FIX: Fixed exceptions being thrown by OnScreenStick and improved warnings related to missing UGUI dependencies for current implementations.

Packages/com.unity.inputsystem/CHANGELOG.md

@@ -10,6 +10,9 @@ however, it has to be formatted properly to pass verification tests.
 
 ## [Unreleased] - yyyy-mm-dd
 
+### Change
+- Added warning messages to both `OnScreenStick` and `OnScreenButton` Inspector editors that would display a warning message in case on-screen control components are added to a `GameObject` not part of a valid UI hierarchy.
+
 ### Fixed
 - Avoid potential crashes from `NullReferenceException` in `FireStateChangeNotifications`.
 - Fixed an issue where a composite binding would not be consecutively triggered after ResetDevice() has been called from the associated action handler [ISXB-746](https://issuetracker.unity3d.com/product/unity/issues/guid/ISXB-746).
@@ -19,8 +22,10 @@ however, it has to be formatted properly to pass verification tests.
 - Fixed error thrown when Cancelling Control Scheme creation in Input Actions Editor.
 - Fixed Scheme Name in Control Scheme editor menu that gets reset when editing devices [ISXB-763](https://issuetracker.unity3d.com/product/unity/issues/guid/ISXB-763).
 - Fixed an issue where `InputActionAsset.FindAction(string, bool)` would throw `System.NullReferenceException` instead of returning `null` if searching for a non-existent action with an explicit action path and using `throwIfNotFound: false`, e.g. searching for "Map/Action" when `InputActionMap` "Map" exists but no `InputAction` named "Action" exists within that map [ISXB-895](https://issuetracker.unity3d.com/product/unity/issues/guid/ISXB-895).
+- Fixed an issue where adding a `OnScreenButton` or `OnScreenStick` to a regular GameObject would lead to exception in editor.
+- Fixed an issue where adding a `OnScreenStick` to a regular GameObject and entering play-mode would lead to exceptions being generated.
 
-## Added
+### Added
 - Added additional device information when logging the error due to exceeding the maximum number of events processed
   set by `InputSystem.settings.maxEventsBytesPerUpdate`. This additional information is available in development builds
   only.

Packages/com.unity.inputsystem/InputSystem/Plugins/OnScreen/OnScreenButton.cs

@@ -1,5 +1,4 @@
 #if PACKAGE_DOCS_GENERATION || UNITY_INPUT_SYSTEM_ENABLE_UI
-using System;
 using UnityEngine.EventSystems;
 using UnityEngine.InputSystem.Layouts;
 
@@ -45,6 +44,29 @@ protected override string controlPathInternal
             get => m_ControlPath;
             set => m_ControlPath = value;
         }
+
+#if UNITY_EDITOR
+        [UnityEditor.CustomEditor(typeof(OnScreenButton))]
+        internal class OnScreenButtonEditor : UnityEditor.Editor
+        {
+            private UnityEditor.SerializedProperty m_ControlPathInternal;
+
+            public void OnEnable()
+            {
+                m_ControlPathInternal = serializedObject.FindProperty(nameof(OnScreenButton.m_ControlPath));
+            }
+
+            public override void OnInspectorGUI()
+            {
+                // Current implementation has UGUI dependencies (ISXB-915, ISXB-916)
+                UGUIOnScreenControlEditorUtils.ShowWarningIfNotPartOfCanvasHierarchy((OnScreenButton)target);
+
+                UnityEditor.EditorGUILayout.PropertyField(m_ControlPathInternal);
+
+                serializedObject.ApplyModifiedProperties();
+            }
+        }
+#endif
     }
 }
 #endif

Packages/com.unity.inputsystem/InputSystem/Plugins/OnScreen/OnScreenControl.cs

@@ -299,5 +299,30 @@ public void Destroy()
         }
 
         private static InlinedArray<OnScreenDeviceInfo> s_OnScreenDevices;
+
+        internal string GetWarningMessage()
+        {
+            return $"{GetType()} needs to be attached as a child to a UI Canvas and have a RectTransform component to function properly.";
+        }
+    }
+
+    internal static class UGUIOnScreenControlUtils
+    {
+        public static RectTransform GetCanvasRectTransform(Transform transform)
+        {
+            var parentTransform = transform.parent;
+            return parentTransform != null ? transform.parent.GetComponentInParent<RectTransform>() : null;
+        }
+    }
+
+#if UNITY_EDITOR
+    internal static class UGUIOnScreenControlEditorUtils
+    {
+        public static void ShowWarningIfNotPartOfCanvasHierarchy(OnScreenControl target)
+        {
+            if (UGUIOnScreenControlUtils.GetCanvasRectTransform(target.transform) == null)
+                UnityEditor.EditorGUILayout.HelpBox(target.GetWarningMessage(), UnityEditor.MessageType.Warning);
+        }
     }
+#endif
 }

