flutter/examples/api/lib/widgets/transitions/size_transition.0.dart

// Copyright 2014 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'package:flutter/material.dart';

/// Flutter code sample for [SizeTransition].

void main() => runApp(const SizeTransitionExampleApp());

class SizeTransitionExampleApp extends StatelessWidget {
  const SizeTransitionExampleApp({super.key});

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      home: SizeTransitionExample(),
    );
  }
}

class SizeTransitionExample extends StatefulWidget {
  const SizeTransitionExample({super.key});

  @override
  State<SizeTransitionExample> createState() => _SizeTransitionExampleState();
}

/// [AnimationController]s can be created with `vsync: this` because of
/// [TickerProviderStateMixin].
class _SizeTransitionExampleState extends State<SizeTransitionExample> with TickerProviderStateMixin {
  late final AnimationController _controller = AnimationController(
    duration: const Duration(seconds: 3),
    vsync: this,
  )..repeat();
  late final Animation<double> _animation = CurvedAnimation(
    parent: _controller,
    curve: Curves.fastOutSlowIn,
  );

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SizeTransition(
        sizeFactor: _animation,
        axis: Axis.horizontal,
        axisAlignment: -1,
        child: const Center(
          child: FlutterLogo(size: 200.0),
        ),
      ),
    );
  }
}