"ghost" tap on radDataBoundListBox

[Marco]

Hello!

I have an issue with the RadDataBoundListbox control in my Windows Phone 8.0 Silverlight app. Sometimes, when I tap on the Listbox, the control feel the pressure in a wrong point. For example, I tap on an element but the tap is on the element below. I've attached an image that describe the situation.

The ListBox use different height items template that change at runtime. PullToRefresh and changing page can't solve the problem. I have this problem on various devices.
This is the code:

<telerikControls:RadDataBoundListBox
                                                         ItemsSource="{Binding ...}" 
                                                         IsPullToRefreshEnabled="True" 
                                                         PullToRefreshIndicatorStyle="{StaticResource PullToRefreshIndicatorStyle}"
                                                         RefreshRequested="lstPost_RefreshRequested"
                                                         UseOptimizedManipulationRouting = "False"
                                                         EmptyContent=""
                                                         telerikCore:InteractionEffectManager.IsInteractionEnabled="True" 
                                                         IsAsyncBalanceEnabled="True"
                                                         ItemAnimationMode="PlayAll"
                                                         ItemTemplate="{StaticResource ...}"
                                                         ItemTemplateSelector="{StaticResource ListTemplateSelector}"
                                                         DataVirtualizationMode="OnDemandAutomatic" 
                                                         Foreground="{x:Null}"
                                                         Grid.Row="1">
                        <i:Interaction.Triggers>
                            <i:EventTrigger EventName="DataRequested">
                                <i:InvokeCommandAction Command="{Binding Path=TManager.AddItems}" CommandParameter="{Binding Path=TManager}" />
                            </i:EventTrigger>
                        </i:Interaction.Triggers>

                        <telerikControls:RadDataBoundListBox.ItemAddedAnimation>
                            <telerikCore:RadFadeAnimation Duration="0:0:0.3" StartOpacity="0" EndOpacity="1">
                                <telerikCore:RadFadeAnimation.Easing>
                                    <CubicEase EasingMode="EaseIn" />
                                </telerikCore:RadFadeAnimation.Easing>
                            </telerikCore:RadFadeAnimation>
                        </telerikControls:RadDataBoundListBox.ItemAddedAnimation>

                        <telerikControls:RadDataBoundListBox.ItemRemovedAnimation>
                            <telerikCore:RadFadeAnimation Duration="0:0:0.3"  StartOpacity="1" EndOpacity="0">
                                <telerikCore:RadFadeAnimation.Easing>
                                    <ExponentialEase EasingMode="EaseOut" />
                                </telerikCore:RadFadeAnimation.Easing>
                            </telerikCore:RadFadeAnimation>
                        </telerikControls:RadDataBoundListBox.ItemRemovedAnimation>

                    </telerikControls:RadDataBoundListBox>

Is this a ListBox bug?
How can I solve this issue?

Thank you!
Marco

[Rosy Topchiyska]

Hello Marco,

Thank you for contacting us.

Unfortunately, we could not reproduce this issue on our side. Could you please send us a sample project that reproduces this issue so our developers will debug it and try to isolate the issue.

I look forward to your reply. 

Regards,
Rosy Topchiyska
Telerik

 

 

[Marco]

Hello Rosy,

thank you for the answer! I'm sorry but I can't provide you a sample because the issue can't be reproduced on a simple project. In my scenario the ListBox is very stressed during the reset of binding (that can be a pull to refresh or others type of refresh of binded elements) because the items templates are very complex (a lot of XAML and nested - native - controls) and various. I noticed that the peroblem can be always reproduced scrolling very fast in the moment of items reset. The only way to return to normality is to scroll enought to "going out" the viewport with items that have the issue. For example, after reset the items 10-20 can't get gesture correctly, but if I scroll to the item 50, the correct behaviour is restored for all the items.

The point is that in my app the user often scroll the ListBox during reset, otherwise I wouldn't have problems.

Is this a ListBox bug?

[Tsvyatko]

Hello Marco,

Thank you for sharing these details regarding your scenario. We have encountered similar issue in scenario closed to the described one. Unfortunately, we have determined that the issue is caused from the ScrollViewer itself (issue was reported to Microsoft - https://connect.microsoft.com/VisualStudio/feedback/details/778947/windows-phone-scrollviewer-component-does-not-update-its-visual-state-from-scrolling-to-notscrolling-when-calling-scrolltoverticaloffset-scrolltohorizontaloffset-while-scroll-animation-is-performed).
Currently, there is no feasible workaround.

Regards,
Tsvyatko
Telerik

 

 

[Anton]

I also experience this issue and it's quite annoying. Can you please share what is the most common reasons of such behavior as I experience it in app that I believe doesn't call ScrollTo methods in any way i.e we are not using methods such as BringIntoView. 

[Tsvyatko]

Hello Anton,

Depending on the setup of RadDataDoundListBox the following scenarios can affected (as they use ScrollToVerticalOffset internally):

 - pull to refresh
 - viewport change (e.g. resize of the control)
 - bring into view
 - fast scrolling of large amount of data near the top of the list


Regards,
Tsvyatko
Telerik

 

 

[Piotr]

Hi Tsvyatko,

We also have this problem when refreshing.
What is the status of the issue? Is there any workaround?


Regards,
Adam
Finanteq

[Tsvyatko]

Hi Piotr,

Thank you for contacting us! Currently, the issue is still present in the framework, thus it reflects in our control as well. Would it be possible to share some additional information regarding the scenario setup as we might be able to find a possible workaround.

Regards,
Tsvyatko
Telerik