【Flutter】タッチするとギミックが表示される円グラフの使い方

初投稿です。７月からFlutterの勉強を始めたひかると申します。

完成画像

結論

下記のパッケージを実装しましょう！
https://pub.dev/packages/fl_chart

#実装方法

pubspec.yamlにfl_chartを記述してPubgetしましょう！

pubspec.yaml

dependencies:
  fl_chart: ^0.40.0

とりあえず使ってみたいという方向けのサンプルコード
(コピペで使えます)

main.dart

import 'package:fl_chart/fl_chart.dart';
import 'package:flutter/material.dart';
import 'indicator.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: PieChartSample2(),
    );
  }
}

class PieChartSample2 extends StatefulWidget {
  @override
  State<StatefulWidget> createState() => PieChart2State();
}

class PieChart2State extends State {
  int touchedIndex = -1;

  @override
  Widget build(BuildContext context) {
    return AspectRatio(
      aspectRatio: 1.3,
      child: Card(
        color: Colors.white,
        child: Row(
          children: <Widget>[
            const SizedBox(
              height: 18,
            ),
            Expanded(
              child: AspectRatio(
                aspectRatio: 1,
                child: PieChart(
                  PieChartData(
                      pieTouchData:
                          PieTouchData(touchCallback: (FlTouchEvent event, pieTouchResponse) {
                        setState(() {
                          if (!event.isInterestedForInteractions ||
                              pieTouchResponse == null ||
                              pieTouchResponse.touchedSection == null) {
                            touchedIndex = -1;
                            return;
                          }
                          touchedIndex = pieTouchResponse.touchedSection!.touchedSectionIndex;
                        });
                      }),
                      borderData: FlBorderData(
                        show: false,
                      ),
                      sectionsSpace: 0,
                      centerSpaceRadius: 40,
                      sections: showingSections()),
                ),
              ),
            ),
            Column(
              mainAxisSize: MainAxisSize.max,
              mainAxisAlignment: MainAxisAlignment.end,
              crossAxisAlignment: CrossAxisAlignment.start,
              children: const <Widget>[
                Indicator(
                  color: Color(0xff0293ee),
                  text: 'First',
                  isSquare: true,
                ),
                SizedBox(
                  height: 4,
                ),
                Indicator(
                  color: Color(0xfff8b250),
                  text: 'Second',
                  isSquare: true,
                ),
                SizedBox(
                  height: 4,
                ),
                Indicator(
                  color: Color(0xff845bef),
                  text: 'Third',
                  isSquare: true,
                ),
                SizedBox(
                  height: 4,
                ),
                Indicator(
                  color: Color(0xff13d38e),
                  text: 'Fourth',
                  isSquare: true,
                ),
                SizedBox(
                  height: 18,
                ),
              ],
            ),
            const SizedBox(
              width: 28,
            ),
          ],
        ),
      ),
    );
  }

  List<PieChartSectionData> showingSections() {
    return List.generate(4, (i) {
      final isTouched = i == touchedIndex;
      final fontSize = isTouched ? 25.0 : 16.0;
      final radius = isTouched ? 60.0 : 50.0;
      switch (i) {
        case 0:
          return PieChartSectionData(
            color: const Color(0xff0293ee),
            value: 40,
            title: '40%',
            radius: radius,
            titleStyle: TextStyle(
                fontSize: fontSize, fontWeight: FontWeight.bold, color: const Color(0xffffffff)),
          );
        case 1:
          return PieChartSectionData(
            color: const Color(0xfff8b250),
            value: 30,
            title: '30%',
            radius: radius,
            titleStyle: TextStyle(
                fontSize: fontSize, fontWeight: FontWeight.bold, color: const Color(0xffffffff)),
          );
        case 2:
          return PieChartSectionData(
            color: const Color(0xff845bef),
            value: 15,
            title: '15%',
            radius: radius,
            titleStyle: TextStyle(
                fontSize: fontSize, fontWeight: FontWeight.bold, color: const Color(0xffffffff)),
          );
        case 3:
          return PieChartSectionData(
            color: const Color(0xff13d38e),
            value: 15,
            title: '15%',
            radius: radius,
            titleStyle: TextStyle(
                fontSize: fontSize, fontWeight: FontWeight.bold, color: const Color(0xffffffff)),
          );
        default:
          throw Error();
      }
    });
  }
}

indicator.dart

import 'package:flutter/material.dart';

class Indicator extends StatelessWidget {
  final Color color;
  final String text;
  final bool isSquare;
  final double size;
  final Color textColor;

  const Indicator({
    Key? key,
    required this.color,
    required this.text,
    required this.isSquare,
    this.size = 16,
    this.textColor = const Color(0xff505050),
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Row(
      children: <Widget>[
        Container(
          width: size,
          height: size,
          decoration: BoxDecoration(
            shape: isSquare ? BoxShape.rectangle : BoxShape.circle,
            color: color,
          ),
        ),
        const SizedBox(
          width: 4,
        ),
        Text(
          text,
          style: TextStyle(fontSize: 16, fontWeight: FontWeight.bold, color: textColor),
        )
      ],
    );
  }
}

おわりに

以上になります。
画面が切り替わったらグラフが動作する記事はありましたが、画面に触れると動作するグラフを記事にしている方を見かけなかったので今回初投稿のネタとして載せました。
それでは！