Fix navigation and history in AboutPage

ILSpy/AboutPage.cs

@@ -18,7 +18,6 @@
 
 using System;
 using System.ComponentModel;
-using System.ComponentModel.Composition;
 using System.IO;
 using System.Linq;
 using System.Net;
@@ -28,14 +27,14 @@ using System.Windows;
 using System.Windows.Controls;
 using System.Windows.Data;
 using System.Windows.Input;
+using System.Windows.Navigation;
 using System.Xml.Linq;
 
 using ICSharpCode.AvalonEdit.Rendering;
 using ICSharpCode.Decompiler;
-using ICSharpCode.ILSpy.Docking;
-using ICSharpCode.ILSpy.ViewModels;
 using ICSharpCode.ILSpy.Properties;
 using ICSharpCode.ILSpy.TextView;
+
 using OSVersionHelper;
 
 namespace ICSharpCode.ILSpy
@@ -45,8 +44,7 @@ namespace ICSharpCode.ILSpy
 	{
 		public override void Execute(object parameter)
 		{
-			MainWindow.Instance.UnselectAll();
-			DockWorkspace.Instance.ActiveTabPage.ShowTextView(Display);
+			MainWindow.Instance.NavigateTo(new RequestNavigateEventArgs(new Uri("resource://aboutpage"), null));
 		}
 		
 		static readonly Uri UpdateUrl = new Uri("https://ilspy.net/updates.xml");
@@ -89,6 +87,7 @@ namespace ICSharpCode.ILSpy
 			foreach (var plugin in App.ExportProvider.GetExportedValues<IAboutPageAddition>())
 				plugin.Write(output);
 			output.WriteLine();
+			output.Address = new Uri("resource://AboutPage");
 			using (Stream s = typeof(AboutPage).Assembly.GetManifestResourceStream(typeof(AboutPage), "ILSpyAboutPage.txt")) {
 				using (StreamReader r = new StreamReader(s)) {
 					string line;

ILSpy/App.xaml.cs

@@ -22,17 +22,16 @@ using System.Diagnostics;
 using System.IO;
 using System.Linq;
 using System.Reflection;
+using System.Text;
 using System.Threading.Tasks;
 using System.Windows;
 using System.Windows.Documents;
 using System.Windows.Navigation;
 using System.Windows.Threading;
 
-using ICSharpCode.ILSpy.TextView;
 using ICSharpCode.ILSpy.Options;
 
 using Microsoft.VisualStudio.Composition;
-using System.Text;
 
 namespace ICSharpCode.ILSpy
 {
@@ -233,20 +232,7 @@ namespace ICSharpCode.ILSpy
 		
 		void Window_RequestNavigate(object sender, RequestNavigateEventArgs e)
 		{
-			if (e.Uri.Scheme == "resource") {
-				AvalonEditTextOutput output = new AvalonEditTextOutput();
-				using (Stream s = typeof(App).Assembly.GetManifestResourceStream(typeof(App), e.Uri.AbsolutePath)) {
-					using (StreamReader r = new StreamReader(s)) {
-						string line;
-						while ((line = r.ReadLine()) != null) {
-							output.Write(line);
-							output.WriteLine();
-						}
-					}
-				}
-				Docking.DockWorkspace.Instance.ShowText(output);
-				e.Handled = true;
-			}
+			ILSpy.MainWindow.Instance.NavigateTo(e);
 		}
 	}
 }

ILSpy/MainWindow.xaml.cs

@@ -25,7 +25,6 @@ using System.IO;
 using System.Linq;
 using System.Reflection.Metadata;
 using System.Reflection.Metadata.Ecma335;
-using System.Runtime.CompilerServices;
 using System.Text;
 using System.Threading.Tasks;
 using System.Windows;
@@ -34,6 +33,7 @@ using System.Windows.Input;
 using System.Windows.Interop;
 using System.Windows.Media;
 using System.Windows.Media.Imaging;
+using System.Windows.Navigation;
 using System.Windows.Threading;
 using ICSharpCode.Decompiler;
 using ICSharpCode.Decompiler.Documentation;
@@ -41,7 +41,6 @@ using ICSharpCode.Decompiler.Metadata;
 using ICSharpCode.Decompiler.TypeSystem;
 using ICSharpCode.Decompiler.TypeSystem.Implementation;
 using ICSharpCode.ILSpy.Analyzers;
-using ICSharpCode.ILSpy.Controls;
 using ICSharpCode.ILSpy.Docking;
 using ICSharpCode.ILSpy.TextView;
 using ICSharpCode.ILSpy.TreeNodes;
@@ -49,7 +48,6 @@ using ICSharpCode.ILSpy.ViewModels;
 using ICSharpCode.TreeView;
 using Microsoft.Win32;
 using OSVersionHelper;
-using Xceed.Wpf.AvalonDock.Layout;
 using Xceed.Wpf.AvalonDock.Layout.Serialization;
 
