swm_chart 0.14.0

Stock World Monitor Charts: high-performance financial charts for Flutter, a native Dart port of TradingView Lightweight Charts.

Stock World Monitor Charts

Stock World Monitor Charts (swm_chart), by Stock World Monitor, are high-performance financial charts for Flutter. The package is a native Dart port of TradingView Lightweight Charts™ (based on v5.2.1), with indicators, technical analysis, drawing tools and trading lines on top.

There is no WebView. Everything is drawn with CustomPainter, and the model/renderer architecture mirrors upstream. Candles, columns and grid lines are drawn in device pixels, the same way upstream draws in bitmap coordinates, so they stay sharp.

Each feature below has its own screenshot, all taken from the example app.

Contents

• Installation
• Quick start
• Features
• Guide
  • Pro chart: a ready-made trading screen
  • Saving and restoring a chart
  • Series, panes and scales
  • Indicators
  • Technical analysis without a chart
  • Legend and tooltip
  • Drawing tools
  • Orders, positions and alerts
  • Overlays
  • Volume profile
  • Forecast fan
  • Chart types and timeframes
  • Compare symbols
  • Several charts in step
  • Sparklines and donut charts
  • Custom series and primitives
• Interaction
• Performance
• Example app
• Notes
• License & attribution

Installation

dependencies:
  swm_chart: ^0.14.0

import 'package:swm_chart/swm_chart.dart';

Requires Flutter 3.32 or newer. Runs on iOS, Android, macOS, Windows, Linux and the web.

Quick start

final chart = ChartController(
  options: const ChartOptions(timeScale: TimeScaleOptions(timeVisible: true)),
);

final candles = chart.addCandlestickSeries();
candles.setData([
  CandlestickData(time: 1704067200, open: 100, high: 105, low: 98, close: 103),
  WhitespaceData(time: 1704153600), // a gap
  // ... time is a UTC timestamp in seconds, strictly ascending
]);

// realtime
candles.update(CandlestickData(time: 1704153600, open: 103, high: 104, low: 101, close: 102));

// widget, needs bounded constraints
Expanded(child: SwmChart(controller: chart));

// later
chart.dispose();

The API names follow upstream (addCandlestickSeries, setData, update, timeScale().fitContent(), scrollToRealTime(), subscribeCrosshairMove, …), so the upstream docs still apply.

Features

Everything in Lightweight Charts v5.2.1 that applies to Flutter is ported:

Area
Series: Candlestick, Bar, Line, Area, Baseline, Histogram, custom series	✅
Whitespace data, line types (simple, stepped, curved monotone)	✅
Chart types: time (ChartController()), yield curve (.yieldCurve), options/price axis (.options)	✅
Multiple panes: stretch factors, draggable separators, add/remove/swap/move, addDefaultPane	✅
Price scales: left, right, overlays (overlayPriceScales); normal, log, percentage, indexed-to-100; edge tick marks, ticks	✅
Time scale: bar spacing, right offset (bars or pixels), fix edges, lock range on resize, uniform distribution, ignore whitespace, conflation	✅
Crosshair: normal / magnet / magnet OHLC / hidden, per pane, setCrosshairPosition, tracking mode	✅
Last value labels, price line source, custom price lines, base line, last price animation	✅
Hit testing: hoveredSeries / hoveredObjectId, hoveredSeriesOnTop	✅
Plugins: primitives API, series markers, up/down markers, text & image watermarks	✅
Localization: locale, date format, month names, price/percentage/tick mark formatters	✅
Events: crosshair move, click, double click, visible logical/time range, size, data changed	✅
Gestures: pan + kinetic, pinch, long-press crosshair, axis drag, double-tap reset, mouse wheel — each switchable like handleScroll / handleScale	✅
Desktop / web: crosshair follows the mouse, resize cursors on axes and separators, primitive cursor	✅
Accessibility: Semantics label and a summary of the last values	✅
Attribution logo (opt-in), takeScreenshot	✅

Not applicable in Flutter: autoSize/resize/width/height (the widget takes its parent's size), chartElement, colorSpace, colorParsers.

