Bottom item in virtual scrolling list occasionally getting clipped or not shown

5 posts, 0 answers
  1. Chris
    Chris avatar
    27 posts
    Member since:
    Jul 2004

    Posted 10 May 2015 Link to this post

    We experience situations where the bottom item in virtual scrolling list occasionally getting clipped, or not shown (which is a bigger problem as the user doesn't realise its not there)...  Its like the scrolling calculation isnt quite 'right'.

     

    To recreate - Use the actual virtual scrolling example http://demos.telerik.com/kendo-ui/grid/virtualization-remote-data.

    Just 'wiggle' the scroll thumb on the grid up and down - and the bottom row seems to shift around - see attached one, two, three - which both should be the same, yet the bottom item changes (this test done in Chrome Version 42.0.2311.135 m). It seems to happen especially when browser not maximised

    Another way to recreate is starting from kendo basic Grid demo at http://demos.telerik.com/kendo-ui/grid/index, and click Edit this example” button to open in Kendo Dojo, and then set as scrollable : {virtual: true}-  and also fails. We performed this test with firefox 37.0.02

    Note also occurs in IE 11.0.9600.17728

     

    Then also recreated with the local data virt example http://demos.telerik.com/kendo-ui/grid/virtualization-local-data  (local-eg1, localeg2)

     

    Help :)

    Thanks

    Chris

  2. Dimo
    Admin
    Dimo avatar
    8486 posts

    Posted 13 May 2015 Link to this post

    Hi Chris,

    We implemented some changes recently, which seem to improve the discussed behavior. Please test with the next internal Kendo UI build, once it becomes available, probably next week.

    On a side note, the last virtualized Grid item can be displayed correctly only if all rows have the same height.

    http://docs.telerik.com/kendo-ui/web/grid/appearance#virtual-scrolling

    Regards,
    Dimo
    Telerik
    Join us on our journey to create the world's most complete HTML 5 UI Framework - download Kendo UI now!
  3. Ab Folk
    Ab Folk avatar
    2 posts
    Member since:
    Oct 2015

    Posted 12 Feb 2016 in reply to Dimo Link to this post

    Dimo,

    We are getting started using the Kendo Grid in virtual mode. I think we are suffering from the same issue as described in this post. We have variable-height rows due to text wrapping so we cannot use fixed row height. As Chris noted, if the user scrolls to the bottom, he would expect to see the last row in the DataSource. We are finding that sometimes as many as 2-3 rows are being clipped. This is not right. We can't ship a product like that. Can we figure some kind of solution/workaround to this? Should I file a ticket?

     Thank you,

    Peter

  4. Dimo
    Admin
    Dimo avatar
    8486 posts

    Posted 15 Feb 2016 Link to this post

    Hi Peter,

    Using identical row heights for all table rows in the Grid is highly recommended when virtual scrolling is enabled. In other words, please ensure the text does not wrap. The following documentation section shows how this can be achieved:

    http://docs.telerik.com/KENDO-UI/controls/data-management/grid/appearance#virtual-scrolling

    Regards,
    Dimo
    Telerik
     
    Join us on our journey to create the world's most complete HTML 5 UI Framework - download Kendo UI now!
     
  5. Ab Folk
    Ab Folk avatar
    2 posts
    Member since:
    Oct 2015

    Posted 16 Feb 2016 in reply to Dimo Link to this post

    Hi Dimo,

     I understand your strong suggestion that we use fixed row heights with virtual scrolling, but we can't accept that for our grids. We really need to have variable row height (see attached PNG).

    I spent the weekend digging into your source code. I think I have a workaround for your VirtualScrollable_scroll() function in kendo.grid.js. I would like to open a ticket with you and maybe we can work something out to have one of your developers investigate. When I open the ticket, I will reference this post, and include my findings.

    Thank you,

    Peter

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