 namespace ICSharpCode.ILSpy
@@ -996,6 +994,10 @@ namespace ICSharpCode.ILSpy
 				if (node != null && node.View(DockWorkspace.Instance.ActiveTabPage))
 					return;
 			}
+			if (newState?.ViewedUri != null) {
+				NavigateTo(new RequestNavigateEventArgs(newState.ViewedUri, null), recordHistory: false);
+				return;
+			}
 			decompilationTask = DockWorkspace.Instance.ActiveTabPage.ShowTextViewAsync(textView => textView.DecompileAsync(this.CurrentLanguage, this.SelectedNodes, new DecompilationOptions() { TextViewState = newState }));
 		}
 
@@ -1078,9 +1080,50 @@ namespace ICSharpCode.ILSpy
 			ignoreDecompilationRequests = false;
 			DecompileSelectedNodes(newState.ViewState as DecompilerTextViewState, false);
 		}
-
 		#endregion
 
+		internal void NavigateTo(RequestNavigateEventArgs e, bool recordHistory = true)
+		{
+			if (e.Uri.Scheme == "resource") {
+				if (e.Uri.Host == "aboutpage") {
+					RecordHistory();
+					DockWorkspace.Instance.ActiveTabPage.ShowTextView(AboutPage.Display);
+					e.Handled = true;
+					return;
+				}
+				AvalonEditTextOutput output = new AvalonEditTextOutput {
+					Address = e.Uri,
+					Title = e.Uri.AbsolutePath,
+					EnableHyperlinks = true
+				};
+				using (Stream s = typeof(App).Assembly.GetManifestResourceStream(typeof(App), e.Uri.AbsolutePath)) {
+					using (StreamReader r = new StreamReader(s)) {
+						string line;
+						while ((line = r.ReadLine()) != null) {
+							output.Write(line);
+							output.WriteLine();
+						}
+					}
+				}
+				RecordHistory();
+				DockWorkspace.Instance.ShowText(output);
+				e.Handled = true;
+			}
+
+			void RecordHistory()
+			{
+				if (!recordHistory)
+					return;
+				var currentState = DockWorkspace.Instance.ActiveTabPage.GetState();
+				if (currentState != null)
+					history.UpdateCurrent(new NavigationState(currentState));
+				ignoreDecompilationRequests = true;
+				UnselectAll();
+				ignoreDecompilationRequests = false;
+				history.Record(new NavigationState(new ViewState { ViewedUri = e.Uri }));
+			}
+		}
+
 		protected override void OnStateChanged(EventArgs e)
 		{
 			base.OnStateChanged(e);

ILSpy/Metadata/Helpers.cs

@@ -91,7 +91,9 @@ namespace ICSharpCode.ILSpy.Metadata
 
 			public ViewState GetState()
 			{
-				return new ViewState { DecompiledNodes = SelectedTreeNode == null ? null : new[] { SelectedTreeNode } };
+				return new ViewState {
+					DecompiledNodes = SelectedTreeNode == null ? null : new HashSet<ILSpyTreeNode>(new[] { SelectedTreeNode })
+				};
 			}
 		}
 

ILSpy/NavigationState.cs

@@ -18,11 +18,13 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using ICSharpCode.ILSpy.TextView;
 using ICSharpCode.TreeView;
 
 namespace ICSharpCode.ILSpy
 {
+	[DebuggerDisplay("Nodes = {treeNodes.Count}, State = [{ViewState}]")]
 	public class NavigationState : IEquatable<NavigationState>
 	{
 		private readonly HashSet<SharpTreeNode> treeNodes;
@@ -32,7 +34,7 @@ namespace ICSharpCode.ILSpy
 
 		public NavigationState(ViewState viewState)
 		{
-			this.treeNodes = new HashSet<SharpTreeNode>(viewState.DecompiledNodes);
+			this.treeNodes = new HashSet<SharpTreeNode>((IEnumerable<SharpTreeNode>)viewState.DecompiledNodes ?? Array.Empty<SharpTreeNode>());
 			ViewState = viewState;
 		}
 
