Preserve size of pie chart no matter number of categories in legend

GemBox.Presentation
5

Try this:

var workbook = ExcelFile.Load("input.xlsx");
var worksheet = workbook.Worksheets[0];
var chart = worksheet.Charts[0];

int r = chart.Position.To.Row.Index;
int c = chart.Position.From.Column.Index;

foreach (var series in chart.Series)
{
    ++r;

    worksheet.Cells[r, c].Value = "■ " + series.DisplayName;

    DrawingColor color = DrawingColor.FromName(DrawingColorName.Black);
    if (series.Fill.FillType == FillFormatType.Solid)
        color = ((SolidFillFormat)series.Fill).Color;
    else if (series.Outline.Fill.FillType == FillFormatType.Solid)
        color = ((SolidFillFormat)series.Outline.Fill).Color;

    worksheet.Cells[r, c].GetCharacters(0, 1).Font.Color = SpreadsheetColor.FromArgb(color.Argb);
}

workbook.Save("output.xlsx");

I hope it helps.

Regards,
Mario