Preserving all selected nodes, foldings state and position of decompiler text view in the navigation history.

ILSpy/DecompilationOptions.cs

@@ -51,7 +51,15 @@ namespace ICSharpCode.ILSpy
 		/// Gets the settings for the decompiler.
 		/// </summary>
 		public DecompilerSettings DecompilerSettings { get; set; }
-		
+
+		/// <summary>
+		/// Gets/sets an optional state of a decompiler text view.
+		/// </summary>
+		/// <remarks>
+		/// This state is used to restore test view's state when decompilation is started by Go Back/Forward action.
+		/// </remarks>
+		public ICSharpCode.ILSpy.TextView.DecompilerTextViewState TextViewState { get; set; }
+
 		public DecompilationOptions()
 		{
 			this.DecompilerSettings = DecompilerSettingsPanel.CurrentDecompilerSettings;

ILSpy/MainWindow.xaml.cs

@@ -46,7 +46,8 @@ namespace ICSharpCode.ILSpy
 	/// </summary>
 	partial class MainWindow : Window
 	{
-		NavigationHistory history = new NavigationHistory();
+		NavigationHistory<Tuple<List<SharpTreeNode>, DecompilerTextViewState>> history =
+			new NavigationHistory<Tuple<List<SharpTreeNode>, DecompilerTextViewState>>();
 		ILSpySettings spySettings;
 		SessionSettings sessionSettings;
 		AssemblyListManager assemblyListManager;
@@ -254,7 +255,7 @@ namespace ICSharpCode.ILSpy
 		{
 			if (e.OldItems != null)
 				foreach (LoadedAssembly asm in e.OldItems)
-					history.RemoveAll(n => n.AncestorsAndSelf().OfType<AssemblyTreeNode>().Any(a => a.LoadedAssembly == asm));
+					history.RemoveAll(n => n.Item1.Any(nd => nd.AncestorsAndSelf().OfType<AssemblyTreeNode>().Any(a => a.LoadedAssembly == asm)));
 		}
 		
 		void LoadInitialAssemblies()
@@ -284,7 +285,7 @@ namespace ICSharpCode.ILSpy
 		{
 			RefreshTreeViewFilter();
 			if (e.PropertyName == "Language") {
-				TreeView_SelectionChanged(null, null);
+				DecompileSelectedNodes();
 			}
 		}
 		
@@ -311,7 +312,7 @@ namespace ICSharpCode.ILSpy
 			if (obj != null) {
 				SharpTreeNode oldNode = treeView.SelectedItem as SharpTreeNode;
 				if (oldNode != null && recordNavigationInHistory)
-					history.Record(oldNode);
+					history.Record(Tuple.Create(treeView.SelectedItems.OfType<SharpTreeNode>().ToList(), decompilerTextView.GetState()));
 				// Set both the selection and focus to ensure that keyboard navigation works as expected.
 				treeView.FocusNode(obj);
 				treeView.SelectedItem = obj;
@@ -426,12 +427,22 @@ namespace ICSharpCode.ILSpy
 		#region Decompile (TreeView_SelectionChanged)
 		void TreeView_SelectionChanged(object sender, SelectionChangedEventArgs e)
 		{
+			DecompileSelectedNodes();
+		}
+
+		private bool ignoreDecompilationRequests;
+
+		private void DecompileSelectedNodes(DecompilerTextViewState state = null)
+		{
+			if (ignoreDecompilationRequests)
+				return;
+
 			if (treeView.SelectedItems.Count == 1) {
 				ILSpyTreeNode node = treeView.SelectedItem as ILSpyTreeNode;
 				if (node != null && node.View(decompilerTextView))
 					return;
 			}
-			decompilerTextView.Decompile(this.CurrentLanguage, this.SelectedNodes, new DecompilationOptions());
+			decompilerTextView.Decompile(this.CurrentLanguage, this.SelectedNodes, new DecompilationOptions() { TextViewState = state });
 		}
 		
 		void SaveCommandExecuted(object sender, ExecutedRoutedEventArgs e)
@@ -447,7 +458,7 @@ namespace ICSharpCode.ILSpy
 		
 		public void RefreshDecompiledView()
 		{
-			TreeView_SelectionChanged(null, null);
+			DecompileSelectedNodes();
 		}
 		
 		public DecompilerTextView TextView {
@@ -478,7 +489,7 @@ namespace ICSharpCode.ILSpy
 		{
 			if (history.CanNavigateBack) {
 				e.Handled = true;
-				SelectNode(history.GoBack(treeView.SelectedItem as SharpTreeNode), false);
+				NavigateHistory(false);
 			}
 		}
 		
