Simplified the accessibility hierarchy

Author: Bianca Marina Stana

Assets/Scripts/Screen Reader/AccessibilityManager.cs

@@ -362,11 +362,7 @@ static void RemoveSubHierarchyForService(AccessibilityService service)
 
         static void CreateSubHierarchyForService(AccessibilityService service)
         {
-            var rootNode = hierarchy.AddNode(service.serviceName);
-            rootNode.role = AccessibilityRole.Container;
-            rootNode.isActive = Application.platform == RuntimePlatform.OSXPlayer; // false;
-
-            service.hierarchy = new AccessibilitySubHierarchy(hierarchy, rootNode);
+            service.hierarchy = new AccessibilitySubHierarchy(hierarchy);
         }
 
         static void GenerateSubHierarchyForService(Scene scene, AccessibilityService service)

Assets/Scripts/Screen Reader/AccessibilitySubHierarchy.cs

@@ -1,3 +1,4 @@
+using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.Accessibility;
 
@@ -17,7 +18,7 @@ public struct AccessibilitySubHierarchy
         /// <summary>
         /// Returns the node used as root for this sub-hierarchy.
         /// </summary>
-        public AccessibilityNode rootNode { get; private set; }
+        public List<AccessibilityNode> rootNodes { get; private set; }
 
         /// <summary>
         /// Returns true if this sub-hierarchy is valid.
@@ -27,39 +28,31 @@ public struct AccessibilitySubHierarchy
         /// <summary>
         /// Constructs a sub-hierarchy from the specified hierarchy and root node.
         /// </summary>
-        /// <param name="mainHierarchy"></param>
-        /// <param name="rootNode"></param>
-        public AccessibilitySubHierarchy(AccessibilityHierarchy mainHierarchy, AccessibilityNode rootNode)
+        /// <param name="hierarchy"></param>
+        public AccessibilitySubHierarchy(AccessibilityHierarchy hierarchy)
         {
-            // Assert that the main hierarchy exists.
-            if (mainHierarchy == null)
-            {
-                throw new System.ArgumentNullException(nameof(mainHierarchy), "The main hierarchy cannot be null.");
-            }
-
-            // Assert that the root node belongs to the main hierarchy.
-            if (rootNode != null && !mainHierarchy.ContainsNode(rootNode))
-            {
-                throw new System.ArgumentException("The root node must belong to the main hierarchy.", nameof(rootNode));
-            }
-
-            // Note: if the root element is null then the sub-hierarchy represents the whole hierarchy.
-            this.mainHierarchy = mainHierarchy;
-            this.rootNode = rootNode;
+            mainHierarchy = hierarchy ?? throw new System.ArgumentNullException(nameof(hierarchy), "The main hierarchy cannot be null.");
+            rootNodes = new List<AccessibilityNode>();
         }
 
         /// <summary>
         /// Disposes the sub-hierarchy removing the root node from the main hierarchy.
         /// </summary>
         public void Dispose()
         {
-            if (mainHierarchy != null && rootNode != null && mainHierarchy.ContainsNode(rootNode))
+            if (mainHierarchy != null)
             {
-                mainHierarchy.RemoveNode(rootNode);
+                foreach (var rootNode in rootNodes)
+                {
+                    if (mainHierarchy.ContainsNode(rootNode))
+                    {
+                        mainHierarchy.RemoveNode(rootNode);
+                    }
+                }
             }
 
             mainHierarchy = null;
-            rootNode = null;
+            rootNodes?.Clear();
         }
 
         /// <summary>
@@ -80,16 +73,16 @@ public bool ContainsNode(AccessibilityNode node)
             }
 
             // We know the node is in the main hierarchy, now we need to check if it's part of this sub-hierarchy.
-            var parentNode = node.parent;
+            var currentNode = node;
 
-            while (parentNode != null)
+            while (currentNode != null)
             {
-                if (parentNode == rootNode)
+                if (rootNodes.Contains(currentNode))
                 {
                     return true;
                 }
 
-                parentNode = parentNode.parent;
+                currentNode = currentNode.parent;
             }
 
             return false;
@@ -159,9 +152,14 @@ public AccessibilityNode InsertNode(int childIndex, string label = null, Accessi
                 return null;
             }
 
-            var actualParent = parent ?? rootNode;
+            var node = mainHierarchy.InsertNode(childIndex, label, parent);
+
+            if (parent == null)
+            {
+                rootNodes.Add(node);
+            }
 
-            return mainHierarchy.AddNode(label, actualParent);
+            return node;
         }
 
         /// <summary>
@@ -178,9 +176,7 @@ public bool MoveNode(AccessibilityNode node, AccessibilityNode newParent, int ne
                 return false;
             }
 
-            var actualParent = newParent ?? rootNode;
-
-            return mainHierarchy.MoveNode(node, actualParent, newChildIndex);
+            return mainHierarchy.MoveNode(node, newParent, newChildIndex);
         }
 
