Strange scrollbar behaviour with VirtualizationStrategyDefinition

16 posts, 0 answers
  1. Igor
    Igor avatar
    29 posts
    Member since:
    Mar 2012

    Posted 02 Oct 2014 Link to this post

    I have a RadDataBoundLisbox defined as below

    <telerikPrimitives:RadDataBoundListBox ItemsSource="{Binding TitleItems}" ItemTemplateSelector="{StaticResource TitleItemTemplateSelector}" SelectedItem="{Binding SelectedTitleItem, Mode=TwoWay}">
        <telerikPrimitives:RadDataBoundListBox.VirtualizationStrategyDefinition>
            <telerikPrimitives:WrapVirtualizationStrategyDefinition Orientation="Horizontal"/>
         </telerikPrimitives:RadDataBoundListBox.VirtualizationStrategyDefinition>
    </telerikPrimitives:RadDataBoundListBox>

    All the items in this listbox are approximately 220px wide so there are always 2 items on one line show. When I scroll the listbox, the scrollbar is not fluid, it jumps, looking like it is skipping every second item. Like scrolling by 2 lines insted of one.
  2. Ves
    Admin
    Ves avatar
    2879 posts

    Posted 07 Oct 2014 Link to this post

    Hi Igor,

    Indeed, we are aware of a problem with the scrollbar "jumping" in such scenario. However, this does not result in skipping items. If you experience this (skipping items) can you please open a support ticket and send us a small project, reproducing the problem, so that we can investigate it? Thank you.

    Best regards,
    Ves
    Telerik
     

    Check out the Telerik Platform - the only platform that combines a rich set of UI tools with powerful cloud services to develop web, hybrid and native mobile apps.

     
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  4. Igor
    Igor avatar
    29 posts
    Member since:
    Mar 2012

    Posted 07 Oct 2014 in reply to Ves Link to this post

    No skipping items, just the scrollbar jumping. I had to use the standard listbox instead.
  5. Rosy Topchiyska
    Admin
    Rosy Topchiyska avatar
    551 posts

    Posted 09 Oct 2014 Link to this post

    Hello Igor,

    The scroll bar of the RadDataBoundListBox uses logical units. This means that it could take discrete positions that correspond to the position of the current item in the source. When you have small amount of items and their total height is big enough, you can see the jumping of the scroll bar as it takes its discrete values.

    Regards,
    Rosy Topchiyska
    Telerik
     

    Check out the Telerik Platform - the only platform that combines a rich set of UI tools with powerful cloud services to develop web, hybrid and native mobile apps.

     
  6. Igor
    Igor avatar
    29 posts
    Member since:
    Mar 2012

    Posted 04 Nov 2014 in reply to Rosy Topchiyska Link to this post

    Any way to fix this? The standard ListBox does not have this problem.
  7. Ves
    Admin
    Ves avatar
    2879 posts

    Posted 07 Nov 2014 Link to this post

    Hi Igor,

    We are working on it, but I am afraid, there is no fix that you could apply at the moment. Please, accept our apologies for the inconvenience.

    Best regards,
    Ves
    Telerik
     

    Check out the Telerik Platform - the only platform that combines a rich set of UI tools with powerful cloud services to develop web, hybrid and native mobile apps.

     
  8. Michael
    Michael avatar
    2 posts
    Member since:
    Aug 2013

    Posted 23 Feb 2015 Link to this post

    Dear community

    I have the same issue with my RadDataBoundListBox. I have a ObservableCollection with an ImageModel with the path to my local image (IsolatedStorage). When I load the images, the ListBox "jumps" (like described above) everytime i update a Property (with 'notify property changed').

    Everything works great except the "jumping" of the list. It jumps to the top position of the current top visible element.

    Exists a workaround now for this problem/bug? I am working with UI for WindowsPhone 8 (2014.3 1201)

    Thank you
  9. Rosy Topchiyska
    Admin
    Rosy Topchiyska avatar
    551 posts

    Posted 26 Feb 2015 Link to this post

    Hello Michael,

    Thank you for contacting us.

    This "jumping" happens only if the property change makes the item's visual element change its size. Unfortunately, we can not suggest a proper workaround at this time.

    Regards,
    Rosy Topchiyska
    Telerik
     

    Check out the Telerik Platform - the only platform that combines a rich set of UI tools with powerful cloud services to develop web, hybrid and native mobile apps.

     
  10. Igor
    Igor avatar
    29 posts
    Member since:
    Mar 2012

    Posted 21 Sep in reply to Rosy Topchiyska Link to this post

    Still no workaround for the jumping?
  11. Rosy Topchiyska
    Admin
    Rosy Topchiyska avatar
    551 posts

    Posted 26 Sep Link to this post

    Hello Igor,

    There is no workaround for this issue at this moment.

    We are interested in your future plans for using Windows Phone 8.0, especially why do you continue to develop applications for Windows Phone 8.0, since there are newer platforms - Windows Universal and Universal Windows Platform.

    We have rich control suites for these platforms and if you miss something from the UI for Windows Phone suite, please share it with us. You can take a look our RadListView control that has been created to replace the legacy control RadDataBoundListBox, which is also available.

    I look forward to your reply.

    Regards,
    Rosy Topchiyska
    Telerik by Progress
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  12. Igor
    Igor avatar
    29 posts
    Member since:
    Mar 2012

    Posted 26 Sep in reply to Rosy Topchiyska Link to this post

    I continue developing (or better say maintaining) a Windows Phone 8 app because the client will not pay for rewriting it to a newer SDK (which would take months a costs much money).
  13. Tsvyatko
    Admin
    Tsvyatko avatar
    833 posts

    Posted 29 Sep Link to this post

    Hi Igor,

    Thank you for clarifying your scenario. 

    We have identified that addressing this issue require a major refactoring in the DataBoundListBox. Unfortunately, I cannot provide a time frame of addressing it.

    I have logged public issue in our feedback portal so you can track its progress.

    Regards,
    Tsvyatko
    Telerik by Progress
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  14. Igor
    Igor avatar
    29 posts
    Member since:
    Mar 2012

    Posted 29 Sep in reply to Tsvyatko Link to this post

    Could you also log the second problem reported by Michael? It is more important for me, the problem that the whole list "jumps" when something changes in a DataTemplate.
  15. Tsvyatko
    Admin
    Tsvyatko avatar
    833 posts

    Posted 03 Oct Link to this post

    Hi Igor,

    would it be possible to specify the exact issue/thread that you are referring to.

    Thank you in advance

    Regards,
    Tsvyatko
    Telerik by Progress
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  16. Igor
    Igor avatar
    29 posts
    Member since:
    Mar 2012

    Posted 03 Oct in reply to Tsvyatko Link to this post

    Just look a few posts up as I mentioned. When I make a change in the DateTemplate using binding that changes some UI (hides or displays an control) that whole list "jumps" meaning it scrolls a bit up or down.
  17. Tsvyatko
    Admin
    Tsvyatko avatar
    833 posts

    Posted 06 Oct Link to this post

    Hello Igor,

    I have added this issue in the feedback portal as well. You can track its progress. Also, you can log issues there directly through your account.

    Regards,
    Tsvyatko
    Telerik by Progress
    Do you want to have your say when we set our development plans? Do you want to know when a feature you care about is added or when a bug fixed? Explore the Telerik Feedback Portal and vote to affect the priority of the items
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