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ExcelApplication supports all Excel chart types, and allows you to insert a chart in a worksheet, create a chart sheet (a worksheet that only contains a chart).

If you open an existing Excel file with ExcelApplication.Open, you can use ExcelWriter's charting objects to modify charts in the spreadsheet.

To create a simple column chart:

  1. Get a Charts collection:

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    ExcelApplication xla = new ExcelApplication();
    Workbook wb = xla.Create();
    Worksheet ws = wb.Worksheets[0];
    Charts chrts = ws.Charts;

    The Charts collection contains all charts in a specified worksheet.

  2. Create an anchor in the worksheet:

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    Anchor anch = ws.CreateAnchor(7, 4, 0, 50);

    An anchor represents the position of a floating object (e.g., a chart) within a worksheet. The chart's top left corner will be placed at the anchor.

  3. Create a blank chart of a specified type, at the anchor you created:

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    Chart chrt = chrts.CreateChart(ChartType.Column.Clustered, anch);

    The ChartType class contains all available chart types (e.g., Column) and sub-types (e.g., Clustered).

  4. Return a SeriesCollection object representing the set of data series in the chart:

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    SeriesCollection sc = chrt.SeriesCollection;

  5. Set the range of category (x) axis values:

    ?
    sc.CategoryData = "Sheet1!A3:C3";

  6. Add a data series to the chart:

    ?
    Series s = sc.CreateSeries("Sheet1!A25:C25");

    The formula passed to CreateSeries represents cells that contain the source values for the new data series.

Example: Creating a Chart

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using System;
using SoftArtisans.OfficeWriter.ExcelWriter;
 
class ChartDemo : System.Web.UI.Page
{
     protected void Page_Load(object sender, System.EventArgs e)
     {
          //--- Create ExcelApplication, a Workbook, and a Worksheet
          ExcelApplication xla = new ExcelApplication();
          Workbook wb = xla.Create();
          Worksheet ws = wb.Worksheets[0];
 
          //--- Put some values into the cells that the
          //--- chart will reference
          System.Random rand = new System.Random();
 
          //--- Headers
          ws.Cells[0, 0].Value = "Month";
          ws.Cells[0, 1].Value = "Sales";
  
          //--- Month and sales
          ws.Cells[1, 0].Value = "Jan";
          ws.Cells[1, 1].Value = rand.Next(1000);
          ws.Cells[2, 0].Value = "Feb";
          ws.Cells[2, 1].Value = rand.Next(1000);
          ws.Cells[3, 0].Value = "Mar";
          ws.Cells[3, 1].Value = rand.Next(1000);
 
          //--- Create an Anchor on Cell B6
          Anchor anch = ws.CreateAnchor(4, 2, 0, 0);
 
          //--- Create the chart
          Chart chrt = ws.Charts.CreateChart(ChartType.Column.Clustered, anch);
 
          //--- Set series collection
          string seriesFormula =
               String.Format("={0}!{1}:{2}", ws.Name,
               ws.Cells[1, 1].Name, ws.Cells[3, 1].Name);
          Series srs = chrt.SeriesCollection.CreateSeries(seriesFormula);
          srs.Name = "Sales";
 
          //--- Set category data
          chrt.SeriesCollection.CategoryData =
               String.Format("{0}!{1}:{2}", ws.Name,
               ws.Cells[1, 0].Name, ws.Cells[3, 0].Name);
 
          xla.Save(wb, Page.Response, "Charts.xls", false);
     }
}

Modifying an Existing Chart

Code sample: Modifying an Existing Chart

When you use ExcelApplication to open a spreadsheet, you can access charts through their names or titles. Chart.getTitle returns a ChartText object representing the title region. ChartText.getText returns the title text. The following function takes a chart's title and returns a Chart object representing the chart. This code can be useful if you want to locate a specific chart in a worksheet but only know its title text:

?
private Chart FindChart(string title)
{
     for (int iChart = 0; iChart < ws.Charts.Count; iChart++)
     {
          Chart chrt = ws.Charts[iChart];
          if (chrt.Title.Text == title)
               return chrt;
     }
     return null;
}

The following example uses the FindChart code to locate a specific chart in a worksheet. The chart series collection is then cleared and re-set to the data imported from a database:

?
private void PopulateMainChart()
{
     //--- Get the data from the database.
     DataTable[] dtArr = GetCategoryQuarterlySales();
 
     //--- Find the main chart based on its title text, and get
     //--- a reference to it.
     Chart mainChart = FindChart("Quarterly Sales 2003");
 
     //--- Clear all the existing series objects from the collection
     SeriesCollection seriesCol = mainChart.SeriesCollection;
     while (seriesCol.Count > 0)
          seriesCol.Remove(0);
 
     //--- Each DataTable has a single row of data.
     int iRow = 29;
     for (int i = 0; i < dtArr.Length; i++)
     {
          DataTable dt = dtArr[i];
 
          //--- Import data from the DataTable.
          ws.ImportData(dt, ws[iRow, 1]);
 
          //--- Add the imported data as a new Series object
          //--- in the chart's collection.  There will be a variable
          //--- number of series objects depending on which categories
          //--- were selected for display.
          Area a = ws.CreateArea(iRow, 2, 1, 4);
          Series srs = seriesCol.CreateSeries(a);
          srs.NameFormula = ws[iRow, 1].Name;
 
          iRow++;
     }
 
     //--- Re-set the category data.  The size will vary
     //--- depending on the selected categories.
     seriesCol.CategoryData =
          ws.CreateArea(29, 1, dtArr.Length, 1).Dimensions;
 
     //--- Add a legend to the chart if desired
     if (bLegend)
     {
          mainChart.Legend.Visible = true;
          mainChart.Legend.Location = Legend.LegendLocation.Top;
     }
     else
     {
          //--- The legend is hidden in the template workbook.
          //--- Hide it again in case it's made visible.
          mainChart.Legend.Visible = false;
     }
}
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