void GraphView_PointTapped(object sender, PointTappedEventArgs e)
{
tappedPoint = e.PlotDataPoint;
tappedLocation = e.Location;
PerformSegue("locationPopoverSegue", this);
}
void GraphView_PointLongPressed(object sender, PointTappedEventArgs e)
{
longPressedMaterial = ViewModel.GetMaterialAtPoint(e.PlotDataPoint);
PerformSegue("layersPopoverSegue", this);
}
