Refresh active gui using callbacks instead of time schedule

Author: josepmariapujol-unity

Packages/com.unity.inputsystem/InputSystem/Editor/InputAssetEditorUtils.cs

@@ -83,23 +83,20 @@ internal static T CreateAsset<T>(T asset, string relativePath) where T : Scripta
             return asset;
         }
 
-        public static VisualElement CreateMakeActiveGui<T>(Func<T> getCurrent, T target, string targetName, string entity, Action<T> apply, bool allowAssignActive = true)
+        public static VisualElement CreateMakeActiveGui<T>(Func<T> getCurrent, T target, string targetName, string entity,
+            Action<T> apply, Action<Action> subscribeToChanges, Action<Action> unsubscribeFromChanges,
+            bool allowAssignActive = true)
             where T : ScriptableObject
         {
             var container = new VisualElement();
-            var lastKnownCurrent = getCurrent();
-            PopulateMakeActiveGui(container, lastKnownCurrent, target, entity, apply, allowAssignActive);
 
-            // Poll for external changes to the active asset (e.g. from Project Settings or Undo).
-            // The scheduled item is automatically stopped when the element leaves the panel.
-            container.schedule.Execute(() =>
-            {
-                var current = getCurrent();
-                if (current == lastKnownCurrent)
-                    return;
-                lastKnownCurrent = current;
-                PopulateMakeActiveGui(container, current, target, entity, apply, allowAssignActive);
-            }).Every(500);
+            void Refresh() => PopulateMakeActiveGui(container, getCurrent(), target, entity, apply, allowAssignActive);
+
+            Refresh();
+
+            // Subscribe for as long as the element is part of a panel, matching the pattern used in InputParameterEditor.
+            container.RegisterCallback<AttachToPanelEvent>(_ => subscribeToChanges(Refresh));
+            container.RegisterCallback<DetachFromPanelEvent>(_ => unsubscribeFromChanges(Refresh));
 
             return container;
         }

Packages/com.unity.inputsystem/InputSystem/Editor/Settings/InputSettingsProvider.cs

@@ -500,8 +500,23 @@ public override VisualElement CreateInspectorGUI()
             };
             root.Add(openButton);
 
-            root.Add(InputAssetEditorUtils.CreateMakeActiveGui(() => InputSystem.settings, target as InputSettings,
-                target.name, "settings", (value) => InputSystem.settings = value));
+            // UndoRedoCallback is void(), not Action, so an adapter is required.
+            // The variable is shared between the two lambdas so the same instance is removed on unsubscribe.
+            Undo.UndoRedoCallback undoRedoAdapter = null;
+            root.Add(InputAssetEditorUtils.CreateMakeActiveGui(
+                () => InputSystem.settings, target as InputSettings,
+                target.name, "settings", (value) => InputSystem.settings = value,
+                handler =>
+                {
+                    InputSystem.onSettingsChange += handler;
+                    undoRedoAdapter = () => handler();
+                    Undo.undoRedoPerformed += undoRedoAdapter;
+                },
+                handler =>
+                {
+                    InputSystem.onSettingsChange -= handler;
+                    Undo.undoRedoPerformed -= undoRedoAdapter;
+                }));
 
             return root;
         }