Flutter – Animation in Route Transition

Routes are simply Pages in Flutter applications. An application often needs to move from one page to another. But to make these transitions smoother, Animations can be used. These animations can be used to curve or tween the Animation object of the PageRouteBuilder class to alter the transition animation. We will discuss them in detail here.

Let’s just build a simple app to better understand the concept. Follow the below steps to do so:

• Add the PageRouteBuilder.
• Add a tween.
• Create an AnimatedWidget
• Create a CurveTween.
• Combine both tweens

Let’s discuss each step in detail:

Adding the PageRouteBuilder:

By using the PageRouteBuilder create two routes with the first route as the “Homepage” with a button “Goto page 2” and the second route with just an empty page named “Page 2”, using the below code:

Dart

import 'package:flutter/material.dart';

main() {
  runApp(const MaterialApp(
    home: Page1(),
  ));
}

class Page1 extends StatelessWidget {
  const Page1({Key? key}) : super(key: key);
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(),
      body: Center(
          child: ElevatedButton(
        onPressed: () {
          Navigator.of(context).push(_createRoute());
        },
        child: const Text('Go to Page 2'),
      )

          // RaisedButton is deprecated
          // We should use ElevatedButton instead

          // child: RaisedButton(
          // child: const Text('Go to Page 2'),
          // onPressed: () {
          //     Navigator.of(context).push(_createRoute());
          // },
          // ),
          ),
    );
  }
}

Route _createRoute() {
  return PageRouteBuilder(
    pageBuilder: (context, animation, secondaryAnimation) => const Page2(),
    transitionsBuilder: (context, animation, secondaryAnimation, child) {
      return child;
    },
  );
}

class Page2 extends StatelessWidget {
  const Page2({Key? key}) : super(key: key);
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(),
      body: const Center(
        child: Text('Page 2'),
      ),
    );
  }
}

Adding a tween:

You can build a tween of an animation object by using the below code :

Dart

transitionsBuilder: (context, animation, secondaryAnimation, child) {
  var begin = Offset(0.0, 1.0);
  var end = Offset.zero;
  var tween = Tween(begin: begin, end: end);
  var offsetAnimation = animation.drive(tween);
  return child;
},

Creating an AnimatedWidget:

The AnimatedWidget has the property of its state once the animation value changes. You can create one like below:

Dart

transitionsBuilder: (context, animation, secondaryAnimation, child) {
  var begin = Offset(0.0, 1.0);
  var end = Offset.zero;
  var tween = Tween(begin: begin, end: end);
  var offsetAnimation = animation.drive(tween);

  return SlideTransition(
    position: offsetAnimation,
    child: child,
  );
},

Creating a CurveTween:

Use the below code to create a CurveTween:

Dart

var curve = Curves.ease;

var curveTween = CurveTween(curve: curve);

Combining both Tweens:

Use the chain() method to combine two tweens as shown below:

Dart

var begin = Offset(0.0, 1.0);
var end = Offset.zero;
var curve = Curves.ease;

var tween = Tween(begin: begin, end: end).chain(CurveTween(curve: curve));

Now use the animation.drive() method to create an Animation object of the combined tweens as shown below:

Dart

return SlideTransition(
  position: animation.drive(tween),
  child: child,
);

Complete Source Code:

Dart

import 'package:flutter/material.dart';

main() {
  runApp(const MaterialApp(
    home: Homepage(),
  ));
}

class Homepage extends StatelessWidget {
  const Homepage({Key? key}) : super(key: key);
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('GeeksForGeeks'),
        backgroundColor: Colors.green,
      ),
      body: Center(
          child: ElevatedButton(
        onPressed: () {
          Navigator.of(context).push(_createRoute());
        },
        child: const Text('Go to Page 2'),
      )

          // RaisedButton is deprecated
          // We should use ElevatedButton instead

          // child: RaisedButton(
          // child: const Text('Go to Page 2'),
          // onPressed: () {
          //     Navigator.of(context).push(_createRoute());
          // },
          // ),

          ),
    );
  }
}

Route _createRoute() {
  return PageRouteBuilder(
    pageBuilder: (context, animation, secondaryAnimation) => const Page2(),
    transitionsBuilder: (context, animation, secondaryAnimation, child) {
      var begin = const Offset(0.0, 1.0);
      var end = Offset.zero;
      var curve = Curves.ease;

      var tween = Tween(begin: begin, end: end).chain(CurveTween(curve: curve));

      return SlideTransition(
        position: animation.drive(tween),
        child: child,
      );
    },
  );
}

class Page2 extends StatelessWidget {
  const Page2({Key? key}) : super(key: key);
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(),
      body: const Center(
        child: Text('Page 2'),
      ),
    );
  }
}

Output: