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

Virtual scrolling pageEvent does not always fire

8 Answers 372 Views
Grid
This is a migrated thread and some comments may be shown as answers.
Peter
Top achievements
Rank 1
Peter asked on 14 Aug 2019, 11:50 AM

When I scroll a virtually scrolling grid then a pageEvent does not always fire. I often see this if I have a scrolled down grid and then quickly scroll to the top with a flick on the mouse (apple magic mouse).

Debugging this, it appears that the PageChangeEvent does not fire for the last change event. When scrolling to the top I often do not get an event that corresponds to the (skip: 0) position. This leads to a grid which is scrolled to the top but does not show any content because the slicing of the data shows record below the currently shown slice.

I have be able to replicate (with some difficulty) this behaviour in the remote data example here:

https://www.telerik.com/kendo-angular-ui/components/grid/scroll-modes/virtual/#toc-virtual-scrolling

Have you seen this behaviour and/or do you have fix/workaround for this behaviour?

 

 

8 Answers, 1 is accepted

Sort by
0
Dimiter Topalov
Telerik team
answered on 16 Aug 2019, 07:58 AM
Hi Peter,

We tried to reproduce the described issue on three separate MacBook machines with both the Magic Mouse and the touch pad and an external scrollpad, and could not.

Can you please try to reproduce the issue in incognito mode or with all browser extensions disabled, as well as in different browsers and let us know whether the issue is reproduced in multiple browsers, as well as what are the exact user actions that lead to it. Ideally, please send us a short video where we can observe what is happening on your end too.

Thank you in advance.

Regards,
Dimiter Topalov
Progress Telerik
Get quickly onboarded and successful with your Telerik and Kendo UI products with the Virtual Classroom free technical training, available to all active customers. Learn More.
0
Dimiter Topalov
Telerik team
answered on 16 Aug 2019, 08:00 AM
Hi Peter,

Just a quick follow-up - here is a convenient tool that you might use for capturing the screen:

https://getkap.co/

Regards,
Dimiter Topalov
Progress Telerik
Get quickly onboarded and successful with your Telerik and Kendo UI products with the Virtual Classroom free technical training, available to all active customers. Learn More.
0
Peter
Top achievements
Rank 1
answered on 16 Aug 2019, 01:53 PM

Thank you Dimiter.

I'll try to reproduce this in the mentioned example and record a video.

 

0
Peter
Top achievements
Rank 1
answered on 16 Aug 2019, 02:15 PM

I replicated the behaviour and have attached a small video that shows the problem. I used the "use virtual scrolling with remote data" example page and opened it in StackBlitz. I modified the code slightly to give me some debug info on the pageEvent state.

Please note that the last skip value is set to 31, but I scrolled to the top of the grid. I would expect to get a skip of 0 in the top of the grid.

I scroll down in "normal" speed, but scroll up as fast as possible.

I use Safari 2.1.2 (14607.3.9) on macOS 10.14.6 (18G87)

Please let me know if you have more questions.

I can't attach the video as it is 16MB. Is there another way I can send it to you?

 

 

 

 

 

0
Dimiter Topalov
Telerik team
answered on 16 Aug 2019, 02:31 PM
Hello Peter,

Thank you for your efforts. You can try to shorten and/or archive the video to reduce its size - only the few seconds that demonstrate the user event when scrolling fast up does not trigger the page change event should be enough.

You can also use any of the multiple online file-sharing utilities, for example:

https://gofile.io/?t=welcome

... or DropBox, Google Docs, etc.

Thank you in advance.

Meanwhile, we will try to reproduce the problem locally using the mentioned online demo.

Regards,
Dimiter Topalov
Progress Telerik
Get quickly onboarded and successful with your Telerik and Kendo UI products with the Virtual Classroom free technical training, available to all active customers. Learn More.
0
Peter
Top achievements
Rank 1
answered on 16 Aug 2019, 03:05 PM

I uploaded the file here: https://gofile.io/?c=hRiTun

Please try to see if you can download it.

 

0
Dimiter Topalov
Telerik team
answered on 16 Aug 2019, 03:16 PM
Hello Peter,

Yes, thank you. I downloaded the video successfully. We will try to replicate the same behavior, and I will update the thread once we have further information.

Regards,
Dimiter Topalov
Progress Telerik
Get quickly onboarded and successful with your Telerik and Kendo UI products with the Virtual Classroom free technical training, available to all active customers. Learn More.
0
Dimiter Topalov
Telerik team
answered on 20 Aug 2019, 07:18 AM
Hi Peter,

We still could not replicate the demonstrated behavior on multiple machines (MacBook Pro). Our best guess is that some specific mouse configuration on your end (a more sensitive setting) could be the reason for the described issue.

I can suggest debouncing the pageChange event as demonstrated in the following online demo, and see whether this will resolve the problem:

https://www.telerik.com/kendo-angular-ui/components/grid/scroll-modes/virtual/#toc-debouncing-pagechange-events

Please let us know how this goes.

Regards,
Dimiter Topalov
Progress Telerik
Get quickly onboarded and successful with your Telerik and Kendo UI products with the Virtual Classroom free technical training, available to all active customers. Learn More.
Tags
Grid
Asked by
Peter
Top achievements
Rank 1
Answers by
Dimiter Topalov
Telerik team
Peter
Top achievements
Rank 1
Share this question
or