Beyond upstream:

Area
Pro chart: a ready-made screen — top bar (interval, chart type, indicator picker and settings, undo, scales), drawing toolbar, style bar for the selected drawing	✅
Save / restore the whole chart as JSON: chart type, scale, indicators with their inputs and styles, drawings, trading lines; indicator templates	✅
73 indicators, one line each: moving averages, bands and stops, momentum, trend, volume, volatility (list)	✅
Technical analysis (Ta): every indicator as a plain function, plus ZigZag, Elliott waves, support / resistance, chart and candlestick patterns, auto trendlines, divergences, Williams fractals, Fibonacci, pivot points, regression channel, volume profile	✅
Legend & tooltip following the crosshair	✅
Drawing tools (30): lines, channels, pitchforks, Fibonacci retracement / extension / time zones, Gann fan, long / short position, anchored VWAP, regression trend, ranges, shapes, callouts; an editor with undo / redo, duplicate, lock, magnet	✅
Trading lines: draggable orders, TP / SL, positions with P&L, price alerts	✅
Overlays: band fill, price levels, volume profile (value area, per session), forecast fan	✅
Chart types & timeframes: Heikin-Ashi, Renko, line break, range bars; resample to minutes … months	✅
Compare symbols on a percentage scale	✅
Crosshair sync across charts, symbols and intervals	✅
Sparklines and donut charts for lists and dashboards	✅

Pro chart: a ready-made trading screen

SwmProChart is the whole trading screen in one widget, around a ProChartController:

• Top bar: the symbol, the interval, the chart type (candles, hollow candles, bars, line, area, baseline, Heikin-Ashi), the indicator picker, undo / redo, and log / percent scale and volume.
• Drawing toolbar on the left, tools in groups, plus magnet (snap to OHLC), keep drawing, hide and remove all.
• Style bar over the selected drawing: color, width, line style, text, lock, duplicate, delete — each change can be undone.
• Indicator picker: the indicators on the chart (show / hide, settings, remove) and all 73 to add, searchable. Settings: inputs and the color, width and visibility of each line.

final pro = ProChartController(symbol: 'BTC/USD', interval: '1h');
pro.setData(bars, volumes: volumes);
pro.addIndicator(IndicatorCatalog.byId('ema')!, values: {'period': 50});

SwmProChart(
  controller: pro,
  intervals: const ['15m', '1h', '4h', '1D'],
  onIntervalChanged: (i) async => pro.setData(await api.bars('BTC/USD', i)),
  actions: [IconButton(icon: const Icon(Icons.save), onPressed: save)],
)

pro.update(tick); // realtime: price, volume, Heikin-Ashi and indicators

The parts are widgets of their own (ProChartTopBar, DrawingToolbar, DrawingStyleBar, IndicatorPicker, showIndicatorSettings) to lay out differently, and DrawingTools.groups / IndicatorCatalog.all are plain lists to build your own.

Saving and restoring a chart

final saved = jsonEncode(pro.saveState());
// later, after setData:
pro.restoreState(jsonDecode(saved));

// indicators only, as a template for other symbols
final template = pro.saveIndicators();
other.restoreIndicators(template);

The state holds the chart type, price scale mode, volume, symbol, interval, each indicator (its catalog id, inputs, line styles, visibility), the drawings (anchored by time) and the trading lines — not the bars.

Series, panes and scales

// volume on its own scale at the bottom of the pane
final volume = chart.addHistogramSeries(const HistogramSeriesOptions(
  priceScaleId: 'volume',
  priceFormat: PriceFormat.volume(),
));
chart.priceScale('volume').applyOptions(
  const PriceScaleOptions(scaleMargins: ScaleMargins(top: 0.8, bottom: 0)),
);

// RSI in a second pane with 70/30 lines
final rsi = chart.addLineSeries(const LineSeriesOptions(color: Colors.purple), 1);
rsi.createPriceLine(const PriceLineOptions(price: 70, lineStyle: LineStyle.dashed));
rsi.createPriceLine(const PriceLineOptions(price: 30, lineStyle: LineStyle.dashed));
chart.panes()[0].setStretchFactor(3);

