NavigationView not updating UIA users about changed selection and exp…

…and state (microsoft/microsoft-ui-xaml#2692)

ModernWpf.Controls/NavigationView/NavigationView.cs

@@ -813,6 +813,12 @@ internal void OnNavigationViewItemInvoked(NavigationViewItem nvi)
             if (updateSelection)
             {
                 var ip = GetIndexPathForContainer(nvi);
+
+                // Determine if we will update collapse/expand which will happen iff the item has children
+                if (DoesNavigationViewItemHaveChildren(nvi))
+                {
+                    m_shouldIgnoreUIASelectionRaiseAsExpandCollapseWillRaise = true;
+                }
                 UpdateSelectionModelSelection(ip);
             }
 
@@ -2133,6 +2139,31 @@ NavigationRecommendedTransitionDirection init()
                 UnselectPrevItem(prevItem, nextItem);
                 ChangeSelectStatusForItem(nextItem, true /*selected*/);
 
+                try
+                {
+                    // Selection changed and we need to notify UIA
+                    // HOWEVER expand collapse can also trigger if an item can expand/collapse
+                    // There are multiple cases when selection changes:
+                    // - Through click on item with no children -> No expand/collapse change
+                    // - Through click on item with children -> Expand/collapse change
+                    // - Through API with item without children -> No expand/collapse change
+                    // - Through API with item with children -> No expand/collapse change
+                    if (!m_shouldIgnoreUIASelectionRaiseAsExpandCollapseWillRaise)
+                    {
+                        if (FrameworkElementAutomationPeer.FromElement(this) is AutomationPeer peer)
+                        {
+                            var navViewItemPeer = (NavigationViewAutomationPeer)peer;
+                            navViewItemPeer.RaiseSelectionChangedEvent(
+                                prevItem, nextItem
+                            );
+                        }
+                    }
+                }
+                finally
+                {
+                    m_shouldIgnoreUIASelectionRaiseAsExpandCollapseWillRaise = false;
+                }
+
                 RaiseSelectionChangedEvent(nextItem, isSettingsItem, recommendedDirection);
                 AnimateSelectionChanged(nextItem);
 
@@ -5314,6 +5345,8 @@ protected override void OnDpiChanged(DpiScale oldDpi, DpiScale newDpi)
 
         bool m_moveTopNavOverflowItemOnFlyoutClose = false;
 
+        bool m_shouldIgnoreUIASelectionRaiseAsExpandCollapseWillRaise = false;
+
         FocusHelper m_leftNavRepeaterFocusHelper;
         FocusHelper m_topNavRepeaterFocusHelper;
 

ModernWpf.Controls/NavigationView/NavigationViewAutomationPeer.cs

@@ -42,5 +42,22 @@ public IRawElementProviderSimple[] GetSelection()
             }
             return new IRawElementProviderSimple[0];
         }
+
+        internal void RaiseSelectionChangedEvent(object oldSelection, object newSelecttion)
+        {
+            if (AutomationPeer.ListenerExists(AutomationEvents.SelectionPatternOnInvalidated))
+            {
+                if (Owner is NavigationView nv)
+                {
+                    if (nv.GetSelectedContainer() is { } nvi)
+                    {
+                        if (FrameworkElementAutomationPeer.CreatePeerForElement(nvi) is { } peer)
+                        {
+                            peer.RaiseAutomationEvent(AutomationEvents.SelectionItemPatternOnElementSelected);
+                        }
+                    }
+                }
+            }
+        }
     }
 }

ModernWpf.Controls/NavigationView/NavigationViewItem.cs

@@ -5,6 +5,7 @@
 using System.Collections.Specialized;
 using System.Diagnostics;
 using System.Windows;
+using System.Windows.Automation;
 using System.Windows.Automation.Peers;
 using System.Windows.Controls;
 using System.Windows.Input;
@@ -280,6 +281,19 @@ void SuggestedToolTipChanged(object newContent)
             m_suggestedToolTipContent = newToolTipContent;
         }
 
+        void OnIsExpandedPropertyChanged(DependencyPropertyChangedEventArgs args)
+        {
+            if (FrameworkElementAutomationPeer.FromElement(this) is AutomationPeer peer)
+            {
+                var navViewItemPeer = (NavigationViewItemAutomationPeer)peer;
+                navViewItemPeer.RaiseExpandCollapseAutomationEvent(
+                    IsExpanded ?
+                        ExpandCollapseState.Expanded :
+                        ExpandCollapseState.Collapsed
+                );
+            }
+        }
+
         void OnIconPropertyChanged(DependencyPropertyChangedEventArgs args)
         {
             UpdateVisualStateNoTransition();

ModernWpf.Controls/NavigationView/NavigationViewItem.properties.cs

@@ -88,12 +88,9 @@ public bool IsExpanded
 
         private static void OnIsExpandedPropertyChanged(DependencyObject sender, DependencyPropertyChangedEventArgs args)
         {
-            ((NavigationViewItem)sender).OnIsExpandedPropertyChanged(args);
-        }
-
-        private void OnIsExpandedPropertyChanged(DependencyPropertyChangedEventArgs args)
-        {
-            IsExpandedChanged?.Invoke(this, args.Property);
+            var owner = (NavigationViewItem)sender;
+            owner.OnIsExpandedPropertyChanged(args);
+            owner.IsExpandedChanged?.Invoke(owner, args.Property);
         }
 
         #endregion

ModernWpf.Controls/NavigationView/NavigationViewItemAutomationPeer.cs

@@ -181,7 +181,7 @@ void IExpandCollapseProvider.Expand()
             }
         }
 
-        void RaiseExpandCollapseAutomationEvent(ExpandCollapseState newState)
+        internal void RaiseExpandCollapseAutomationEvent(ExpandCollapseState newState)
         {
             if (AutomationPeer.ListenerExists(AutomationEvents.PropertyChanged))
             {