@@ -44,8 +46,16 @@ namespace ICSharpCode.ILSpy
 
 		public bool Equals(NavigationState other)
 		{
-			// TODO: should this care about the view state as well?
-			return this.treeNodes.SetEquals(other.treeNodes);
+			if (!this.treeNodes.SetEquals(other.treeNodes))
+				return false;
+
+			if (object.ReferenceEquals(this.ViewState, other.ViewState))
+				return true;
+
+			if (this.ViewState == null)
+				return false;
+
+			return this.ViewState.Equals(other.ViewState);
 		}
 	}
 }

ILSpy/TextView/AvalonEditTextOutput.cs

@@ -83,6 +83,12 @@ namespace ICSharpCode.ILSpy.TextView
 		public string IndentationString { get; set; } = "\t";
 
 		public string Title { get; set; }
+
+		/// <summary>
+		/// Gets/sets the <see cref="Uri"/> that is displayed by this view.
+		/// Used to identify the AboutPage and other views built into ILSpy in the navigation history.
+		/// </summary>
+		public Uri Address { get; set; }
 		
 		internal readonly List<VisualLineElementGenerator> elementGenerators = new List<VisualLineElementGenerator>();
 		

ILSpy/TextView/DecompilerTextView.cs

@@ -71,6 +71,7 @@ namespace ICSharpCode.ILSpy.TextView
 		BracketHighlightRenderer bracketHighlightRenderer;
 		FoldingManager foldingManager;
 		ILSpyTreeNode[] decompiledNodes;
+		Uri currentAddress;
 		
 		DefinitionLookup definitionLookup;
 		TextSegmentCollection<ReferenceSegment> references;
@@ -647,6 +648,7 @@ namespace ICSharpCode.ILSpy.TextView
 			if (this.DataContext is PaneModel model) {
 				model.Title = textOutput.Title;
 			}
+			currentAddress = textOutput.Address;
 		}
 		#endregion
 		
@@ -1010,7 +1012,7 @@ namespace ICSharpCode.ILSpy.TextView
 		
 		public DecompilerTextViewState GetState()
 		{
-			if (decompiledNodes == null)
+			if (decompiledNodes == null && currentAddress == null)
 				return null;
 
 			var state = new DecompilerTextViewState();
@@ -1018,7 +1020,8 @@ namespace ICSharpCode.ILSpy.TextView
 				state.SaveFoldingsState(foldingManager.AllFoldings);
 			state.VerticalOffset = textEditor.VerticalOffset;
 			state.HorizontalOffset = textEditor.HorizontalOffset;
-			state.DecompiledNodes = decompiledNodes;
+			state.DecompiledNodes = decompiledNodes == null ? null : new HashSet<ILSpyTreeNode>(decompiledNodes);
+			state.ViewedUri = currentAddress;
 			return state;
 		}
 
@@ -1059,9 +1062,16 @@ namespace ICSharpCode.ILSpy.TextView
 		#endregion
 	}
 
-	public class ViewState
+	[DebuggerDisplay("Nodes = {DecompiledNodes}, ViewedUri = {ViewedUri}")]
+	public class ViewState : IEquatable<ViewState>
 	{
-		public ILSpyTreeNode[] DecompiledNodes;
+		public HashSet<ILSpyTreeNode> DecompiledNodes;
+		public Uri ViewedUri;
+
+		public virtual bool Equals(ViewState other)
+		{
+			return ViewedUri == other.ViewedUri && (DecompiledNodes == other.DecompiledNodes || DecompiledNodes?.SetEquals(other.DecompiledNodes) == true);
+		}
 	}
 	
 	public class DecompilerTextViewState : ViewState
@@ -1084,5 +1094,16 @@ namespace ICSharpCode.ILSpy.TextView
 				foreach (var folding in list)
 					folding.DefaultClosed = !ExpandedFoldings.Any(f => f.Item1 == folding.StartOffset && f.Item2 == folding.EndOffset);
 		}
+
+		public override bool Equals(ViewState other)
+		{
+			if (other is DecompilerTextViewState vs) {
+				return base.Equals(vs)
+					&& FoldingsChecksum == vs.FoldingsChecksum
+					&& VerticalOffset == vs.VerticalOffset
+					&& HorizontalOffset == vs.HorizontalOffset;
+			}
+			return false;
+		}
 	}
 }