ohlcv_chart — the most complete candlestick chart for Flutter, with every drawing tool and indicator #

Read the changelog and the docs. This package moves quickly — a release can carry several new indicators, a new widget or two, and behaviour that has been sharpened since the last one. The list below is a summary and goes stale between releases; CHANGELOG.md says what actually changed and why, and doc/ has a page per feature with the detail. Both are worth a minute before you upgrade, and before you conclude something is missing.

Support #

The full package is free to use in your own projects — every chart type, all 31 indicators and all 29 drawing tools, nothing held back, nothing paywalled, commercial projects included. I keep it updated weekly: new indicators, drawing tools and fixes land as I use it myself.

If it saves you some work, all I ask in return is:

• ⭐ a star on the repository
• 👍 a like on the package on pub.flutter-io.cn
• 👤 a follow on GitHub

That is the whole price, and it is what keeps the weekly updates coming.

A candlestick (K-line) and market-depth chart for Flutter, drawn entirely with CustomPainter — no WebView, no JavaScript bridge.

Named for the open-high-low-close-volume bars it renders.

Features #

• Eight chart types — candles, OHLC bars, a line, a step line, a filled area, an HLC area, a baseline chart and columns — plus Heikin-Ashi, Renko, three-line break, Kagi, point & figure and range bars as transforms of the candles themselves.
• 31 indicators, each a configured instance rather than a flag — so ATR(8), ATR(14) and ATR(20) are three panes, with their own settings and colours.
• Main-chart overlays — MA, EMA, BOLL, SAR, VWAP in three flavours — whole-series, anchored to a candle, or restarted each session with standard-deviation bands — Supertrend, Keltner and Donchian channels, the Ichimoku Cloud, pivot points and a volume profile.
• Swing readers — a zigzag through the swing highs and lows, Fibonacci retracement of the last swing, and Elliott wave labels, all sized to the market by default.
• Sub-charts — MACD, KDJ, RSI, WR, CCI, ATR, OBV, MFI, DMI, Aroon, Stochastic RSI, ROC, TRIX, a volume average and the Awesome oscillator, each in its own stacked pane — resizable and reorderable by dragging.
• Linear, logarithmic, percentage or indexed-to-100 price axis, so a decade of compounding reads as well as an afternoon — invertible, with the window's high, low and average close markable on it.
• A price scale you can drag — pull the labels to stretch or flatten the candles, drag the chart to slide the window, double-tap to fit it back; from code as well, through the controller.
• A price axis that can be pinned — lockPriceScale holds it at one range instead of refitting it to whatever is on screen, so scrolling moves the candles under a scale that stays put rather than rescaling every number on the axis; and priceAxisWidth holds a gutter back for the labels, so the candles stop short of them instead of sliding underneath.
• Axes that read as round numbers — both axes choose their values first and are ruled where the labels fall, so a price scale steps 69000, 69500, 70000 and an intraday date axis lands on the hour, never on whatever value happened to fall on an evenly spaced pixel.
• 29 drawing tools — levels and rays, trend lines, arrows, extended lines, boxes, ellipses, triangles, parallel channels, pitchforks, Gann fans and boxes, four Fibonacci tools, a regression trend with its bands, XABCD patterns, multi-leg paths, price and date brackets, a measuring tool, planned positions with their risk-to-reward, notes, callouts, flags and freehand strokes; each placed by tap or drag, then dragged, locked, hidden and removed.
• A line editor that opens on selection: colour, opacity, thickness, solid/dashed/dotted stroke, fill, label text and visibility, alerts, lock and delete — every option list, control and pixel of it configurable through DrawingStyle.
• Undo and redo, through a ChartDrawingController that owns the drawings and their history, with ⌘Z, ⇧⌘Z and Delete on the chart itself.
• Select several and edit them together — shift- or ⌘-click, or ⌘A; then drag, restyle or delete the lot in one step, with ⌘C/⌘V/⌘D to copy and ⌘]/⌘[ to restack.
• Exact coordinates — a dialog over any drawing's anchors, each price and candle typed in rather than placed by eye.
• Style templates — save one drawing's look and put it on the rest.
• Indicator templates — a named set of indicators saved and put on any chart in one gesture, with four starter sets to begin from.
• A layout that persists — every drawing serialises, so jsonEncode(drawings.toJson()) and ChartDrawings.fromJson are the whole story.