         /// <summary>
@@ -203,12 +199,12 @@ public void RemoveNode(AccessibilityNode node, bool removeChildren = true)
         /// </summary>
         public void Clear()
         {
-            if (rootNode != null)
+            if (rootNodes is { Count: > 0 })
             {
                 // Removes from the last to the first to avoid messing up the indices.
-                for (var i = rootNode.children.Count - 1; i >= 0; i--)
+                for (var i = rootNodes.Count - 1; i >= 0; i--)
                 {
-                    mainHierarchy.RemoveNode(rootNode.children[i]);
+                    mainHierarchy.RemoveNode(rootNodes[i]);
                 }
             }
             else

Assets/Scripts/Screen Reader/UITk/UITkAccessibilityService.cs

@@ -27,51 +27,8 @@ public UITkAccessibilityService() : base("UITk", 100)
             AssistiveSupport.nodeFocusChanged += OnNodeFocusChanged;
         }
 
-        bool m_NeedsToRecomputeRootFrames;
-
-        public void DirtyRootFrames()
-        {
-            m_NeedsToRecomputeRootFrames = true;
-        }
-
-        public void UpdateRootAndPanelFrames()
-        {
-            m_NeedsToRecomputeRootFrames = true;
-
-            foreach (var accessibilityUpdater in m_AccessibilityUpdaters)
-            {
-                accessibilityUpdater.UpdateRootFrame();
-            }
-
-            var serviceRootFrame = Rect.zero;
-
-            foreach (var panelNode in hierarchy.rootNode.children)
-            {
-                // Calculate the union of all root nodes frames.
-                if (panelNode.frame.size != Vector2.zero)
-                {
-                    Encompass(ref serviceRootFrame, panelNode.frame);
-                }
-            }
-
-            hierarchy.rootNode.frame = serviceRootFrame;
-            void Encompass(ref Rect a, Rect b)
-            {
-                a.xMin = Math.Min(a.xMin, b.xMin);
-                a.yMin = Math.Min(a.yMin, b.yMin);
-                a.xMax = Math.Max(a.xMax, b.xMax);
-                a.yMax = Math.Max(a.yMax, b.yMax);
-            }
-        }
-
         public override void Update()
         {
-            if (m_NeedsToRecomputeRootFrames)
-            {
-                UpdateRootAndPanelFrames();
-                m_NeedsToRecomputeRootFrames = false;
-            }
-
             foreach (var accessibilityUpdater in m_AccessibilityUpdaters)
             {
                 accessibilityUpdater.Update();
@@ -172,11 +129,6 @@ public override void SetUp(Scene scene)
                 }
 
                 var panel = uiDocument.runtimePanel;
-                var rootAcc = uiDocument.rootVisualElement.GetOrCreateAccessibleProperties();
-
-                rootAcc.label = uiDocument.rootVisualElement.name;
-                rootAcc.active = Application.platform == RuntimePlatform.OSXPlayer; // false;
-                rootAcc.role = AccessibilityRole.Container;
 
                 if (!panels.Contains(panel))
                 {

Assets/Scripts/Screen Reader/UITk/VisualTreeAccessibilityUpdater.cs

@@ -34,24 +34,11 @@ enum NotificationType
         VisualElement m_VisualTree;
         IVisualElementScheduledItem m_UpdateJob;
         UITkAccessibilityService m_AccessibilityService;
-        AccessibilitySubHierarchy m_SubHierarchy;
 
         /// <summary>
         /// The sub-hierarchy this updater is managing.
         /// </summary>
-        public AccessibilitySubHierarchy hierarchy
-        {
-            get => m_SubHierarchy;
-            set
-            {
-                m_SubHierarchy = value;
-
-                if (m_SubHierarchy.isValid && visualTree != null)
-                {
-                    DirtyRootFrame();
-                }
-            }
-        }
+        public AccessibilitySubHierarchy hierarchy { get; set; }
 
         /// <summary>
         /// The panel of the visual tree being managed.
@@ -111,14 +98,10 @@ public VisualTreeAccessibilityUpdater(IPanel panel, VisualElement visualTree, UI
             m_AccessibilityService = service;
             visualTree.RegisterCallback<AttachToPanelEvent>(OnAttachmentToPanel);
             visualTree.RegisterCallback<GeometryChangedEvent>(OnGeometryChanged);
-
-            DirtyRootFrame();
         }
 
         void OnGeometryChanged(GeometryChangedEvent evt)
         {
-            DirtyRootFrame();
-
             // OnScreenDebug.Log("OnGeometryChanged " + evt.target);
 
             OnVersionChanged(evt.target as VisualElement, VersionChangeType.Size | VersionChangeType.Transform);
@@ -187,11 +170,10 @@ VisualElementAccessibilityHandler CreateHandler(VisualElement element)
 
         void InsertNode(VisualElementAccessibilityHandler parentHandler, VisualElementAccessibilityHandler accHandler)
         {
-            var p = parentHandler;
-            var parentNode = p?.node;
+            var parentNode = parentHandler?.node;
 
