Exploring using IVsHierarchyItem as basis for new DTE

Author: madskristensen

src/Community.VisualStudio.Toolkit.Shared/Events/SelectionEvents.cs

@@ -23,15 +23,26 @@ internal SelectionEvents()
         /// Fires when the selection changes
         /// </summary>
         public event EventHandler<SelectionChangedEventArgs>? SelectionChanged;
-        
+
         /// <summary>
         /// Fires when the UI Context changes.
         /// </summary>
-        public event EventHandler<UIContextChangedEventArgs>? UIContextChanged; 
+        public event EventHandler<UIContextChangedEventArgs>? UIContextChanged;
 
         int IVsSelectionEvents.OnSelectionChanged(IVsHierarchy pHierOld, uint itemidOld, IVsMultiItemSelect pMISOld, ISelectionContainer pSCOld, IVsHierarchy pHierNew, uint itemidNew, IVsMultiItemSelect pMISNew, ISelectionContainer pSCNew)
         {
-            SelectionChanged?.Invoke(this, new SelectionChangedEventArgs(pHierOld, pHierNew));
+            ThreadHelper.ThrowIfNotOnUIThread();
+
+            ThreadHelper.JoinableTaskFactory.RunAsync(async delegate
+            {
+                await ThreadHelper.JoinableTaskFactory.SwitchToMainThreadAsync();
+
+                IVsHierarchyItem? from = await pHierOld.ToHierarcyItemAsync(itemidOld);
+                IVsHierarchyItem? to = await pHierNew.ToHierarcyItemAsync(itemidNew);
+
+                SelectionChanged?.Invoke(this, new SelectionChangedEventArgs(from, to));
+            }).FireAndForget();
+
             return VSConstants.S_OK;
         }
 
@@ -55,7 +66,7 @@ public class SelectionChangedEventArgs : EventArgs
         /// <summary>
         /// Creates a new instance of the EventArgs.
         /// </summary>
-        public SelectionChangedEventArgs(IVsHierarchy from, IVsHierarchy to)
+        public SelectionChangedEventArgs(IVsHierarchyItem? from, IVsHierarchyItem? to)
         {
             From = from;
             To = to;
@@ -64,11 +75,11 @@ public SelectionChangedEventArgs(IVsHierarchy from, IVsHierarchy to)
         /// <summary>
         /// What the selection was before the change.
         /// </summary>
-        public IVsHierarchy From { get; }
+        public IVsHierarchyItem? From { get; }
 
         /// <summary>
         /// What the selection is currently after the change.
         /// </summary>
-        public IVsHierarchy To { get; }
+        public IVsHierarchyItem? To { get; }
     }
 }

src/Community.VisualStudio.Toolkit.Shared/ExtensionMethods/IVsHierarchyExtensions.cs

@@ -1,6 +1,9 @@
 using System;
+using System.Threading.Tasks;
+using Community.VisualStudio.Toolkit;
 using EnvDTE;
 using Microsoft.Internal.VisualStudio.PlatformUI;
+using Microsoft.VisualStudio.ComponentModelHost;
 
 namespace Microsoft.VisualStudio.Shell.Interop
 {
@@ -30,6 +33,23 @@ public static bool TryGetItemProperty<T>(this IVsHierarchy hierarchy, uint itemI
             return true;
         }
 
+        /// <summary>
+        /// Converts a <see cref="IVsHierarchy"/> to a <see cref="IVsHierarchyItem"/>.
+        /// </summary>
+        /// <returns>Returns <see langword="null"/> if unable to get the hierarchy item.</returns>
+        public static async Task<IVsHierarchyItem?> ToHierarcyItemAsync(this IVsHierarchy hierarchy, uint itemId)
+        {
+            if (hierarchy == null) return null;
+                
+            await ThreadHelper.JoinableTaskFactory.SwitchToMainThreadAsync();
+            IComponentModel components = await VS.GetRequiredServiceAsync<SComponentModel, IComponentModel>();
+
+            IVsHierarchyItemManager? manager = components.GetService<IVsHierarchyItemManager>();
+
+            manager.TryGetHierarchyItem(hierarchy, itemId, out IVsHierarchyItem? item);
+            return item;
+        }
+
         /// <summary>
         /// Converts an IVsHierarchy to a Project.
         /// </summary>
@@ -47,6 +67,23 @@ public static bool TryGetItemProperty<T>(this IVsHierarchy hierarchy, uint itemI
             return obj as Project;
         }
 
+        /// <summary>
+        /// Converts an IVsHierarchy to a ProjectItem.
+        /// </summary>
+        public static ProjectItem? ToProjectItem(this IVsHierarchy hierarchy, uint itemId)
+        {
+            ThreadHelper.ThrowIfNotOnUIThread();
+
+            if (hierarchy == null)
+            {
+                throw new ArgumentNullException(nameof(hierarchy));
+            }
+
+            hierarchy.GetProperty(itemId, (int)__VSHPROPID.VSHPROPID_ExtObject, out var obj);
+
+            return obj as ProjectItem;
+        }
+
         /// <summary>
         /// Returns whether the specified <see cref="IVsHierarchy"/> is an 'SDK' style project.
         /// </summary>