Question

My objective: return coordinates and shapes so that I can roll my own custom hover text to a .NET Charting image. This would be no problem if I were using the ASP.NET control (which renders both an image tag and an HTML <map> tag; however, I’m in the MVC world so I’m returning the chart as a binary image. Here’s the gist:

public virtual FileStreamResult Chart()
{
    //Set up chart
    Chart Chart1 = new Chart();
    Chart1.RenderType = RenderType.ImageTag;

    Chart1.ChartAreas.Add(new ChartArea("First"));

    //Add some lovely data
    Series s = new Series();
    s.Name = "Tasks";
    s.Points.AddXY("Task 1", 5, 8);
    s.ChartArea = "First";
    s.ChartType = SeriesChartType.RangeBar;

    //Add a tooltip - This **should** make the MapAreas collection populate.
    s.ToolTip = "Hello World";

    Chart1.Series.Add(s);

    if (Chart1.MapAreas.Count == 0)
        CryRiver(); //Always executed. :*(

    //Output image as FileStreamResult
    //...
}

The Problem: No matter what I do, I cannot get the MapAreas collection to contain anything. I believe this to be because the coordinates don’t get populated until the image actually renders.

How do I get at the coordinates of the map areas for the charted data when rendering an image as binary?

Thanks!

Answer 1

Found an answer; not sure if it’s the best one.

One must call Chart1.RenderControl(); before the Chart1.MapAreas gets populated.