WPF - ComboBox - Prevent Scrolling - WIthout using Code Behind

Question

Issue

I need to prevent scrolling through the ComboBox selected items when the mouse hovers over the closed ComboBox.

I have seen this done using code behind (e.g. this), but I need to do it without code behind, in a way that could be easily reused throughout the project.

For example, elsewhere in our project we use IValueConverter to do make a StaticResource that can easily be added where required.

Question

Is there a way to make a StaticResource for the ComboBox that could prevent scrolling?

Is there an interface like IValueConveter that could be used in place of the EventSetter Handler?

Answer 1

but I need to do it without code behind, in a way that could be easily reused throughout the project.

So wrap the code-behind functionality in an attached behaviour:

public static class NoScrollingBehaviour
{
    public static bool GetEnabled(ComboBox comboBox) =>
        (bool)comboBox.GetValue(EnabledProperty);

    public static void SetEnabled(ComboBox comboBox, bool value) =>
        comboBox.SetValue(EnabledProperty, value);

    public static readonly DependencyProperty EnabledProperty =
        DependencyProperty.RegisterAttached(
        "Enabled",
        typeof(bool),
        typeof(NoScrollingBehaviour),
        new UIPropertyMetadata(false, OnEnabledChanged));

    private static void OnEnabledChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        ComboBox comboBox = (ComboBox)d;
        if (GetEnabled(comboBox))
        {
            FrameworkElementFactory stackPanel = new FrameworkElementFactory(typeof(StackPanel));
            stackPanel.AddHandler(FrameworkElement.RequestBringIntoViewEvent, new RequestBringIntoViewEventHandler(OnRequestBringIntoView));
            comboBox.ItemsPanel = new ItemsPanelTemplate() { VisualTree = stackPanel };
        }
    }

    private static void OnRequestBringIntoView(object sender, RequestBringIntoViewEventArgs e)
    {
        if (Keyboard.IsKeyDown(Key.Down) || Keyboard.IsKeyDown(Key.Up))
            return;

        e.Handled = true;
    }
}

You can then easily reuse it for different ComboBox elements:

<ComboBox local:NoScrollingBehaviour.Enabled="true" />