NSurvey - Pie Charts

Feb 22, 2005
by David Cumps

Originally published on my old blog at cumps.be on February 22, 2005.

NSurvey already provides general charts displaying the results, but it uses a bar chart and I had to output pie charts as well. So, I implemented them as well.

First, I created a new page, called PieChartReport.aspx, which was empty. After this I used the same code as the BarChartReport and filled up a ChartPointCollection, which I then used to create a new PieChart, render it and send it back to the client

ChartEngine engine = new ChartEngine();
ChartCollection charts = new ChartCollection(engine);

engine.Size = new Size(350, 400);
engine.Charts = charts;
engine.Title = new ChartText();

if (questions.Questions[0].IsParentQuestionIdNull()) {
  engine.Title.Text = Server.HtmlDecode(
          Regex.Replace(questions.Questions[0].QuestionText, "<[^>]*>", " "));
} else {
  String questionText = String.Format("{0} - {1}",
                      questions.Questions[0]["ParentQuestionText"].ToString(),
                      questions.Questions[0].QuestionText);
  questionText = questionText.Replace(Environment.NewLine, "");
  questionText = questionText.Replace("\t", "");
  questionText = questionText.Replace("<p>", "");
  questionText = questionText.Replace("</p>", "");
  engine.Title.Text = Server.HtmlDecode(
                                 Regex.Replace(questionText, "<[^>]*>", " "));
}

PieChart pie = new PieChart(data);
engine.Charts.Add(pie);
ChartLegend legend = new ChartLegend();
legend.Position = LegendPosition.Bottom;
engine.HasChartLegend = true;
engine.Legend = legend;
engine.GridLines = GridLines.None;