Функции

// Some code
import 'package:flutter/material.dart';

class FunctionScreen extends StatefulWidget {
  const FunctionScreen({super.key});

  @override
  State<FunctionScreen> createState() => _FunctionScreenState();
}

class _FunctionScreenState extends State<FunctionScreen> {
  String name = 'Baiastan';
  double number = 9;
  double weight = 98.99;
  bool isSunny = false;
  bool isNight = true;

  // = , +=, -=, /=, *=
  //+, -,\, *, ++, --

  // Scaffold, Container, Text, Icon, Image,
  Scaffold screen = Scaffold(
    backgroundColor: Colors.orange,
  );

  Container cube = Container();

  // Переменные - сущест
  //

  void increment() {
    setState(() {
      number += 1;
    });
  }

  void decrement() {
    setState(() {
      number -= 1;
    });
  }

  void divide() {
    setState(() {
      number /= 2;
    });
  }

  void multiply() {
    setState(() {
      number *= 2;
    });
  }

  bool isFavorite = false; // false нет -  true да

  void like() {
    setState(() {
      isFavorite = !isFavorite;
    });
  }

  bool isObscureText = true;

  void hide() {
    setState(() {
      isObscureText = !isObscureText;
    });
  }

  // Действие на экране
  // не повторять один тот же код -

  // Elf, Person, Orc, Gnome

  String attack = '';

  void attackElf() {
    setState(() {
      attack = 'Эльф лук';
    });
  }

  void attackPerson() {
    setState(() {
      attack = 'Человек меч';
    });
  }

  void attackOrc() {
    setState(() {
      attack = 'Орк топор';
    });
  }

  void attackGnome() {
    setState(() {
      attack = 'Гном молот';
    });
  }

  // Порядковый параметры
  void attackI(String title) {
    setState(() {
      attack = title;
    });
  }

  //

  int c = 0;

  void sum(int a, int b) {
    setState(() {
      c = a + b;
    });
  }

  TextEditingController aController = TextEditingController();
  TextEditingController bController = TextEditingController();

  // Объязательные параметры

  void minus({required int a, required int b}) {
    setState(() {
      c = a - b;
    });
  }

  // Деление - усножение -
  // Контейнер - тернарный оператор

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SafeArea(
        child: Column(
          children: [
            Text(
              '$number',
              style: TextStyle(fontSize: 30),
            ),

            Row(
              mainAxisAlignment: MainAxisAlignment.spaceBetween,
              children: [
                IconButton(
                  onPressed: () {
                    increment();
                  },
                  icon: Icon(Icons.add),
                ),

                ElevatedButton(
                  onPressed: () {
                    decrement();
                  },
                  child: Text('минус '),
                ),

                TextButton(
                  onPressed: () {
                    divide();
                  },
                  child: Text('/'),
                ),

                InkWell(
                  onTap: () {
                    multiply();
                  },
                  child: Text('*'),
                ),
              ],
            ),

            IconButton(
              onPressed: () {
                like();
              },
              icon: Icon(
                isFavorite ? Icons.favorite : Icons.favorite_border,
                color: isFavorite ? Colors.red : Colors.black,
                size: 50,
              ),
            ),

            Padding(
              padding: const EdgeInsets.all(8.0),
              child: TextField(
                obscureText: isObscureText,
                decoration: InputDecoration(
                  border: OutlineInputBorder(),

                  suffixIcon: InkWell(
                    onTap: () {
                      hide();
                    },
                    child: Icon(
                      isObscureText ? Icons.visibility : Icons.visibility_off,
                    ),
                  ),
                ),
              ),
            ),

            SizedBox(
              height: 30,
            ),
            Text(
              'Атака - $attack',
              style: TextStyle(fontSize: 40),
            ),
            Row(
              mainAxisAlignment: MainAxisAlignment.spaceAround,
              children: [
                ElevatedButton(
                  onPressed: () {
                    attackI('Лук');
                  },
                  child: Text('Эльф'),
                ),
                ElevatedButton(
                  onPressed: () {
                    attackI('Меч');
                  },
                  child: Text('Человек'),
                ),
                ElevatedButton(
                  onPressed: () {
                    attackI('Топор');
                  },
                  child: Text('Орк'),
                ),
                ElevatedButton(
                  onPressed: () {
                    attackI('Молот');
                  },
                  child: Text('Гном'),
                ),
              ],
            ),

            Padding(
              padding: const EdgeInsets.all(8.0),
              child: Row(
                children: [
                  Expanded(
                    child: TextField(
                      controller: aController,
                      decoration: InputDecoration(
                        border: OutlineInputBorder(),
                        hintText: 'a',
                      ),
                    ),
                  ),
                  SizedBox(
                    width: 10,
                  ),
                  Expanded(
                    child: TextField(
                      controller: bController,
                      decoration: InputDecoration(
                        border: OutlineInputBorder(),
                        hintText: 'b',
                      ),
                    ),
                  ),
                ],
              ),
            ),