// markers
final markers = createSeriesMarkers(candles, [
  SeriesMarker(time: t, position: SeriesMarkerPosition.belowBar,
      shape: SeriesMarkerShape.arrowUp, color: Colors.green, text: 'Buy'),
]);

// watermark
createTextWatermark(chart.panes()[0],
    const TextWatermarkOptions(lines: [TextWatermarkLine(text: 'SWM Chart')]));

// log / percentage scale
chart.priceScale().applyOptions(const PriceScaleOptions(mode: PriceScaleMode.logarithmic));

// load more history when the user scrolls near the first bar
chart.timeScale().subscribeVisibleLogicalRangeChange((range) {
  if (range != null && range.from < 20) { /* fetch older bars, then setData */ }
});

Yield curves and options chains:

final yields = ChartController.yieldCurve(); // time = months
yields.addLineSeries().setData([LineData(time: 3, value: 5.4), LineData(time: 120, value: 4.3)]);

final chain = ChartController.options(precision: 0); // time = strike price

Indicators

chart.addIndicator(Bollinger(), source: candles);          // over the candles
chart.addIndicator(Ema(50), source: candles);
final rsi = chart.addIndicator(Rsi(14), source: candles);   // its own pane, 70 / 30 levels
chart.addIndicator(Macd(), source: candles);
chart.addIndicator(Vwap(), source: candles, volume: volumeSeries);
rsi.remove();

73 built in. Overlays go on the price pane, the rest in a pane of their own with their usual levels:

Group	Indicators
Moving averages	Sma, Ema, Wma, Hma, Dema, Tema, Rma, Vwma, Alma, Lsma, Zlema, T3, McGinley, Kama, Envelope, Alligator
Bands, clouds, stops	Bollinger, Keltner, Donchian, Ichimoku (cloud projected ahead), Supertrend, ParabolicSar, ChandelierExit
Momentum	Rsi, StochRsi, Stochastic, Macd, Ppo, WilliamsR, Cci, Roc, Momentum, Cmo, Tsi, Trix, UltimateOscillator, AwesomeOscillator, AcceleratorOscillator, Dpo, Coppock, Kst, FisherTransform, ConnorsRsi, Rvi, Smi
Trend	Adx, Aroon, Vortex, ElderRay, BalanceOfPower, Choppiness, MassIndex, SineWave, EvenBetterSinewave
Volume	Vwap, Obv, Mfi, Cmf, AccumulationDistribution, ChaikinOscillator, PriceVolumeTrend, VolumeIndexes (NVI / PVI), Klinger, ForceIndex, EaseOfMovement, VolumeOscillator, VolumeSma
Volatility	Atr, StandardDeviation, HistoricalVolatility, BollingerPercentB, BollingerWidth, UlcerIndex

Sma, Ema, Wma, Bollinger, Rsi, Macd, Stochastic, Atr, Vwap and Ichimoku only recompute the last bar on a tick. Extend Indicator (lines, compute(input, from, out)) or TaIndicator (series(bars)) for your own, or call computeAll to use the math without a chart.

Technical analysis without a chart

Ta has the same math as plain functions over a list of bars, plus the analysis tools — for screeners, alerts and backtests:

final bars = [for (final c in candles) TaPoint(date: c.date, open: c.o, high: c.h, low: c.l, close: c.c, volume: c.v)];
final rsi = Ta.rsi(bars);                        // List<double?>
final zigzag = Ta.zigzag(bars, deviation: 1);    // swings of 1% or more
final waves = Ta.elliottWaves(bars);             // automatic Elliott count
final lines = Ta.autoTrendlines(bars);           // support / resistance trend lines
final levels = Ta.supportResistance(bars);       // support / resistance levels
final patterns = Ta.detectPatterns(bars);        // head & shoulders, triangles, flags…
final candlesticks = Ta.candlePatterns(bars);    // engulfing, doji, hammer…
final bullish = Ta.rsiBullishDivergence(bars);
final hull = Ta.hma(bars, 21);                   // any indicator, as a series
final s = Ta.stochRsi(bars);                     // several lines come as a record: s.k, s.d
final f = Ta.fractals(bars);                     // Williams fractals: f.up, f.down (bar indices)

Every result lines up with the bars, null through the warm-up. The Analysis demo in the example app draws them on a chart: the ZigZag as a line series, the Elliott count as a PathDrawing, trend lines as TrendLineDrawings, levels with PriceLevelsPrimitive and candlestick patterns as markers.

