inabox/inabox.wpf/Converters/AbstractConverter.cs

using System;
using System.Globalization;
using System.Windows;
using System.Windows.Data;
using Org.BouncyCastle.X509.Extension;

namespace InABox.WPF;


public class UtilityConverterEventArgs : EventArgs
{
    public object Value { get; private set; }
    public object Parameter { get; private set; }

    public UtilityConverterEventArgs(object value, object parameter)
    {
        Value = value;
        Parameter = parameter;
    }
}

public delegate void UtilityCoverterEvent(object sender, UtilityConverterEventArgs args);

public interface IValueConverter<TIn, TOut> : IValueConverter
{
}

// Freezable is a way that might allow us to pass in a DataContext (ie Viewmodel) 
// to static resources with XAML.  Not yet tested, kept for reference
// The uncertain bit is the DependencyProperty "typeof(IValueConverter)" - this
// might not do what we want, as I suspect it might require a concrete type?
// Ref: https://thomaslevesque.com/2011/03/21/wpf-how-to-bind-to-data-when-the-datacontext-is-not-inherited/
public abstract class AbstractConverter<TIn, TOut> : /*Freezable, */ IValueConverter<TIn, TOut>
{

    public event UtilityCoverterEvent? Converting;
    public event UtilityCoverterEvent? Deconverting;

    public abstract TOut Convert(TIn value);

    public virtual TIn? Deconvert(TOut value)
    {
        return default;
    }

    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        var typed = value is TIn tin ? tin : default;
        Converting?.Invoke(this, new UtilityConverterEventArgs(typed, parameter));
        return Convert(typed);
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        var typed = value is TOut tout ? tout : default;
        Deconverting?.Invoke(this, new UtilityConverterEventArgs(typed, parameter));
        return Deconvert(typed);
    }

    // #region Freezable
    //
    // protected override Freezable CreateInstanceCore()
    // {
    //     return (Freezable)Activator.CreateInstance(this.GetType())!;
    // }
    //
    // public static readonly DependencyProperty DataContextProperty =
    //     DependencyProperty.Register(nameof(DataContext), typeof(object), typeof(IValueConverter),
    //         new UIPropertyMetadata(null));
    //
    // public object DataContext
    // {
    //     get { return (object)GetValue(DataContextProperty); }
    //     set { SetValue(DataContextProperty, value); }
    // }
    //
    // #endregion


}

public class NullConverter<T> : AbstractConverter<T, T>
{
    public override T Convert(T value)
    {
        return value;
    }
}