Toolkit2/Framework/Avalonia/Markups/ParameterBindingExtension.cs

using Avalonia;
using Avalonia.Controls;
using Avalonia.Data;
using Avalonia.Markup.Xaml;
using Toolkit.Framework.Foundation;

namespace Toolkit.Framework.Avalonia;

public class ParameterBindingExtension : MarkupExtension, IParameter
{
    private static readonly AttachedProperty<object> ValueProperty =
        AvaloniaProperty.RegisterAttached<ParameterBindingExtension, Control, object>("Value");

    private readonly Binding? valueBinding;

    public ParameterBindingExtension(string key, object value)
    {
        Key = key;
        valueBinding = value.ToBinding();
    }

    public string? Key { get; }

    public KeyValuePair<string, object>? GetValue(object target)
    {
        if (target is AvaloniaObject avaloniaObject)
        {
            if (valueBinding is not null)
            {
                avaloniaObject.Bind(ValueProperty, valueBinding);
                return new KeyValuePair<string, object>(Key, (dynamic)avaloniaObject.GetValue(ValueProperty));
            }
        }

        return default;
    }

    public override object ProvideValue(IServiceProvider serviceProvider)
    {
        return this;
    }
}