flutter 数据可视化——折线图

1、pubspec文件管理Flutter应用程序的assets(资源，如图片、package等)。 在pubspec.yaml中，通过网址“https://pub.dartlang.org/packages/charts_flutter”确认版本号后，将charts_flutter（0.5.0或更高版本）添加到依赖项列表。

2、在Android Studio的编辑器视图中查看pubspec时，单击右上角的 Packages get，或者在命令行输入“flutter packages get”；这会将依赖包安装到您的项目。

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

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'Flutter Demo',
      theme: new ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: new MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

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

  final String title;

  @override
  _MyHomePageState createState() => new _MyHomePageState();
}

class ClicksPerYear {
  final String year;
  final int clicks;
  final charts.Color color;

  ClicksPerYear(this.year, this.clicks, Color color)
      : this.color = new charts.Color(
      r: color.red, g: color.green, b: color.blue, a: color.alpha);
}


class TimeSeriesSales {
  final DateTime time;
  final int sales;

  TimeSeriesSales(this.time, this.sales);
}

class _MyHomePageState extends State {
  int _counter = 4;

  final serialdata = [
    new TimeSeriesSales(new DateTime(2017, 9, 1), 5),
    new TimeSeriesSales(new DateTime(2017, 9, 2), 25),
    new TimeSeriesSales(new DateTime(2017, 9, 3), 100),
    new TimeSeriesSales(new DateTime(2017, 9, 4), 75),
  ];
  Random random = new Random();

  void _incrementCounter() {
    setState(() {
      _counter++;
      serialdata.add(new TimeSeriesSales(new DateTime(2017, 9, _counter), random.nextInt(100)));
    });
  }

  @override
  Widget build(BuildContext context) {
    List> seriesList = [
      new charts.Series(
        id: 'Sales',
        colorFn: (_, __) => charts.MaterialPalette.blue.shadeDefault,
        domainFn: (TimeSeriesSales sales, _) => sales.time,
        measureFn: (TimeSeriesSales sales, _) => sales.sales,
        data: serialdata,
      )
    ];

    var chart = new charts.TimeSeriesChart(
      seriesList,
      animate: true,
    );
    var chartWidget = new Padding(
      padding: new EdgeInsets.all(32.0),
      child: new SizedBox(
        height: 200.0,
        child: chart,
      ),
    );

    return new Scaffold(
      appBar: new AppBar(
        title: new Text(widget.title),
      ),
      body: new Center(
        child: new Column(
          children: [
            chartWidget,
          ],
        ),
      ),
      floatingActionButton: new FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: new Icon(Icons.add),
      ),
    );
  }
}