Widgets básicos de layout
Domine widgets essenciais de layout, como Row, Column, Container e Stack, para criar interfaces de usuário estruturadas e responsivas.
Widgets básicos de layout é uma aula grátis de Flutter Mobile Development no CoddyKit. Esta é a aula 2 de 4. Você pode ler a aula completa abaixo gratuitamente — depois pratica ao vivo no navegador com um editor de código integrado e um tutor de IA 24/7. Faz parte do caminho de aprendizado de Flutter Mobile Development, e seu progresso é sincronizado entre a web e o app CoddyKit. O curso de Flutter Mobile Development inclui 4 aulas no total.
Partes desta aula ainda não foram traduzidas e aparecem em inglês.
Why Layouts Matter
In Flutter, everything is a widget! To build complex and beautiful user interfaces, you need to arrange these widgets on the screen.
Layout widgets are special widgets designed to help you organize other widgets, defining their size, position, and how they interact with each other.
Meet the Container
The Container widget is one of the most versatile layout widgets. Think of it as a customizable box that can hold a single child widget.
You can use it to:
- Add padding or margins
- Set background colors or decorations
- Define specific width and height
- Transform its position or rotation
Simple Colored Box
Let's create a basic Container with a child Text widget. Notice how we set its color and padding.
import 'package:flutter/material.dart';
void main() {
runApp(const MyApp());
}
class MyApp extends StatelessWidget {
const MyApp({super.key});
@override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
appBar: AppBar(title: const Text('Container Demo')),
body: Center(
child: Container(
padding: const EdgeInsets.all(20.0),
color: Colors.blueAccent,
child: const Text(
'Hello from Container!',
style: TextStyle(color: Colors.white, fontSize: 18),
),
),
),
),
);
}
}Horizontal with Row
When you need to arrange multiple widgets side-by-side horizontally, the Row widget is your go-to. It takes a list of widgets as its children.
Row automatically tries to fit its children along the horizontal axis, and you can control their alignment within the row.
Row of Buttons
Here's how you can place three buttons next to each other using a Row. We'll add some spacing between them.
import 'package:flutter/material.dart';
void main() {
runApp(const MyApp());
}
class MyApp extends StatelessWidget {
const MyApp({super.key});
@override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
appBar: AppBar(title: const Text('Row Demo')),
body: Center(
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: <Widget>[
ElevatedButton(onPressed: () {}, child: const Text('Button 1')),
ElevatedButton(onPressed: () {}, child: const Text('Button 2')),
ElevatedButton(onPressed: () {}, child: const Text('Button 3')),
],
),
),
),
);
}
}Vertical with Column
Just as Row arranges widgets horizontally, the Column widget arranges them vertically, one below the other.
It also takes a list of children and lets you control their vertical alignment.
Stacked Text Fields
Let's create a simple login-like form using a Column to stack two TextFields and a button vertically.
import 'package:flutter/material.dart';
void main() {
runApp(const MyApp());
}
class MyApp extends StatelessWidget {
const MyApp({super.key});
@override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
appBar: AppBar(title: const Text('Column Demo')),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
const Padding(
padding: EdgeInsets.all(8.0),
child: TextField(
decoration: InputDecoration(labelText: 'Username'),
),
),
const Padding(
padding: EdgeInsets.all(8.0),
child: TextField(
obscureText: true,
decoration: InputDecoration(labelText: 'Password'),
),
),
ElevatedButton(onPressed: () {}, child: const Text('Login')),
],
),
),
),
);
}
}Aligning Children
Both Row and Column use two important properties for alignment:
mainAxisAlignment: How children are positioned along the primary axis (horizontal forRow, vertical forColumn). Examples:start,center,end,spaceAround.crossAxisAlignment: How children are positioned along the perpendicular axis (vertical forRow, horizontal forColumn). Examples:start,center,end,stretch.
These give you fine control over your layouts!
Overlapping with Stack
Sometimes you need to place widgets on top of each other, like text over an image. That's where the Stack widget comes in.
Stack allows you to layer multiple children widgets. You can control their exact position within the stack using the Positioned widget.
Image with Text Overlay
Let's put some text directly on top of an image using a Stack. We'll use Positioned to place the text precisely.
import 'package:flutter/material.dart';
void main() {
runApp(const MyApp());
}
class MyApp extends StatelessWidget {
const MyApp({super.key});
@override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
appBar: AppBar(title: const Text('Stack Demo')),
body: Center(
child: SizedBox(
width: 300,
height: 200,
child: Stack(
children: <Widget>[
Image.network(
'https://picsum.photos/300/200',
fit: BoxFit.cover,
),
const Positioned(
bottom: 10,
left: 10,
child: Text(
'Beautiful Scenery',
style: TextStyle(
color: Colors.white,
fontSize: 20,
fontWeight: FontWeight.bold,
shadows: [
Shadow(blurRadius: 5, color: Colors.black)
],
),
),
),
],
),
),
),
),
);
}
}Layout Challenge
Which of the following widgets are primarily used for arranging multiple children widgets in a single direction (either horizontally or vertically)?
Layouts Mastered!
Great job! You've now mastered the fundamental layout widgets in Flutter:
Container: A versatile box for single children, offering padding, margin, color, and size control.Row: Arranges multiple children horizontally.Column: Arranges multiple children vertically.Stack: Layers children on top of each other, often used withPositioned.
Understanding these is key to building any Flutter UI!
Perguntas Frequentes
A aula “Widgets básicos de layout” é grátis?
Sim — o texto completo de “Widgets básicos de layout” é grátis para ler aqui na web. Para praticá-la interativamente (um editor de código integrado e um tutor de IA 24/7) e desbloquear o restante do curso de Flutter Mobile Development, atualize para CoddyKit PRO. O curso de Flutter Mobile Development inclui 4 aulas no total.
O que vou aprender em “Widgets básicos de layout”?
Domine widgets essenciais de layout, como Row, Column, Container e Stack, para criar interfaces de usuário estruturadas e responsivas. Você pratica Flutter Mobile Development com código prático que executa diretamente no navegador, e um tutor de IA 24/7 responde suas dúvidas enquanto trabalha na aula.
Preciso ter experiência prévia para começar Flutter Mobile Development?
Nenhuma experiência prévia é necessária. Flutter Mobile Development no CoddyKit é estruturado para alunos iniciantes até avançados, então você pode começar aqui ou desde o início e aprender no seu ritmo. Esta é a aula 2 de 4.
Quanto tempo leva a aula “Widgets básicos de layout”?
A maioria das aulas CoddyKit leva cerca de 5–10 minutos. Cada uma é compacta e interativa, então você faz progresso constante e retoma exatamente de onde parou entre web e app.
Posso escrever e executar código nesta aula de Flutter Mobile Development?
Sim. Cada aula de Flutter Mobile Development inclui um editor de código integrado, então você escreve e executa código real direto no navegador e recebe feedback de IA instantaneamente — nenhuma configuração local necessária.
Todas as aulas deste curso
- Widgets sem estado versus com estado
- Widgets básicos de layout
- Elementos interativos da interface
- Criando Listas Roláveis com ListView