Could it possible to add Crosshair feature to chart?

[AndrewKhloptsau]

Hello everyone! Could it possible to add crosshair feature to chart? It's very useful thing with custom axes.

More information https://js.devexpress.com/Documentation/ApiReference/UI_Components/dxChart/Configuration/crosshair/

[beto-rodriguez]

Hi an thanks for the issue!

This is a great feature that is missing currently in the library, I will keep this issue open to track this implementation.

[AndrewKhloptsau]

I wrote custom crosshair, maybe it will be helpful.
So the main points for custom crosshair:

1. Creating lines is really easy with using RectangularSection when Xi==Xj and Yi==Yj.
2. Crosshair subscribes to MouseMove CartesianChart event.
3. I recommend using Animation for it, so without animation the movement of the crosshair will be "jump"
4. The worst thing is CrosshairLabel, because i didn't find any useful way how to create custom label on chart Axis. So for creating Labels i had to use ColumnSeries DataLabel with Fill=Color.Empty and recalculate position for labels (ObservablePoint coordinates) on each chart update. Also for correct scaling Y Label position i had to create a new invisible Y Axis and bind ColumnSeries to it (ScalesYAt) and update MinLimit = _mainY.VisibleDataBounds.Min and MaxLimit = _mainY.VisibleDataBounds.Max for this axis on each data update.

Note: DataLabelPadding don't work very well in this case (you can see it on screenshot) and i haven't fixed it yet.

[beto-rodriguez]

This is going to be included in the next version of the library.

Sample here:
https://github.com/beto-rodriguez/LiveCharts2/blob/dev/samples/ViewModelsSamples/Axes/Style/ViewModel.cs