Implement TaBar on your own bar class to pass it in directly. Import package:swm_chart/ta.dart for just this part.

Legend and tooltip

createLegend(chart, const LegendOptions(title: 'BTC/USD · 1h'));
createLegend(chart, const LegendOptions(mode: LegendMode.tooltip));

Rows at the top-left of each pane (OHLC and change for candles, one row per indicator) follow the crosshair, or show the last bar when it is hidden. In tooltip mode a box follows the crosshair instead. Prices are shown as prices even on a percentage scale. The Indicators screenshots show both: the legend on the left, the tooltip on the right.

Drawing tools

DrawingEditor puts a drawing layer on a pane and edits it with the pointer:

final editor = DrawingEditor(chart,
    onCreated: (d) => save(d), onChanged: (d) => save(d));

// pick a tool: taps place the anchors, or drag out a two-point tool
editor.tool = (id, anchors) => TrendLineDrawing(id: id, anchors: anchors, extendRight: true);

// without a tool: tap selects, drag moves, drag a handle reshapes
editor.deleteSelected();

Built in:

Group	Drawings
Lines	TrendLineDrawing (also ray, extended line, arrow), HorizontalLineDrawing (line, ray), VerticalLineDrawing, CrossLineDrawing
Channels	ParallelChannelDrawing, RegressionTrendDrawing, PitchforkDrawing (Andrews, Schiff, modified Schiff)
Fibonacci, Gann	FibRetracementDrawing, FibExtensionDrawing (trend-based), FibTimeZoneDrawing, GannFanDrawing
Patterns	PathDrawing (Elliott impulse and correction, XABCD, any labels)
Forecasting, measuring	PositionDrawing (long / short: target, stop, R:R, amounts), PriceRangeDrawing, DateRangeDrawing, MeasureDrawing, AnchoredVwapDrawing (with bands)
Shapes, text	RectangleDrawing, EllipseDrawing, FreehandDrawing, TextDrawing, CalloutDrawing

AnchoredVwapDrawing and RegressionTrendDrawing read the price series (source); give the codec the same series to load them (DrawingCodec(source: candles, volume: volume)).

Undo / redo. editor.undo() / editor.redo() step through adding, moving, reshaping and deleting (canUndo, canRedo, onHistoryChanged). editor.update(id, (d) => ...) changes a drawing's style, text or lock as one undoable step; editor.duplicate(id) copies one.

Save / load. DrawingCodec saves drawings as JSON with the anchors stored by time, so they stay put when older history is paged in:

final codec = DrawingCodec();
final saved = jsonEncode(codec.encodeAll(editor.drawings, chart.timeScale().logicalToTime));
// later, once the data is loaded:
editor.layer.drawings = codec.decodeAll(jsonDecode(saved), chart.timeScale().timeToLogical);

Alerts on drawings. Drawing.pricesAt(logical) / editor.pricesAt(time) give a drawing's price(s) at a bar — e.g. to alert when the price crosses a trend line.

Anchors are a fractional logical index and a price, so drawings can extend past the last bar. For anything else, extend Drawing (anchorCount, paint, hitDistance). Set snap for a magnet, keepTool to draw several in a row, and TrackingModeOptions(longPressCrosshair: false) to edit with long presses.

Lower level: chart.subscribePointer offers each drag (and long press) in a pane to your handler; return true on down to take it, and the chart won't scroll. PaneApi.priceToCoordinate / coordinateToPrice and the price on click events convert between pixels and prices.

