poc-misc/PatchNumericUpDownPoC/HexadecimalNumericUpDownPatcher.cs

using System;
using System.Reflection;
using System.Windows.Forms;
using HarmonyLib;

namespace PatchNumericUpDownPoC
{
    internal static class HexadecimalNumericUpDownPatcher
    {
        private static readonly Harmony Harmony = new Harmony(nameof(HexadecimalNumericUpDownPatcher));

        private static bool _isPatched;
        private static AccessTools.FieldRef<UpDownBase, bool> _userEditRef;
        private static MethodInfo _mOriginal;
        private static MethodInfo _mPrefix;

        public static void DoPatch()
        {
            if (_isPatched) return;

            _mOriginal = AccessTools.Method(typeof(NumericUpDown), "ParseEditText");
            if (null == _mOriginal) return;

            _mPrefix = SymbolExtensions.GetMethodInfo(() => Prefix(null));
            _userEditRef = AccessTools.FieldRefAccess<UpDownBase, bool>("userEdit");

            Harmony.Patch(_mOriginal, new HarmonyMethod(_mPrefix));

            _isPatched = true;
        }

        public static void UnPatch()
        {
            if (false == _isPatched) return;

            Harmony.Unpatch(_mOriginal, _mPrefix);
        }

        // ReSharper disable once InconsistentNaming
        private static bool Prefix(NumericUpDown __instance)
        {
            if (false == __instance.Hexadecimal) return true;

            try
            {
                var parsedValue = Convert.ToDecimal(Convert.ToUInt64(__instance.Text, 16));

                if (parsedValue < __instance.Minimum)
                    parsedValue = __instance.Minimum;
                if (parsedValue > __instance.Maximum)
                    parsedValue = __instance.Maximum;
                __instance.Value = parsedValue;
            }
            catch
            {
                //Do nothing
            }
            finally
            {
                _userEditRef(__instance) = false;
            }
            return false;
        }
    }
}