如何使饼图具有交互性？未获取图表_flutter的饼图onChangedListener回调

import 'package:flutter/material.dart';
import 'package:charts_flutter/flutter.dart' as charts;

class InteractivePieChart extends StatefulWidget {
  @override
  _InteractivePieChartState createState() => _InteractivePieChartState();
}

class _InteractivePieChartState extends State<InteractivePieChart> {
  int selectedSliceIndex;

  List<charts.Series> _seriesList;

  void _onSelectionChanged(charts.SelectionModel model) {
    final selectedDatum = model.selectedDatum;

    setState(() {
      if (selectedDatum.isNotEmpty) {
        selectedSliceIndex = selectedDatum.first.index;
      } else {
        selectedSliceIndex = null;
      }
    });
  }

  @override
  void initState() {
    super.initState();

    // Initialize the data for the pie chart
    var data = [
      ChartData('Category 1', 30),
      ChartData('Category 2', 40),
      ChartData('Category 3', 20),
      ChartData('Category 4', 10),
    ];

    _seriesList = [
      charts.Series<ChartData, String>(
        id: 'chartData',
        domainFn: (ChartData data, _) => data.category,
        measureFn: (ChartData data, _) => data.value,
        data: data,
        labelAccessorFn: (ChartData data, _) => '${data.category}: ${data.value}%',
      ),
    ];
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Interactive Pie Chart'),
      ),
      body: Center(
        child: charts.PieChart(
          _seriesList,
          animate: true,
          animationDuration: Duration(milliseconds: 500),
          behaviors: [
            charts.SelectNearest(),
            charts.DomainHighlighter(),
          ],
          defaultRenderer: charts.ArcRendererConfig(
            arcRendererDecorators: [
              charts.ArcLabelDecorator(
                labelPosition: charts.ArcLabelPosition.auto,
              ),
            ],
          ),
          selectionModels: [
            charts.SelectionModelConfig(
              type: charts.SelectionModelType.info,
              changedListener: _onSelectionChanged,
            ),
          ],
        ),
      ),
    );
  }
}

class ChartData {
  final String category;
  final int value;

  ChartData(this.category, this.value);
}