LocalSpend-Tracker/lib/common/widgets/charts/outside_label.dart

/// Simple pie chart with outside labels example.
import 'package:charts_flutter/flutter.dart' as charts;
import 'package:flutter/material.dart';

class PieOutsideLabelChart extends StatelessWidget {
  PieOutsideLabelChart(this.seriesList, {this.animate});

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

  final List<charts.Series> seriesList;
  final bool animate;

  @override
  Widget build(BuildContext context) {
    return new charts.PieChart(seriesList,
        animate: animate,
        // Add an [ArcLabelDecorator] configured to render labels outside of the
        // arc with a leader line.
        //
        // Text style for inside / outside can be controlled independently by
        // setting [insideLabelStyleSpec] and [outsideLabelStyleSpec].
        //
        // Example configuring different styles for inside/outside:
        //       new charts.ArcLabelDecorator(
        //          insideLabelStyleSpec: new charts.TextStyleSpec(...),
        //          outsideLabelStyleSpec: new charts.TextStyleSpec(...)),
        defaultRenderer: new charts.ArcRendererConfig(arcRendererDecorators: [
          new charts.ArcLabelDecorator(
              labelPosition: charts.ArcLabelPosition.outside)
        ]));
  }

  /// Create one series with sample hard coded data.
  static List<charts.Series<LinearSales, int>> _createSampleData() {
    final data = [
      new LinearSales(0, 23),
      new LinearSales(1, 44),
      new LinearSales(2, 25),
      new LinearSales(3, 15),
    ];

    return [
      new charts.Series<LinearSales, int>(
        id: 'Sales',
        domainFn: (LinearSales sales, _) => sales.year,
        measureFn: (LinearSales sales, _) => sales.sales,
        data: data,
        // Set a label accessor to control the text of the arc label.
        labelAccessorFn: (LinearSales row, _) => '${row.year}: ${row.sales}',
      )
    ];
  }
}

/// Sample linear data type.
class LinearSales {
  LinearSales(this.year, this.sales);

  final int year;
  final int sales;
}