lbry-sdk/dart/packages/ver/lib/time_series_chart.dart

import 'dart:math';
import 'package:flutter/material.dart';
import 'package:charts_flutter/flutter.dart' as charts;
import 'package:charts_flutter/src/base_chart_state.dart' as state;
import 'package:charts_common/common.dart' as common;
import 'package:lbry/lbry.dart';


class SimpleTimeSeriesChart extends StatefulWidget {
    SimpleTimeSeriesChart({Key key}) : super(key: key);
    @override
    _SimpleTimeSeriesChartState createState() => _SimpleTimeSeriesChartState();
}


class _SimpleTimeSeriesChartState extends State<SimpleTimeSeriesChart> {
    final List<LoadDataPoint> loadData = [];
    final List<charts.Series<LoadDataPoint, DateTime>> loadSeries = [];
    final List<charts.Series<LoadDataPoint, DateTime>> timeSeries = [];
    final Random rand = Random();
    LoadGenerator loadGenerator;

    @override
    void initState() {
        super.initState();
        loadSeries.add(
            charts.Series<LoadDataPoint, DateTime>(
                id: 'Load',
                colorFn: (_, __) => charts.MaterialPalette.black.darker,
                domainFn: (LoadDataPoint load, _) => load.time,
                measureFn: (LoadDataPoint load, _) => load.load,
                data: loadData,
            )
        );
        loadSeries.add(
            charts.Series<LoadDataPoint, DateTime>(
                id: 'Success',
                colorFn: (_, __) => charts.MaterialPalette.green.shadeDefault,
                domainFn: (LoadDataPoint load, _) => load.time,
                measureFn: (LoadDataPoint load, _) => load.success,
                data: loadData,
            )
        );
        loadSeries.add(
            charts.Series<LoadDataPoint, DateTime>(
                id: 'Backlog',
                colorFn: (_, __) => charts.MaterialPalette.red.shadeDefault,
                domainFn: (LoadDataPoint load, _) => load.time,
                measureFn: (LoadDataPoint load, _) => load.backlog,
                data: loadData,
            )
        );
        loadSeries.add(
            charts.Series<LoadDataPoint, DateTime>(
                id: 'Catch-up',
                colorFn: (_, __) => charts.MaterialPalette.yellow.shadeDefault,
                domainFn: (LoadDataPoint load, _) => load.time,
                measureFn: (LoadDataPoint load, _) => load.catchup,
                data: loadData,
            )
        );
        timeSeries.add(
            charts.Series<LoadDataPoint, DateTime>(
                id: 'Avg. Success Time',
                colorFn: (_, __) => charts.MaterialPalette.green.shadeDefault,
                domainFn: (LoadDataPoint load, _) => load.time,
                measureFn: (LoadDataPoint load, _) => load.avg_success,
                data: loadData,
            )
        );
        timeSeries.add(
            charts.Series<LoadDataPoint, DateTime>(
                id: 'Avg. Catch-up Time',
                colorFn: (_, __) => charts.MaterialPalette.yellow.shadeDefault,
                domainFn: (LoadDataPoint load, _) => load.time,
                measureFn: (LoadDataPoint load, _) => load.avg_catchup,
                data: loadData,
            )
        );
        var increase = 2;
        loadData.add(LoadDataPoint());
        loadGenerator = LoadGenerator((t, stats) {
            setState(() {
                //if (loadData.length > 60) loadData.removeAt(0);
                loadData.add(stats);
            });
            increase = max(1, min(30, (increase*1.1).ceil())-stats.backlog);
            t.load = increase;//rand.nextInt(10)+5;
            return true;
        })..start();
    }

    @override
    void dispose() {
      loadGenerator.stop();
      super.dispose();
    }

    @override
    Widget build(BuildContext context) {
        return Column(children: <Widget>[
            SizedBox(height: 250.0, child: BetterTimeSeriesChart(loadSeries)),
            SizedBox(height: 250.0, child: BetterTimeSeriesChart(timeSeries)),
        ]);
    }

}


class BetterTimeSeriesChart extends charts.TimeSeriesChart {

    final int itemCount;
    final Object lastItem;

    BetterTimeSeriesChart(
        List<charts.Series<dynamic, DateTime>> seriesList):
            itemCount = seriesList[0].data.length,
            lastItem = seriesList[0].data.last,
            super(seriesList, behaviors: [charts.SeriesLegend()]);

    @override
    void updateCommonChart(common.BaseChart baseChart, charts.BaseChart oldWidget,
        state.BaseChartState chartState) {
        super.updateCommonChart(baseChart, oldWidget, chartState);
        final prev = oldWidget as BetterTimeSeriesChart;
        if (itemCount != prev?.itemCount || lastItem != prev?.lastItem) {
            chartState.markChartDirty();
        }
    }

}