Building a Responsive Login Page with Flutter
As a cross-platform application framework, Flutter enables you to develop apps that look and feel great on any platform using a single codebase. With the release of Flutter 3.0, Windows, macOS, and web platforms are now completely stable. This means that when developing an app for these platforms, you must take into account different device specifications and ensure that the appeal of your app is consistent and provides users with a seamless experience.
Understanding Responsive Design
To achieve responsiveness in your app, you need to consider the different screen sizes and orientations of various devices. Fortunately, Flutter provides a variety of widgets and classes to help you create responsive layouts, including MediaQuery, LayoutBuilder, Expanded, Flexible, and AspectRatio.
Approaches to Responsive Design
In this article, we’ll explore two main approaches to building a responsive login page using Flutter: MediaQuery and LayoutBuilder. We’ll also examine how to use these approaches to create a responsive login page that looks great on all platforms.
MediaQuery Class
The MediaQuery class has a .of method that takes in a context and gives you access to the size (width/height) and orientation (portrait/landscape) of your current app. Here’s an example:
dart
MediaQuery.of(context).size.width
LayoutBuilder Class
The LayoutBuilder class has a builder property that allows you to access a BoxConstraint object. This object contains constraint information for a specific widget, which can be used to calculate the widget’s maximum width and height. Here’s an example:
dart
LayoutBuilder(
builder: (context, constraints) {
return Container(
width: constraints.maxWidth,
height: constraints.maxHeight,
);
},
)
Building a Responsive Login Page
To build a responsive login page, we’ll use the LayoutBuilder class to create a widget that adapts to different screen sizes. We’ll also use the MediaQuery class to get the current screen size and orientation.
Here’s an example of how to use these classes to build a responsive login page:
dart
class LoginScreen extends StatelessWidget {
@override
Widget build(BuildContext context) {
return LayoutBuilder(
builder: (context, constraints) {
if (constraints.maxWidth < 600) {
return LoginMobile();
} else if (constraints.maxWidth < 900) {
return LoginTablet();
} else {
return LoginDesktop();
}
},
);
}
}
Login Mobile
The LoginMobile widget is designed for small screens and contains a simple login form with a email and password field, as well as a button to submit the form.
dart
class LoginMobile extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Column(
children: [
TextFormField(
decoration: InputDecoration(
labelText: 'Email',
),
),
TextFormField(
decoration: InputDecoration(
labelText: 'Password',
),
),
SizedBox(height: 20),
ElevatedButton(
onPressed: () {},
child: Text('Login'),
),
],
);
}
}
Login Desktop
The LoginDesktop widget is designed for large screens and contains a split screen with an image and a login form.
dart
class LoginDesktop extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Row(
children: [
Expanded(
child: Image.asset('assets/image.jpg'),
),
Expanded(
child: LoginMobile(),
),
],
);
}
}
By using the LayoutBuilder and MediaQuery classes, we’ve created a responsive login page that adapts to different screen sizes and orientations.