TreeViewPanel.IsVirtualizing and ScrollBar problem

[Lauren Nickerson]

Well basically, I'm virtualizing the RadTreeView and I get a problem with the scroll bar where it gets smaller as I scroll down. Isn't there a way where it already knows what size it should be and just use that size from the start? That's how the native WPF TreeView works.

This is what I'm talking about:

http://www.screencast.com/users/CarloToribio/folders/Jing/media/97917e36-82fd-469a-8fb5-379767fa5974

Thanks.

[Tina Stancheva]

Hi Lauren Nickerson,

Since the virtualization of both the RadTreeView and the native TreeView lies on the same principles, the behavior of the ScrollViewer in the case you described is the same in both controls. Also it is an expected behavior and as far as I know you cannot workaround it.

I also attached a project containing both RadTreeView and TreeView in order to compare their behavior when virtualized. Can you take a look at it and let me know if I missing something.

Thank you in advance.

All the best,
Tina Stancheva
the Telerik team

[Andrew]

Hello,

 

I know this is an old post but I am running into similar issues today. It seems like the RadTreeView's virtualization doesn't handle the vertical size of the scrollbar until it has scrolled and seen each item.

I tried running the old above example and the issue was present in that example as well. I attached 2 screen shots from that demo demonstrating the issue.

 

Thanks,

Andrew

[Martin Ivanov]

Hello Andrew,

This behavior comes by design - initially the scrollviewer will respect only the currently loaded viewport. When you scroll down the scrollbar range will increase. Currently, this behavior cannot be altered. 

A possible approach that you could try is to implement the scrolling manually using a ScrollBar or a ScrollViewer control placed outside of the RadTreeView control and sync it with the treeview based on its ScrollViewer and the expanded items count.

Regards,
Martin Ivanov
Progress Telerik