android - 我如何在 main dart 中运行图表？ - flutter

Question

我正尝试在 flutter 中运行库中的图表。我无法使用 main.dart 运行。

主飞镖:

import './widgets/chart.dart';

void main() {
  runApp(
    new MaterialApp(
      home: PointsLineChart(),
    ),
  );
}

图表.飞镖:

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

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

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

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

  @override
  Widget build(BuildContext context) {
    return new charts.LineChart(seriesList,
        animate: animate,
        defaultRenderer: new charts.LineRendererConfig(includePoints: true));
  }

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

    return [
      new charts.Series<LinearSales, int>(
        id: 'Sales',
        colorFn: (_, __) => charts.MaterialPalette.blue.shadeDefault,
        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);
}

我遇到的错误是在 main.dart 中我需要输入一些内容才能运行 chart.dart。在 PointsLineChart() 中，

它给我错误:

预计需要 1 个参数，但找到 0 个。dart(not_enough_required_arguments) (新) PointsLineChart(List> seriesList, {bool animate}) → PointsLineChart

Answer 1

PointsLineChart 的构造函数有两个参数:

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

而在您的 main.dart 中，您没有给出参数:

home: PointsLineChart(),// here you need to add two arguments!!!

修改如下代码:

runApp(
new MaterialApp(
  home: PointsLineChart(PointsLineChart.createSampleData(), animate: false),
),

);

同时将 _createSampleData 更改为 createSampleData 以使其公开。