Tooltip overload

[Ekedev]

For some reason when I enable tooltips it displays every value in the series and not the value I am hovering over. I have a few thousand points in my series, but even when I zoom down to a level where the data should be granular I still see all the values in my series in the tooltip.

this is my LineSeries

chan0Series = new LineSeries
{
Name = "Channel 0",
Values = this._observableValuesChan0,
Fill = null,
GeometryFill = null,
GeometryStroke = null,
Stroke = new SolidColorPaint(chan0Color) { StrokeThickness = 2 },
ScalesYAt = 0,
LineSmoothness = 0,
TooltipLabelFormatter = (chartPoint) => $"{chartPoint.PrimaryValue}"
};

and the xaml

<lvc:CartesianChart x:Name="lvcHistChart" ZoomMode="X" ZoomingSpeed=".5"
Series="{Binding Series}" XAxes="{Binding XAxes}" YAxes="{Binding YAxes}" TooltipPosition="Top"
LegendPosition="Right">
</lvc:CartesianChart>

[alexachso]

Hello,
Did you find a solution for this? I am experiencing the same issue.
Thank you!

[jradio610]

Same issue here as well.

[langejay]

What is the value range in your data (x axis)?

[alexachso]

Hi,

Here is an actual example :)
This is the chart I have.

As you can see the tooltip shows me lots of points. I wouldn't mind that much if it was showing me all the Y points for the same X. (because in my case I have multiple Y points for the same X point).

And btw, when I zoom, the tooltip is all over the place... It even sometimes show it on my second screen.

[langejay]

you need to try to change the Unit Width for the chart. As expected your values are <1 unit apart. Try changing the unit width to something like 0.1 to 0.08 for your case.

will be somthing like

Chart.XAxis[0].UnitWidth = 0.09;

Hope that helps!

---

I am not sure if this is technically correct but I think this is used as a kind of 'detection band' to determine the 'breadth' of values to show in the tooltip.

I have had to develop an algorithm that TRIES to determine the UnitWidth based on '8 pixels'. To do this however I have had to make some assumptions as the pixel width of the 'data area' is not provided. Just the Width of the entire Cartesian plot.

It is something like:

public override void UpdateUnitWidth()
{
  double? min = XAxis.MinLimit;
  if (min == null)
  {
    List<double> mins = VM.GetXMin();
    if (mins.Count > 0) min = mins.Min();
  }

  double? max = XAxis.MaxLimit;
  if (max == null)
  {
    List<double> maxs = VM.GetXMax();
    if (maxs.Count > 0) max = maxs.Max();
  }

  if (min != null && max != null && min != max) {

    var pixelWidth = this.ActualWidth;
    if (pixelWidth > 0)
    {
      double dataWidth = (double)max - (double)min;
      double approxUnitsPerPixel = dataWidth / (pixelWidth - 70); // 70 approximate account for padding, axisy etc
      if (approxUnitsPerPixel < 1) XAxis.UnitWidth = 1;
      else XAxis.UnitWidth = approxUnitsPerPixel * 8;

    }
  }
  
}

`

Note that the VM.Get... functions run a method that collects the min and max values for each series displayed in my View Model. It is something you will need to alter/add for your own case.

Its crude, but it seems to work ok for me. It is actioned when there is a zoom or the data is first drawn.

It would be good if the next release provided

• the min and max of displayed series data without having to generate your own algorithm (when min/max limit is set to null).
• The pixel width of the plot area (similar to ActualWidth but PlotAreaWidth for exapmple) so I don't have to guestimate.

[alexachso]

Thank you so much! Yes, it works!

I never thought about the unit width. My reason behind this was that if I configure the min and max to NULL (so it can autodetect the min and max) I assumed I don't need to worry about the unitwidth because I thought that the software can compute the unitwidth of the axis by applying the next formula by itself:

unitwidth = (max - min) / numberOfPointsInOneSeries; (The series that has the most number of points)

(I know it is not accurate... because you could have 2 points on the same X for example, but I guess it is better than assuming unitwidth always to 1). Your override function is even better than the simple formula I described above. I really like your approach on guesstimating the unitwidth.

I am not complaining! I really like this library! If we can have a healthy discussion about on how to improve it a little bit why not do so? :)

Thank you again!

PS: I know it's not the thread for, but I observed that when I zoom it seems that the limiter factor on stop zooming is to have at least 6 drawn points of one series. Can I configure this limit of 6 drawn points to say 3 points or even 2 points instead so I can zoom a little bit further?