ClassicAssist.Avalonia/ClassicAssist/UI/Misc/EnumBindingSourceExtension.cs

using System;
using System.Windows.Markup;

namespace ClassicAssist.UI.Misc
{
    /*
     * https://brianlagunas.com/a-better-way-to-data-bind-enums-in-wpf/
     */
    public class EnumBindingSourceExtension : MarkupExtension
    {
        private Type _enumType;

        public EnumBindingSourceExtension()
        {
        }

        public EnumBindingSourceExtension( Type enumType )
        {
            EnumType = enumType;
        }

        public Type EnumType
        {
            get => _enumType;
            set
            {
                if ( value != _enumType )
                {
                    if ( null != value )
                    {
                        Type enumType = Nullable.GetUnderlyingType( value ) ?? value;

                        if ( !enumType.IsEnum )
                        {
                            throw new ArgumentException( "Type must be for an Enum." );
                        }
                    }

                    _enumType = value;
                }
            }
        }

        public override object ProvideValue( IServiceProvider serviceProvider )
        {
            if ( null == _enumType )
            {
                throw new InvalidOperationException( "The EnumType must be specified." );
            }

            Type actualEnumType = Nullable.GetUnderlyingType( _enumType ) ?? _enumType;
            Array enumValues = Enum.GetValues( actualEnumType );

            if ( actualEnumType == _enumType )
            {
                return enumValues;
            }

            Array tempArray = Array.CreateInstance( actualEnumType, enumValues.Length + 1 );
            enumValues.CopyTo( tempArray, 1 );
            return tempArray;
        }
    }
}