How to disable ScrollViewer in ListBox?

user_194890 0
Viewed 19421

I have a ListBox. It has internal ScrollViewer, so I can scroll ListBox content with mouse wheel. It works fine until I set item template that contains another ListBox (in fact, I have 4 nested ListBoxes =)). Problem is that internal ListBox's ScrollViewer steals wheeling event. Is there any easy way to prevent this behavior?

I had ListBox with ItemContainerStyle like this: 

<Style x:Key="ListBoxItemStyle" TargetType="{x:Type ListBoxItem}">
    <Setter Property="BorderBrush" Value="Black"/>
     ... 
</Style>
<ListBox ItemContainerStyle="{StaticResource ListBoxItemStyle}" />

How can I set style for ItemContainer's item border in resources like this? As I know ContentPresenter is item container of ItemsControl. But it hasn't Border, so I can't style it.

scrollviewer listbox xaml wpf
6 Answers

I like to create a behavior for this type of thing.

xmlns:bhv="http://schemas.microsoft.com/xaml/behaviors"

<ListView ItemsSource="{Binding Items}">
    <bhv:Interaction.Behaviors>
        <bhvs:NoScrollingBehavior/>
    </bhv:Interaction.Behaviors>
</ListView>

The behavior itself.

public class NoScrollingBehavior : Behavior<UIElement>
{
    public NoScrollingBehavior()
    { }

    protected override void OnAttached()
    {
        base.OnAttached();
        AssociatedObject.PreviewMouseWheel += PreviewMouseWheel;
    }

    protected override void OnDetaching()
    {
        AssociatedObject.PreviewMouseWheel -= PreviewMouseWheel;
        base.OnDetaching();
    }

    private void PreviewMouseWheel(object sender, MouseWheelEventArgs e)
    {
        e.Handled = true;
        var eventArg = new MouseWheelEventArgs(e.MouseDevice, e.Timestamp, e.Delta);
        eventArg.RoutedEvent = UIElement.MouseWheelEvent;
        eventArg.Source = sender;
        var parent = ((Control)sender).Parent as UIElement;
        parent.RaiseEvent(eventArg);
    }
}
user_11127090

Here is a variant with DependencyProperty, if you don't like behaviors

public class IgnoreScrollingBehavior
{
    public static readonly DependencyProperty IgnoreScrollingProperty =
        DependencyProperty.RegisterAttached("IgnoreScrolling", typeof(bool),
            typeof(IgnoreScrollingBehavior), new UIPropertyMetadata(false, OnIgnoreScrollingChanged));

    public static bool GetIgnoreScrolling(UIElement uIElement)
    {
        return (bool)uIElement.GetValue(IgnoreScrollingProperty);
    }

    public static void SetIgnoreScrolling(UIElement uIElement, bool value)
    {
        uIElement.SetValue(IgnoreScrollingProperty, value);
    }

    private static void OnIgnoreScrollingChanged(DependencyObject depOpj, DependencyPropertyChangedEventArgs e)
    {
        if (depOpj is not UIElement item)
        {
            return;
        }

        if (e.NewValue is bool boolean)
        {
            if (boolean)
            {
                item.PreviewMouseWheel += OnPreviewMouseWheel;
            }
            else
            {
                item.PreviewMouseWheel -= OnPreviewMouseWheel;
            }
        }
    }

    private static void OnPreviewMouseWheel(object sender, MouseWheelEventArgs e)
    {
        e.Handled = true;
        MouseWheelEventArgs eventArg = new(e.MouseDevice, e.Timestamp, e.Delta)
        {
            RoutedEvent = UIElement.MouseWheelEvent,
            Source = sender
        };
        UIElement parent = ((Control)sender).Parent as UIElement;
        parent.RaiseEvent(eventArg);
    }
}

This is how it is used

<Listbox b:IgnoreScrollingBehavior.IgnoreScrolling="True".../>
user_164732590

You can use this ! No Wheel stolen.

<ListBox ScrollViewer.HorizontalScrollBarVisibility="Disabled"
     ScrollViewer.VerticalScrollBarVisibility="Disabled" ...
</ListBox>
user_33173240
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