Flutter - Fade a Widget In and Out
Last Updated : 16 Oct, 2023
The AnimatedOpacity widget in Flutter allows you to animate the opacity (transparency) of a child widget. You can use it to smoothly fade in or out a widget. In this article, we are going to implement the AnimatedOpacity Widget in Flutter and see the basic syntax of it. A sample video is given below to get an idea about what we are going to do in this article.
Basic Syntax of AnimatedOpacity Widget
AnimatedOpacity(
duration: const Duration(milliseconds: 300), // Duration for the opacity animation
opacity: 0.5, // Opacity value (0.0 to 1.0) to control visibility
child: YourChildWidget(), // The widget you want to animate
)
Required Tools
To build this app, you need the following items installed on your machine:
- Visual Studio Code / Android Studio
- Android Emulator / iOS Simulator / Physical Device device.
- Flutter Installed
- Flutter plugin for VS Code / Android Studio.
Step By Step Implementation
Step 1: Create a New Project in Android Studio
To set up Flutter Development on Android Studio please refer to Android Studio Setup for Flutter Development, and then create a new project in Android Studio please refer to Creating a Simple Application in Flutter.
Step 2: Import the Package
First of all import material.dart file.
import 'package:flutter/material.dart';
Step 3: Execute the main Method
Here the execution of our app starts.
Dart void main() { runApp(MyApp()); } Step 4: Create MyApp Class
In this class we are going to implement the MaterialApp , here we are also set the Theme of our App.
Dart class MyApp extends StatelessWidget { @override Widget build(BuildContext context) { return MaterialApp( title: 'AnimatedOpacity Example', // App title theme: ThemeData( primarySwatch: Colors.green, // App's primary theme color ), debugShowCheckedModeBanner: false, home: AnimatedOpacityExample(), // Main home page ); } } Step 5: Create AnimatedOpacityExample Class
In this class we are going to Implement the AnimatedOpacity widget . Comments are added for better understanding.
AnimatedOpacity(
duration: Duration(seconds: 1), // Animation duration
opacity: _isVisible ? 1.0 : 0.0, // Opacity value based on visibility
child: Container(
width: 200,
height: 200,
color: Colors.blue, // Color of the box
child: Center(
child: Text(
'Fading Box', // Text displayed inside the box
style: TextStyle(
color: Colors.white, // Text color
fontSize: 20.0, // Text font size
),
),
),
),
),
Dart class AnimatedOpacityExample extends StatefulWidget { @override _AnimatedOpacityExampleState createState() => _AnimatedOpacityExampleState(); } class _AnimatedOpacityExampleState extends State<AnimatedOpacityExample> { bool _isVisible = true; // A variable to control the visibility of the box void _toggleVisibility() { setState(() { _isVisible = !_isVisible; // Toggle the visibility when the button is pressed }); } @override Widget build(BuildContext context) { return Scaffold( appBar: AppBar( title: Text('AnimatedOpacity Example'), // AppBar title ), body: Center( child: Column( mainAxisAlignment: MainAxisAlignment.center, children: <Widget>[ AnimatedOpacity( duration: Duration(seconds: 1), // Animation duration opacity: _isVisible ? 1.0 : 0.0, // Opacity value based on visibility child: Container( width: 200, height: 200, color: Colors.blue, // Color of the box child: Center( child: Text( 'Fading Box', // Text displayed inside the box style: TextStyle( color: Colors.white, // Text color fontSize: 20.0, // Text font size ), ), ), ), ), SizedBox(height: 20), // SizedBox for spacing ElevatedButton( onPressed: _toggleVisibility, // Call _toggleVisibility when the button is pressed child: Text(_isVisible ? 'Hide' : 'Show'), // Button text ), ], ), ), ); } } Here is the full Code of main.dart file
Dart import 'package:flutter/material.dart'; void main() { runApp(MyApp()); } class MyApp extends StatelessWidget { @override Widget build(BuildContext context) { return MaterialApp( title: 'AnimatedOpacity Example', // App title theme: ThemeData( primarySwatch: Colors.green, // App's primary theme color ), debugShowCheckedModeBanner: false, home: AnimatedOpacityExample(), // Main home page ); } } class AnimatedOpacityExample extends StatefulWidget { @override _AnimatedOpacityExampleState createState() => _AnimatedOpacityExampleState(); } class _AnimatedOpacityExampleState extends State<AnimatedOpacityExample> { bool _isVisible = true; // A variable to control the visibility of the box void _toggleVisibility() { setState(() { _isVisible = !_isVisible; // Toggle the visibility when the button is pressed }); } @override Widget build(BuildContext context) { return Scaffold( appBar: AppBar( title: Text('AnimatedOpacity Example'), // AppBar title ), body: Center( child: Column( mainAxisAlignment: MainAxisAlignment.center, children: <Widget>[ AnimatedOpacity( duration: Duration(seconds: 1), // Animation duration opacity: _isVisible ? 1.0 : 0.0, // Opacity value based on visibility child: Container( width: 200, height: 200, color: Colors.blue, // Color of the box child: Center( child: Text( 'Fading Box', // Text displayed inside the box style: TextStyle( color: Colors.white, // Text color fontSize: 20.0, // Text font size ), ), ), ), ), SizedBox(height: 20), // SizedBox for spacing ElevatedButton( onPressed: _toggleVisibility, // Call _toggleVisibility when the button is pressed child: Text(_isVisible ? 'Hide' : 'Show'), // Button text ), ], ), ), ); } } Output:
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