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Flutter Mobile Development · レッスン

明示的アニメーションとHero

`AnimationController`と`Tween`を使った明示的アニメーションを習得し、Heroウィジェットで魅力的な共有要素遷移を作成します。

「明示的アニメーションとHero」はCoddyKit上の無料Flutter Mobile Developmentレッスンです。 これはレッスン3/4です。 下記で完全なレッスンを無料で読むことができます。その後、ブラウザ内の組み込みコードエディタと24時間対応のAIチューターでハンズオン演習できます。 これはFlutter Mobile Development学習パスの一部であり、ウェブとCoddyKitアプリ全体で進捗が同期されます。 Flutter Mobile Developmentコースには全4レッスンが含まれています。

このレッスンの一部はまだ翻訳されておらず、英語で表示されています。

Intro to Explicit Animations

Welcome to explicit animations! Unlike implicit animations (which animate automatically when properties change), explicit animations give you full control.

You define how and when an animation runs, its duration, and its curve. This is powerful for complex, custom effects.

AnimationController: The Conductor

At the heart of explicit animations is the AnimationController. Think of it as the conductor of an orchestra, managing the animation's playback.

  • It generates a new value every frame.
  • It controls the animation's duration.
  • It can be forwarded, reversed, or repeated.

It needs a TickerProviderStateMixin to synchronize with the screen refresh rate.

Setting Up AnimationController

You typically initialize an AnimationController in your widget's initState and dispose of it in dispose to prevent memory leaks.

Here's a basic setup:

import 'package:flutter/material.dart';

class MyAnimationScreen extends StatefulWidget {
  @override
  _MyAnimationScreenState createState() => _MyAnimationScreenState();
}

class _MyAnimationScreenState extends State<MyAnimationScreen> with SingleTickerProviderStateMixin {
  late AnimationController _controller;

  @override
  void initState() {
    super.initState();
    _controller = AnimationController(
      duration: const Duration(seconds: 2),
      vsync: this,
    );
  }

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

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Controller Setup')),
      body: Center(
        child: Text('Animation controller ready!')
      ),
    );
  }
}

void main() {
  runApp(MaterialApp(home: MyAnimationScreen()));
}

Tween: Defining the Range

While AnimationController provides a value from 0.0 to 1.0 over its duration, a Tween (short for 'in-betweening') defines the range of values you actually want to animate.

  • A Tween maps the controller's 0.0-1.0 range to your desired begin and end values.
  • Common types include Tween, ColorTween, and SizeTween.

Connecting Tween & Controller

To use a Tween, you create an Animation object by calling animate() on the Tween, passing your AnimationController.

This Animation object will then yield values within your defined range as the controller progresses from 0.0 to 1.0.

import 'package:flutter/material.dart';

class MyTweenExample extends StatefulWidget {
  @override
  _MyTweenExampleState createState() => _MyTweenExampleState();
}

class _MyTweenExampleState extends State<MyTweenExample> with SingleTickerProviderStateMixin {
  late AnimationController _controller;
  late Animation<double> _animation;

  @override
  void initState() {
    super.initState();
    _controller = AnimationController(
      duration: const Duration(seconds: 2),
      vsync: this,
    );
    // Define a tween that animates a double from 0.0 to 200.0
    _animation = Tween<double>(begin: 0.0, end: 200.0).animate(_controller);
    _controller.forward(); // Start the animation
  }

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

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Tween Connection')),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Text('Animation value: ${_animation.value.toStringAsFixed(2)}'),
            // Note: This won't update automatically without a listener or AnimatedBuilder yet
          ],
        )
      ),
    );
  }
}

void main() {
  runApp(MaterialApp(home: MyTweenExample()));
}

AnimatedBuilder for Efficiency

To make your UI react to animation values, you could use addListener and setState. However, AnimatedBuilder is a more efficient widget for this.

It rebuilds only the animating part of your widget tree, preventing unnecessary rebuilds of static widgets.

import 'package:flutter/material.dart';

class MyAnimatedBuilder extends StatefulWidget {
  @override
  _MyAnimatedBuilderState createState() => _MyAnimatedBuilderState();
}

class _MyAnimatedBuilderState extends State<MyAnimatedBuilder> with SingleTickerProviderStateMixin {
  late AnimationController _controller;
  late Animation<double> _animation;

  @override
  void initState() {
    super.initState();
    _controller = AnimationController(
      duration: const Duration(seconds: 2),
      vsync: this,
    );
    _animation = Tween<double>(begin: 50.0, end: 150.0).animate(_controller);