Orders, positions and alerts

final trading = TradingLines(candles,
    onDragEnd: (line) => broker.modify(line.id, line.price),
    onAlert: (alert, price) => notify('${alert.id} at $price'));
trading
  ..add(TradingLine(id: 'pos', kind: TradingLineKind.position, price: 29730, quantity: 0.5))
  ..add(TradingLine(id: 'tp', kind: TradingLineKind.takeProfit, price: 30480, quantity: 0.5))
  ..add(TradingLine(id: 'sl', kind: TradingLineKind.stopLoss, price: 29340, quantity: 0.5))
  ..add(TradingLine(id: 'a1', kind: TradingLineKind.alert, price: 30240));

Orders, TP / SL and alerts can be dragged (rounded to the price step); labels show the quantity and P&L against the position or the last price. Alerts fire when the last price crosses them (AlertCondition).

Overlays

Primitives attached to a series with series.attachPrimitive(...):

• BandFillPrimitive: a filled band between two lines (Bollinger, Keltner, an Ichimoku cloud with a second colour where the lines cross).
• PriceLevelsPrimitive: pivots, support / resistance, Fibonacci zones, with optional axis labels and hit ids.
• VolumeProfilePrimitive and SessionVolumeProfilePrimitive: see Volume profile.
• FanPrimitive: see Forecast fan.

Volume profile

final vp = Ta.volumeProfile(bars, buckets: 32);
print('POC ${vp.pocPrice}, value area ${vp.valueAreaLow}–${vp.valueAreaHigh}');

candles.attachPrimitive(VolumeProfilePrimitive(
  bins: [for (final b in vp.buckets)
    VolumeProfileBin(low: b.priceLow, high: b.priceHigh, volume: b.volume, upVolume: b.upVolume)],
  options: const VolumeProfileOptions(valueArea: 0.7), // VAH / VAL dashed, the rest dimmed
));

// one profile per trading day, each over its own bars (intraday data)
final sessions = Ta.sessionVolumeProfiles(bars, buckets: 24);
candles.attachPrimitive(SessionVolumeProfilePrimitive(sessions: [
  for (final s in sessions)
    SessionProfile(from: times[s.from], to: times[s.to], bins: [
      for (final b in s.profile.buckets)
        VolumeProfileBin(low: b.priceLow, high: b.priceHigh, volume: b.volume, upVolume: b.upVolume),
    ]),
]));

The value area is the range around the point of control holding 70% of the volume (Ta.valueAreaShare), grown toward the busier side one row at a time; Ta.valueArea(volumes, poc) computes it for any profile. Sessions are calendar days by default — pass sessionOf for anything else. To follow the bars on screen, refit the bins in subscribeVisibleLogicalRangeChange.

Forecast fan

final fan = FanPrimitive(
  anchorTime: last.time,
  anchorValue: last.close,
  steps: [for (final s in forecast)
    FanStep(mid: s.mid, ranges: [(s.lo80, s.hi80), (s.lo95, s.hi95)])],
);
candles.attachPrimitive(fan);
chart.timeScale().applyOptions(const TimeScaleOptions(rightOffset: 20)); // room ahead

Steps sit on the logical index past the last bar, so no whitespace data is needed; the ranges take part in autoscale.

Chart types and timeframes

candles.setData(heikinAshi(bars));
candles.setData(renko(bars, boxSize: 50));   // also lineBreak, rangeBars
final hourly = resample(minuteBars, const Timeframe.hours(1));   // .weeks(), .months()
final live = Resampler(const Timeframe.minutes(15));
candles.update(live.add(tick));                  // streaming

Compare symbols

chart.addComparison(ethBars, title: 'ETH');   // switches the scale to %
chart.addComparison(solBars, title: 'SOL');

Removing the last comparison (removeComparison) restores the scale mode.

Several charts in step

final sync = CrosshairSync([(hourlyChart, hourlyCandles), (fourHourChart, fourHourCandles)]);
// …
sync.dispose();

Pointing at a moment on one chart moves every other chart's crosshair to the same time — across symbols, and across intervals: on a 4h chart it lands on the bar holding that hour. timeScale().timeToLogical / logicalToTime convert between times and fractional bar indices, between bars and past them.

Sparklines and donut charts

For list rows and cards, SwmSparkline draws a small line without a chart engine behind it — no axes, scales or gestures:

SwmSparkline(
  values: closes,          // oldest first; non-finite values are skipped
  width: 80,
  height: 32,
  baseline: previousClose, // optional dashed reference; decides green / red
  curved: true,
)

SwmSparklinePainter paints the same line onto any Canvas, e.g. into an image with a PictureRecorder.

