flutter_design_patterns/lib/main.dart

import 'package:flutter/material.dart';

void main() {
  runApp(const MyApp());
}

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
        useMaterial3: true,
      ),
      home: const MyHomePage(),
    );
  }
}

class LikeButtonDecorator extends StatelessWidget {
  const LikeButtonDecorator({super.key, required this.child, required this.height, required this.width});

  final Widget child;
  final double height, width;

  @override
  Widget build(BuildContext context) {
    return SizedBox(
      height: height,
      width: width,
      child: Stack(
        children: [
          Center(child: child),
          Padding(
            padding: const EdgeInsets.all(2.0),
            child: Align(
              alignment: Alignment.topRight,
              child: Container(
                padding: const EdgeInsets.all(3.0),
                decoration: const BoxDecoration(shape: BoxShape.circle, color: Colors.blue),
                child: const Icon(Icons.thumb_up, color: Colors.white, size: 16),
              ),
            ),
          ),
        ],
      ),
    );
  }
}

class AnimatedPulsingBorderDecorator extends StatefulWidget {
  const AnimatedPulsingBorderDecorator({super.key, required this.child});

  final Widget child;

  @override
  State<StatefulWidget> createState() => AnimatedPulsingBorderDecoratorState();
}

class AnimatedPulsingBorderDecoratorState extends State<AnimatedPulsingBorderDecorator>
    with SingleTickerProviderStateMixin {
  late final AnimationController controller;
  late final Animation<double> paddingAnimation;

  @override
  void initState() {
    super.initState();
    controller = AnimationController(
      duration: const Duration(milliseconds: 750),
      vsync: this,
    );
    paddingAnimation = Tween<double>(begin: 0.0, end: 3.0).animate(controller);
    controller.repeat(reverse: true);
  }

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

  @override
  Widget build(BuildContext context) {
    return AnimatedBuilder(
      builder: (context, _) {
        return Container(
          padding: EdgeInsets.all(paddingAnimation.value),
          decoration: BoxDecoration(color: Colors.amber, borderRadius: BorderRadius.circular(15.0)),
          child: widget.child,
        );
      },
      animation: paddingAnimation,
    );
  }
}

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

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Theme.of(context).colorScheme.inversePrimary,
        title: const Text('Decorator'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            const Text(
              'Decorators!!',
            ),
            LikeButtonDecorator(
                height: 30,
                width: 160,
                child: ElevatedButton(
                  onPressed: () {},
                  child: const SizedBox(
                    height: 30,
                    width: 160,
                    child: Center(child: Text('Like Me!')),
                  ),
                )),
            const SizedBox(height: 20),
            AnimatedPulsingBorderDecorator(
                child: ElevatedButton(onPressed: () {}, child: const Text('Pulsing goodness!!')))
          ],
        ),
      ),
    );
  }
}