RadCartesianChart hangs when using ScatterLineSeries with sliding ObservableCollection on iOS

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Steve
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Steve asked on 08 Aug 2023, 02:46 PM

Issue is only present on iOS.  Android and windows work as expected.

When using a ScatterLineSeries with a ItemSource set to an ObservableCollection the Chart control has a tendency to hang and lock the application when the ObservableCollection data slides (items are removed at position 0, and items are added to the end)

    When the issue occurs iOS Device log has entries such as:

    "default 09:31:45.095875-0500 myApp.Client.Mobile Hang detected: 0.39s (always-on hang reporting)"

    //this is called once during the setup of the control

    var data = new ObservableCollection<SeriesData>(); ScatterLineSeries lineSeries = new ScatterLineSeries() { DisplayName = series.Name, XValueBinding = new PropertyNameDataPointBinding(nameof(SeriesData.XScaled)), YValueBinding = new PropertyNameDataPointBinding(nameof(SeriesData.YScaled)), ItemsSource = data, }; chart.Series.Add(lineSeries);

    //this is called periodically as new data is available to display

    public void AddSeriesData(IEnumerable<SeriesData> data) { float? min = null; float? max = null; lock (_data) { foreach (var d in data) { d.XScaled = d.X; d.YScaled = ((d.Y ?? 0) - d.Series.MinValue) / (d.Series.MaxValue - d.Series.MinValue) * 100; if (_data.TryGetValue(d.Series, outvar collection)) { collection.Add(d); max = d.XScaled; min = collection[0].XScaled; while (max - min > settings.XAxisRange) {

    //application will start to hang here, once items are removed from beginning of the collection collection.RemoveAt(0); min = collection[0].XScaled; } } } } if (max != null) { xAxis.Maximum = max.Value; xAxis.Minimum = max.Value - settings.XAxisRange; } }

    public class SeriesData
        {
            public readonly Series Series;
            public readonly float? X;
            public readonly float? Y;
    
            public float? XScaled { get; internal set; }
            public float? YScaled { get; internal set; }
    
            public SeriesData(Series series, float? x, float? y)
            {
                Series = series;
                X = x;
                Y = y;
            }
        }
    Steve
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    commented on 09 Aug 2023, 02:39 PM

    In general, the iOS chart doesn't seem to handle data points with null values or points that are outside of their respective axis' min/max range, and either has a tendency to cause the application to hang when the chart is displayed.
    Didi
    Telerik team
    commented on 11 Aug 2023, 12:39 PM

    Hi Steve,

    Could you please send me a sample project with implementation you have? I want to research the behavior by using the exact setup you have. Chat works with null values, still, I see you updated the min and max axis values runtime? Is this correct? 

    Steve
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    commented on 15 Aug 2023, 07:23 PM | edited

    Hi Didi,

    Please see the attached sample project as requested.

    Testing on my iPad 10, after adding 4 to 6 series (add series by clicking the button), the app would be come slow to respond as soon as data reached the end of the chart and series data was removed from the source (observablecollection).  Hang detections were also noted by watching the console log for the ipad while it's running.

    Please let me know if you have any questions while you evaluate this sample.

    Thanks,

    Didi
    Telerik team
    commented on 18 Aug 2023, 09:24 AM

    Hi Steve,

    Thank you for the provided file. Due to security reasons, may I ask you to attach the project to the forum, or open a support ticket and attach it there. You have support tickets you can use and you can write directly to the Telerik support by submitting support tickets. 

    I see the file size is a bit large. You can reduce its size by deleting bin and obj folders from the project, then archive it and attach it. 

    Note that I removed the google drive link from your reply.

    No answers yet. Maybe you can help?

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