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What is widgets in Flutter?
  • Difficulty Level : Expert
  • Last Updated : 17 Nov, 2020

Flutter is Google’s UI toolkit for crafting beautiful, natively compiled iOS and Android apps from a single code base. To build any application we start with widgets – The building block of flutter applications. Widgets describe what their view should look like given their current configuration and state. It includes a text widget, row widget, column widget, container widget, and many more. 

Widgets: Each element on a screen of the Flutter app is a widget. The view of the screen completely depends upon the choice and sequence of the widgets used to build the app. And the structure of the code of an app is a tree of widgets. 

Category of Widgets: There are mainly 14 categories in which the flutter widgets are divided. They are mainly segregated on the basis of the functionality they provide in a flutter application.

  1. Accessibility: These are the set of widgets that make a flutter app more easily accessible.
  2. Animation and Motion: These widgets add animation to other widgets.
  3. Assets, Images, and Icons: These widgets take charge of assets such as display images and show icons.
  4. Async: These provide async functionality in the flutter application.
  5. Basics: These are the bundle of widgets which are absolutely necessary for the development of any flutter application.
  6. Cupertino: These are the ios designed widgets.
  7. Input: This set of widgets provide input functionality in a flutter application.
  8. Interaction Models: These widgets are here to manage touch events and route users to different views in the application.
  9.  Layout: This bundle of widgets helps in placing the other widgets on the screen as needed.
  10. Material Components: This is a set of widgets that mainly follow material design by Google.
  11. Painting and effects: This is the set of widgets which apply visual changes to their child widgets without changing their layout or shape.
  12. Scrolling: This provides sacrollability of to a set of other widgets that are not scrollable by default.
  13. Styling: This deals with the theme, responsiveness, and sizing of the app.
  14. Text: This display text.

Types of Widgets: There are broadly two types of widgets in the flutter: 

  1. Stateless Widget
  2. Stateful Widget

Example: The Layout Tree of basic app screen: 



Dart




import 'package:flutter/material.dart';
 
void main() => runApp(GeeksforGeeks()); 
 
class GeeksforGeeks extends StatelessWidget { 
  @override 
  Widget build(BuildContext context) { 
    return MaterialApp( home: Scaffold( backgroundColor: Colors.lightGreen,
                                       appBar: AppBar( backgroundColor: Colors.green,
                                       title: Text("GeeksforGeeks"), ),
                                        
   body: Container( child: Center( child: Text("Hello Geeks!!"), ), ), ), ); } } 

 
 

Description of the Widgets Used: 

  • Scaffold – Implements the basic material design visual layout structure.
  • AppBar – To create a bar at the top of the screen.
  • Text  To write anything on the screen.
  • Container – To contain any widget.
  • Center – To provide center alignment to other widgets.

Output: 
 

 

Widgets in Flutter Example

 

 

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