modular-avatar/Editor/Inspector/MAEditorBase.cs

using System.Reflection;
using UnityEditor;
using UnityEditor.UIElements;
using UnityEngine;
using UnityEngine.UIElements;

namespace nadena.dev.modular_avatar.core.editor
{
    // This class performs common setup for Modular Avatar editors, including ensuring that only one instance of the\
    // logo is rendered per container.
    public abstract class MAEditorBase : Editor
    {
        private MAVisualElement _visualElement;
        private bool _suppressOnceDefaultMargins;

        protected virtual VisualElement CreateInnerInspectorGUI()
        {
            return null;
        }

        private void RebuildUI()
        {
            CreateInspectorGUI();
        }

        public sealed override VisualElement CreateInspectorGUI()
        {
            if (_visualElement == null)
            {
                _visualElement = new MAVisualElement();
                Localization.OnLangChange += RebuildUI;
            }
            else
            {
                _visualElement.Clear();
            }

            _visualElement.Add(new LogoElement());

            // CreateInspectorElementFromEditor does a bunch of extra setup that makes our inspector look a little bit
            // nicer. In particular, the label column won't auto-size if we just use IMGUIElement, for some reason 

            var inner = CreateInnerInspectorGUI();

            bool innerIsImgui = (inner == null);
            if (innerIsImgui)
            {
                var throwaway = new InspectorElement();

                var m_CreateIMGUIInspectorFromEditor = typeof(InspectorElement)
                    .GetMethod("CreateIMGUIInspectorFromEditor", BindingFlags.NonPublic | BindingFlags.Instance);
                var m_CreateInspectorElementUsingIMGUI = typeof(InspectorElement)
                    .GetMethod("CreateInspectorElementUsingIMGUI", BindingFlags.NonPublic | BindingFlags.Instance);

                Debug.Log($"CreateIMGUIInspectorFromEditor found: {m_CreateIMGUIInspectorFromEditor != null}");
                Debug.Log($"CreateInspectorElementUsingIMGUI found: {m_CreateInspectorElementUsingIMGUI != null}");

                if (m_CreateIMGUIInspectorFromEditor != null)
                {
                    inner = m_CreateIMGUIInspectorFromEditor.Invoke(throwaway,
                        new object[] { serializedObject, this, false }) as VisualElement;
                }
                else if (m_CreateInspectorElementUsingIMGUI != null)
                {
                    inner = m_CreateInspectorElementUsingIMGUI.Invoke(throwaway,
                        new object[] { this }) as VisualElement;
                }
                else
                {
                    Debug.Log(
                        "Neither CreateIMGUIInspectorFromEditor nor CreateInspectorElementUsingIMGUI found, for inspector " +
                        GetType());
                    inner = new VisualElement();
                }
            }

            _visualElement.Add(inner);

            _suppressOnceDefaultMargins = innerIsImgui;
            return _visualElement;
        }

        public override bool UseDefaultMargins()
        {
            var useDefaults = !_suppressOnceDefaultMargins;
            _suppressOnceDefaultMargins = false;
            return useDefaults;
        }

        public sealed override void OnInspectorGUI()
        {
            InspectorCommon.DisplayOutOfAvatarWarning(targets);

            OnInnerInspectorGUI();
        }

        protected abstract void OnInnerInspectorGUI();

        protected virtual void OnDestroy()
        {
            Localization.OnLangChange -= RebuildUI;
        }
    }

    internal class MAVisualElement : VisualElement
    {
    }
}