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Flutter UI #89: Fun with Candlestick Chart in Flutter

Tutorial and code of Candlestick Chart in Flutter. Copy and paste the below code as per your requirements.

flutter_candlesticks_chart:
intl:
import 'dart:collection';
import 'dart:math';
import 'package:flutter/material.dart';
import 'package:flutter_candlesticks_chart/flutter_candlesticks_chart.dart';
import 'package:intl/intl.dart' as intl;

void main() {
  var data = generateData();
  runApp(
    MaterialApp(
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        appBar: AppBar(
          backgroundColor: Colors.grey,
          title: const Center(child: Text('Candlestick Chart'),),
        ),
        body: MyApp(
            data: data,
            assetEventCollections: generateEvents(data)
        ),
      ),
    ),
  );
}

List<AssetEventCollection> generateEvents(List<CandleStickChartData> data) {
  return [
    AssetEventCollection(
      dateTime: data[(data.length/3).floor()].dateTime,
      assetEvents: [
        AssetEvent(
          type: AssetEventType.ernings,
          description: 'Earnings for quarter',
          link: 'LINK_TO_FILE',
        ),
        AssetEvent(
          type: AssetEventType.notice,
          description: 'Notice to the market',
          link: 'LINK_TO_FILE',
        ),
      ],
    ),
    AssetEventCollection(
      dateTime: data[(data.length/2).floor()].dateTime,
      assetEvents: [
        AssetEvent(
          type: AssetEventType.dividends,
          description: 'Dividends',
          link: 'LINK_TO_FILE',
        ),
      ],
    ),
    AssetEventCollection(
      dateTime: data[(2*data.length/3).floor()].dateTime,
      assetEvents: [
        AssetEvent(
          type: AssetEventType.split,
          description: 'Stock Split 1:4',
          link: 'LINK_TO_FILE',
        ),
      ],
    )
  ];
}

List<CandleStickChartData> generateData() {
  var nGenerated = 70;
  var endDate = DateTime.parse('20190802');
  List<CandleStickChartData> generatedData = [
    CandleStickChartData(
      open: 1000000.0,
      high: 1010000.0,
      low: 990000.0,
      close: 1005000.0,
      volume: 300000000.0,
      dateTime: endDate.subtract(Duration(days: nGenerated)),
    ),
  ];
  var rng = Random();
  for (var j = 0; j < nGenerated; j++) {
    var lastData = generatedData.last;
    var open = lastData.close;
    var close = open*(1+ rng.nextDouble()*0.05 - 0.025);
    generatedData.add(
        CandleStickChartData(
          open: open,
          close: close,
          high: close*(1 + rng.nextDouble()*0.015),
          low: open*(1 - rng.nextDouble()*0.01),
          volume: lastData.volume*(1+ rng.nextDouble()*0.4 - 0.2),
          dateTime: endDate.subtract(Duration(days: nGenerated - j + 1)),
        )
    );
  }
  generatedData.removeAt(0);
  return generatedData;
}

class MyApp extends StatefulWidget {
   const MyApp({Key? key,
    required this.data,
    this.assetEventCollections = const [],
  }) : super(key: key);
  final List<CandleStickChartData> data;
  final List<AssetEventCollection> assetEventCollections;

  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  bool _darkMode = true;
  Offset _cursorPosition = const Offset(-1, -1);
  var assetEventCollectionsMap = HashMap<DateTime, AssetEventCollection>();
  final List<ChartEvent> chartEvents = <ChartEvent>[];

  void setCursorPosition(Offset newPosition) {
    setState(() {
      _cursorPosition = newPosition;
    });
  }

  void clearCursor() {
    setState(() {
      _cursorPosition = const Offset(-1, -1);
    });
  }

