How to prevent the Key.Enter pressed event handled by ListBox with Avalonia 12.0.1?

[love-linger]

I have a ListBox that shows some commands, and user can use arrow keys to change selection and press Key.Enter to trigger the selected command:

In 11.x, since UpdateSelectionFromEventSource does not mark this key event as handled, I can just add an handler to KeyDown event to do this.

       protected override void OnKeyDown(KeyEventArgs e)
       {
            ...
            else if (e.Key == Key.Space || e.Key == Key.Enter)
            {
                UpdateSelectionFromEventSource(
                    e.Source,
                    true,
                    e.KeyModifiers.HasFlag(KeyModifiers.Shift),
                    ctrl);
            }

            base.OnKeyDown(e);
        }

But when using 12.0.1, the Key.Enter event is marked as handled by ListBox after UpdateSelection

            switch (eventArgs)
            {
                case PointerEventArgs pointerEvent when ShouldTriggerSelection(container, pointerEvent):
                case KeyEventArgs keyEvent when ShouldTriggerSelection(container, keyEvent):
                case FocusChangedEventArgs:
                    UpdateSelection(containerIndex, true,
                        ItemSelectionEventTriggers.HasRangeSelectionModifier(container, eventArgs),
                        ItemSelectionEventTriggers.HasToggleSelectionModifier(container, eventArgs),
                        eventArgs is PointerEventArgs { Properties.IsRightButtonPressed: true },
                        eventArgs is FocusChangedEventArgs);

                    eventArgs.Handled = true; // Marked as handled
                    return true;

                default:
                    return false;
            }

I can not just use KeyDown="OnListKeyDown" to handle Key.Enter pressing.

Do you have any better suggestions?

[rabbitism]

I assume this is for source git? Can you point me to the source code snippet?

[love-linger]

• Avalonia 11

  Avalonia/src/Avalonia.Controls/ListBox.cs

  Lines 129 to 159 in ebc6056

  	protected override void OnKeyDown(KeyEventArgs e)
  	{
  	var hotkeys = Application.Current!.PlatformSettings?.HotkeyConfiguration;
  	var ctrl = hotkeys is not null && e.KeyModifiers.HasAllFlags(hotkeys.CommandModifiers);
  	if (!ctrl &&
  	e.Key.ToNavigationDirection() is { } direction &&
  	direction.IsDirectional())
  	{
  	e.Handled |= MoveSelection(
  	direction,
  	WrapSelection,
  	e.KeyModifiers.HasAllFlags(KeyModifiers.Shift));
  	}
  	else if (SelectionMode.HasAllFlags(SelectionMode.Multiple) &&
  	hotkeys is not null && hotkeys.SelectAll.Any(x => x.Matches(e)))
  	{
  	Selection.SelectAll();
  	e.Handled = true;
  	}
  	else if (e.Key == Key.Space || e.Key == Key.Enter)
  	{
  	UpdateSelectionFromEventSource(
  	e.Source,
  	true,
  	e.KeyModifiers.HasFlag(KeyModifiers.Shift),
  	ctrl);
  	}
  	base.OnKeyDown(e);
  	}

• Avalonia 12
  

  Avalonia/src/Avalonia.Controls/Primitives/SelectingItemsControl.cs

  Lines 882 to 912 in 88e0f67

  	public virtual bool UpdateSelectionFromEvent(Control container, RoutedEventArgs eventArgs)
  	{
  	if (eventArgs.Handled)
  	{
  	return false;
  	}
  	var containerIndex = IndexFromContainer(container);
  	if (containerIndex == -1)
  	{
  	return false;
  	}
  	switch (eventArgs)
  	{
  	case PointerEventArgs pointerEvent when ShouldTriggerSelection(container, pointerEvent):
  	case KeyEventArgs keyEvent when ShouldTriggerSelection(container, keyEvent):
  	case FocusChangedEventArgs:
  	UpdateSelection(containerIndex, true,
  	ItemSelectionEventTriggers.HasRangeSelectionModifier(container, eventArgs),
  	ItemSelectionEventTriggers.HasToggleSelectionModifier(container, eventArgs),
  	eventArgs is PointerEventArgs { Properties.IsRightButtonPressed: true },
  	eventArgs is FocusChangedEventArgs);
  	eventArgs.Handled = true;
  	return true;
  	default:
  	return false;
  	}
  	}

[love-linger]

You can just create an demo project that only contains a ListBox in a Window. Add a KeyDown event handler to that ListBox. Then you will see that pressing Key.Enter will not trigger the custom handler because it is marked handled by ListBoxItem.OnKeyDown

[rabbitism]

You can register with code behind:

<Window xmlns="https://github.com/avaloniaui"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
        x:Class="TestApp.MainWindow"
        Title="TestApp">
    <ListBox Name="list" >
        <ListBoxItem>Item 1</ListBoxItem>
        <ListBoxItem>Item 2</ListBoxItem>
        <ListBoxItem>Item 3</ListBoxItem>
    </ListBox>
</Window>

using Avalonia.Controls;
using Avalonia.Input;

namespace TestApp;

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
        list.AddHandler(KeyDownEvent, List_OnKeyDown, handledEventsToo: true);
    }

    private void List_OnKeyDown(object? sender, KeyEventArgs e)
    {
        throw new System.NotImplementedException();
    }
}

Notice the handledEventsToo arugment.

[love-linger]

My need is not only to capture the enter keydown event, but also to intercept the event, that is, I don't want the selection to be changed this matter.

[rabbitism]

Then probably you need to specify this Handler to be added with RoutingStrategies.Tunnel, and handle it.