Top

ChartDataLabel.Top property

Gets or sets the distance of the data label in points from the top edge of the chart or from the position specified by its Position property, depending on the value of the TopMode property.

public double Top { get; set; }

Remarks

The value of the property changes proportionally if the chart shape is resized.

The property cannot be set in a Word 2016 chart.

Examples

Shows how to place data labels of doughnut chart outside doughnut.

Document doc = new Document();
DocumentBuilder builder = new DocumentBuilder(doc);

const int chartWidth = 432;
const int chartHeight = 252;
Shape shape = builder.InsertChart(ChartType.Doughnut, chartWidth, chartHeight);
Chart chart = shape.Chart;
ChartSeriesCollection seriesColl = chart.Series;
// Delete default generated series.
seriesColl.Clear();

// Hide the legend.
chart.Legend.Position = LegendPosition.None;

// Generate data.
const int dataLength = 20;
double totalValue = 0;
string[] categories = new string[dataLength];
double[] values = new double[dataLength];

for (int i = 0; i < dataLength; i++)
{
    categories[i] = $"Category {i}";
    values[i] = dataLength - i;
    totalValue = totalValue + values[i];
}

ChartSeries series = seriesColl.Add("Series 1", categories, values);
series.HasDataLabels = true;

ChartDataLabelCollection dataLabels = series.DataLabels;
dataLabels.ShowValue = true;
dataLabels.ShowLeaderLines = true;

// The Position property cannot be used for doughnut charts. Let's place data labels using the Left and Top
// properties around a circle outside of the chart doughnut.
// The origin is in the upper left corner of the chart.

const double titleAreaHeight = 25.5; // This can be calculated using title text and font.
const double doughnutCenterY = titleAreaHeight + (chartHeight - titleAreaHeight) / 2;
const double doughnutCenterX = chartWidth / 2d;
const double labelHeight = 16.5; // This can be calculated using label font.
const double oneCharLabelWidth = 12.75; // This can be calculated for each label using its text and font.
const double twoCharLabelWidth = 17.25; // This can be calculated for each label using its text and font.
const double yMargin = 0.75;
const double labelMargin = 1.5;
const double labelCircleRadius = chartHeight - doughnutCenterY - yMargin - labelHeight / 2;

// Because the data points start at the top, the X coordinates used in the Left and Top properties of
// the data labels point to the right and the Y coordinates point down, the starting angle is -PI/2.
double totalAngle = -System.Math.PI / 2;
ChartDataLabel previousLabel = null;

for (int i = 0; i < series.YValues.Count; i++)
{
    ChartDataLabel dataLabel = dataLabels[i];

    double value = series.YValues[i].DoubleValue;
    double labelWidth;
    if (value < 10)
        labelWidth = oneCharLabelWidth;
    else
        labelWidth = twoCharLabelWidth;
    double labelSegmentAngle = value / totalValue * 2 * System.Math.PI;
    double labelAngle = labelSegmentAngle / 2 + totalAngle;
    double labelCenterX = labelCircleRadius * System.Math.Cos(labelAngle) + doughnutCenterX;
    double labelCenterY = labelCircleRadius * System.Math.Sin(labelAngle) + doughnutCenterY;
    double labelLeft = labelCenterX - labelWidth / 2;
    double labelTop = labelCenterY - labelHeight / 2;

    // If the current data label overlaps other labels, move it horizontally.
    if ((previousLabel != null) &&
        (System.Math.Abs(previousLabel.Top - labelTop) < labelHeight) &&
        (System.Math.Abs(previousLabel.Left - labelLeft) < labelWidth))
    {
        // Move right on the top, left on the bottom.
        bool isOnTop = (totalAngle < 0) || (totalAngle >= System.Math.PI);
        int factor;
        if (isOnTop)
            factor = 1;
        else
            factor = -1;

        labelLeft = previousLabel.Left + labelWidth * factor + labelMargin;
    }

    dataLabel.Left = labelLeft;
    dataLabel.LeftMode = ChartDataLabelLocationMode.Absolute;
    dataLabel.Top = labelTop;
    dataLabel.TopMode = ChartDataLabelLocationMode.Absolute;

    totalAngle = totalAngle + labelSegmentAngle;
    previousLabel = dataLabel;
}

doc.Save(ArtifactsDir + "Charts.DoughnutChartLabelPosition.docx");

See Also

ChartDataLabel.ShowValue ChartDataLabel.TopMode