在.Net6 Core中使用NPOI excel nuget包为柱形图中的每一列设置不同的颜色

Question

我有使用 Npoi 包生成 Excel 文件的代码，其中 Excel 工作表上的数据创建柱形图。我的柱形图中有 4 列，默认情况下所有列的颜色均为蓝色。我想为柱形图中的每个列设置自定义颜色，即我想要 4 列有 4 种不同的颜色。 如何使用 NPOI 包来实现这一点？

using NPOI.SS.UserModel;
using NPOI.SS.UserModel.Charts;
using NPOI.SS.Util;
using NPOI.XSSF.UserModel;
using System;
using System.IO;

namespace ColumnChart
{
class Program
{
    const int NUM_OF_ROWS = 4;
    const int NUM_OF_COLUMNS = 2;
    private static void CreateChart(ISheet sheet, IDrawing drawing, IClientAnchor anchor, string serieTitle, int startDataRow, int endDataRow, int columnIndex)
    {
        XSSFChart chart = (XSSFChart)drawing.CreateChart(anchor);

        IColumnChartData<string, double> columnChartData = chart.ChartDataFactory.CreateColumnChartData<string, double>();
        IChartLegend legend = chart.GetOrCreateLegend();
        legend.Position = LegendPosition.Bottom;

        IChartAxis bottomAxis = chart.ChartAxisFactory.CreateCategoryAxis(AxisPosition.Bottom);
        bottomAxis.MajorTickMark = AxisTickMark.None;
        IValueAxis leftAxis = chart.ChartAxisFactory.CreateValueAxis(AxisPosition.Left);
        leftAxis.Crosses = AxisCrosses.AutoZero;
        leftAxis.SetCrossBetween(AxisCrossBetween.Between);


        IChartDataSource<string> categoryAxis = DataSources.FromStringCellRange(sheet, new CellRangeAddress(startDataRow, endDataRow, 0, 0));
        IChartDataSource<double> valueAxis = DataSources.FromNumericCellRange(sheet, new CellRangeAddress(startDataRow, endDataRow, columnIndex, columnIndex));
        var serie = columnChartData.AddSeries(categoryAxis, valueAxis);
        serie.SetTitle("Categories of Risk Associated");

        chart.Plot(columnChartData, bottomAxis, leftAxis);
    }
    static void Main(string[] args)
    {
        using (IWorkbook wb = new XSSFWorkbook())
        {
            ISheet sheet = wb.CreateSheet();

            IRow row;
            ICell cell;
            for (int rowIndex = 0; rowIndex < NUM_OF_ROWS; rowIndex++)
            {
                row = sheet.CreateRow((short)rowIndex);
                for (int colIndex = 0; colIndex < NUM_OF_COLUMNS; colIndex++)
                {
                    cell = row.CreateCell((short)colIndex);
                    if (colIndex == 0)
                        cell.SetCellValue("X" + rowIndex);
                    else
                    {
                        var x = colIndex * (rowIndex + 1);
                        cell.SetCellValue(x * x + 2 * x + 1);
                    }
                }
            }
            XSSFDrawing drawing = (XSSFDrawing)sheet.CreateDrawingPatriarch();
            XSSFClientAnchor anchor = (XSSFClientAnchor)drawing.CreateAnchor(0, 0, 0, 0, 3, 3, 10, 12);

            CreateChart(sheet, drawing, anchor, "s1", 0, 9, 1);
            using (FileStream fs = File.Create("C:\\Users\\lenovo\\Downloads\\columnChart.xlsx"))
            {
                wb.Write(fs, false);
            }
            Console.WriteLine("Done!");
            Console.ReadLine();
        }
    }
  }
}

生成的柱形图示例

需要柱形图样本

Answer 1

尝试在

chart.Plot(columnChartData, bottomAxis, leftAxis);

后添加以下代码

chart.Plot(columnChartData, bottomAxis, leftAxis);

var plotaArea = chart.GetCTChart().plotArea;
plotaArea.barChart[0].ser[0].dPt = new List<NPOI.OpenXmlFormats.Dml.Chart.CT_DPt>();

for(int index = 0; index < endDataRow - startDataRow; index++)
{
    var dpt = new NPOI.OpenXmlFormats.Dml.Chart.CT_DPt();
    dpt.idx = new NPOI.OpenXmlFormats.Dml.Chart.CT_UnsignedInt();
    dpt.idx.val = (uint)index;
    dpt.spPr = new NPOI.OpenXmlFormats.Dml.Chart.CT_ShapeProperties();
    var solidFill = dpt.spPr.AddNewSolidFill();
    var color = solidFill.AddNewSrgbClr();
    // random color
    color.val = new byte[] { (byte)(125 + index*5), (byte)(50 + index * 8), (byte)(100 + index * 11) };

    plotaArea.barChart[0].ser[0].dPt.Add(dpt);
}

随机颜色的结果是

您需要将逻辑添加到

for

循环中，并根据当前

color.val

设置

dataRow

。

System.Drawing.Color

可以帮助你。您可以这样设置值：

color.val = new byte[] { Color.Red.R, Color.Red.G, Color.Red.B }