Added GenerateMask to AssetsHelpers;

Editor/AssetsHelpers/BaseClasses/OutputOptionVisualProvider.cs

@@ -0,0 +1,29 @@
+using UnityEngine.UIElements;
+
+namespace Misaki.ArtToolEditor
+{
+    public class OptionsVisualProvider
+    {
+        public object dataSource;
+
+        internal virtual VisualElement ContentOnTop()
+        {
+            return null;
+        }
+
+        internal virtual VisualElement ContentAfterList()
+        {
+            return null;
+        }
+
+        internal virtual VisualElement ContentBeforeButton()
+        {
+            return null;
+        }
+
+        internal virtual VisualElement ContentOnBottom()
+        {
+            return null;
+        }
+    }
+}

Editor/AssetsHelpers/BaseClasses/OutputOptionVisualProvider.cs.meta

@@ -0,0 +1,2 @@
+fileFormatVersion: 2
+guid: 2e57d7629d0768349be0c97c5e07dffe