The performance of my RadListView is abysmal for large collections of items. 

I'm following all the documentation here: http://docs.telerik.com/devtools/xamarin/controls/listview/features/listview-features-load-on-demand but also looked at the official ListView documentation here: https://developer.xamarin.com/guides/xamarin-forms/user-interface/listview/performance/#Caching_Strategy

How can I enable ListViewCachingStrategy.RecycleElement for RadListView?

Hi,

The RadListView does not extend the native XamarinForms ListView component. We rely on our native Android, iOS and UWP implementations. This is why the performance improvements implemented in the XamarinForms component cannot be applied to our RadListView.

Could you please share more details about your setup? How are the items loaded? How is the Template of the items defined? How much items you try to visualize? What makes you think the performance is not good enough?

If you share more details about the scenario and the requirements we might be able to suggest a better approach to achieve the required setup.

Regards,
Pavel R. Pavlov
Progress Telerik

My cell template contains a Grid component with 7 labels and 1 image component. Images are loaded from a remote URL. Lists can contain 1500+ elements. 

And...? Do you have any performance issues? Maybe your performance issues (if appears), are related to usage of OOTB Xamarin Forms **Image** element.
I suggest to use FFImageLoading, which has loading/caching/downstamping mechanisms against **CachedImage** (you can use it, instead of default **Image**).
TL;DR - use at least Aspect="AspectFit" +DownsampleToViewSize="True" properties on it.

For me, usage of:
-Telerik RadListView + Image == laggly UI during fast scrolling, even for 5 elements at list

-Telerik RadListView + FFImageLoading == smooth UI during during fast scrolling, even for 30 elements (haven't test in on hundreds or thousands)

@Namyslaw, the core issue is that RadListView instantiates all cells for each element in the ItemSource. This is never an economic behavior on mobile and should be addressed ASAP.

Also, FFImageLoading fails OOTB on iOS with an UIKitThreadAccessException... useless...

 

UIKit.UIKitThreadAccessException: UIKit Consistency error: you are calling a UIKit method that can only be invoked from the UI thread.
  at UIKit.UIApplication.EnsureUIThread () [0x00023] in /Users/builder/data/lanes/4691/d2270eec/source/xamarin-macios/src/UIKit/UIApplication.cs:88 
  at UIKit.NSDataAsset.get_Data () [0x00000] in /Users/builder/data/lanes/4691/d2270eec/source/xamarin-macios/src/build/ios/native/UIKit/NSDataAsset.g.cs:117 
  at FFImageLoading.DataResolvers.BundleDataResolver+<Resolve>d__1.MoveNext () [0x00369] in <8242b6346c404272a5f37bad37b4ee65>:0 

Hello,

We are aware that the performance of the RadListView can be improved. We have exposed a feedback item which is related with the described setup. Customers can vote and follow the item so that they will be notified when we provide a fix.

At the moment of writing we cannot bind to any specific time frame for providing a fix. The implementation priority depends on the votes of the item hence every vote counts.

Regards,
Pavel R. Pavlov
Progress Telerik

Pavel, this is unacceptable behavior.

 

Telerik components are marketed as extending Xamarin.Forms components, not as imposing other limitations...

Please address asap!

Michael said:

Also, FFImageLoading fails OOTB on iOS with an UIKitThreadAccessException... useless...

 

UIKit.UIKitThreadAccessException: UIKit Consistency error: you are calling a UIKit method that can only be invoked from the UI thread.
  at UIKit.UIApplication.EnsureUIThread () [0x00023] in /Users/builder/data/lanes/4691/d2270eec/source/xamarin-macios/src/UIKit/UIApplication.cs:88 
  at UIKit.NSDataAsset.get_Data () [0x00000] in /Users/builder/data/lanes/4691/d2270eec/source/xamarin-macios/src/build/ios/native/UIKit/NSDataAsset.g.cs:117 
  at FFImageLoading.DataResolvers.BundleDataResolver+<Resolve>d__1.MoveNext () [0x00369] in <8242b6346c404272a5f37bad37b4ee65>:0 

I'm using **FFImageLoading** without any issues at Android and iOS.
In many ways - inside mentioned Telerik RadListView (at attachments thumbnails), inside Telerik RadListView (as customer logo image) as well as outside Telerik components - as app logo at standard Xamarin Page etc.

Namysław said:

Michael said:

Also, FFImageLoading fails OOTB on iOS with an UIKitThreadAccessException... useless...

 

UIKit.UIKitThreadAccessException: UIKit Consistency error: you are calling a UIKit method that can only be invoked from the UI thread.
  at UIKit.UIApplication.EnsureUIThread () [0x00023] in /Users/builder/data/lanes/4691/d2270eec/source/xamarin-macios/src/UIKit/UIApplication.cs:88 
  at UIKit.NSDataAsset.get_Data () [0x00000] in /Users/builder/data/lanes/4691/d2270eec/source/xamarin-macios/src/build/ios/native/UIKit/NSDataAsset.g.cs:117 
  at FFImageLoading.DataResolvers.BundleDataResolver+<Resolve>d__1.MoveNext () [0x00369] in <8242b6346c404272a5f37bad37b4ee65>:0 

I'm using **FFImageLoading** without any issues at Android and iOS.
In many ways - inside mentioned Telerik RadListView (at attachments thumbnails), inside Telerik RadListView (as customer logo image) as well as outside Telerik components - as app logo at standard Xamarin Page etc.

 

Can we please stop discussing FFImageLoading? I clearly described the faulty and expected behavior when I use RadListView. The behavior is completely agnostic of content of the list views cells... It is 10 month now and nothing has been done about this...

Hi, Michael,

I am sorry to hear that you are still experiencing performance issues in the described scenario. Actually, the feedback item that my colleague has provided is already fixed. We would like to investigate the scenario you have in more details so we can identify what exactly might be the root of the issue. Would it be possible to create a ticket and attach a sample with your specific setup so we can test it from our side?

In the meantime, as you have mentioned previously that you suppose the issue is that the RadListView control creates all the necessary visual elements for all of the items within your source collection - the control supports UI Virtualization and would reuse the visual elements for the different items within its ItemsSource. Please make sure that the control is not placed within a layout that will measure its height with infinity(such as a StackLayout) as this would break the UI virtualization and would result in such slow performance. 

Regards,
Stefan Nenchev
Progress Telerik