Flutter Chart

最近要在一个flutter的应用上实现图表,在官方的库里找到了一个现成的chart library。

pub.dev的地址:

​https://pub.flutter-io.cn/packages/charts_flutter​

这个库应该是google官方自己实现的,github的地址是:

​https://github.com/google/charts​

他们有一个案例页面:

​https://google.github.io/charts/flutter/gallery.html​

使用前,请先在项目根目录下使用pub get进行安装:

flutter pub add charts_flutter

接着在项目的pubspec.yaml中添加依赖:

dependencies:
charts_flutter: ^0.12.0

之后,就可以在dart文件中使用了。

我在lib文件夹下新建了一个pie.dart 的文件:

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

class SimplePieChart extends StatelessWidget {
final Listcharts.Series> seriesList; final bool animate;
SimplePieChart(this.seriesList, {this.animate});
/// Creates a [PieChart] with sample data and no transition. factory SimplePieChart.withSampleData() {
return new SimplePieChart(
_createSampleData(), // Disable animations for image tests. animate: false, ); }

factory SimplePieChart.withInputData(seriesList) {
return new SimplePieChart(seriesList, animate: true); }

@override Widget build(BuildContext context) {
return Container(
child: new charts.PieChart(seriesList, animate: animate), ); }

/// Create one series with sample hard coded data. static List> _createSampleData() {
final data = [
new LinearSales(0, 1), new LinearSales(1, 99), ];
return [
new charts.SeriesLinearSales, 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 double sales;
LinearSales(this.year, this.sales);
}

这个文件实现了两个基本类,LinearSales是数据格式,SimplePieChart实现了一个简单的饼图。

在main.dart中引用了pie.dart,具体的实现使用了官方例子中的SimplePieChart的代码。

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

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 Chart',
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: '图表'),
);
}
}

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();
}

class _MyHomePageState extends StateMyHomePage> {
double p = 50.0;
@override
Widget build(BuildContext context) {
// 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(
child: Column(crossAxisAlignment: CrossAxisAlignment.start,

// Center is a layout widget. It takes a single child and positions it
// in the middle of the parent.
children: [
Expanded(
flex: 3,
child: new SimplePieChart.withInputData([
new charts.SeriesLinearSales, int>(
id: 'Sales',
domainFn: (LinearSales sales, _) => sales.year,
measureFn: (LinearSales sales, _) => sales.sales,
data: [
new LinearSales(0, 100 - p),
new LinearSales(1, p),
],
)
])),

])),
);

}
}

项目的git:​​https://gitee.com/stewart71/flutter_chart_example​

以后如果用到其他chart,还会继续更新。

文章来源于互联网:Flutter Chart

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