Flutter Widgets Cheatsheet: Categories, Types and Basic Widgets

Flutter is Google’s UI toolkit for crafting beautiful, natively compiled iOS and Android apps using a single code base. The Flutter app is designed using widgets – These are the basic building blocks of every Flutter application. Widgets describe what the app UI should look like given its current configuration and state.

There are multiple Flutter widgets, the articles give you a quick look into the basic Flutter widgets, types, and categories. 

Flutter has become a star in the eyes of Android and iOS developers by empowering them to build cross-platform apps using a single codebase. The technology seems to be successfully overcoming the three big challenges in app development. 

• There is no need to have separate teams for Android and iOS development, just hire one team and implement the cross-platform development functionality of Flutter. 
• Improves productivity and speeds up development with Dart’s “Just in Time” and “Ahead of  Time” compilation. And thus it helps to reduce the development cost to half.
• Unlike other cross-platform options, Flutter makes the app more beautiful, stable, and consistent. 

All that brings much relief for the developer's community as they now have more time for creative things in app development. 

Well, now we know how useful Flutter is for smoothly building beautiful cross-platform apps. Let's know about the basic building blocks of the Flutter application known as Flutter widgets. 

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Flutter Widgets: 

Each element on the Flutter UI is a widget such as text, container, image, button, animations, and motions. So, the view of a screen completely depends on the choice and the sequence of the Flutter widgets used in building the application. Therefore the structure formed by the application code is called a tree of widgets. 

These widgets can be classified into the following fourteen  categories according to the functionality they provide in the Flutter application.

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Flutter Widget types

In general Flutter widgets are classified into two categories,

1. Stateless Widget
2. Stateful Widget

However, you can find more classes in the hierarchy of Flutter sources. 

• StatelessWidget: The widget does not require a mutable state. 

• StatefulWidget: The widget has a mutable state i.e state information can be read synchronously when it is built and it may change during the widget's lifetime. Therefore it's essential to ensure that the state is promptly notified when the change occurs using setState.   

• ProxyWidget: The Widget has a child widget provided to it, instead of building a new widget. It is useful as a base class for other widgets like InheritedWidget and ParentDataWidget. 

• RenderObjectWidget: It provides the configuration for the RenderObjectElements, which wrap RenderObjects, that provide the actual rendering of the application.

• InheritedWidget: It is a base class for widgets that efficiently propagates information down the tree. To obtain the near instance of a particular type of inherited widget from a build context, use BuildContext.dependOnInheritedWidgetOfExactType.

• When referenced in this way, it causes the consumer to rebuild when the inherited widget itself changes state. 

• ParentDataWidget:  It is a base class for a widget that hooks ParentData information to children of RenderObjectWidgets.  It is used to provide a per-child configuration for RenderObjectWidgets  with more than one child.  

• LeafRenderObjectWidget: It is a superclass for RenderObjectWidgets that configure RenderObject subclasses that have no children.

• SingleChildRenderObjectWidget: It is a superclass for RenderObjectWidgets that configure RenderObject subclasses that have a single child slot.

• MultiChildRenderObjetWidget: It is a superclass for RenderObjectWidgets that configure RenderObject subclasses that have a single list of children.

• _NullWidget: Zero cost widget. Use it when you need a placeholder.

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Most commonly used Flutter Widgets with the example 

1. Appbar

A Material Design app bar. An app bar consists of a toolbar and potentially other widgets, such as a TabBar and a FlexibleSpaceBar.

Example:

1     import 'package:flutter/material.dart';
2     

1     void main() {
2      runApp(gfgApp()); //MaterialApp
3    }
4    
5    MaterialApp gfgApp() {
6      return MaterialApp(
7        home: Scaffold(
8          appBar: AppBar(
9            title: const Text('My demo app'),
10          ), //AppBar
11          body: const Center(
12            child: Text(
13              'Hello Geeks',
14              style: TextStyle(fontSize: 24),
15            ), //Text
16          ), // center
17        ), //Scaffold
18        debugShowCheckedModeBanner: false, //Removing Debug Banner
19      );
20    }
21    
22     

Output:

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2. Column

Layout a list of child widgets in the vertical direction.

Example:

1     import 'package:flutter/material.dart';
2    
3    
4    //function to trigger build
5    void main() {
6      runApp(const MyApp());
7    }
8    
9    
10    class MyApp extends StatelessWidget {
11      const MyApp({Key? key}) : super(key: key);
12    
13    
14      @override
15      Widget build(BuildContext context) {
16        return MaterialApp(
17          title: 'My Demo App',
18          theme: ThemeData(
19            primarySwatch: Colors.blue,
20          ), // ThemeData
21          home: const MyHomePage(),
22          debugShowCheckedModeBanner: false,
23        ); // MaterialApp
24      }
25    }
26    
27    
28    class MyHomePage extends StatefulWidget {
29      const MyHomePage({Key? key}) : super(key: key);
30    
31    
32      @override
33    // ignore: library_private_types_in_public_api
34      _MyHomePageState createState() => _MyHomePageState();
35    }
36    
37    
38    class _MyHomePageState extends State 

Output:

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3. Container

 A convenience widget that combines common painting, positioning, and sizing widgets.

