Detect when WPF listview scrollbar is at the bottom?

Question

Is there a way to detect if the scrollbar from the ScrollViewer in a ListView has reached the bottom of the virtual scroll space? I would like to detect this to fetch more items from the server to put into the bound ObservableCollection on the listview.

Right now I'm doing this:

private void currentTagNotContactsList_scrollChanged(object sender, ScrollChangedEventArgs e) {

    ListView v = (ListView)sender;


    if (e.VerticalOffset + e.ViewportHeight == e.ExtentHeight) {
     Debug.Print("At the bottom of the list!");
    }

}

Is this even correct? I also need to differentiate between the vertical scrollbar causing the event and the horizontal scrollbar causing it (i.e. I don't want to keep generating calls to the server if you scroll horizontally at the bottom of the box).

Thanks.

Answer 1

I figured it out. It seems I should have been getting events from the ScrollBar (<ListView ScrollBar.Scroll="currentTagNotContactsList_Scroll" in XAML) itself, rather than the viewer. This works, but I just have to figure a way to avoid the event handler being called repeatedly once the scrollbar is down. Maybe a timer would be good:

private void currentTagNotContactsList_Scroll(object sender, ScrollEventArgs e) {

ScrollBar sb = e.OriginalSource as ScrollBar;

if (sb.Orientation == Orientation.Horizontal)
 return;

if (sb.Value == sb.Maximum) {
 Debug.Print("At the bottom of the list!");

}

}