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What would be the easiest way of changing the zero line on a mountain chart?

I am plotting seabed elevations along a particular route. These values are always negative. Rather than shading the area above the dataseries (up to a value of 0) I would like to the shading to happen below the series (up to a specified negative value, which I would set to a depth well below my deepest point).

I have considered:
+ shifting my data points and working with a custom label formatter
+ swapping chart surface background and mountain area colours, but then the gridlines appear on the wrong side of the series

I noticed from the documentation that there is a zeroCoord parameter in the protected RenderMountainArea method, but I’m not sure how to best override it…

Any suggestions?

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Best Answer

Hi there,

Please, try overriding the InternalDraw(..) method in this way:

        protected override void InternalDraw(IRenderContext2D renderContext, IRenderPassData renderPassData)
            var theDeepestPoint = -100;

            var zeroCoord = (float)(CurrentRenderPassData.IsVerticalChart
                                  ? Math.Min(Width + 1, CurrentRenderPassData.YCoordinateCalculator.GetCoordinate(theDeepestPoint))
                                  : Math.Min(Height + 1, CurrentRenderPassData.YCoordinateCalculator.GetCoordinate(theDeepestPoint)));

            var gradientRotationAngle = GetChartRotationAngle(renderPassData);

            using (var areaBrush = renderContext.CreateBrush(AreaBrush, Opacity))
            using (var linePen = renderContext.CreatePen(SeriesColor, AntiAliasing, StrokeThickness, Opacity))
                RenderMountainArea(renderContext, linePen, areaBrush, PointMarker,
                                    zeroCoord, gradientRotationAngle);

Does it do the trick?


We’ve now added the property ZeroLineY to FastMountainRenderableSeries, so you can change this yourself. It also works for Column Series

/// Gets or sets the value which determines the zero line in Y direction.
/// Used to set the bottom of a column, or the zero line in a mountain
public double ZeroLineY
    get { return (double)GetValue(ZeroLineYProperty); }
    set { SetValue(ZeroLineYProperty, value); }

Best regards,

  • Jelle Muylle
    Dear Yuriy, that does indeed work! Thanks, Jelle
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