fcs/lib/charts/lines.dart

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

import '../model/product_model.dart';

typedef void ProductClick(DateTime date, Map<String, int> measures);

class ProductsChart extends StatelessWidget {
  static final numberFormatter = new NumberFormat("#,###");
  final ChartData chartData;
  final ProductClick productClick;
  const ProductsChart(this.chartData, {Key key, this.productClick})
      : super(key: key);
  factory ProductsChart.fromModel(ProductModel productModel,
      {ProductClick productClick}) {
    return new ProductsChart(_createData(productModel),
        productClick: productClick);
  }

  static ChartData _createData(ProductModel productModel) {
    List<charts.Series<TimeSeriesSales, DateTime>> list = [];
    var min = 9999, max = 0;
    productModel.products.forEach((p) {
      List<TimeSeriesSales> data = [];
      if (p.priceHistory != null) {
        var dateKeys = {};
        p.priceHistory.entries.forEach((e) {
          dateKeys[DateTime.parse(e.key)] = e.value;
        });

        var sortedKeys = dateKeys.keys.toList()..sort((a, b) => b.compareTo(a));
        sortedKeys.forEach((k) {
          var v = dateKeys[k];
          data.add(new TimeSeriesSales(k, v));
          if (v < min) min = v;
          if (v > max) max = v;
        });
      }

      list.add(new charts.Series<TimeSeriesSales, DateTime>(
        id: p.name,
        colorFn: (_, __) => charts.ColorUtil.fromDartColor(Color(p.color)),
        domainFn: (TimeSeriesSales sales, _) => sales.time,
        measureFn: (TimeSeriesSales sales, _) => sales.sales,
        data: data,
        labelAccessorFn: (TimeSeriesSales series, _) =>
            '${numberFormatter.format(series.sales)}',
        measureFormatterFn: (TimeSeriesSales series, _) => (n) => "s",
      ));
    });
    var chartData = ChartData(list, min, max);
    return chartData;
  }

  @override
  Widget build(BuildContext context) {
    return charts.TimeSeriesChart(
      chartData.seriesList,
      animate: true,
      defaultRenderer: new charts.LineRendererConfig(
        includePoints: true,
      ),
      primaryMeasureAxis: new charts.NumericAxisSpec(
          tickProviderSpec: new charts.BasicNumericTickProviderSpec(
              zeroBound: false, desiredTickCount: 10),
          renderSpec: new charts.GridlineRendererSpec(
              lineStyle: charts.LineStyleSpec(
            dashPattern: [4, 4],
          ))),
      selectionModels: [
        new charts.SelectionModelConfig(
          type: charts.SelectionModelType.info,
          updatedListener: _onSelectionChanged,
        )
      ],
    );
  }

  _onSelectionChanged(charts.SelectionModel model) {
    final selectedDatum = model.selectedDatum;
    if (selectedDatum.isNotEmpty) {
      var _time = selectedDatum.first.datum.time;
      Map<String, int> _measures = <String, int>{};

      selectedDatum.forEach((charts.SeriesDatum datumPair) {
        _measures[datumPair.series.displayName] = datumPair.datum.sales;
      });
      if (productClick != null) {
        productClick(_time, _measures);
      }
    }
  }
}

class TimeSeriesSales {
  final DateTime time;
  final int sales;

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

class ChartData {
  final List<charts.Series> seriesList;
  final num min, max;
  ChartData(this.seriesList, this.min, this.max);
}