This is a migrated thread and some comments may be shown as answers.

Limitations of Virtual Scrolling

8 Answers 612 Views

Grid

This is a migrated thread and some comments may be shown as answers.

Kaan asked on 22 Nov 2016, 09:20 AM

Hello!

I have some questions regarding the limitations of virtual scrolling and I am referring to your documentation: http://docs.telerik.com/kendo-ui/controls/data-management/grid/appearance#virtual-scrolling

1) "Virtual scrolling relies on a fake scrollbar. Its size is not determined
by the browser, but is calculated based on the average row height of
the data that is already loaded. As a result, variable row heights may
cause unexpected behavior, such as inability to scroll to the last rows
on the last page." and "Virtual scrolling relies on calculating the average row height based on
already loaded data. Having a large variance of row heights or an
unknown number of rows that are not bound to data (such as group
headers) might cause unexpected behavior:":
To prevent this, I am calling resize(true) on the grid widget every time the data is bound (dataBound event handler). It seems like this works, but am I missing something?

2) "Virtual scrolling is not compatible with grouping, hierarchy, and editing":
I am using a grid with batch editing mode, and it seems to work. Could you please share some details about what's not compatible with editing exactly?
And what are the known incompatibilities with grouping? I have found out, that the grid does not remember collapsed groups when the page size is crossed while scrolling and the next page of data items is bound to the grid, so the collapsed groups get automatically expanded again. Also, if a group is being collapsed, the space of the previous shown data items remains blank, instead of the next group being shown immediately below.

Thank you in advance for providing information about the grid virtual scrolling limitations of the current Kendo UI release version.

Best regards,

Kaan

8 Answers, 1 is accepted

answered on 28 Nov 2016, 01:53 PM

Hi,

Thank you for your clarifications.

Inline editors behave very similar in paging mode. They will also be reset when browsing to another page. So at least this behavior is not worse in virtual scrolling mode.

However, the grouping functionality is very important for our business application. That collapsing a group will not pull records from below is not very beautiful, but we can live with that. The bigger problem is when having groups with large data sets. When you collapse such a group and you want to scroll down to the next group, all the collapsed groups will be expanded as soon as the next virtual page is hit by the user. This breaks the grid usability for the user.

Do you think this could be solved by incorporating your example on how to "Persist Collapsed State of Grouped Records" (http://docs.telerik.com/kendo-ui/controls/data-management/grid/how-to/state/persist-grouped-grid-collapsed-details-state#persist-collapsed-state-of-grouped-records)? Do you have any experience with that? Are there any known issues or downsides of adding "Persist Collapsed State of Grouped Records" functionality to virtual scrolling? If this could be solved, virtual scrolling would be a wonderful solution for our business application.

Best regards,

Kaan

answered on 06 Sep 2017, 04:13 PM

Hello Peter,

There aren't plans as of current to introduce grouping support with virtual scrolling. As explained in the docs,virtual scrolling relies on calculating the average row height based on already loaded data. Having a large variance of row heights or an unknown number of rows that are not bound to data (such as group headers) prevents the correct calculation of the scroll height.
A limitation of virtual scrolling, which will soon be resolved, is data editing. This is already in development.

Regards,
Tsvetina
Progress Telerik

Try our brand new, jQuery-free Angular 2 components built from ground-up which deliver the business app essential building blocks - a grid component, data visualization (charts) and form elements.