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Scroll position indicator when using VirtualQueryableCollectionView
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Ronald
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Ronald asked on 08 Nov 2013, 09:24 AM

I have a requirement to handle a large number of records in a grid. So my radgrid is set to deferred scrolling and is lazy loading the records using VirtualQueryableCollectionView. That works really well.

My problem is in the scroll position indicator. I can't bind it to a property in the record because they are not loaded yet. Setting scroll mode to real time is not an option. What would be best solution here?

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Dimitrina
Telerik team
answered on 12 Nov 2013, 11:07 AM
Hello,

When the ScrollMode is Deferred, then no action will be performed and no Items will be requested before you release the mouse and stop dragging the scrollbar. 
 
I am afraid we cannot suggest different when using the VirtualQueryableCollectionView.

Regards,
Didie
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Pavan
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answered on 24 Dec 2013, 02:19 PM

Hi I have the same issue. When the deferred scrolling is enabled I would like to give my customer some kind of feedback about the scroll position at which Item he would land if he leaves the scroll bar. Can you please suggest some kind of alternative for this may be handling of a mouse down event on the scroll viewer etc.
 

I think this is a very common requirement and would add a lot of value to the VirtualQueryableCollectionView.

Thanks,
PD.

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Dimitrina
Telerik team
answered on 25 Dec 2013, 10:13 AM
Hello,

I am afraid this is not possible as the item to be eventually displayed is still not presented. This is the case until the user releases the scrollbar to a particular position and then the items to be displayed into view are actually loaded.

Regards,
Didie
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Ronald
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answered on 27 Dec 2013, 08:31 AM

The biggest problem is that it will always show the scroll position indicator even if not configured.

There are two solutions:
1. Make it possible to hide the scroll position indicator entirely.
2. Make it possible to show the row index.
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Dimitrina
Telerik team
answered on 27 Dec 2013, 02:18 PM
Hi,

Please add the following style to the resources of your page:
<Style TargetType="telerik:ScrollPositionIndicator">
     <Setter Property="Opacity" Value="0" />
 </Style>

This should permanently hide the indicator.


Regards,
Didie
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Pavan
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answered on 30 Dec 2013, 08:32 AM
Hi Didie,

Hiding the Scroll Position Indicator gets rid of the misleading tool tip, but I cannot use it for my use case.

I really need the ability to display my custom information which I can provide as a property from the View Model. But the important thing for me to know from the Grid is really the Deferred Scroll Position or the Index. Can you provide a Dependency Property on the grid "DefferredScrollPosition" Which gives me the scroll Index. I can use this to give some details to the User from the view model to be bound to the tool tip. [I understand that not all the items are presented in the grid and hence showing automatically relevant information is not possible but I can give the relevant information if the gird is able to provide me the deferred scroll position].

Would be really nice if there is a workaround at least for the time being to know the deferred scroll index.
 
Kind Regards,
Pavan.
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Dimitrina
Telerik team
answered on 30 Dec 2013, 01:33 PM
Hello Pavan,

I will discuss your request with my colleagues.

What I can currently suggest you would be to subscribe for the Scroll event of the ScrollBar and then try calculating the index (the current scroll position) yourself.
For example:
void radGridView_DataLoaded(object sender, EventArgs e)
 {
     var scrollBar = this.radGridView.ChildrenOfType<ScrollBar>().FirstOrDefault();
     if (scrollBar != null)
     {
         scrollBar.Scroll += scrollBar_Scroll;
     }
 }
 
 void scrollBar_Scroll(object sender, ScrollEventArgs e)
 {
     // calculate where you are based on the e.NewValue value
 }

Regards,
Didie
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Dimitrina
Telerik team
answered on 14 Jan 2014, 04:26 PM
Hi,

We have discussed your request on our planning meeting. I am afraid we cannot consider adding an additional template to display the deferred scroll index.

Regards,
Didie
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Vinay
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answered on 27 Jul 2018, 12:11 PM

Can somebody tell a way to print the horizontal scrollbar of Radgrid using DocumentViewer

 

THANKS,

Vinay

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Ronald
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Dimitrina
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Pavan
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Ronald
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