Implement copy and paste property

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Editor/CopyAndPasteProperty.cs

@@ -0,0 +1,66 @@
+#if UNITY_2019_3_OR_NEWER
+using UnityEditor;
+using UnityEngine;
+
+namespace MackySoft.SerializeReferenceExtensions.Editor
+{
+	public static class CopyAndPasteProperty
+	{
+
+		const string kCopiedPropertyPathKey = "SerializeReferenceExtensions.CopiedPropertyPath";
+		const string kClipboardKey = "SerializeReferenceExtensions.CopyAndPasteProperty";
+
+		static readonly GUIContent kPasteContent = new GUIContent("Paste Property");
+
+		[InitializeOnLoadMethod]
+		static void Initialize ()
+		{
+			EditorApplication.contextualPropertyMenu += OnContextualPropertyMenu;
+		}
+
+		static void OnContextualPropertyMenu (GenericMenu menu, SerializedProperty property)
+		{
+			if (property.propertyType == SerializedPropertyType.ManagedReference)
+			{
+				// NOTE: When the callback function is called, the SerializedProperty is rewritten to the property that was being moused over at the time,
+				// so a new SerializedProperty instance must be created.
+				SerializedProperty clonedProperty = property.Copy();
+
+				menu.AddItem(new GUIContent($"Copy \"{property.propertyPath}\" property"), false, Copy, clonedProperty);
+
+				string copiedPropertyPath = SessionState.GetString(kCopiedPropertyPathKey, string.Empty);
+				if (!string.IsNullOrEmpty(copiedPropertyPath))
+				{
+					menu.AddItem(new GUIContent($"Paste \"{copiedPropertyPath}\" property"), false, Paste, clonedProperty);
+				}
+				else
+				{
+					menu.AddDisabledItem(kPasteContent);
+				}
+			}
+		}
+
+		static void Copy (object customData)
+		{
+			SerializedProperty property = (SerializedProperty)customData;
+			string json = JsonUtility.ToJson(property.managedReferenceValue);
+			SessionState.SetString(kCopiedPropertyPathKey, property.propertyPath);
+			SessionState.SetString(kClipboardKey, json);
+		}
+
+		static void Paste (object customData)
+		{
+			SerializedProperty property = (SerializedProperty)customData;
+			string json = SessionState.GetString(kClipboardKey, string.Empty);
+			if (string.IsNullOrEmpty(json))
+			{
+				return;
+			}
+
+			Undo.RecordObject(property.serializedObject.targetObject, "Paste Property");
+			JsonUtility.FromJsonOverwrite(json, property.managedReferenceValue);
+			property.serializedObject.ApplyModifiedProperties();
+		}
+	}
+}
+#endif