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The RangeLineSeries<TModel> draws each point with two smoothed cubic-bezier curves — one through the high endpoints and one through the low endpoints — and fills the band between them. This is the natural shape for min / max envelopes: daily temperature ranges, forecast confidence intervals, weather bands, stock high / low channels, sensor tolerance windows, anything where the underlying quantity lives somewhere inside a per-point range rather than a single value.

The simplest way to feed the series is the RangeValue helper in LiveChartsCore.Defaults (shared with RangeColumnSeries and RangeRowSeries), which carries Low and High and maps to the coordinate slots the series expects (PrimaryValue = High, TertiaryValue = Low).

Series = new ISeries[]
{
    new RangeLineSeries<RangeValue>
    {
        Name = "Temperature",
        Values = new []
        {
            new RangeValue(low:  8, high: 16),  // Jan
            new RangeValue(low:  9, high: 17),  // Feb
            new RangeValue(low: 11, high: 20),  // Mar
            new RangeValue(low: 13, high: 23),  // Apr
            new RangeValue(low: 16, high: 27),  // May
            new RangeValue(low: 20, high: 31),  // Jun
            // ...
        }
    }
};

XAxes = new[]
{
    new Axis { Labels = new[] { "Jan", "Feb", "Mar", "Apr", "May", "Jun" } }
};

YAxes = new[]
{
    new Axis { Labeler = v => $"{v:0}°C" }
};

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Custom models

When you don't want to use RangeValue, register a Mapping that fills the coordinate slots from your own type. The slot mapping mirrors RangeColumnSeries and RangeRowSeries: PrimaryValue carries the high endpoint, TertiaryValue carries the low endpoint, and SecondaryValue is the category index.

new RangeLineSeries<MyReading>
{
    Values = myReadings,
    Mapping = (reading, index) =>
        new Coordinate(reading.Max, index, reading.Min, 0, 0, 0, Error.Empty)
}

Paints

The series exposes the usual Stroke and Fill properties, with a small twist:

• Stroke paints both the high curve and the low curve.
• Fill paints the band area between them.
• GeometryStroke and GeometryFill style the markers at each high / low endpoint.

A Stroke = null (or Paint.Default) hides both curves while keeping the band; a Fill = null hides the band while keeping the two curves on their own.

Tooltip

By default each point's tooltip shows {low} → {high} formatted through the Y axis labeler — so a numeric axis renders numbers, and a DateTimeAxis would render dates without any extra wiring.

To customize the body text — for example to add a unit suffix — set YToolTipLabelFormatter:

new RangeLineSeries<RangeValue>
{
    Values = temperatures,
    YToolTipLabelFormatter = point =>
        $"{point.Coordinate.TertiaryValue:0}°C → {point.Coordinate.PrimaryValue:0}°C"
}

Smoothing

LineSmoothness controls the cubic-bezier tangent strength on both curves, exactly like LineSeries — 0 = straight polyline, 1 = fully curved (default 0.65). The two curves always share the same smoothness; if you need independently-shaped curves, draw two LineSeries instead and skip the band.

Animation

New points enter at the midpoint of their [Low, High] range with zero size, then expand symmetrically outward to the high and low endpoints. The SoftDeleteOrDispose animation mirrors this: both markers collapse back to the midpoint as the point is removed. The midpoint baseline preserves the visual intent of the range — there's no meaningful "pivot" for a series whose points don't include zero.

Swapped endpoints

If a point's Low > High, each curve still traces whichever endpoint it was given — so the band crosses over itself at that point. The series does not silently normalize the values; if [Low, High] order matters to your data model, swap them on the way in.

Stacking

Range line series are not stackable — ranges have no natural baseline to accumulate from.

Hit-testing and tooltips

The per-point hover area covers the full band column at that X (from the high pixel to the low pixel, half a unit-width on each side of the point), so hovering anywhere inside the band picks up the point's tooltip. ExactMatch strategies hit the high / low markers themselves.

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