SwmDonut shows shares of a whole, e.g. a portfolio's allocation:

SwmDonut(
  slices: [
    for (final h in holdings) SwmDonutSlice(value: h.value, color: h.color),
  ],
  size: 130,
  innerRadius: 38,
  thickness: 30,
  selected: touched,                       // drawn thicker
  onSelect: (i) => setState(() => touched = i), // null on release
  center: Text(touched == null ? 'Total' : holdings[touched!].symbol),
)

Custom series and primitives

Custom series: implement CustomSeriesView<T> (priceValues, draw) and add it with chart.addCustomSeries(view).

Custom drawings: extend ChartPrimitive (override paint, priceAxisLabels, timeAxisLabels, autoscaleInfo, hitTest) and attach it with series.attachPrimitive(...) or pane.attachPrimitive(...). The paint context gives the crosshair's bar (crosshairIndex) and position.

Interaction

	Touch	Mouse
Crosshair	tap to show / hide, then drag to move it; or long-press and move	follows the pointer
Scroll / zoom	drag (locked to its main direction), pinch	drag, wheel
Scale an axis	drag it; double-tap resets	drag it; double-click resets
Resize panes	drag the separator	drag the separator (resizeRow cursor)

Performance

Frame times in profile mode with 100k candles plus 100k volume columns (example/integration_test/perf_test.dart):

Scenario	iPhone build / raster (avg, ms)	macOS build / raster (avg, ms)
Scroll at normal zoom	1.9 / 1.4	1.0 / 1.2
Realtime update every frame	2.1 / 1.9	1.3 / 1.7
Crosshair moving	1.9 / 2.3	0.6 / 0.9
All 100k visible, conflation on	2.4 / 2.1	1.1 / 1.2
All 100k visible, conflation off	28.7 / 16.9	16 / 8

The chart paints in two layers: a crosshair move or the last price pulse repaints only the overlay (crosshair, legend, trading lines, drawings), not the series.

When users can zoom out over tens of thousands of bars, turn on TimeScaleOptions(enableConflation: true) (optionally with precomputeConflationOnInit), as upstream recommends.

Run the benchmark yourself:

cd example
flutter drive --profile -d <device> \
  --driver=test_driver/perf_driver.dart --target=integration_test/perf_test.dart

Example app

example/ has six tabs:

• Trading: switchable series types, volume, SMA, an RSI pane with buy/sell markers, a watermark, live updates, an OHLC legend, history lazy-loading, log/percentage scales, dark mode.
• Pro: SwmProChart with live ticks, four intervals, and buttons that save the whole chart to JSON and restore it.
• Yields and Options: the two non-time chart types.
• Pro tools: drawings, overlays, indicators, orders, trend indicators with a tooltip, technical analysis, session volume profiles, a forecast fan, Heikin-Ashi, Renko, compare and synced 1h / 4h charts.
• Watchlist: sparklines and a donut.

cd example && flutter run

Every screenshot in this README comes from it: tool/screenshots.sh <simulator-udid>.

Notes

• time is a num: UTC seconds on time charts, months on yield curves, prices on options charts. series.data() returns values and whitespace.
• Labels use the UTC components of time. To show exchange-local time, shift the timestamps or pass LocalizationOptions.timeFormatter / TimeScaleOptions.tickMarkFormatter.
• Inside a vertical ListView, vertical drags go to the list; set handleScroll: HandleScrollOptions(vertTouchDrag: false) so the chart never claims them.
• SwmChart(semanticsLabel: ...) names the chart for screen readers; its value lists each series' last value.
• SeriesOptions are generated by tool/gen_series_options.py; edit the script, not lib/src/series_options.dart.

License & attribution

Apache License 2.0 (see LICENSE and NOTICE). The code is derived from TradingView Lightweight Charts™. Upstream's NOTICE requires apps that use it to show attribution to TradingView with a link to https://www.tradingview.com/, e.g. on an About screen. The chart can show the TradingView logo for you (layout.attributionLogo: true, off by default; pass SwmChart(onAttributionLogoTap: ...) to open the link).