How to make tooltips show up when mouse hovers over data point

Question

I've been searching for some sort of tutorial focusing on how tooltips to work, but have not had much luck.

I have a test project where I render a line chart with five data points. When I instantiate the Chart object I set IsMapEnabled = true. When I define the series I try to set the tool tip.

  private void DefineSeries() {
     var series = new Series();
     series.ToolTip = "#VALY";
     series.PostBackValue = "#Index";
     var x = new[] {0, 1, 2, 3, 4, 5};
     var y = new[] {0, 4, 5, 3, 7, 2};
     for ( int i = 0; i < x.Length; i++ ) {
         series.Points.Add( new DataPoint( x[ i ], y[ i ] ) );
     }
     series.ChartType = SeriesChartType.Line;
     DefineSeriesStyle( series );
     chart_.Series.Add( series );   
  }

The chart renders as expected, but a tooltip does not display when the mouse hovers over a data point. I am clearly missing a step somewhere, but I have no idea what it is.

EDIT: Code that shows the Action method and constructor for the chart view model and subsequent function call.

  public ActionResult CausedOutPoint() {
     var causedOut = new CausedOutViewModel();
     var path = Server.MapPath( "~" ) + "CausedOut.Png";
     causedOut.Chart.SaveImage( path, ChartImageFormat.Png );
     return File( path, "img/png" );
  }

  public CausedOutViewModel() {
     chart_ = new Chart {IsMapEnabled = true};
     chart_.PostPaint += chart__PostPaint;
     chart_.RenderType = RenderType.ImageMap;
     chart_.ID = "CausedOut";
     InitializeChart( chart_ );
     chart_.Width = new Unit( 1200, UnitType.Pixel );
     chart_.Height = new Unit( 800, UnitType.Pixel );
     CreateTitles();
  }

  private void InitializeChart( ) {
     DefineSeries();
     DefineChartArea();
  }

Did you set an ID for the `Chart`, as referenced in the accepted answer for [MSChart / Asp.net Charts dont show tooltips](http://stackoverflow.com/questions/9456506/mschart-asp-net-charts-dont-show-tooltips)? — Karl Anderson, Aug 23 '13 at 15:56
I did see that during my searches. I tried it and still nothing. — BrianM, Aug 23 '13 at 16:11

score 0 · Answer 1 · edited May 23 '17 at 12:05

0

You are doing something in DefineSeriesStyle that disables the tooltips. I have tested your method without the statement DefineSeriesStyle( series ); and the tooltips are shown.

For a comprehensive overview on tooltips, custom tooltips refer my previous answer for a similar question. Show tooltip in LineSeries WinForms Chart?

edited May 23 '17 at 12:05

Community

1
1

answered Aug 26 '13 at 11:16

Joe Vi

473
4
10

I tried commenting out the `DefineSeriesStyle` and it still didn't work. The only thing I do in the method is set the series color, marker style, etc. I don't touch the tooltip properties (label or otherwise) at all. So I think this might point to how I am rendering the chart. I edited more code into the original post that shows the Action method, view model constructor, and the `InitializeChart` method. – BrianM Aug 26 '13 at 18:31

BrianM · Accepted Answer · 2013-08-26T20:51:21.683

urns out my issue was that I was no rendering the map area for my chart. For those who run into a the same problem his the code that fixed my problem:

The controller

  public ActionResult CausedOutPoint() {
     var ms = (byte[])Session[ "MS" ];
     return File( ms, "img/png" );
  }

  public ActionResult CausedOutMap(string name)
  {

     var causedOut = new CausedOutViewModel();
     var ms = new MemoryStream();
     causedOut.Chart.SaveImage(ms, ChartImageFormat.Png);
     Session[ "MS" ] = ms.ToArray();
     return Content( causedOut.Chart.GetHtmlImageMap( name ) );
  }

Necessary Razor in the Index.csthml

    <img  src="@Url.Action("CausedOutPoint")" usemap="#CausedOut"/>
    @{
        Html.RenderAction("CausedOutMap", new { name = "causedOut"});
    }

How to make tooltips show up when mouse hovers over data point

2 Answers2