In Flutter, controlling the visibility of widgets based on conditions is essential for creating dynamic and responsive user interfaces. The Visibility widget allows you to show or hide a single widget by setting its visible property to true or false based on a condition. This is particularly useful for optimizing screen space and enhancing user experience by displaying only relevant information.
For example, you can hide a loading spinner once data is loaded or show a message only when a user is logged in. This flexibility ensures that your app adapts to different scenarios, making it more interactive and user-friendly.
flutter create visibility_demo.cd visibility_demo.main.dart:
import 'package:flutter/material.dart';
void main() {
runApp(const MyApp());
}
class MyApp extends StatelessWidget {
const MyApp({Key? key}) : super(key: key);
@override
Widget build(BuildContext context) {
return MaterialApp(
home: const MyHomePage(),
);
}
}
class MyHomePage extends StatefulWidget {
const MyHomePage({Key? key}) : super(key: key);
@override
State<MyHomePage> createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
bool _isVisible = true;
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: const Text('Visibility Demo'),
),
body: Center(
child: Visibility(
visible: _isVisible,
child: Container(
width: 100,
height: 100,
color: Colors.blue,
),
),
),
floatingActionButton: FloatingActionButton(
onPressed: () {
setState(() {
_isVisible = !_isVisible;
});
},
child: Icon(_isVisible ? Icons.visibility : Icons.visibility_off),
),
);
}
}
flutter run in the terminal to start the app.This setup will create a simple Flutter app where a blue box’s visibility toggles when the floating action button is pressed.
Here’s how you can implement conditional visibility for a single widget using the Visibility widget in Flutter:
Set up a new Flutter project:
flutter create visibility_example
cd visibility_example
Import necessary packages:
import 'package:flutter/material.dart';
Define a boolean variable to track visibility:
bool isWidgetVisible = true;
Create the widget you want to conditionally show or hide:
Widget myWidget = Container(
width: 200,
height: 200,
color: Colors.blue,
);
Use the Visibility widget to conditionally show or hide the widget:
Visibility(
visible: isWidgetVisible,
child: myWidget,
);
Implement a button to toggle the visibility:
ElevatedButton(
onPressed: () {
setState(() {
isWidgetVisible = !isWidgetVisible;
});
},
child: Text('Toggle Widget Visibility'),
);
Combine everything in a StatefulWidget:
class MyHomePage extends StatefulWidget {
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
bool isWidgetVisible = true;
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Visibility Example'),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Visibility(
visible: isWidgetVisible,
child: Container(
width: 200,
height: 200,
color: Colors.blue,
),
),
SizedBox(height: 20),
ElevatedButton(
onPressed: () {
setState(() {
isWidgetVisible = !isWidgetVisible;
});
},
child: Text('Toggle Widget Visibility'),
),
],
),
),
);
}
}
This code sets up a simple Flutter app where a blue container’s visibility can be toggled using a button.
To control the visibility of a widget in Flutter using boolean conditions, you can use the Visibility widget. Here’s a concise example:
Import necessary packages:
import 'package:flutter/material.dart';
Define a boolean variable to track visibility:
bool isWidgetVisible = true;
Create the widget you want to conditionally show or hide:
Widget myWidget = Container(
width: 200,
height: 200,
color: Colors.blue,
);
Use the Visibility widget to control visibility:
Visibility(
visible: isWidgetVisible,
child: myWidget,
);
Implement a button to toggle visibility:
ElevatedButton(
onPressed: () {
setState(() {
isWidgetVisible = !isWidgetVisible;
});
},
child: Text('Toggle Widget Visibility'),
);
Complete example in a stateful widget:
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
home: MyHomePage(),
);
}
}
class MyHomePage extends StatefulWidget {
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
bool isWidgetVisible = true;
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Visibility Example'),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Visibility(
visible: isWidgetVisible,
child: Container(
width: 200,
height: 200,
color: Colors.blue,
),
),
SizedBox(height: 20),
ElevatedButton(
onPressed: () {
setState(() {
isWidgetVisible = !isWidgetVisible;
});
},
child: Text('Toggle Widget Visibility'),
),
],
),
),
);
}
}
This code demonstrates how to use a boolean condition to control the visibility of a widget in Flutter. The Visibility widget’s visible property is set based on the boolean variable isWidgetVisible, which is toggled by pressing the button.
Here’s how you can create toggle buttons to dynamically change the visibility of a widget in Flutter:
Set up a boolean variable to track the visibility state:
bool isWidgetVisible = true;
Use the Visibility widget to conditionally show or hide the widget:
Visibility(
visible: isWidgetVisible,
child: Container(
width: 200,
height: 200,
color: Colors.blue,
),
);
Create a button to toggle the visibility:
ElevatedButton(
onPressed: () {
setState(() {
isWidgetVisible = !isWidgetVisible;
});
},
child: Text('Toggle Widget Visibility'),
);
Combine everything in your widget tree:
@override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: [
Visibility(
visible: isWidgetVisible,
child: Container(
width: 200,
height: 200,
color: Colors.blue,
),
),
ElevatedButton(
onPressed: () {
setState(() {
isWidgetVisible = !isWidgetVisible;
});
},
child: Text('Toggle Widget Visibility'),
),
],
),
),
);
}
This setup allows you to toggle the visibility of a single widget using a button.
Here are the steps:
Set up a new Flutter project:
flutter create visibility_test_app
Import necessary packages:
import 'package:flutter/material.dart';
Define a boolean variable to track visibility:
bool isWidgetVisible = true;
Wrap the widget you want to hide/show with the Visibility widget:
Visibility(
visible: isWidgetVisible,
child: YourWidget(),
);
Create a button to toggle visibility:
ElevatedButton(
onPressed: () {
setState(() {
isWidgetVisible = !isWidgetVisible;
});
},
child: Text('Toggle Visibility'),
);
Run the app and test the visibility toggle.
That’s it! This will allow you to hide or show a widget based on a condition in your Flutter app.
You can use the Visibility widget from the material library.
The Visibility widget takes two properties: visible and child. The visible property is a boolean that determines whether the child widget should be displayed or not.
Visibility( visible: isWidgetVisible, child: YourWidget(),);In this code, isWidgetVisible is a boolean variable that tracks whether the widget should be visible or not. When isWidgetVisible is true, the widget will be displayed; when it’s false, the widget will be hidden.
ElevatedButton( onPressed: () { setState(() { isWidgetVisible = !isWidgetVisible; }); }, child: Text('Toggle Visibility'),);This code will toggle the visibility of the widget every time the button is pressed.
Overall, using the Visibility widget with conditions is a powerful way to dynamically control the visibility of widgets in Flutter and create more interactive and user-friendly interfaces.