如何在Flutter的Doughnut图表的孔中添加饼图，我尝试使用Stack小部件，但仅适用于文本

Question

我正在尝试为我的项目在Flutter中用饼形图填充甜甜圈图的孔，但无法这样做。

                             Expanded(
                             child:Stack(
                              children:<Widget>[
                             charts.PieChart(
                               _seriesPieData1,
                            animate: true,
                            animationDuration: Duration(milliseconds: 500),
                            selectionModels: [
                              new charts.SelectionModelConfig(
                                type: charts.SelectionModelType.info,
                              ),
                            ],
                               defaultRenderer: new charts.ArcRendererConfig(arcWidth: 25),
                             ),
                               Center
                                (
                                 child: charts.PieChart(
                                   _seriesPieData,
                                   animate: true,
                                   animationDuration: Duration(milliseconds: 500),
                                   selectionModels: [
                                     new charts.SelectionModelConfig(
                                       type: charts.SelectionModelType.info,
                                     ),
                                   ],
                                     defaultRenderer: new charts.ArcRendererConfig(arcRendererDecorators: [
                                       new charts.ArcLabelDecorator(
                                           labelPosition: charts.ArcLabelPosition.inside)
                                     ],),
                                 ),
                               ),
                            ],
                               ),
                          ),

Answer 1

我使用Container并将这两个图表的高度和宽度设置为相同。

child: Stack(         
          children: <Widget>[
            Container(
              //color: Colors.blue,
              height: 300.0,
              width: 300.0,
              child: dpc,
            ),
            Container(
             // color: Colors.blue,
              height: 300.0,
              width: 300.0,
              child: PieChart(dataMap: dataMap, showLegends: false,),
            )

完整代码

import 'package:flutter/material.dart';
/// Donut chart example. This is a simple pie chart with a hole in the middle.
import 'package:charts_flutter/flutter.dart' as charts;
import 'package:pie_chart/pie_chart.dart';

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

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        // This is the theme of your application.
        //
        // Try running your application with "flutter run". You'll see the
        // application has a blue toolbar. Then, without quitting the app, try
        // changing the primarySwatch below to Colors.green and then invoke
        // "hot reload" (press "r" in the console where you ran "flutter run",
        // or simply save your changes to "hot reload" in a Flutter IDE).
        // Notice that the counter didn't reset back to zero; the application
        // is not restarted.
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  // This widget is the home page of your application. It is stateful, meaning
  // that it has a State object (defined below) that contains fields that affect
  // how it looks.

  // This class is the configuration for the state. It holds the values (in this
  // case the title) provided by the parent (in this case the App widget) and
  // used by the build method of the State. Fields in a Widget subclass are
  // always marked "final".

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}
Map<String, double> dataMap = new Map();

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;


  @override
  void initState() {
    super.initState();
    dataMap.putIfAbsent("Flutter", () => 5);
    dataMap.putIfAbsent("React", () => 3);
    dataMap.putIfAbsent("Xamarin", () => 2);
    dataMap.putIfAbsent("Ionic", () => 2);
  }

  void _incrementCounter() {
    setState(() {
      // This call to setState tells the Flutter framework that something has
      // changed in this State, which causes it to rerun the build method below
      // so that the display can reflect the updated values. If we changed
      // _counter without calling setState(), then the build method would not be
      // called again, and so nothing would appear to happen.
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {
    var dpc = DonutPieChart.withSampleData();
    // This method is rerun every time setState is called, for instance as done
    // by the _incrementCounter method above.
    //
    // The Flutter framework has been optimized to make rerunning build methods
    // fast, so that you can just rebuild anything that needs updating rather
    // than having to individually change instances of widgets.
    return Scaffold(
      appBar: AppBar(
        // Here we take the value from the MyHomePage object that was created by
        // the App.build method, and use it to set our appbar title.
        title: Text(widget.title),
      ),
      body: Center(
        // Center is a layout widget. It takes a single child and positions it
        // in the middle of the parent.
        child: Stack(
          // Column is also layout widget. It takes a list of children and
          // arranges them vertically. By default, it sizes itself to fit its
          // children horizontally, and tries to be as tall as its parent.
          //
          // Invoke "debug painting" (press "p" in the console, choose the
          // "Toggle Debug Paint" action from the Flutter Inspector in Android
          // Studio, or the "Toggle Debug Paint" command in Visual Studio Code)
          // to see the wireframe for each widget.
          //
          // Column has various properties to control how it sizes itself and
          // how it positions its children. Here we use mainAxisAlignment to
          // center the children vertically; the main axis here is the vertical
          // axis because Columns are vertical (the cross axis would be
          // horizontal).
          //mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Container(
              //color: Colors.blue,
              height: 300.0,
              width: 300.0,
              child: dpc,
            ),
            Container(
             // color: Colors.blue,
              height: 300.0,
              width: 300.0,
              child: PieChart(dataMap: dataMap, showLegends: false,),
            )
            ,
          /*  Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.display1,
            ),*/
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }
}



class DonutPieChart extends StatelessWidget {
  final List<charts.Series> seriesList;
  final bool animate;

  DonutPieChart(this.seriesList, {this.animate});

  /// Creates a [PieChart] with sample data and no transition.
  factory DonutPieChart.withSampleData() {
    return new DonutPieChart(
      _createSampleData(),
      // Disable animations for image tests.
      animate: false,
    );
  }


  @override
  Widget build(BuildContext context) {
    return new charts.PieChart(seriesList,
        animate: animate,
        // Configure the width of the pie slices to 60px. The remaining space in
        // the chart will be left as a hole in the center.
        defaultRenderer: new charts.ArcRendererConfig(arcWidth: 60));
  }

  /// Create one series with sample hard coded data.
  static List<charts.Series<LinearSales, int>> _createSampleData() {
    final data = [
      new LinearSales(0, 100),
      new LinearSales(1, 75),
      new LinearSales(2, 25),
      new LinearSales(3, 5),
    ];

    return [
      new charts.Series<LinearSales, int>(
        id: 'Sales',
        domainFn: (LinearSales sales, _) => sales.year,
        measureFn: (LinearSales sales, _) => sales.sales,
        data: data,
      )
    ];
  }
}

/// Sample linear data type.
class LinearSales {
  final int year;
  final int sales;

  LinearSales(this.year, this.sales);
}