1import 'package:flutter/material.dart';
2 
3/// Implicit animation example showing basic fade animation
4///
5/// This example demonstrates:
6/// - AnimatedOpacity for fade in/out
7/// - State-driven animation triggers
8/// - Simple, declarative animation code
9 
10void main() => runApp(const ImplicitAnimationApp());
11 
12class ImplicitAnimationApp extends StatelessWidget {
13  const ImplicitAnimationApp({super.key});
14 
15  @override
16  Widget build(BuildContext context) {
17    return MaterialApp(
18      title: 'Implicit Animation',
19      theme: ThemeData(
20        colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
21      ),
22      home: const FadeExample(),
23    );
24  }
25}
26 
27class FadeExample extends StatefulWidget {
28  const FadeExample({super.key});
29 
30  @override
31  State<FadeExample> createState() => _FadeExampleState();
32}
33 
34class _FadeExampleState extends State<FadeExample> {
35  bool _visible = true;
36 
37  @override
38  Widget build(BuildContext context) {
39    return Scaffold(
40      appBar: AppBar(title: const Text('Implicit Fade')),
41      body: Center(
42        child: Column(
43          mainAxisAlignment: MainAxisAlignment.center,
44          children: [
45            AnimatedOpacity(
46              opacity: _visible ? 1.0 : 0.0,
47              duration: const Duration(milliseconds: 500),
48              curve: Curves.easeInOut,
49              child: const FlutterLogo(size: 100),
50            ),
51            const SizedBox(height: 20),
52            ElevatedButton(
53              onPressed: () => setState(() => _visible = !_visible),
54              child: Text(_visible ? 'Fade Out' : 'Fade In'),
55            ),
56          ],
57        ),
58      ),
59    );
60  }
61}
62 
63/// AnimatedContainer example - animating multiple properties
64class AnimatedContainerExample extends StatefulWidget {
65  const AnimatedContainerExample({super.key});
66 
67  @override
68  State<AnimatedContainerExample> createState() =>
69      _AnimatedContainerExampleState();
70}
71 
72class _AnimatedContainerExampleState extends State<AnimatedContainerExample> {
73  bool _expanded = false;
74 
75  @override
76  Widget build(BuildContext context) {
77    return Scaffold(
78      appBar: AppBar(title: const Text('Animated Container')),
79      body: Center(
80        child: Column(
81          mainAxisAlignment: MainAxisAlignment.center,
82          children: [
83            AnimatedContainer(
84              duration: const Duration(milliseconds: 300),
85              curve: Curves.easeInOut,
86              width: _expanded ? 200 : 100,
87              height: _expanded ? 200 : 100,
88              decoration: BoxDecoration(
89                color: _expanded ? Colors.blue : Colors.red,
90                borderRadius: BorderRadius.circular(_expanded ? 20 : 8),
91              ),
92              child: const FlutterLogo(),
93            ),
94            const SizedBox(height: 20),
95            ElevatedButton(
96              onPressed: () => setState(() => _expanded = !_expanded),
97              child: Text(_expanded ? 'Shrink' : 'Expand'),
98            ),
99          ],
100        ),
101      ),
102    );
103  }
104}
105 
106/// TweenAnimationBuilder example - custom tween without boilerplate
107class TweenAnimationBuilderExample extends StatefulWidget {
108  const TweenAnimationBuilderExample({super.key});
109 
110  @override
111  State<TweenAnimationBuilderExample> createState() =>
112      _TweenAnimationBuilderExampleState();
113}
114 
115class _TweenAnimationBuilderExampleState
116    extends State<TweenAnimationBuilderExample> {
117  bool _animated = false;
118 
119  @override
120  Widget build(BuildContext context) {
121    return Scaffold(
122      appBar: AppBar(title: const Text('Tween Animation Builder')),
123      body: Center(
124        child: Column(
125          mainAxisAlignment: MainAxisAlignment.center,
126          children: [
127            TweenAnimationBuilder<double>(
128              tween: Tween<double>(begin: 0, end: 1),
129              duration: const Duration(seconds: 1),
130              curve: Curves.easeInOut,
131              builder: (context, value, child) {
132                return Opacity(
133                  opacity: value,
134                  child: Transform.scale(scale: value, child: child),
135                );
136              },
137              child: const FlutterLogo(size: 100),
138            ),
139            const SizedBox(height: 20),
140            ElevatedButton(
141              onPressed: () => setState(() => _animated = !_animated),
142              child: const Text('Animate'),
143            ),
144          ],
145        ),
146      ),
147    );
148  }
149}
150