canto/Assets/Scripts/UI/UiElementInstance.cs

using System;
using R3;
using UnityEngine;
using UnityEngine.UIElements;

namespace KitsuneCafe.UI
{
    public class UiElementInstance : MonoBehaviour, IDisposable
    {
        private IUiElement uiElement;
        private VisualElement visualElement;

        private readonly CompositeDisposable activeEffects = new();

        private bool configured = false;

        public void Configure(IUiElement uiElement, VisualElement visualElement)
        {
            configured = true;
            this.uiElement = uiElement;
            this.visualElement = visualElement;

            activeEffects.Clear();

            uiElement.Configure(visualElement);

            Raise(UiEvent.OnCreate);
        }

        private void Raise(UiEvent evt)
        {
            foreach (var effect in uiElement.GetEffectsFor(evt))
            {
                // using explicit null comparison because of the way
                // GameObjects handle being null
                if (effect != null)
                {
                    effect.Instantiate()
                        .Execute(visualElement, destroyCancellationToken)
                        .Subscribe()
                        .AddTo(activeEffects);
                }
            }
        }

        public void Dispose()
        {
            if (!configured) { return; }

            Raise(UiEvent.OnDestroy);

            activeEffects.Dispose();
            activeEffects.Clear();

            uiElement = default;
            visualElement = default;

            configured = false;
        }

        private void OnDisable()
        {
            Dispose();
        }

        private void OnDestroy()
        {
            Dispose();
        }
    }
}