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@Filmaluco
Created December 9, 2022 17:33
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import 'dart:math';
import 'package:flutter/material.dart';
void main() {
runApp(const MyApp());
}
class MyApp extends StatelessWidget {
const MyApp({super.key});
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
// This is the theme of your application.
//
// Try running your application with "flutter run". You'll see the
// application has a blue toolbar. Then, without quitting the app, try
// changing the primarySwatch below to Colors.green and then invoke
// "hot reload" (press "r" in the console where you ran "flutter run",
// or simply save your changes to "hot reload" in a Flutter IDE).
// Notice that the counter didn't reset back to zero; the application
// is not restarted.
primarySwatch: Colors.blue,
),
home: const MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
const MyHomePage({super.key, required this.title});
// This widget is the home page of your application. It is stateful, meaning
// that it has a State object (defined below) that contains fields that affect
// how it looks.
// This class is the configuration for the state. It holds the values (in this
// case the title) provided by the parent (in this case the App widget) and
// used by the build method of the State. Fields in a Widget subclass are
// always marked "final".
final String title;
@override
State<MyHomePage> createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
int _counter = 0;
Color? _backgroundColor;
void _incrementCounter() {
setState(() {
// This call to setState tells the Flutter framework that something has
// changed in this State, which causes it to rerun the build method below
// so that the display can reflect the updated values. If we changed
// _counter without calling setState(), then the build method would not be
// called again, and so nothing would appear to happen.
_counter++;
_changeBackgroundcolor();
});
}
void _decrementCounter() {
if (_counter == 0) return;
setState(() {
_counter--;
_changeBackgroundcolor();
});
}
void _changeBackgroundcolor() {
_backgroundColor = Color.fromRGBO(
Random().nextInt(255),
Random().nextInt(255),
Random().nextInt(255),
1.0,
);
}
@override
void initState() {
super.initState();
debugPrint('Estado iniciado: Só é chamado uma vez por inicialização.');
}
@override
void didChangeDependencies() {
super.didChangeDependencies();
debugPrint(
'Dependências é alteradas: Só é chamado quando uma dependência muda, ou na primeira vez que é iniciado o estado, após o initState.');
}
@override
void didUpdateWidget(covariant MyHomePage oldWidget) {
super.didUpdateWidget(oldWidget);
debugPrint(
'Widget atualizado, estado atualizado: Sempre que é atualizado o widget dono deste estado é invococado este método. Podem ser comparadas as propriedades do oldWidget com o widget atual.');
}
@override
void dispose() {
super.dispose();
debugPrint(
'Widget destruído: Só é chamado uma vez, quando o widget é destruído e, correspondentemente, o seu estado.');
}
@override
Widget build(BuildContext context) {
// This method is rerun every time setState is called, for instance as done
// by the _incrementCounter method above.
//
// The Flutter framework has been optimized to make rerunning build methods
// fast, so that you can just rebuild anything that needs updating rather
// than having to individually change instances of widgets.
return Scaffold(
backgroundColor: _backgroundColor,
appBar: AppBar(
// Here we take the value from the MyHomePage object that was created by
// the App.build method, and use it to set our appbar title.
title: Text(widget.title),
),
body: Center(
// Center is a layout widget. It takes a single child and positions it
// in the middle of the parent.
child: Column(
// Column is also a layout widget. It takes a list of children and
// arranges them vertically. By default, it sizes itself to fit its
// children horizontally, and tries to be as tall as its parent.
//
// Invoke "debug painting" (press "p" in the console, choose the
// "Toggle Debug Paint" action from the Flutter Inspector in Android
// Studio, or the "Toggle Debug Paint" command in Visual Studio Code)
// to see the wireframe for each widget.
//
// Column has various properties to control how it sizes itself and
// how it positions its children. Here we use mainAxisAlignment to
// center the children vertically; the main axis here is the vertical
// axis because Columns are vertical (the cross axis would be
// horizontal).
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
FlutterLogo(
size: _counter >= 10 ? 200.0 : 0.0,
),
// Outra maneira de inserir o widget com base na condição. Ao contrário do exemplo anterior, o widget aqui só é
// inserido mesmo quando a condição é válida, enquanto que no outro caso apenas muda o tamanho de 0 até 200 com base na condição.
/*
if(_counter >= 10) const FlutterLogo(
size:200.0,
),*/
Text(
'$_counter',
style: Theme.of(context).textTheme.headline4,
),
ElevatedButton(
onPressed: () {
setState(() {
_counter = 0;
});
},
child: Text("Reset")),
],
),
),
floatingActionButton: Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: [
Padding(
padding: const EdgeInsets.only(left: 30),
child: FloatingActionButton(
onPressed: _decrementCounter,
tooltip: 'Decrement',
child: const Icon(Icons.remove),
),
),
FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: const Icon(Icons.add),
),
],
), // This trailing comma makes auto-formatting nicer for build methods.
);
}
}
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