[]
Gets the chart format of the trendline.
IChartFormat Format { get; }
ReadOnly Property Format As IChartFormat
worksheet.Range["A1:A4"].Value = new object[] { 10, 20, 30, 40 };
IShape shape = worksheet.Shapes.AddChart(ChartType.ColumnClustered, 20, 20, 360, 220);
shape.Chart.SeriesCollection.Add(worksheet.Range["A1:A4"], RowCol.Columns);
ITrendline trendline = shape.Chart.SeriesCollection[0].Trendlines.Add();
IChartFormat format = trendline.Format;
format.Line.Color.RGB = Color.Blue;