             // Keep track of insertion index for each parent node.
-            var index = p?.nextInsertionIndex ?? m_RootNextInsertionIndex;
+            var index = parentHandler?.nextInsertionIndex ?? m_RootNextInsertionIndex;
             var node = hierarchy.InsertNode(index, accHandler.ownerElement.name, parentNode);
 
             accHandler.node = node;
@@ -202,9 +184,9 @@ void InsertNode(VisualElementAccessibilityHandler parentHandler, VisualElementAc
 
             m_HandlersForNodes[node] = accHandler;
 
-            if (p != null)
+            if (parentHandler != null)
             {
-                p.nextInsertionIndex++;
+                parentHandler.nextInsertionIndex++;
             }
             else
             {
@@ -216,14 +198,13 @@ void InsertNode(VisualElementAccessibilityHandler parentHandler, VisualElementAc
 
         bool MoveNode(VisualElementAccessibilityHandler parentElement, VisualElementAccessibilityHandler accHandler)
         {
-            var p = parentElement;
-            var parentNode = p?.node;
-            var index = p?.nextInsertionIndex ?? m_RootNextInsertionIndex;
+            var parentNode = parentElement?.node;
+            var index = parentElement?.nextInsertionIndex ?? m_RootNextInsertionIndex;
             var moved = hierarchy.MoveNode(accHandler.node, parentNode, index);
 
-            if (p != null)
+            if (parentElement != null)
             {
-                p.nextInsertionIndex++;
+                parentElement.nextInsertionIndex++;
             }
             else
             {
@@ -431,19 +412,6 @@ void GetMinMaxY(Vector3[] vector, out float min, out float max)
             }
         }
 
-        void DirtyRootFrame()
-        {
-            m_AccessibilityService.DirtyRootFrames();
-        }
-
-        public void UpdateRootFrame()
-        {
-            if (hierarchy.isValid)
-            {
-                hierarchy.rootNode.frame = GetScreenPosition(visualTree);
-            }
-        }
-
         void UpdateNode(VisualElementAccessibilityHandler accElement)
         {
             if (!IsNodeValid(accElement.node))
@@ -528,30 +496,9 @@ public void Update()
             Update(visualTree);
         }
 
-        string GetPanelName(VisualElement ve)
-        {
-            // Try to get the name of the panel using reflection.
-            var panel = ve.panel;
-
-            if (panel == null)
-            {
-                return null;
-            }
-
-            var panelType = panel.GetType();
-            var nameProperty = panelType.GetProperty("name");
-
-            if (nameProperty != null)
-            {
-                return nameProperty.GetValue(panel, null) as string;
-            }
-
-            return null;
-        }
-
         NotificationType m_Notification = NotificationType.None;
 
-        void Update(VisualElement visualTree)
+        void Update(VisualElement ve)
         {
             var shouldSendNotification = false;
 
@@ -563,13 +510,8 @@ void Update(VisualElement visualTree)
             {
                 if (!hierarchy.isValid)
                 {
-                    var panelName = GetPanelName(visualTree);
-                    var rootNode = m_AccessibilityService.hierarchy.AddNode(string.IsNullOrEmpty(panelName) ?
-                        visualTree.name : panelName);
-                    rootNode.role = AccessibilityRole.Container;
-                    rootNode.isActive = Application.platform == RuntimePlatform.OSXPlayer;
-                    hierarchy = new AccessibilitySubHierarchy(m_AccessibilityService.hierarchy.mainHierarchy, rootNode);
-                    DirtyRootFrame();
+                    hierarchy = new AccessibilitySubHierarchy(m_AccessibilityService.hierarchy.mainHierarchy);
+
                     shouldSendNotification = true;
                 }
 
@@ -580,24 +522,24 @@ void Update(VisualElement visualTree)
 
                 var modalElement = currentModalElement;
 
-                UpdateAccessibilityHierarchyRecursively(visualTree, null, false, true);
+                UpdateAccessibilityHierarchyRecursively(ve, null, false, true);
 
                 // If there is a current modal element or if the current model element has changed then update the
                 // active state of all nodes.
                 if (currentModalElement != null || currentModalElement != modalElement)
                 {
                     OnScreenDebug.Log("Updating active state from modality " + currentModalElement?.name);
-                    UpdateActiveStateFromModalityRecursively(visualTree);
+                    UpdateActiveStateFromModalityRecursively(ve);
                 }
             }
 
             if (shouldSendNotification || m_Notification.HasFlag(NotificationType.ScreenChanged))
             {
-                visualTree.schedule.Execute(() => AssistiveSupport.notificationDispatcher.SendScreenChanged());
+                ve.schedule.Execute(() => AssistiveSupport.notificationDispatcher.SendScreenChanged());
             }
             else if (m_Notification.HasFlag(NotificationType.LayoutChanged))
             {
-                visualTree.schedule.Execute(() => AssistiveSupport.notificationDispatcher.SendLayoutChanged());
+                ve.schedule.Execute(() => AssistiveSupport.notificationDispatcher.SendLayoutChanged());
             }
         }