Charting

gistfile1.cs

using System.Collections.Generic;
using System.Drawing;
using System.IO;
using System.Web.UI.DataVisualization.Charting;

namespace Charting
{
    public static class ChartingHelpers
    {
        public enum ImageFormat
        {
            PNG = 1,
            JPEG = 2,
            GIF = 3,
            BMP = 4
        }

        /// <summary>
        /// Converts an ImageFormat into a ChartImageFormat for use in the charting tools
        /// </summary>
        /// <param name="format"></param>
        /// <returns></returns>
        internal static ChartImageFormat ToChartImageFormat(this ImageFormat format)
        {
            switch (format)
            {
                case ImageFormat.JPEG
                    return ChartImageFormat.Jpeg;

                case ImageFormat.GIF:
                    return ChartImageFormat.Gif;

                case ImageFormat.BMP
                    return ChartImageFormat.Bmp;

                default:
                    return ChartImageFormat.Png;
            }
        }

        /// <summary>
        /// Generates a Pie Chart
        /// </summary>
        /// <param name="height">Image Height</param>
        /// <param name="width">Image Width</param>
        /// <param name="backgroundColour">Chart Background Colour</param>
        /// <param name="elements">Elements</param>
        /// <param name="format">Expected Image Format</param>
        /// <returns>Image in the format specified in the <paramref name="format"/>Format attribute</returns>
        public static byte[] GeneratePieChart(int height, int width, Color backgroundColour, List<ChartElement> elements, ImageFormat format)
        {
            var chart = new Chart
            {
                BackColor = backgroundColour,
                Height = height,
                Width = width
            };

            if (elements != null)
            {
                var area = new ChartArea("chartArea");
                area.BackColor = Color.Transparent;
                var series = new Series("series");
                series.ChartArea = "chartArea";
                series.ChartType = SeriesChartType.Pie;
                series.Font = new Font("Segeo UI", 11.0f, FontStyle.Regular, GraphicsUnit.Pixel);
                foreach (var element in elements)
                {
                    series.Points.Add(new DataPoint
                                      {
                                          AxisLabel = element.ShouldDisplayLegend ? element.Legend : null,
                                          Color = element.ElementColour,
                                          LabelForeColor = element.TextColour,
                                          YValues = new [] { element.Value }
                                      });
                }
                chart.Series.Add(series);
                chart.ChartAreas.Add(area);
            }

            using (var memStream = new MemoryStream())
            {
                chart.SaveImage(memStream, format.ToChartImageFormat());
                memStream.Seek(0, SeekOrigin.Begin); // put it back to the beginning
                return memStream.ToArray();
            }
        }
    }
}