• A drawing manager — a ready-made panel listing what is drawn, with show/hide, lock, delete, undo, redo and clear.
• Price alerts on a level, a trend line, either side of a channel or every step of a retracement, reported when the market crosses one.
• Indicator alerts — an RSI over 70, a histogram turning positive — and panes that can be logarithmic or read as a percentage, with any indicator computable over another's output.
• Higher timeframes — a daily moving average on a fifteen-minute chart, through TimeframeIndicator; each candle reads the last higher-timeframe bar that had closed when it opened, so the line never repaints and never shows a value from its own future.
• A right-click menu on the chart and on any drawing — coordinates, duplicate, restack, lock, hide, alert, delete; paste, select all, fit the scale, undo — with your own items added through one builder.
• Crosshair on hover and an OHLC legend above the chart, which is how a chart reads on a desktop.
• Or no interaction at all — scrollEnabled and zoomEnabled turn the chart's own gestures off, for an intraday session, a thumbnail or a figure that is meant to sit still rather than be navigated; your own code can still drive it.
• Driven from your own code — KChartController zooms, scrolls back to the live candle and hands you the chart as a PNG.
• The visible window, read and set — which candles are on screen, go-to-date, fit-to-screen, and a callback whenever it moves.
• An overview strip — ChartOverview draws the whole history under the chart with the visible window lit; drag it to scrub, drag its edges to zoom, tap to jump.
• Charts kept in step — ChartLink holds any number of charts on the same window and crosshair, so scrolling, zooming or pointing at one carries the rest with it; ChartLink.all() carries the crosshair's price and the price axis too, for one market shown twice.
• Compare a second instrument — overlay any number of other series, rebased so relative performance reads off the same axis, matched to your candles by time.
• Bar replay — rewind to any candle and step or play the market forward, with the indicators only knowing what has arrived.
• Buy/sell signal markers pinned to candles.
• Event marks — earnings, dividends, splits and news badged under the candle they happened on, and tappable.
• Orders and positions — live lines from your venue, tagged with side, size and P&L, and draggable to amend.
• Extended-hours shading — the pre-market and after-hours stretches washed behind the candles — and a per-bar colour of your own.
• Depth chart — a separate DepthChart widget for the order book, drawn as the cumulative curve, a per-rung histogram, both at once, or a numeric ladder of price, size and running total, on a linear, log or percentage axis and zoomable to the levels around the mid, with an optional bid/ask ratio bar underneath showing which way the resting orders lean.
• Info dialog on long press, either the built-in Material popup or your own builder.
• "Now price" line with a live countdown to the close of the current candle.
• Session dividers and a display time zone, so an intraday chart breaks where the trader's day does.
• SVG watermark loaded from an asset path you supply.
• Fully themeable — ChartStyle for geometry, ChartColors for every colour, DrawingStyle for the drawing tools; ChartTranslations for every label. Filled or hollow candles, dashed or solid crosshair, pane separators, axis-label pills and a placed, tinted watermark.
• Fits its box — the candles take whatever height the volume and indicator panes leave, so the chart works from a phone to a desktop window without arithmetic on your side.

Install #

dependencies:
  ohlcv_chart: ^2.4.1

Quick start #

Feed a KChartWidget a List<KLineEntity>, having run DataUtil.calculate over it so the indicator fields are populated:

import 'package:ohlcv_chart/ohlcv_chart.dart';

DataUtil.calculate(candles);

KChartWidget(
  candles,
  ChartColors(),
  isTrendLine: false,
  timeFrame: const Duration(minutes: 15),
  indicators: [MaIndicator(period: 20), MacdIndicator()],
  fixedLength: 2,
);

That is a working chart. The candlestick chart page covers the rest of the constructor, and the example app is a tour of every switch in the package.

Documentation #

One page per feature, in doc/:

Notes #

• The zoom slider renders only where there is no pinch gesture — web and desktop.
• watermarkAssetPath must point at an SVG registered in your app's pubspec.yaml assets; a missing asset is ignored and the chart renders without a watermark.

Credits #

The rendering core began as a derivative of the open-source k_chart package and has since been substantially extended with drawing tools, signals, multi-indicator stacking and a reworked painter pipeline.

License #

MIT — see LICENSE.