  Function(ChartEvent) buildDialog(BuildContext buildContext) {
    return (ChartEvent chartEvent) async {
      var assetEventCollection = assetEventCollectionsMap[chartEvent.dateTime];
      var assetEvents = assetEventCollection?.assetEvents;
      var modalTextFontSize = 14.0;
      var bodyTextStyle = TextStyle(
        color: Colors.white,
        fontSize: modalTextFontSize,
        fontWeight: FontWeight.normal,
      );
      var titleTextStyle = TextStyle(
        color: Colors.white,
        fontSize: modalTextFontSize,
        fontWeight: FontWeight.bold,
      );
      List<Widget> widgetList = [];
      var padding = 20;
      for (var i = 0; i < assetEvents!.length; i++) {
        var assetEvent = assetEvents[i];
        String eventTitle;
        switch(assetEvent.type) {
          case AssetEventType.ernings:
            eventTitle = 'Earnings';
            break;
          case AssetEventType.dividends:
            eventTitle = 'Dividends';
            break;
          case AssetEventType.split:
            eventTitle = 'Split';
            break;
          case AssetEventType.notice:
            eventTitle = 'Notice to the market';
            break;
        }
        eventTitle += ' - ' +
            intl.DateFormat('dd/MM/yyyy').format(assetEventCollection!.dateTime);
        widgetList.add(
            Container(
              padding: EdgeInsets.all(padding.toDouble()),
              width: double.infinity,
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Text(eventTitle, style: titleTextStyle),
                  const SizedBox(
                    height: 2,
                    width: double.infinity,
                  ),
                  Text(assetEvent.description, style: bodyTextStyle),
                ],
              ),
            )
        );
        widgetList.add(
            Container(
                color: Colors.black,
                height: 1,
                width: double.infinity
            )
        );
      }
      widgetList.removeLast();
      var modalContainer = Column(
        mainAxisAlignment: MainAxisAlignment.spaceBetween,
        mainAxisSize: MainAxisSize.min,
        children: widgetList,
      );
      await showDialog(
        context: buildContext,
        builder: (context) {
          return AlertDialog(
            backgroundColor: Colors.grey[900],
            contentPadding: const EdgeInsets.all(0),
            content: modalContainer,
          );
        },
      ).then((_) {
        clearCursor();
      });
    };
  }

  String getCircleLetter(AssetEventType type) {
    switch(type) {
      case AssetEventType.ernings:
        return 'E';
        break;
      case AssetEventType.dividends:
        return 'D';
        break;
      case AssetEventType.split:
        return 'S';
        break;
      case AssetEventType.notice:
        return 'N';
        break;
      default:
        throw Exception('Unnadentified type');
        break;
    }
  }

  @override
  Widget build(BuildContext context) {
    var data = widget.data;
    var assetEventCollections = widget.assetEventCollections;
    String buttonText;
    ChartInfoBoxStyle infoBoxStyle;
    Color backgroundColor, cursorColor;
    if (_darkMode) {
      buttonText = "Light Mode";
      infoBoxStyle = ChartInfoBoxThemes.getDarkTheme();
      backgroundColor = Colors.black;
      cursorColor = Colors.white;
    } else {
      buttonText = "Dark Mode";
      infoBoxStyle = ChartInfoBoxThemes.getLightTheme();
      backgroundColor = Colors.white;
      cursorColor = Colors.black;
    }
    var lastData = widget.data.last;
    var lineColor = lastData.close >= lastData.open ? Colors.green : Colors.red;
    infoBoxStyle.dateFormatStr = 'dd/MM/yyyy';
    infoBoxStyle.chartI18N = const CandleChartI18N(
      open: "Abertura",
      close: "Fecha",
      high: "Máxima",
      low: "Mínima",
    );