    _controller.forward(); // Start animation
  }

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

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('AnimatedBuilder Demo')),
      body: Center(
        child: AnimatedBuilder(
          animation: _animation,
          builder: (context, child) {
            return Container(
              width: _animation.value,
              height: _animation.value,
              color: Colors.blue,
              child: Center(child: Text('Size', style: TextStyle(color: Colors.white))),
            );
          },
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          _controller.reset();
          _controller.forward();
        },
        child: Icon(Icons.play_arrow),
      ),
    );
  }
}

void main() {
  runApp(MaterialApp(home: MyAnimatedBuilder()));
}

Introducing Hero Widgets

Hero widgets enable a stunning shared-element transition between routes (screens). When you navigate from one screen to another, a Hero widget flies from its position on the first screen to its new position on the second screen.

This creates a visually appealing and intuitive user experience, indicating a connection between the two screens.

Implementing Hero Transitions

To use a Hero widget, you need two widgets (one on each screen) with the exact same tag. When navigation occurs between these screens, Flutter handles the animation automatically.

The tag must be unique across all Hero widgets currently on the screen.

import 'package:flutter/material.dart';

// First Screen
class FirstScreen extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('First Screen')),
      body: Center(
        child: GestureDetector(
          onTap: () {
            Navigator.push(
              context, MaterialPageRoute(builder: (_) => SecondScreen()));
          },
          child: Hero(
            tag: 'hero-image-tag',
            child: Container(
              width: 100,
              height: 100,
              color: Colors.red,
              child: Center(child: Text('Tap Me', style: TextStyle(color: Colors.white))),
            ),
          ),
        ),
      ),
    );
  }
}

// Second Screen
class SecondScreen extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Second Screen')),
      body: Center(
        child: Hero(
          tag: 'hero-image-tag',
          child: Container(
            width: 300,
            height: 300,
            color: Colors.blue,
            child: Center(child: Text('Big Hero', style: TextStyle(color: Colors.white))),
          ),
        ),
      ),
    );
  }
}

void main() {
  runApp(MaterialApp(home: FirstScreen()));
}

Explicit Animations & Heroes Quiz

Which of the following statements about AnimationController and Hero widgets are true?

Recap: Explicit Animations & Heroes

In this lesson, you mastered explicit animations and Hero widgets:

  • Explicit Animations: Offer fine-grained control over animation playback using AnimationController and Tween.
  • AnimationController: Manages animation duration and playback (forward, reverse).
  • Tween: Defines the specific range of values an animation will traverse.
  • AnimatedBuilder: An efficient way to rebuild only the animated parts of your UI.
  • Hero Widgets: Create captivating shared-element transitions between screens using matching tag properties.

You now have powerful tools to create dynamic and engaging user interfaces!

よくある質問

「明示的アニメーションとHero」レッスンは無料ですか？

はい。「明示的アニメーションとHero」の完全なテキストはこのウェブで無料で読めます。インタラクティブに演習し（組み込みコードエディタと24時間対応のAIチューター）、Flutter Mobile Developmentコースの残りをアンロックするには、CoddyKit PROにアップグレードしてください。 Flutter Mobile Developmentコースには全4レッスンが含まれています。

「明示的アニメーションとHero」で何を学びますか？

`AnimationController`と`Tween`を使った明示的アニメーションを習得し、Heroウィジェットで魅力的な共有要素遷移を作成します。 ブラウザで直接実行するハンズオンコードでFlutter Mobile Developmentを演習し、24時間対応のAIチューターがレッスンを進める中での質問に答えます。

Flutter Mobile Developmentを始めるのに経験は必要ですか？

事前経験は必要ありません。CoddyKitのFlutter Mobile Developmentは初級者から上級者向けに構成されているため、ここから始めるか最初から始めて、自分のペースで進むことができます。 これはレッスン3/4です。

「明示的アニメーションとHero」レッスンにはどのくらい時間がかかりますか？

ほとんどのCoddyKitレッスンは約5～10分かかります。各レッスンはコンパクトでインタラクティブなので、着実に進歩し、ウェブとアプリ全体で正確に前回の場所から再開できます。

このFlutter Mobile Developmentレッスンでコードを書いて実行できますか？

はい。すべてのFlutter Mobile Developmentレッスンに組み込みコードエディタが含まれているため、ブラウザでリアルコードを書いて実行し、即座のAIフィードバックを取得できます。ローカル設定は不要です。

このコースのすべてのレッスン

  1. CustomPainterとCanvas
  2. 暗黙的アニメーション
  3. 明示的アニメーションとHero
  4. スタガードアニメーションと物理ベースアニメーション
← Flutter Mobile Developmentに戻る