com.misaki.ao-volume/Editor/PropertyDrawer/PopupBooleanDrawer.cs

using System.Collections.Generic;
using UnityEditor;
using UnityEngine;
using UnityEngine.UIElements;

namespace Misaki.AoVolume.Editor
{
    [CustomPropertyDrawer(typeof(PopupBooleanAttribute))]
    public class PopupBooleanDrawer : PropertyDrawer
    {
        private static readonly GUIContent[] _popupContent = { new("False"), new("True") };
        private static readonly List<bool> _popupOptions = new() { false, true };

        public override void OnGUI(Rect position, SerializedProperty property, GUIContent label)
        {
            var value = property.boolValue;
            var index = value ? 1 : 0;

            EditorGUI.BeginChangeCheck();
            index = EditorGUI.Popup(position, label, index, _popupContent);
            if (EditorGUI.EndChangeCheck())
            {
                property.boolValue = index == 1;
            }
        }

        public override VisualElement CreatePropertyGUI(SerializedProperty property)
        {
            var popupField = new PopupField<bool>(property.displayName, _popupOptions, false);
            popupField.AddToClassList(PopupField<bool>.alignedFieldUssClassName);
            popupField.bindingPath = property.propertyPath;

            return popupField;
        }
    }
}