如何在charts_flutter中更改条形图中条形的宽度？

Question

尝试将charts_flutter 用于条形图，但找不到用于减小简单条形图中条形宽度的属性。

以下是我的模拟：

另外，不知道怎么做：

-在此包中添加以下索引

-在条内添加值，如模拟所示。

以下是我的代码：

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

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

  factory HiddenTicksAndLabelsAxis.withSampleData() {
    return new HiddenTicksAndLabelsAxis(
      _createSampleData(),
      // Disable animations for image tests.
      animate: true,
    );
  }


  @override
  Widget build(BuildContext context) {
    return new charts.BarChart(
      seriesList,
      animate: animate,

      /// Assign a custom style for the measure axis.
      ///
      /// The NoneRenderSpec can still draw an axis line with
      /// showAxisLine=true.
      primaryMeasureAxis:
          new charts.NumericAxisSpec(renderSpec: new charts.NoneRenderSpec()),

      /// This is an OrdinalAxisSpec to match up with BarChart's default
      /// ordinal domain axis (use NumericAxisSpec or DateTimeAxisSpec for
      /// other charts).
      domainAxis: new charts.OrdinalAxisSpec(
          // Make sure that we draw the domain axis line.
          showAxisLine: true,
          // But don't draw anything else.
          renderSpec: new charts.NoneRenderSpec()),
    );
  }

  /// Create series list with single series
  static List<charts.Series<OrdinalSales, String>> _createSampleData() {
    final globalSalesData = [
      new OrdinalSales('2014', 3, Colors.lightGreen),
      new OrdinalSales('2015', 6,Colors.lightBlue),
      new OrdinalSales('2016', 0.5,Colors.red),
      // new OrdinalSales('2017', 750000),
    ];

    return [
      new charts.Series<OrdinalSales, String>(
        id: 'Global Revenue',
        domainFn: (OrdinalSales sales, _) => sales.year,
        measureFn: (OrdinalSales sales, _) => sales.sales,
        colorFn: (OrdinalSales sales, _) => sales.color,

        data: globalSalesData,
      ),
    ];
  }
}

/// Sample ordinal data type.
class OrdinalSales {
  final String year;
  final double sales;

  final charts.Color color;

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

我是新手，如有问题请多多包涵。

Answer 1

您可以在new charts.BarRendererConfig 内部使用maxBarWidthPx 来设置条的最大宽度。

示例：

var chart = charts.BarChart(
   series,
   animate: true,
   vertical: true,
   defaultRenderer: new charts.BarRendererConfig(
     maxBarWidthPx: 40,
   ),
),
...

Answer 2

目前还没有设置条形宽度的功能。问题已公开，请参阅Here。

您可以通过barGroupingType: charts.BarGroupingType.grouped 最小化条形宽度并将fillColorFn: (Mileage mileage, _) => charts.ColorUtil.fromDartColor(Colors.transparent) 设置在charts.Series 中没有中间的。

我在下面分享我的代码：

输出：

代码：

custom_rounded_bars.dart 文件，

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

class CustomRoundedBars extends StatelessWidget {
  final List<dynamic> data;
  final bool animate;

  CustomRoundedBars(this.data, {this.animate});


  @override
  Widget build(BuildContext context) {

    var seriesList = _createSampleData(data);

    return new charts.BarChart(
      seriesList,
      animate: animate,
      barGroupingType: charts.BarGroupingType.grouped,
      defaultRenderer: new charts.BarRendererConfig(
          cornerStrategy: const charts.ConstCornerStrategy(30)),
    );
  }

  /// Create one series with sample hard coded data.
  static List<charts.Series<Mileage, String>> _createSampleData(dynamic data) {

    return [
      new charts.Series<Mileage, String>(
        id: 'mileage1',
        colorFn: (_, __) => charts.MaterialPalette.blue.shadeDefault,
        domainFn: (Mileage mileage, _) => mileage.day,
        measureFn: (Mileage mileage, _) => mileage.km,
        data: data,
        fillColorFn: (Mileage mileage, _) => charts.ColorUtil.fromDartColor(Colors.transparent),
      ),
      new charts.Series<Mileage, String>(
        id: 'mileage',
        colorFn: (_, __) => charts.MaterialPalette.blue.shadeDefault,
        domainFn: (Mileage mileage, _) => mileage.day,
        measureFn: (Mileage mileage, _) => mileage.km,
        data: data,
      ),
      new charts.Series<Mileage, String>(
        id: 'mileage2',
        colorFn: (_, __) => charts.MaterialPalette.blue.shadeDefault,
        domainFn: (Mileage mileage, _) => mileage.day,
        measureFn: (Mileage mileage, _) => mileage.km,
        data: data,
        fillColorFn: (Mileage mileage, _) => charts.ColorUtil.fromDartColor(Colors.transparent),
      ),
    ];
  }

}

analytics_page.dart 文件，

import 'package:easytrax/Common/custom_rounded_bars.dart';
import 'package:flutter/material.dart';



class AnalyticsPage extends StatefulWidget {
  static const String page = 'analytics_page';
  @override
  _AnalyticsPageState createState() => _AnalyticsPageState();
}

class _AnalyticsPageState extends State<AnalyticsPage> {

  List<Mileage> _createSampleData(){
    final data = [
      new Mileage(10, 'April 27'),
      new Mileage(38, 'April 28'),
      new Mileage(60, 'April 29'),
      new Mileage(20, 'April 30'),
      new Mileage(45, 'May 01'),
      new Mileage(35, 'May 02'),
      new Mileage(55, 'May 03'),
    ];

    return data;
  }

  @override
  Widget build(BuildContext context) {


    var data = _createSampleData();


    return Scaffold(
      body:Container(
        child: Column(
          children: [
            Container(
              padding: EdgeInsets.all(16.0),
              height: 300.0,
              child: CustomRoundedBars(data),
            ),
          ],
        ),
      ),
    );
  }
}



/// data type.
class Mileage {
  final int km;
  final String day;

  Mileage(this.km, this.day);
}

Answer 3

在条形渲染器内部有一个 strokeWidthPx 属性

defaultRenderer: new charts.BarRendererConfig(
    strokeWidthPx: 1.0,
)

Answer 4

栏的大小取决于父窗口小部件的大小。 在我的情况下，我使用垂直条形图。 Size 是实用程序的响应大小：

MediaQuery.of(context).size;

我正在使用它来使其具有响应性，但如果是水平的，您可以使用您的高度或宽度。

Container(
  height: size.height * 0.1 * list.length +
    (size.height * 0.05),
  child: SimpleBarChart(),
),

最后我将每个列表项的高度设置为 size.height * 0.1（设备的 10% 高度），并且（重要）我添加了父度量的一半（size.height * 0.05），因为这将是测量轴的高度（在我的情况下（如果你有水平（正常），则为你的宽度））。

希望你能找到解决办法。编码愉快！