wpf graph getChildrenAtPoint

[ga@bimal]

I have a  wpf on which I add Point Annotations and Range Annotation programmatically, when the user clicks the the buttons "Take Point Annotation" and "Take Range Annoation". I would like to select an annotation when the user clicks on it an make him able to modify or delete. I used getChildrenAtPoint method of the graph but the collection that this method returns is always empty... 

My graph definition is: 

<ni:Graph Name="graph" HitTestMode="RenderedInterpolation" PlotAreaMouseLeftButtonUp="graph_PlotAreaMouseLeftButtonUp">
            <ni:Graph.Axes>
                <ni:AxisDouble x:Name="xAxis" Range="0,10" Orientation="Horizontal"></ni:AxisDouble>
                <ni:AxisDouble x:Name="yAxis" Range="0,20" Orientation="Vertical"></ni:AxisDouble>
            </ni:Graph.Axes>
            <ni:Graph.Children>
                <ni:Cursor Name="simpleCursor">
                    <ni:Cursor.ValuePresenter>
                        <nic:ValueFormatterGroup>
                            <nic:ValueFormatterGroup.DefaultFormatter>
                                <nic:GeneralValueFormatter x:Name="valueFormatter" Format="0.00"></nic:GeneralValueFormatter>                               
                            </nic:ValueFormatterGroup.DefaultFormatter>
                        </nic:ValueFormatterGroup>                     
                    </ni:Cursor.ValuePresenter>
                </ni:Cursor>
                <ni:MultiPlotCursor Name="mpCursor" Visibility="Hidden"></ni:MultiPlotCursor>
                <ni:RangeCursor Name="rangeCursor" HorizontalRange="4,6" VerticalRange="4,6" Visibility="Hidden"></ni:RangeCursor>
            </ni:Graph.Children>
        </ni:Graph>          

and the the addAnnotation method is:

private void TakeRangeAnnotation_Executed(object sender, ExecutedRoutedEventArgs e)
        {
            WindowAnnotation dialog = new WindowAnnotation();
            if (dialog.ShowDialog() == true)
            {
                NationalInstruments.Controls.RangeAnnotation ann = new NationalInstruments.Controls.RangeAnnotation();
                ann.HorizontalRange = rangeCursor.ActualHorizontalRange;
                ann.VerticalRange = rangeCursor.ActualVerticalRange;
                ann.Label = dialog.Annotation;
                ann.HorizontalAxis = xAxis;
                ann.VerticalAxis = yAxis;
                graph.Children.Add(ann);
            }
        }

I call the getChlidrenAtPoint method on the PlotAreaMouseLeftButtonUp event:

private void graph_PlotAreaMouseLeftButtonUp(object sender, MouseButtonEventArgs e)
        {
            Point mousePos = e.GetPosition(graph);
            Point screenPos = graph.GetPlotAreaPosition(e);
            IEnumerable<object> children1 = graph.GetChildrenAtPoint(mousePos);
            IEnumerable<object> children2 = graph.GetChildrenAtPoint(screenPos);

 I tried both mouse position and PlotAreaPosition but the two collections are always empty, also if I click on a Range Annotation 

[phansen · Accepted solution]

I was able to reproduce the issue you were seeing, and confirmed there is a bug in our code that prevents annotations from appearing in hit test results. We have created a work item to fix this issue.

To workaround this, here is an example of how you can perform manual hit testing for a RangeAnnotation in a graph configured with double horizontal and vertical axes:

    double[] dataValue = graph.ScreenToData(plot, screenPos).Cast<double>().ToArray();

    foreach( var rangeAnnotation in graph.Children.OfType<RangeAnnotation>() ) {
        var horizontalRange = (Range<double>)rangeAnnotation.HorizontalRange;
        var verticalRange = (Range<double>)rangeAnnotation.VerticalRange;

        if( horizontalRange.Contains(dataValue[0])
             && verticalRange.Contains(dataValue[1]) ) {
            // matching range annotation found
        }
    }

[mattiaven]

Problem Solved? If so, please set Phansen answer as the correct one.

Thanks.

Mattia

[phansen]

Just wanted to let you know this issue (#374462) was fixed in the Measurement Studio 2013 release.