Packages/com.unity.inputsystem/InputSystem/Plugins/OnScreen/OnScreenStick.cs

@@ -112,9 +112,14 @@ private void Start()
                 m_PointerMoveAction.Enable();
             }
 
+            // Unable to setup elements according to settings if a RectTransform is not available (ISXB-915, ISXB-916).
+            if (!(transform is RectTransform))
+                return;
+
             m_StartPos = ((RectTransform)transform).anchoredPosition;
 
             if (m_Behaviour != Behaviour.ExactPositionWithDynamicOrigin) return;
+
             m_PointerDownPos = m_StartPos;
 
             var dynamicOrigin = new GameObject(kDynamicOriginClickable, typeof(Image));
@@ -132,38 +137,39 @@ private void Start()
 
         private void BeginInteraction(Vector2 pointerPosition, Camera uiCamera)
         {
-            var canvasRect = transform.parent?.GetComponentInParent<RectTransform>();
-            if (canvasRect == null)
+            var canvasRectTransform = UGUIOnScreenControlUtils.GetCanvasRectTransform(transform);
+            if (canvasRectTransform == null)
             {
-                Debug.LogError("OnScreenStick needs to be attached as a child to a UI Canvas to function properly.");
+                Debug.LogError(GetWarningMessage());
                 return;
             }
 
             switch (m_Behaviour)
             {
                 case Behaviour.RelativePositionWithStaticOrigin:
-                    RectTransformUtility.ScreenPointToLocalPointInRectangle(canvasRect, pointerPosition, uiCamera, out m_PointerDownPos);
+                    RectTransformUtility.ScreenPointToLocalPointInRectangle(canvasRectTransform, pointerPosition, uiCamera, out m_PointerDownPos);
                     break;
                 case Behaviour.ExactPositionWithStaticOrigin:
-                    RectTransformUtility.ScreenPointToLocalPointInRectangle(canvasRect, pointerPosition, uiCamera, out m_PointerDownPos);
+                    RectTransformUtility.ScreenPointToLocalPointInRectangle(canvasRectTransform, pointerPosition, uiCamera, out m_PointerDownPos);
                     MoveStick(pointerPosition, uiCamera);
                     break;
                 case Behaviour.ExactPositionWithDynamicOrigin:
-                    RectTransformUtility.ScreenPointToLocalPointInRectangle(canvasRect, pointerPosition, uiCamera, out var pointerDown);
+                    RectTransformUtility.ScreenPointToLocalPointInRectangle(canvasRectTransform, pointerPosition, uiCamera, out var pointerDown);
                     m_PointerDownPos = ((RectTransform)transform).anchoredPosition = pointerDown;
                     break;
             }
         }
 
         private void MoveStick(Vector2 pointerPosition, Camera uiCamera)
         {
-            var canvasRect = transform.parent?.GetComponentInParent<RectTransform>();
-            if (canvasRect == null)
+            var canvasRectTransform = UGUIOnScreenControlUtils.GetCanvasRectTransform(transform);
+            if (canvasRectTransform == null)
             {
-                Debug.LogError("OnScreenStick needs to be attached as a child to a UI Canvas to function properly.");
+                Debug.LogError(GetWarningMessage());
                 return;
             }
-            RectTransformUtility.ScreenPointToLocalPointInRectangle(canvasRect, pointerPosition, uiCamera, out var position);
+
+            RectTransformUtility.ScreenPointToLocalPointInRectangle(canvasRectTransform, pointerPosition, uiCamera, out var position);
             var delta = position - m_PointerDownPos;
 
             switch (m_Behaviour)
@@ -253,9 +259,14 @@ private Camera GetCameraFromCanvas()
 
         private void OnDrawGizmosSelected()
         {
-            Gizmos.matrix = ((RectTransform)transform.parent).localToWorldMatrix;
+            // This will not produce meaningful results unless we have a rect transform (ISXB-915, ISXB-916).
+            var parentRectTransform = transform.parent as RectTransform;
+            if (parentRectTransform == null)
+                return;
+
+            Gizmos.matrix = parentRectTransform.localToWorldMatrix;
 
-            var startPos = ((RectTransform)transform).anchoredPosition;
+            var startPos = parentRectTransform.anchoredPosition;
             if (Application.isPlaying)
                 startPos = m_StartPos;
 
@@ -457,6 +468,9 @@ public void OnEnable()
 
             public override void OnInspectorGUI()
             {
+                // Current implementation has UGUI dependencies (ISXB-915, ISXB-916)
+                UGUIOnScreenControlEditorUtils.ShowWarningIfNotPartOfCanvasHierarchy((OnScreenStick)target);
+
                 EditorGUILayout.PropertyField(m_MovementRange);
                 EditorGUILayout.PropertyField(m_ControlPathInternal);
                 EditorGUILayout.PropertyField(m_Behaviour);