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Last Updated: 17 Jul 2025 07:22 by Garry
Luis
Created on: 16 Jul 2025 12:48
Category: WrapLayout
Type: Bug Report
2
WrapLayout can crash when setting ItemWidth via the SizeChanged event

Ran into this issue - which seems to be dependent on how the content gets rendered, so it will fail 100% of the time on specific configurations, resulting in unusable applications.

I've found this issue on Android but there's no telling if the issue is cross platform - as it may depend on item sizings and layout, it may also be reproducible on other platforms, I just haven't hit it yet. The device you run it on may also influence the result, as different resolutions and scalings will impact how items are rendered on screen. I've reproduced this on a Pixel 7 (real device), Samsung A21s (real device) and Pixel 7 Pro (emulator).

Repro steps

  1. Create a new maui sample app, with the relevant Telerik components/initialisation.
  2. Add the xaml and code shown below to the MainPage.
  3. Run the application
  4. OBSERVE
    1. ArgumentOutOfRangeException will be thrown in RadWrapLayoutManager.ArrangeChildren
  5. Stop the app. Comment out the last item being added to the wrap layout and run the app again.
  6. OBSERVE
    1. It will run fine.

MainPage.xaml - use this as the page content:

    <ScrollView Padding="15,0,15,15">
        <VerticalStackLayout Spacing="25">
            <telerik:RadWrapLayout
                x:Name="BrokenLayout"
                Margin="-5"
                SizeChanged="BrokenLayout_SizeChanged"
                StretchLastChild="False">
                <BindableLayout.ItemTemplate>
                    <DataTemplate>
                        <Grid
                            Margin="3.75"
                            Padding="3.75"
                            BackgroundColor="LightGreen">
                            <Label
                                FontAttributes="Bold"
                                FontSize="11"
                                LineBreakMode="TailTruncation"
                                MaxLines="2"
                                Text="{Binding}"
                                VerticalOptions="End" />
                        </Grid>
                    </DataTemplate>
                </BindableLayout.ItemTemplate>
            </telerik:RadWrapLayout>
        </VerticalStackLayout>
    </ScrollView>

MainPage.xaml.cs code

    public partial class MainPage : ContentPage
    {
        public MainPage()
        {
            InitializeComponent();
            List<string> items = new List<string>();

            items.Add("TSONE");
            items.Add("N ANCETOIDO");
            items.Add("ADDKNEDEGO LW");
            items.Add("A EFCTTLIAH");
            items.Add("OHACP HTATTO");
            items.Add("AASESII NAYXB/RFKL");
            items.Add("EMIQULENOCE PTCTL");
            items.Add("SCNSTUGRRIOEMA TEU");
            items.Add("EPEENSX");
            items.Add("BRUXEROL TAA");
            items.Add("TVLRETAAX ER");
            items.Add("SMA SELISD");
            items.Add("NIAEGOEEATIRUPR SVT");
            items.Add("CTPLRCELT AO");
            items.Add("REAREPTIRDQ U");
            items.Add("ASEDP TUR");
            items.Add("CJTEUT ORPDEAP");
            items.Add(" CECCRNTARODTO");
            items.Add("- FLEOUTEQRUOPWSL");
            items.Add("PINTRNMEU REEQTU");
            items.Add("RE LWSRANKOGIO TNT");
            items.Add("KAREBTA KE");
            items.Add("ITTANIW MIEG"); // comment out this one and it'll run fine. keep it and it'll fail.

            BindableLayout.SetItemsSource(this.BrokenLayout, items);
        }

        private double _width = 0;
        private double minItemWidth = 110.0;
        private double maxItemWidth = 160.0;

        private void BrokenLayout_SizeChanged(object sender, EventArgs e)
        {
            if (sender is RadWrapLayout wl
                && wl.Width > 0 
                && (int)Math.Floor(wl.Width) is int widthInt
                && widthInt != this._width)
            {
                this._width = widthInt;

                double? candidateItemWidth = null;
                var itemCount = wl.Children.Count;

                if (itemCount > 0 && itemCount * maxItemWidth >= widthInt)
                {
                    var columnCount = (int)Math.Ceiling(widthInt / maxItemWidth);

                    candidateItemWidth = (int)Math.Floor((double)widthInt / columnCount);

                    if (candidateItemWidth > 1.25 * maxItemWidth)
                    {
                        columnCount += 1;
                        candidateItemWidth = (int)Math.Floor((double)widthInt / columnCount);
                    }
                    else if (candidateItemWidth < minItemWidth)
                    {
                        columnCount -= 1;
                        candidateItemWidth = (int)Math.Floor((double)widthInt / columnCount);
                    }
                }

                wl.ItemWidth = candidateItemWidth ?? maxItemWidth;
            }
        }
    }

Error:

System.ArgumentOutOfRangeException: 'Index was out of range. Must be non-negative and less than the size of the collection. (Parameter 'index')'

 	0xFFFFFFFFFFFFFFFF in Android.Runtime.RuntimeNativeMethods.monodroid_debugger_unhandled_exception	C#
 	0x1A in Android.Runtime.JNINativeWrapper._unhandled_exception at /Users/runner/work/1/s/xamarin-android/src/Mono.Android/Android.Runtime/JNINativeWrapper.g.cs:12,5	C#
 	0x26 in Android.Runtime.JNINativeWrapper.Wrap_JniMarshal_PPZIIII_V at /Users/runner/work/1/s/xamarin-android/src/Mono.Android/Android.Runtime/JNINativeWrapper.g.cs:441,26	C#
 	0x8 in System.ThrowHelper.ThrowArgumentOutOfRange_IndexMustBeLessException	C#
 	0x9 in System.Collections.Generic.List<double>.get_Item	C#
 	0x205 in Telerik.Maui.RadWrapLayoutManager.ArrangeChildren	C#

 
1 comment
Garry
Posted on: 17 Jul 2025 07:22

The cause of this crash seems to be when you have a series of items `RadWrapLayout` they take up only the size they need. If you then change the size to make them all take up an equal amount of space it can push items onto a new row.

The `RadWrapLayoutManager.ArrangeChildren` method does not handle that scenario well and tries to get the height (or width) of a length from the `lengths` array that is outside the range of the collection causing the error above.

Having the method be more robust and handle items changing size and potentially pushing them onto new rows (or columns) would be ideal for us.

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