Question

I have an ASP Chart that uses a timer to refresh an updatepanel, simulating a “realtime” graph (essentially the guide at https://web.archive.org/web/20201205213920/https://www.4guysfromrolla.com/articles/121609-1.aspx under “Creating Real Time Charts”). I’ve added functionality that allows you to dynamically add a series to the chart, but the new series always starts from the 0 point on the x-axis. This is a problem when there is already data on the chart that has been “ticking” for some time, because the new series starts from 0 and appears “shifted” to the left. How can I shift that series to the right to align it’s x-axis time with that of the other, “older” series?

Here’s a picture of an example–the blue line was added first, then the yellow line a few seconds later.

http://content.screencast.com/users/johnkemnetz/folders/Jing/media/c3c954fc-66c1-4d4d-a272-3e4b4f211e5a/ex.png

Answer 1

I figured this issue out myself. Here’s what I did:

if(chart.Series.Count > 0)
{
    /*Get the most recent Y-val to fill in empty spaces (if you fill with 0,
     *you'll end up with a "leap" on the first visible data point)*/
    double hiddenData = getMostRecentValue(newSeriesName);
    foreach (DataPoint dp in chart.Series[0].Points)
    {
        newSeries.AddXY(dp.XValue, hiddenData);
        newSeries.Last().Color = Color.Transparent;
    }
}
//etc. add newSeries to chart

Basically, I add “dummy values” for all those data points that didn’t exist in the new series, then hide them using Color.Transparent.
Hope this helps other people!