    if (chartEvents.isEmpty) {
      for (var assetEventCollection in assetEventCollections) {
        var dateTime = assetEventCollection.dateTime;
        assetEventCollectionsMap[dateTime] = assetEventCollection;
        var assetEvents = assetEventCollection.assetEvents;
        String circleText;
        var eventType = assetEvents.first.type;
        if (assetEvents.length > 1 &&
            !assetEvents.every((e) => e.type == eventType)
        ) {
          circleText = assetEvents.length.toString();
        } else {
          circleText = getCircleLetter(eventType);
        }
        chartEvents.add(
            ChartEvent(
              dateTime: dateTime,
              circleText: circleText,
              fn: buildDialog(context),
            )
        );
      }
    }
    return OrientationBuilder(
      builder: (context, orientation) {
        return Container(
          color: backgroundColor,
          padding: const EdgeInsets.only(bottom: 3),
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            mainAxisSize: MainAxisSize.max,
            children: <Widget>[
              Container(
                width: 150,
                margin: const EdgeInsets.only(
                  top: 5,
                  bottom: 5,
                ),
                child: RaisedButton(
                    child: Center(
                      child: Text(
                        buttonText,
                      ),
                    ),
                    onPressed: () {
                      setState(() {
                        _darkMode = !_darkMode;
                      });
                    }
                ),
              ),
              Expanded(
                child: GestureDetector(
                  onLongPressStart: (detail) {
                    setCursorPosition(detail.localPosition);
                  },
                  onLongPressMoveUpdate: (detail) {
                    setCursorPosition(detail.localPosition);
                  },
                  onTapDown: (detail) {
                    setCursorPosition(detail.localPosition);
                  },
                  onHorizontalDragStart: (detail) {
                    setCursorPosition(detail.localPosition);
                  },
                  onHorizontalDragUpdate: (detail) {
                    setCursorPosition(detail.localPosition);
                  },
                  onVerticalDragStart: (detail) {
                    setCursorPosition(detail.localPosition);
                  },
                  onVerticalDragUpdate: (detail) {
                    setCursorPosition(detail.localPosition);
                  },
                  onTapUp: (detail) {
                    clearCursor();
                  },
                  onVerticalDragEnd: (detail) {
                    clearCursor();
                  },
                  onHorizontalDragEnd: (detail) {
                    clearCursor();
                  },
                  onLongPressEnd: (detail) {
                    clearCursor();
                  },
                  child: CandleStickChart(
                    data: data,
                    gridLineStyle: const ChartGridLineStyle(
                      gridLineAmount: 4,
                      showXAxisLabels: true,
                      xAxisLabelCount: 4,
                      enableGridLines: true,
                    ),
                    candleSticksStyle: const CandleSticksStyle(
                      labelPrefix: ' R\$ ',
                      valueLabelBoxType: ValueLabelBoxType.arrowTag,
                    ),
                    volumeProp: 0.2,
                    formatValueLabelWithK: true,
                    infoBoxStyle: infoBoxStyle,
                    cursorStyle: CandleChartCursorStyle(
                      cursorColor: cursorColor,
                      showCursorCircle: false,
                      cursorOffset: const Offset(0, 50),
                      cursorLabelBoxColor: Colors.green,
                    ),
                    cursorPosition: _cursorPosition,
                    lineValues: [
                      LineValue(
                        value: lastData.close,
                        lineColor: lineColor,
                        dashed: true,
                      ),
                    ],
                    chartEvents: chartEvents,
                    chartEventStyle: ChartEventStyle(
                      textStyle: const TextStyle(
                        color: Colors.white,
                        fontSize: 13,
                        fontWeight: FontWeight.bold,
                      ),
                      circleRadius: 13,
                      circlePaint: Paint()
                        ..color = Colors.orange
                        ..style = PaintingStyle.fill,
                      circleBorderPaint: Paint()
                        ..color = Colors.orange
                        ..style = PaintingStyle.stroke,
                    ),
                  ),
                ),
              ),
            ],
          ),
        );
      },
    );
  }
}

class AssetEventCollection {
  AssetEventCollection({
    required this.dateTime,
    required this.assetEvents,
  });
  final DateTime dateTime;
  final List<AssetEvent> assetEvents;
}

class AssetEvent {
  AssetEvent({
    required this.type,
    required this.description,
    required this.link,
  });
  final AssetEventType type;
  final String description;
  final String link;
}

enum AssetEventType {
  ernings,
  dividends,
  split,
  notice,
}

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