candlestick-chart.md

Candlestick chart

KChartWidget takes a List<KLineEntity>. Call DataUtil.calculate before the first build, and again whenever new candles arrive, to compute indicator values in place:

import 'package:ohlcv_chart/ohlcv_chart.dart';

DataUtil.calculate(candles);

KChartWidget(
  candles,
  ChartColors(),
  timeFrame: const Duration(minutes: 15),
  indicators: [MaIndicator(period: 20), BollIndicator(), MacdIndicator()],
  timeFormat: TimeFormat.YEAR_MONTH_DAY_WITH_HOUR,
  fixedLength: 2,
  onLoadMore: (isRight) {
    if (!isRight) fetchOlderCandles();
  },
);

Required and common parameters

Only the candles and colours are required: KChartWidget(candles, ChartColors()) is a complete chart.

Parameter	Purpose
timeFrame	Adds a countdown to candle close on the current-price tag
isTrendLine	Enables the drawing tools when true
watermark	Any widget, drawn faintly over the chart — see Theming

Data model

KLineEntity.fromJson accepts the common OHLCV shape (open, high, low, close, vol, time/id). You can also construct entities directly.

Loading history

onLoadMore is called when scrolling reaches an edge: false at the oldest candle and true at the newest. It fires once per arrival at an edge, not on every frame.

To load older data, prepend the fetched candles and pass the longer list to the chart. The chart preserves its position in the data, so the view does not jump.

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