W / 8) + (W / 16), H);
    canvas.drawLine(pRightFoot1, pRightFoot2, paintRightFoot);

    // draw left eye.
    Paint paintLeftEye = Paint()..color = Colors.white;
    Offset offsetLeftEye = Offset((W / 2) - (2 * (W / 24)), (H / 6) - (2 * (H / 36)));
    double radiusLeftEye = W / 24;
    canvas.drawCircle(offsetLeftEye, radiusLeftEye, paintLeftEye);

    // draw right eye.
    Paint paintRightEye = Paint()..color = Colors.white;
    Offset offsetRightEye = Offset((W / 2) + (2*(W / 24)), (H / 6) - (2 * (H / 36)));
    double radiusRightEye = W/24;
    canvas.drawCircle(offsetRightEye, radiusRightEye, paintRightEye);

    // draw a mouth.
    Paint paintMount = Paint()
      ..color = Colors.white
      ..strokeWidth = W / 50;
    Offset pLeftMount1 = Offset((W / 2) - (2 * (W / 24)), (H/6) + (3 * (H / 48)));
    Offset pLeftMount2 = Offset((W / 2) + (2 * (W / 24)),  (H/6) + (3 * (H / 48)));
    canvas.drawLine(pLeftMount1, pLeftMount2, paintMount);
  }
  
  @override
  bool shouldRepaint(MyHumanPainter oldDelegate) {
    return false;
  }
}