Example:

1     import 'package:flutter/material.dart';
2    
3    void main() => runApp(const MyApp());
4    
5    class MyApp extends StatelessWidget {
6    const MyApp({Key? key}) : super(key: key);
7    
8    @override
9    Widget build(BuildContext context) {
10      return MaterialApp(
11      home: Scaffold(
12        appBar: AppBar(
13        title: const Text("Container example"),
14        ),
15        body: Container(
16        child:const Text("Hello! i am inside a container!",
17          style: TextStyle(fontSize: 20)),
18        ),
19      ),
20      );
21    }
22    }
23    
24     

Output: 

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4. ElevatedButton

A Material Design elevated button. A filled button whose material elevates when pressed.

Example: 

1     ElevatedButton(
2              child: Text('Elevated Button'),
3              style: ElevatedButton.styleFrom(
4                primary: Colors.blue,
5              ),
6              onPressed: () {},
7            ), 

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5. FlutterLogo

The Flutter logo, in the widget form. This widget respects the IconTheme.

Example:

1     import 'package:flutter/material.dart';
2     
3    //Material design library
4    void main() {
5    runApp(
6      //widget tree starts here
7      MaterialApp(
8      home: Scaffold(
9        appBar: AppBar(
10        leading: Container(
11          color: Colors.white,
12          padding: EdgeInsets.all(3),
13          /** FlutterLogo Widget **/
14          child: FlutterLogo(
15          size: 10,
16          ), //FlutterLogo
17        ), //Container
18        title: Text('Hello Dev'),
19        backgroundColor: Colors.blueAccent[400],
20        centerTitle: true,
21        ), //AppBar
22        body: Center(
23        child: Container(
24          /** FlutterLogo Widget **/
25          child: FlutterLogo(
26          size: 300,
27          textColor: Colors.blue,
28          style: FlutterLogoStyle.stacked,
29          ), //FlutterLogo
30        ), //Container
31        ), //Center
32      ), //Scaffold
33      ), //MaterialApp
34    );
35    }
36    
37     

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6. Icon

A Material Design icon.

Example:

1     import 'package:flutter/material.dart';
2     
3    void main() => runApp(const MyApp());
4     
5    /// main application widget
6    class MyApp extends StatelessWidget {
7      const MyApp({Key? key}) : super(key: key);
8     
9      static const String _title = 'Flutter Application';
10     
11      @override
12      Widget build(BuildContext context) {
13        return MaterialApp(
14          title: _title,
15          home: Scaffold(
16            appBar: AppBar(title: const Text(_title)),
17            body: const MyStatelessWidget(),
18          ),
19        );
20      }
21    }
22     
23    /// stateless widget that the main application instantiates
24    class MyStatelessWidget extends StatelessWidget {
25      const MyStatelessWidget({Key? key}) : super(key: key);
26     
27      @override
28      Widget build(BuildContext context) {
29        return Column(
30          crossAxisAlignment: CrossAxisAlignment.stretch,
31          children: const  

Output:

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7. Image

 A widget that displays an image.

Example:

1     import 'package:flutter/material.dart';  
2     
3    void main() => runApp(MyApp());  
4     
5    class MyApp extends StatelessWidget {  
6      @override  
7      Widget build(BuildContext context) {  
8        return MaterialApp(  
9          home: Scaffold(  
10            appBar: AppBar(  
11                title: Text('Flutter Image Demo'),  
12            ),  
13            body: Center(  
14              child: Column(  
15                children:  

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8. Placeholder

A widget that draws a box that represents where other widgets will one day be added.

Example:

1      SizedBox(height: 10),
2                Container(
3                  height: 100,
4                  child: Placeholder(color: RED),
5                ),
6     

 Output:

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9. Row

 Layout a list of child widgets in the horizontal direction.

Example:

1     import 'package:flutter/material.dart';
2    
3    
4    //function to trigger build
5    void main() {
6      runApp(const MyApp());
7    }
8    
9    
10    class MyApp extends StatelessWidget {
11      const MyApp({Key? key}) : super(key: key);
12    
13    
14      @override
15      Widget build(BuildContext context) {
16        return MaterialApp(
17          title: 'My Demo App',
18          theme: ThemeData(
19            primarySwatch: Colors.blue,
20          ), // ThemeData
21          home: const MyHomePage(),
22          debugShowCheckedModeBanner: false,
23        ); // MaterialApp
24      }
25    }
26    
27    
28    class MyHomePage extends StatefulWidget {
29      const MyHomePage({Key? key}) : super(key: key);
30    
31    
32      @override
33    // ignore: library_private_types_in_public_api
34      _MyHomePageState createState() => _MyHomePageState();
35    }
36    
37    
38    class _MyHomePageState extends State 

Output:

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‍10. Text

A run of text with a single style.

Example:

1     import 'package:flutter/cupertino.dart';
2    import 'package:flutter/gestures.dart';
3    import 'package:flutter/material.dart';
4     
5    void main() {
6      runApp(MyApp());
7    }
8     
9    class MyApp extends StatelessWidget {
10      @override
11      Widget build(BuildContext context) {
12        return MaterialApp(
13          home: Scaffold(
14            appBar: AppBar(
15              title: Text("Flutter Text Widget"),
16            ),
17            body: Text("This is text"),
18          ),
19        );
20      }
21    }
22    
23     

Output:

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Also, read our article on medium to know about the popular animation widgets for creating an intuitive UI. 

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Summing up: 

And here you have it; everything about the Flutter widgets!! Hope you find it useful to get a quick view of Flutter's basic widgets, categories, and types. 

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