feat: Started setting GUI.changed to true when a different type is chosen in the dropdown so that one can register for 'value changed' events

Author: SolidAlloy

Editor/Drawers/TypeReferencePropertyDrawer.cs

@@ -1,5 +1,6 @@
 namespace TypeReferences.Editor.Drawers
 {
+    using System.Collections.Generic;
     using TypeReferences;
     using UnityEditor;
     using UnityEngine;
@@ -14,6 +15,8 @@ namespace TypeReferences.Editor.Drawers
     [CustomPropertyDrawer(typeof(TypeOptionsAttribute), true)]
     public class TypeReferencePropertyDrawer : PropertyDrawer
     {
+        private static readonly Dictionary<(SerializedObject serializedObject, string path), string> _valuesCache = new Dictionary<(SerializedObject serializedObject, string path), string>();
+
         public override float GetPropertyHeight(SerializedProperty property, GUIContent label)
         {
             return EditorStyles.popup.CalcHeight(GUIContent.none, 0f);
@@ -48,6 +51,13 @@ private void DrawTypeReferenceField(Rect position, SerializedProperty property)
                 serializedTypeRef.TypeNameAndAssembly = string.Empty;
             }
 
+            // This is needed for the 'value changed' event to propagate up, so that if someones subscribes to
+            // value changed events through UI Elements, they will receive a notification.
+            // We can determine that the value changed only by comparing it with the previous value because the dropdown
+            // opens a new window and when the type is changed, the focus is on the window, not on this property drawer.
+            if (!PreviousCurrentValuesEqual(serializedTypeRef.TypeNameProperty))
+                GUI.changed = true;
+
             var dropdownDrawer = new TypeDropdownDrawer(selectedType, typeOptionsAttribute, fieldInfo?.DeclaringType);
 
             var fieldDrawer = new TypeFieldDrawer(
@@ -58,5 +68,24 @@ private void DrawTypeReferenceField(Rect position, SerializedProperty property)
 
             fieldDrawer.Draw();
         }
+        
+        private static bool PreviousCurrentValuesEqual(SerializedProperty typeNameProperty)
+        {
+            var key = (typeNameProperty.serializedObject, typeNameProperty.propertyPath);
+            
+            if (_valuesCache.TryGetValue(key, out string previousValue))
+            {
+                if (typeNameProperty.stringValue == previousValue)
+                {
+                    return true;
+                }
+
+                _valuesCache[key] = typeNameProperty.stringValue;
+                return false;
+            }
+
+            _valuesCache.Add(key, typeNameProperty.stringValue);
+            return true;
+        }
     }
 }

Editor/Util/SerializedTypeReference.cs

@@ -10,15 +10,15 @@
     /// </summary>
     internal readonly struct SerializedTypeReference
     {
+        public readonly SerializedProperty TypeNameProperty;
         private readonly SerializedObject _parentObject;
-        private readonly SerializedProperty _typeNameProperty;
         private readonly SerializedProperty _guidProperty;
         private readonly SerializedProperty _guidAssignmentFailedProperty;
 
         public SerializedTypeReference(SerializedProperty typeReferenceProperty)
         {
             _parentObject = typeReferenceProperty.serializedObject;
-            _typeNameProperty = typeReferenceProperty.FindPropertyRelative(nameof(TypeReference._typeNameAndAssembly));
+            TypeNameProperty = typeReferenceProperty.FindPropertyRelative(nameof(TypeReference._typeNameAndAssembly));
             _guidProperty = typeReferenceProperty.FindPropertyRelative(nameof(TypeReference.GUID));
             _guidAssignmentFailedProperty = typeReferenceProperty.FindPropertyRelative(nameof(TypeReference.GuidAssignmentFailed));
 
@@ -27,11 +27,11 @@ public SerializedTypeReference(SerializedProperty typeReferenceProperty)
 
         public string TypeNameAndAssembly
         {
-            get => _typeNameProperty.stringValue;
+            get => TypeNameProperty.stringValue;
             set => SetTypeNameAndAssembly(value);
         }
 
-        public bool TypeNameHasMultipleDifferentValues => _typeNameProperty.hasMultipleDifferentValues;
+        public bool TypeNameHasMultipleDifferentValues => TypeNameProperty.hasMultipleDifferentValues;
 
         private bool GuidAssignmentFailed
         {
@@ -47,14 +47,14 @@ private bool GuidAssignmentFailed
             Justification = "The method is used by TypeFieldDrawer in C# 7")]
         public void SetTypeNameAndAssembly(string value)
         {
-            _typeNameProperty.stringValue = value;
+            TypeNameProperty.stringValue = value;
             _guidProperty.stringValue = GetClassGuidFromTypeName(value);
             _parentObject.ApplyModifiedProperties();
         }
 
         public void SetType(Type type)
         {
-            _typeNameProperty.stringValue = TypeReference.GetTypeNameAndAssembly(type);
+            TypeNameProperty.stringValue = TypeReference.GetTypeNameAndAssembly(type);
             _guidProperty.stringValue = TypeReference.GetClassGUID(type);
             _parentObject.ApplyModifiedProperties();
         }