In MVVM, how to scroll to the previously selected GanttTask

[Jacky]

In MVVM, how to scroll to the previously selected GanttTask when I update whole ObservableCollection gantt tasks?

Thanks,

-Jacky

 

[Dinko | Tech Support Engineer]

Hello Jacky,

Thank you for contacting us.

An approach which you can try is to create a SelectedTask property in your view model and bind it to the SelectedItem property of the RadGanttView. This property will preserve the item selected by the user. When you reset the collection you can use the ScrollView method for an example of the RadGanttView to scroll to a specific location. There is a Scrolling help article in our documentation which describes how you can set up RadGanttView so that the view is scrolled to a specified location.

Regards,
Dinko
Progress Telerik

[Jacky]

Hi Dinko,

Thank you for reply. but in an MVVM scenario, how can I call "ScrollView"  from my view model ?

Thanks,

 

[Jacky]

I  setup a SelectedTask (two way) in my view ,  I set back SelectedTask to previous task after I reset the collection. but the section didn't show up.

[Jacky]

I tried to directly use control like below. but it didn't work.

private void ResourceGantt_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
var gantt = sender as RadGanttView;
var previousItems = e.RemovedItems;
var newItems = e.AddedItems;
if (newItems.Count == 0 && previousItems.Count > 0)
{
gantt.SelectedItem = previousItems[0];
gantt.ScrollingService.ScrollIntoView(previousItems[0]);
}
}

[Jacky]

if  previous Item is gantt's grandchild, it can't be set to select item?

[Dinko | Tech Support Engineer]

Hi Jacky,

Keep in mind that when you reset the collection new items will be created. You need to get the item from the new collection which correspondents to the previously selected item and set this item to the property bound to the SelectedItem of the RadGanttView. I have modified the project from my previous reply to demonstrates this approach. 

Regards,
Dinko
Progress Telerik