            Text(
              '$c',
              style: TextStyle(fontSize: 40),
            ),
            Row(
              mainAxisAlignment: MainAxisAlignment.spaceBetween,
              children: [
                ElevatedButton(
                  onPressed: () {
                    sum(
                      int.tryParse(aController.text)!,
                      int.tryParse(bController.text)!,
                    );
                  },
                  child: Text('Sum'),
                ),

                ElevatedButton(
                  onPressed: () {
                    minus(
                      b: int.tryParse(bController.text)!,
                      a: int.tryParse(aController.text)!,
                    );
                  },
                  child: Text('Minus'),
                ),
              ],
            ),
          ],
        ),
      ),
    );
  }
}

// Some code
import 'package:flutter/material.dart';

class OnboardingScreen extends StatefulWidget {
  const OnboardingScreen({super.key});

  @override
  State<OnboardingScreen> createState() => _OnboardingScreenState();
}

class _OnboardingScreenState extends State<OnboardingScreen> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: PageView(
        children: [
          _page(
            image: 'assets/apple.png',
            title: 'Buy grocery',
            subtitle:
                'Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy',
          ),
          _page(
            image: 'assets/birds.png',
            title: 'Buy food',
            subtitle:
                'Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy',
          ),
          _page(
            image: 'assets/lesson01/food/coke.png',
            title: 'Buy coke ',
            subtitle:
                'Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy',
          ),
        ],
      ),
    );
  }

  Widget _page({
    required String image,
    required String title,
    required String subtitle,
  }) {
    return Column(
      mainAxisAlignment: MainAxisAlignment.end,
      children: [
        Image.asset(image),
        SizedBox(
          height: 300,
        ),
        Text(
          title,
          style: TextStyle(fontSize: 30, fontWeight: FontWeight.bold),
        ),
        SizedBox(
          height: 70,
        ),
        Text(
          subtitle,
        ),
        SizedBox(
          height: 100,
        ),

        Row(
          children: [
            _textButton(text: 'Skip'),
            _spacerWidget(),
            _circleAvatarWidget(color: Colors.green),
            _circleAvatarWidget(color: Colors.grey),
            _circleAvatarWidget(color: Colors.grey),
            _spacerWidget(),
            _textButton(text: 'Next'),
          ],
        ),
        SizedBox(
          height: 100,
        ),
      ],
    );
  }

  Widget _circleAvatarWidget({required Color color}) {
    return Padding(
      padding: const EdgeInsets.symmetric(horizontal: 5),
      child: CircleAvatar(
        radius: 5,
        backgroundColor: color,
      ),
    );
  }

  Widget _spacerWidget() {
    return Spacer();
  }

  Widget _textButton({required String text}) {
    return TextButton(onPressed: () {}, child: Text(text));
  }

  //
}

// Some code
import 'package:flutter/material.dart';

class Function01Screen extends StatefulWidget {
  const Function01Screen({super.key});

  @override
  State<Function01Screen> createState() => _Function01ScreenState();
}

class _Function01ScreenState extends State<Function01Screen> {
  void run() {}

  //DRY - Don't repeat your code

  //Порядковый
  void delete(String name, int age, double weight, bool isFavorite) {}

  //Объя
  void save({
    required String name,
    required int age,
    required double weight,
    required bool isFavorite,
  }) {}

  Widget _container({
     double height = 200,
    required double width,
     Color color = Colors.red,
  }) {
    return Container(
      height: height,
      width: width,
      color: color,
    );
  }

  // =, +=, -=, *=, /=
  // +, -, /, *

  //Порядковые параметры
  //Объязательные параметры
  //Дефолтные параметры

  // Var - const - dynamic - final -
  // Необъязательные параметры
  // Методы - параметры -
  // if else -

  // Регистрации - логин
  // калькулятор

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Column(
        children: [
          Center(
            child: TextButton(
              onPressed: () {
                run();

                delete('Baiastan', 26, 76.87, true);

                save(
                  name: 'Baiastan',
                  age: 26,
                  weight: 76.98,
                  isFavorite: true,
                );

                save(weight: 98.78, age: 45, name: 'Aladin', isFavorite: true);
              },
              child: Text('Hello'),
            ),
          ),

          // _container(height: 200, width: 100, color: Colors.red),
          // _container(height: 200, width: 300, color: Colors.green),
          // _container(height: 300, width: 200, color: Colors.red),
          
          _container(width: 100),
          _container(width: 200, color: Colors.green),
          _container(width: 300, height: 150)
          

        ],
      ),
    );
  }
}