CODEWITHSUNDEEP
c#windows-phone-7windows-phone-8windows-phone-7.1
user1058145
user1058145

Reputation: 13

Windows Phone: How do I keep ScrollViewer totally disabled until explicitly re-enabling it

My issue is that I have a very simple Listbox with a list of items. I noticed that when I disable the ScrollViewer from the MainPage_Loaded event, the ScrollViewer can be re-enabled by swiping the Listbox diagonally at any direction.

I have tried setting the property from XAML:

<ListBox ScrollViewer.VerticalScrollBarVisibility="Disabled" ...../>

I also tried to do it from code:

var myScrollviewer = VisualTreeHelper.GetChild(MyListBox, 0) as ScrollViewer;
myScrollviewer.HorizontalScrollBarVisibility = ScrollBarVisibility.Disabled;
myScrollviewer.VerticalScrollBarVisibility = ScrollBarVisibility.Disabled;

Straight vertical and horizontal swipe do indicate that the ScrollViewer is disabled but when I swipe diagonally without lifting my hand from the screen, the items in the listbox start scrolling up and down. This behavior seems like a bug!

Can someone tell me how to totally disable the scrollviewer so diagonal swiping doesn't temporarily re-enable the scrollviewer?

This behavior is affecting my underline task of dragging an item while the scrollviewer is disabled.

Thanks

Upvotes: 1

Views: 1848

Answers (1)

keyboardP
keyboardP

Reputation: 69372

That's interesting, haven't noticed that before. It may be a bug but to get around it try setting the ScrollViewer's ManipulationMode property to Control to let the OS know that you'll be handling the ScrollViewer at the control level rather than letting the system handle it. 

<ListBox ScrollViewer.ManipulationMode="Control" 
         ScrollViewer.VerticalScrollBarVisibility="Disabled"
         ScrollViewer.HorizontalScrollBarVisibility="Disabled" .../>

However, when you re-enable it, set the ManipulationMode back to System for a smoother scrolling.

Update based on comments

To re-enable the scrollviewer, do this

var myScrollviewer = VisualTreeHelper.GetChild(MyListBox, 0) as ScrollViewer;
myScrollviewer.HorizontalScrollBarVisibility = ScrollBarVisibility.Auto;
myScrollviewer.VerticalScrollBarVisibility = ScrollBarVisibility.Auto;
//key part - use SetValue to set ManipluationMode.System/Control
myScrollviewer.SetValue(ScrollViewer.ManipulationModeProperty, ManipulationMode.System);

If you need to disable it again, you can do the same thing but with the disabled properties and ManipulationMode.Control.

var myScrollviewer = VisualTreeHelper.GetChild(MyListBox, 0) as ScrollViewer;
myScrollviewer.HorizontalScrollBarVisibility = ScrollBarVisibility.Disabled;
myScrollviewer.VerticalScrollBarVisibility = ScrollBarVisibility.Disabled;
//key part - use SetValue to set ManipluationMode.System/Control
myScrollviewer.SetValue(ScrollViewer.ManipulationModeProperty, ManipulationMode.Control);

Upvotes: 1

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