I will answer myself, for the first problem, we can erase both lines.

The second one, I have performed everything in the code behind and it works.

And my third new issue, how to template the popup window to be of the same type of the normal tooltip of a normal line serie or the legend?

Thank you

Thank you for the post.

I have copy pasted the code in my silverlight app, that but I am getting some issues, it can't resolve the symbols placement and placementTarget.

1. _tooltipContainer.Placement = PlacementMode.Relative;
2. _tooltipContainer.PlacementTarget = _scatterSeries;

Also, I am trying to develop a MVVM pattern and I can not give a class from my viewModel in my view, so I can't create a class to fill the tooltip. Any other Idea? thank you

Here's how you could make the tooltip show up whenever you are over a scatterlineseries:

<Window.Resources>
        <local:TestData x:Key="data" />
    </Window.Resources>
    
    
    <Grid>
        <igChart:XamDataChart x:Name="theChart"
                              Loaded="theChart_Loaded">
            <igChart:XamDataChart.Axes>
                <igChart:NumericXAxis x:Name="xAxis" />
                <igChart:NumericYAxis x:Name="yAxis" />
            </igChart:XamDataChart.Axes>

            <igChart:XamDataChart.Series>
                <igChart:ScatterLineSeries x:Name="scatter"
                                       XAxis="{Binding ElementName=xAxis}"
                                       YAxis="{Binding ElementName=yAxis}"
                                       XMemberPath="XValue"
                                       YMemberPath="YValue"
                                       ItemsSource="{StaticResource data}"
                                           Thickness="3"
                                       
                                       >
                </igChart:ScatterLineSeries>
            </igChart:XamDataChart.Series>
        </igChart:XamDataChart>
        
        <Popup x:Name="thePopup" IsOpen="False">
            <Border Background="White" BorderBrush="Gray" BorderThickness="1" Padding="4">
            <StackPanel Orientation="Horizontal">
                <TextBlock Text="{Binding XValue}" />
                <TextBlock Text=", " />
                <TextBlock Text="{Binding YValue}" />
            </StackPanel>
            </Border>
        </Popup>
    </Grid>

with code behind:

public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        private ScatterTooltipManager<TestDataItem> _manager;

        private void theChart_Loaded(object sender, RoutedEventArgs e)
        {
            _manager = new ScatterTooltipManager<TestDataItem>(
                theChart,
                theChart.Series[0] as ScatterBase,
                (i) => i.XValue,
                (i) => i.YValue,
                thePopup);
        }
    }

    public class ScatterTooltipManager<T>
    {
        private ScatterBase _scatterSeries = null;
        private Func<T, double> _xMapping = null;
        private Func<T, double> _yMapping = null;
        private Popup _tooltipContainer = null;

        public ScatterTooltipManager(
            XamDataChart chart,
            ScatterBase scatterSeries,
            Func<T, double> xMapping,
            Func<T, double> yMapping,
            Popup tooltipContainer)
        {
            chart.SeriesMouseMove += new DataChartMouseEventHandler(chart_SeriesMouseMove);
            chart.SeriesMouseLeave += new DataChartMouseEventHandler(chart_SeriesMouseLeave);
            _scatterSeries = scatterSeries;
            _xMapping = xMapping;
            _yMapping = yMapping;
            _tooltipContainer = tooltipContainer;
        }

        void chart_SeriesMouseLeave(object sender, ChartMouseEventArgs e)
        {
            if (e.Series == _scatterSeries)
            {
                _tooltipContainer.IsOpen = false;
            }
        }

        void chart_SeriesMouseMove(object sender, ChartMouseEventArgs e)
        {
            if (e.Series != _scatterSeries)
            {
                return;
            }

            var item = FindClosestItem(e);
            var pos = e.GetPosition(_scatterSeries);

            _tooltipContainer.Placement = PlacementMode.Relative;
            _tooltipContainer.PlacementTarget = _scatterSeries;
            _tooltipContainer.HorizontalOffset = pos.X + 10;
            _tooltipContainer.VerticalOffset = pos.Y + 10;
            _tooltipContainer.DataContext = item;
            _tooltipContainer.IsOpen = true;
        }

        private object FindClosestItem(ChartMouseEventArgs e)
        {
            var pos = e.GetPosition(_scatterSeries);
            var viewport = new Rect(0, 0, _scatterSeries.ActualWidth, _scatterSeries.ActualHeight);
            var x = _scatterSeries.XAxis.GetUnscaledValue(
                pos.X,
                _scatterSeries.Chart.WindowRect,
                viewport);
            var y = _scatterSeries.YAxis.GetUnscaledValue(
                pos.Y,
                _scatterSeries.Chart.WindowRect,
                viewport);

            var minDistance = double.MaxValue;
            T minItem = default(T);
            foreach (var item in _scatterSeries.ItemsSource.OfType<T>())
            {
                var itemX = _xMapping(item);
                var itemY = _yMapping(item);
                var dist = GetDistance(itemX, itemY, x, y);

                if (dist < minDistance)
                {
                    minDistance = dist;
                    minItem = item;
                }
            }

            return minItem;
        }

        private double GetDistance(double itemX, double itemY, double x, double y)
        {
            return Math.Sqrt(Math.Pow(itemX - x, 2) + Math.Pow(itemY - y, 2));
        }
    }

    public class TestDataItem
    {
        public double XValue { get; set; }
        public double YValue { get; set; }
    }

    public class TestData
        : ObservableCollection<TestDataItem>
    {
        public TestData()
        {
            Add(new TestDataItem()
            {
                XValue = 0,
                YValue = 0
            });
            Add(new TestDataItem()
            {
                XValue = 1,
                YValue = 1
            });
            Add(new TestDataItem()
            {
                XValue = 2,
                YValue = 2
            });
            Add(new TestDataItem()
            {
                XValue = 3,
                YValue = 3
            });
            Add(new TestDataItem()
            {
                XValue = 4,
                YValue = 4
            });
            Add(new TestDataItem()
            {
                XValue = 5,
                YValue = 5
            });
        }
    }

Hope this helps!
-Graham

Hi Graham,

I enabled the the markers for the series and - voila - there is a ToolTip. Thank you very much for your help so far.

I look forward to read more about it. Maybe i can enable/disable this behaviour depending on the ammount of data or let the user pick his/her poison.

Anyways, keep up the good work!

Enrico

Currently the default behavior for the scatter series it to only show the tooltips when you are over a marker, as it can be somewhat expensive to determine which point you are closest too, if you have a lot of points and are over a connecting line.

You should be able to do something in application code to get the tooltips to function over the line though, I'll get back to you.

-Graham