animated_size_sample.dart

/// Flutter code sample for AnimatedSize

// This example makes a [Container] react to being touched, causing the child
// of the [AnimatedSize] widget, here a [FlutterLogo], to animate.

import 'package:flutter/material.dart';

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

/// This is the main application widget.
class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  static const String _title = 'Flutter Code Sample';

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: _title,
      home: Scaffold(
        appBar: AppBar(title: const Text(_title)),
        body: const Center(
          child: MyStatefulWidget(),
        ),
      ),
    );
  }
}

/// This is the stateful widget that the main application instantiates.
class MyStatefulWidget extends StatefulWidget {
  const MyStatefulWidget({Key? key}) : super(key: key);

  @override
  State<MyStatefulWidget> createState() => _MyStatefulWidgetState();
}

/// This is the private State class that goes with MyStatefulWidget.
class _MyStatefulWidgetState extends State<MyStatefulWidget>
    with SingleTickerProviderStateMixin {
  double _size = 50.0;
  bool _large = false;

  void _updateSize() {
    setState(() {
      _size = _large ? 250.0 : 100.0;
      _large = !_large;
    });
  }

  @override
  Widget build(BuildContext context) {
    return GestureDetector(
      onTap: () => _updateSize(),
      child: Container(
        color: Colors.amberAccent,
        child: AnimatedSize(
          vsync: this,
          curve: Curves.easeIn,
          duration: const Duration(seconds: 1),
          child: FlutterLogo(size: _size),
        ),
      ),
    );
  }
}