Charts within a listview correctly display on 1st occurence - when refreshed they are not being displayed

[Spotty]

I have a custom  Item template within a listview which actually includes a graph (pie chart).   The xaml is as follows

 <ListView x:Name="List1">

                <ListView.ItemTemplate>

                    <DataTemplate>

                        <ViewCell>

                            <StackLayout Orientation="Horizontal" >

                                <chart:SfChart>

                                    <chart:SfChart.BackgroundColor>

                                        <Color>Gray</Color>

                                    </chart:SfChart.BackgroundColor>

                                    <chart:DoughnutSeries ItemsSource ="{Binding MyProperty}" XBindingPath="Item" YBindingPath="Value">

                                        <chart:DoughnutSeries.ColorModel>

                                            <chart:ChartColorModel Palette="Custom" CustomBrushes="{StaticResource Colors}"/>

                                        </chart:DoughnutSeries.ColorModel>

                                    </chart:DoughnutSeries>

                                </chart:SfChart>

                                <StackLayout Orientation="Vertical">

                                    <StackLayout Orientation="Horizontal" >

                                        <!--<Label Text="StartTime"></Label>-->

                                        <Label FontSize="Small" Text="{Binding StartTime}"></Label>

                                        <!--<Label Text="COunt"></Label>-->

                                        <Label FontSize="Small" Text="{Binding QuestionCount}"></Label>

                                    </StackLayout>

                                    <StackLayout Orientation="Horizontal" >

                                        <Label Text="Correct"></Label>

                                        <Label FontSize="Small"  Text="{Binding Correct}"></Label>

                                        <Label FontSize="Small" Text="Incorrect"></Label>

                                        <Label FontSize="Small" Text="{Binding Incorrect}"></Label>

                                        <Label FontSize="Small" Text="Skipped"></Label>

                                        <Label FontSize="Small" Text="{Binding Skipped}"></Label>

                                    </StackLayout>

                                </StackLayout>

                            </StackLayout>

                        </ViewCell>

                    </DataTemplate>

                </ListView.ItemTemplate>

            </ListView>

When the pae is loaded the following code is run 

            QuizResults = GetTestHistory();

            if (QuizResults.Count() != 0)

            {

                Data1 = new ObservableCollection<VmQuizData>();

                //Lets use this to display the list

                foreach (var item in QuizResults)

                {

                    Data1.Add(new VmQuizData()

                    {

                        ID = item.Id,

                        Correct = item.Correct,

                        Incorrect = item.Incorrect,

                        Skipped = item.Skipped

                    });

                }

                List1.ItemsSource = Data1;

                //List1.ItemsSource = QuizResults;

                LblNoHistory.IsVisible = false;

                List1.IsVisible = true;

            }

            else

            {

                LblNoHistory.IsVisible = true;

                List1.IsVisible = false;

            }

This displays the pie charts correctly and they are displayed for each item.   

However, there is a refresh button which when clicked and should redisplay the data results in the correct values in the labels being displayed however the graphs are just shown as blank dark squares where the pie charts were previously displayed.

I'm not sure why the charts are not subsequently displaying despite the data showing correctly - or the way to remedy.

Attachment: ChartProb_9b259b86.zip

[Suyamburaja Jayakumar]

Hi Spotty, 

 

Greetings from Syncfusion. 

 

We have analyzed the provided code snippet and you can resolve by setting  the HorizontalOptions and VerticalOptions for chart. Please refer the below code snippet for more details. 

 

XAML: 

<ListView x:Name="List1"> 

     <ListView.ItemTemplate> 

         <DataTemplate> 

              <ViewCell> 

                  <StackLayout Orientation="Horizontal" > 

                            <chart:SfChart HorizontalOptions="FillAndExpand"      VerticalOptions="FillAndExpand"> 

    . . . . . .  

 

                        </StackLayout> 

                    </ViewCell> 

                </DataTemplate> 

            </ListView.ItemTemplate> 

 

        </ListView> 

 

Please let us know if you need any further assistance on this.  

  

Regards,  

Suyamburaja J. 

[Spotty]

Could you elaborate on why they display initially, but on the refresh don't.

[Suyamburaja Jayakumar]

Hi Spotty, 

 

We would like to let you know what is reported in a DoughtSeries issue is a bug, and we have already logged this bug internally. We have planned to move this fix forward in our upcoming Volume 1 2020 release, which is expected to be rolled out by the end of March 2020.  

  

Previously provided solution is just a workaround to resolve that reported issue. 

 

Regards, 

Suyamburaja J.