Native Controls Wrappers / IOS / Chart / PointLabels

Chart for Xamarin.iOS: Point Labels Customization

TKChart lets you customize point labels using TKChartPointLabelStyle's properties. However, sometimes you may need to draw specific shapes for the labels. In such cases you should sublcass TKChartPointLabel to create your own label and implement TKChartDelegate to use it.

Customization using TKChartPointLabelStyle properties

Here is an example how to customize point labels changing TKChartPointLabelStyle settings.

TKChartLineSeries lineSeries = new TKChartLineSeries (dataPoints.ToArray ());
lineSeries.Selection = TKChartSeriesSelection.DataPoint;
lineSeries.Style.PointShape = new TKPredefinedShape (TKShapeType.Circle, new SizeF (8, 8));
lineSeries.Style.PointLabelStyle.TextHidden = false;
lineSeries.Style.PointLabelStyle.LabelOffset = new UIOffset (0, -24);
lineSeries.Style.PointLabelStyle.Insets = new UIEdgeInsets (-1, -5, -1, -5);
lineSeries.Style.PointLabelStyle.LayoutMode = TKChartPointLabelLayoutMode.Manual;
lineSeries.Style.PointLabelStyle.Font = UIFont.SystemFontOfSize (10);
lineSeries.Style.PointLabelStyle.TextAlignment = UITextAlignment.Center;
lineSeries.Style.PointLabelStyle.TextColor = UIColor.White;
lineSeries.Style.PointLabelStyle.Fill = new TKSolidFill (new UIColor ((float)(108 / 255.0), (float)(181 / 255.0), (float)(250 / 255.0), (float)1.0));
lineSeries.Style.PointLabelStyle.ClipMode = TKChartPointLabelClipMode.Hidden;

Custom point labels

Subclassing TKChartPointLabel lets you perform custom drawing and calculate the size of the point label. Once you create your own label you should implement TKChartDelegate to use it.

public override TKChartPointLabel LabelForDataPoint (TKChart chart, TKChartData dataPoint, string propertyName, TKChartSeries series, nuint dataIndex)
{
    TKChartDataPoint point = (TKChartDataPoint)dataPoint;
    if (series.Index == (nuint)this.selectedSeriesIndex && dataIndex == (nuint)this.selectedDataPointIndex) {
        return new MyPointLabel (point, series, String.Format ("{0}", point.DataYValue));
    }


    return new TKChartPointLabel (point, series, String.Format ("{0}", point.DataYValue));
}

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