ScrollViewer events for Windows Phone 8

Question

I have got a listbox. And the listbox items can be images, text, audio,video etc. The Items are fetched using Internet and sometimes the list becomes too long. I want to implement a "Go To Top" feature in my listbox which are used in many websites. As soon as the users start scrolling, a button appears which takes them to the top, and if they scroll back to the top, the button disappears.

The problem is I do not know what to do. If I disable the scrollviewer of my listbox and put the listbox inside a scrollviewer, then I do not know which of the scrollviewer's events and properties should I use?

SonofNun SonofNun · Accepted Answer · 2014-07-19T18:13:46

You could use the ScrollStateChanged event on the RadDataboundListBox to see if the listbox is being scrolled. If it is, you can then show your ScrollToTop button.

Something like this:

private void RadDataBoundListBox_ScrollStateChanged(object sender, ScrollStateChangedEventArgs e)
{
    if (e.NewState == ScrollState.Scrolling)
    {
        // Code to show the ScrollToTop button
    }
}

You could play around with the different ScrollStates to show and hide the ScrollToTop button at different times. (i.e. when NewState == ScrollState.TopStretch, you could hide the button.)

If you are binding to the ItemsSource of the ListBox, you can use the BringIntoView method as mentioned above.

RadDataBoundListBox.BringIntoView(BoundObservableCollection[0]);

I hope this helps. Thanks, Joshua

ScrollViewer events for Windows Phone 8

2 Answers