Animate the description of a text entry field

Silksong.ModMenu/Elements/DynamicDescriptionChoiceElement.cs

@@ -136,6 +136,7 @@ private static void HookOnSelect(ILManipulationInfo info)
     private static void HookOnDeselect(ILManipulationInfo info)
     {
         ILCursor cursor = new(info.Context);
+
         int locIndex = 1;
         while (
             cursor.TryGotoNext(

Silksong.ModMenu/Elements/TextInput.cs

@@ -48,6 +48,9 @@ public TextInput(LocalizedText label, ITextModel<T> model, LocalizedText descrip
             InputField.contentType = InputField.ContentType.IntegerNumber;
         else if (floatTypes.Contains(typeof(T)))
             InputField.contentType = InputField.ContentType.DecimalNumber;
+
+        input.AddComponent<DescriptionAnimationHelper>().DescriptionAnimator =
+            DescriptionText.gameObject.GetComponent<Animator>();
     }
 
     /// <summary>

Silksong.ModMenu/Internal/DescriptionAnimationHelper.cs

@@ -0,0 +1,83 @@
+using System.Collections;
+using UnityEngine;
+using UnityEngine.EventSystems;
+using UnityEngine.UI;
+
+namespace Silksong.ModMenu.Internal;
+
+internal class DescriptionAnimationHelper
+    : MonoBehaviour,
+        ISelectHandler,
+        IDeselectHandler,
+        ICancelHandler
+{
+    private Selectable _selectable;
+    public Animator? DescriptionAnimator { get; set; }
+
+    void Awake()
+    {
+        _selectable = GetComponent<Selectable>();
+    }
+
+    public void OnDeselect(BaseEventData eventData)
+    {
+        StartCoroutine(ValidateDeselect(eventData, false));
+    }
+
+    // My best attempt to imitate the code from MenuSelectable.ValidateDeselect
+    private IEnumerator ValidateDeselect(BaseEventData eventData, bool force)
+    {
+        if (DescriptionAnimator == null)
+        {
+            yield break;
+        }
+
+        GameObject? prevSelectedObject = EventSystem.current.currentSelectedGameObject;
+
+        yield return new WaitForEndOfFrame();
+
+        if (!(EventSystem.current.currentSelectedGameObject != null || force))
+        {
+            InputHandler ih = ManagerSingleton<InputHandler>.Instance;
+            if (ih && !ih.acceptingInput)
+            {
+                while (!ih.acceptingInput)
+                {
+                    yield return null;
+                }
+            }
+            yield return null;
+        }
+
+        if (EventSystem.current.currentSelectedGameObject != null || force)
+        {
+            DescriptionAnimator.ResetTrigger(MenuSelectable._showPropId);
+            DescriptionAnimator.SetTrigger(MenuSelectable._hidePropId);
+        }
+        else if (prevSelectedObject != null && prevSelectedObject.activeInHierarchy)
+        {
+            EventSystem.current.SetSelectedGameObject(prevSelectedObject);
+        }
+    }
+
+    public void OnSelect(BaseEventData eventData)
+    {
+        if (DescriptionAnimator == null)
+        {
+            return;
+        }
+
+        if (!_selectable.interactable)
+        {
+            return;
+        }
+
+        DescriptionAnimator.ResetTrigger(MenuSelectable._hidePropId);
+        DescriptionAnimator.SetTrigger(MenuSelectable._showPropId);
+    }
+
+    public void OnCancel(BaseEventData eventData)
+    {
+        StartCoroutine(ValidateDeselect(eventData, true));
+    }
+}