如何使用charts_flutter包在Flutter中显示工具提示

dependencies:
  flutter:
    sdk: flutter
  charts_flutter: ^0.11.0

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

class SalesData {
  final String year;
  final int sales;

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

List<charts.Series<SalesData, String>> seriesList = [
  charts.Series(
    id: 'Sales',
    data: [
      SalesData('2016', 100),
      SalesData('2017', 75),
      SalesData('2018', 200),
      SalesData('2019', 150),
    ],
    domainFn: (SalesData sales, _) => sales.year,
    measureFn: (SalesData sales, _) => sales.sales,
  ),
];

charts.BarChart(
  seriesList,
  animate: true,
)

charts.BarChart(
  seriesList,
  animate: true,
  behaviors: [
    charts.SeriesLegend(),
    charts.ChartTitle('Year', behaviorPosition: charts.BehaviorPosition.bottom),
    charts.ChartTitle('Sales', behaviorPosition: charts.BehaviorPosition.start),
    charts.ChartTitle('Tooltip', behaviorPosition: charts.BehaviorPosition.end),
    charts.TooltipBehavior(),
  ],
)

Container(
  height: 300,
  child: charts.BarChart(
    seriesList,
    animate: true,
    behaviors: [
      charts.SeriesLegend(),
      charts.ChartTitle('Year', behaviorPosition: charts.BehaviorPosition.bottom),
      charts.ChartTitle('Sales', behaviorPosition: charts.BehaviorPosition.start),
      charts.ChartTitle('Tooltip', behaviorPosition: charts.BehaviorPosition.end),
      charts.TooltipBehavior(),
    ],
  ),
)