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Chart types

chartType sets how the candle area is rendered:

KChartWidget(
  candles,
  ChartColors(),
  timeFrame: const Duration(minutes: 15),
  chartType: ChartType.bars,       // candles, bars, line, area, baseline
  baselinePrice: 42_000,           // baseline only; defaults to the oldest close in view
);

Bars, baseline, area, step line, HLC area and columns

ChartType Rendering
candles Filled or hollow body with wicks (default)
bars OHLC bars: high-low range with open tick on the left and close tick on the right
line Line through closing prices
area Line with a filled area below
baseline Line filled towards a baseline, in the up colour above and the down colour below
stepLine Line that holds each close until the next
hlcArea Filled high-low range with the close drawn through it
columns One column per candle, from the baseline to the close

For backward compatibility, isLine: true is equivalent to ChartType.area.

Candle transforms

Heikin-Ashi, Renko, three-line break, Kagi, point & figure and range bars change the candle data itself rather than how it is drawn, so they are provided as transforms. Pass the candles through CandleTransforms, then compute indicators on the result:

final ha = CandleTransforms.heikinAshi(candles);
DataUtil.calculate(ha);

final bricks = CandleTransforms.renko(
  candles,
  brickSize: CandleTransforms.atrBrickSize(candles) ?? 25,
);
DataUtil.calculate(bricks);

KChartWidget(ha, ChartColors(), /* … */);

Heikin-Ashi candles beside the same market as Renko bricks

Heikin-Ashi produces one candle per source candle at the same timestamps, so drawings stay in place. The other transforms are price-based and not time-based; each output bar carries the combined volume of the candles it covers.

Transform New bar condition
renko(brickSize:) Close moves one full brick beyond the previous brick; reversals require two
lineBreak(lines: 3) Close beyond the previous block; reversals must exceed the extreme of the last lines blocks
kagi(reversal:, asPercent:) Price retraces by reversal from the extreme; each segment represents a full trend
pointAndFigure(boxSize:, reversalBoxes: 3) Price moves a full box, based on highs and lows; a new column requires reversalBoxes boxes
rangeBars(range:) Price moves range from the bar's open

atrBrickSize derives a brick, box, reversal or range size from the average true range:

final step = CandleTransforms.atrBrickSize(candles) ?? candles.last.close * 0.005;

final blocks = CandleTransforms.lineBreak(candles);
final segments = CandleTransforms.kagi(candles, reversal: step);
final columns = CandleTransforms.pointAndFigure(candles, boxSize: step);
final bars = CandleTransforms.rangeBars(candles, range: step);

Line break, Kagi, point & figure and range bars

All transforms return standard candles with their own timestamps, so the chart, indicators and drawing tools work without changes. Note that bar meaning differs by transform: a Kagi segment is a complete trend, a point & figure candle is a column of boxes, and a range bar covers exactly range.

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