WP8 ScrollViewer scroll ended

Question

Can anyone suggest how I can determine the end of scrollview's scrolling in windows phone 8? LayoutUpdated event allows one to determine when scrolling is in progress, but there is no event, which will allow to determine the end of the scroll.

Edit: There is some misunderstanding in the phrase "end of the scrolling". I do not need to determine the state when user scrolls to the end of scrollviewer. What I need is to determine the end of scrolling. It does not depend on what part of scrolviwer has been already scrolled.

Have you checked this link : http://blogs.msdn.com/b/slmperf/archive/2011/06/30/windows-phone-mango-change-listbox-how-to-detect-compression-end-of-scroll-states.aspx ? — Shmwel, Jun 02 '14 at 13:25
No, I hadn`t, but according to users` comments the mechanism described in the link is designed for listbox and has some problems with ScrollViwer. Also the used version of WP is 7. — Vahagn Nahapetyan, Jun 02 '14 at 13:34

Muhammad Saifullah · Answer 1 · 2014-06-02T13:57:57.187

2

Use ViewChanged property instead of LayoutUpdated. below is how you can detect the end of scrollviwer

sample xaml

<ScrollViewer Name="scrollViewer" Height="200" ViewChanged="scrollViewer_ViewChanged">
        <StackPanel Name="canContentContaner" Height="auto" Background="Orange"                           Orientation="Vertical">
            <Button Height="60" Content="TEst button"></Button>
            <Button Height="60" Content="TEst button"></Button>
            <Button Height="60" Content="TEst button"></Button>
            <Button Height="60" Content="TEst button"></Button>
            <Button Height="60" Content="TEst button"></Button>
            <Button Height="60" Content="TEst button"></Button>
        </StackPanel>
    </ScrollViewer>

Event handler

 private async void scrollViewer_ViewChanged(object sender, ScrollViewerViewChangedEventArgs e)
    {
        if (e.IsIntermediate==false) //&& scrollViewer.VerticalOffset >= canContentContaner.ActualHeight - scrollViewer.ActualHeight)
        {
           //The scrolling has ended..
        }
    }

Hope this helps.

edited Jun 02 '14 at 13:57

answered Jun 02 '14 at 13:46

Muhammad Saifullah

4,292
1
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What I need is to determine the end of the scrolling. I mean, you can finish scrolling in the middle of the stackpanel. – Vahagn Nahapetyan Jun 02 '14 at 13:52
Updated the code. now it will determine that the scrolling has finished(see the ViewChanged event handler) Hope this helps – Muhammad Saifullah Jun 02 '14 at 13:59
Muhammad, I tried your code, but there is no such an event (ViewChanged) in ScrollViewer. Do I need to import/use some DLLs/namespaces? – Vahagn Nahapetyan Jun 02 '14 at 14:07
The above solution works for windows phone 8.1. I will check for its alternative for windows phone 8. – Muhammad Saifullah Jun 02 '14 at 15:30

score 2 · Answer 2 · answered Jun 03 '14 at 07:01

Found solution in http://blogs.msdn.com/b/ptorr/archive/2010/07/23/how-to-detect-when-a-list-is-scrolling-or-not.aspx

FrameworkElement element = VisualTreeHelper.GetChild(viewer, 0) as FrameworkElement; 
if (element != null) 
{ 
  VisualStateGroup group = FindVisualState(element, "ScrollStates"); 
  if (group != null) 
  { 
    group.CurrentStateChanging += (s, args) => PageTitle.Text = args.NewState.Name; 
  } 
} 

VisualStateGroup FindVisualState(FrameworkElement element, string name) 
{ 
  if (element == null) 
   return null;

IList groups = VisualStateManager.GetVisualStateGroups(element); 
foreach (VisualStateGroup group in groups) 
if (group.Name == name) 
  return group;

return null; 
}

Scroll end can be detected:

group.CurrentStateChanging += (s, args) =>
                    {
                        if (args.OldState.Name == "Scrolling" && args.NewState.Name == "NotScrolling")
                        {

                            //Scroll end
                        }
                    };

And how to detect if it is scrolling to top or to bottom? – lenden Aug 04 '14 at 10:55 — lenden, Aug 04 '14 at 10:55

score 1 · Answer 3 · edited May 23 '17 at 12:24

1

Here you have multiple options : Flick Events, Manipulation events.

Check my answer here

edited May 23 '17 at 12:24

Community

1
1

answered Jun 02 '14 at 13:48

vITs

1,651
12
30

Sorry, I guess I was not clear in my question. I do not need to implement lazy load mechanism or determine the state when user scrolls to the end of the scrollviewer. What I need is to determine when scrolling ends. Scrolling can be finished in any position of scrollbar. – Vahagn Nahapetyan Jun 02 '14 at 13:57
Ohh..In this case you can use Flick events...you can get offset of scroll position in its handler and by using VerticalVelocity value you can tackle the position – vITs Jun 02 '14 at 13:59
I tried to do so, but the thing is, that you can scroll scrollviewer without stopping and by making dozens of gestures. The event what I used was "MouseLeave". – Vahagn Nahapetyan Jun 02 '14 at 14:12
No need of MouseLeave.Check these [forum1](http://stackoverflow.com/questions/17148985/implement-flick-gesture-via-gestureservice-from-windows-phone-8) and [forum2](http://stackoverflow.com/questions/21399514/implement-swipe-event-on-wp8).Your idea related to Flick events will get cleared. – vITs Jun 03 '14 at 05:10

WP8 ScrollViewer scroll ended

3 Answers3