@@ -492,9 +503,27 @@ namespace ICSharpCode.ILSpy
 		{
 			if (history.CanNavigateForward) {
 				e.Handled = true;
-				SelectNode(history.GoForward(treeView.SelectedItem as SharpTreeNode), false);
+				NavigateHistory(true);
 			}
 		}
+
+		void NavigateHistory(bool forward)
+		{
+			var currentSelection = treeView.SelectedItems.OfType<SharpTreeNode>().ToList();
+			var state = decompilerTextView.GetState();
+			var combinedState = Tuple.Create(currentSelection, state);
+			var newState = forward ? history.GoForward(combinedState) : history.GoBack(combinedState);
+
+			this.ignoreDecompilationRequests = true;
+			treeView.SelectedItems.Clear();
+			foreach (var node in newState.Item1)
+			{
+				treeView.SelectedItems.Add(node);
+			}
+			ignoreDecompilationRequests = false;
+			DecompileSelectedNodes(newState.Item2);
+		}
+
 		#endregion
 		
 		#region Analyzer

ILSpy/NavigationHistory.cs

@@ -10,10 +10,10 @@ namespace ICSharpCode.ILSpy
 	/// <summary>
 	/// Stores the navigation history.
 	/// </summary>
-	sealed class NavigationHistory
+	sealed class NavigationHistory<T>
 	{
-		List<SharpTreeNode> back = new List<SharpTreeNode>();
-		List<SharpTreeNode> forward = new List<SharpTreeNode>();
+		List<T> back = new List<T>();
+		List<T> forward = new List<T>();
 		
 		public bool CanNavigateBack {
 			get { return back.Count > 0; }
@@ -23,27 +23,27 @@ namespace ICSharpCode.ILSpy
 			get { return forward.Count > 0; }
 		}
 		
-		public SharpTreeNode GoBack(SharpTreeNode oldNode)
+		public T GoBack(T oldNode)
 		{
 			if (oldNode != null)
 				forward.Add(oldNode);
 			
-			SharpTreeNode node = back[back.Count - 1];
+			T node = back[back.Count - 1];
 			back.RemoveAt(back.Count - 1);
 			return node;
 		}
 		
-		public SharpTreeNode GoForward(SharpTreeNode oldNode)
+		public T GoForward(T oldNode)
 		{
 			if (oldNode != null)
 				back.Add(oldNode);
 			
-			SharpTreeNode node = forward[forward.Count - 1];
+			T node = forward[forward.Count - 1];
 			forward.RemoveAt(forward.Count - 1);
 			return node;
 		}
 		
-		public void RemoveAll(Predicate<SharpTreeNode> predicate)
+		public void RemoveAll(Predicate<T> predicate)
 		{
 			back.RemoveAll(predicate);
 			forward.RemoveAll(predicate);
@@ -55,7 +55,7 @@ namespace ICSharpCode.ILSpy
 			forward.Clear();
 		}
 		
-		public void Record(SharpTreeNode node)
+		public void Record(T node)
 		{
 			forward.Clear();
 			back.Add(node);

ILSpy/TextView/DecompilerTextView.cs

@@ -267,9 +267,9 @@ namespace ICSharpCode.ILSpy.TextView
 		/// <summary>
 		/// Shows the given output in the text view.
 		/// </summary>
-		void ShowOutput(AvalonEditTextOutput textOutput, IHighlightingDefinition highlighting = null)
+		void ShowOutput(AvalonEditTextOutput textOutput, IHighlightingDefinition highlighting = null, DecompilerTextViewState state = null)
 		{
-			Debug.WriteLine("Showing {0} characters of output", textOutput.TextLength);
+			Debug.WriteLine("Showing {0} characters of output", textOutput.TextLength); 
 			Stopwatch w = Stopwatch.StartNew();
 			
 			textEditor.ScrollToHome();
@@ -287,6 +287,11 @@ namespace ICSharpCode.ILSpy.TextView
 			textEditor.Document = textOutput.GetDocument();
 			Debug.WriteLine("  Assigning document: {0}", w.Elapsed); w.Restart();
 			if (textOutput.Foldings.Count > 0) {
+				if (state != null) {
+					state.RestoreFoldings(textOutput.Foldings);
+					textEditor.ScrollToVerticalOffset(state.VerticalOffset);
+					textEditor.ScrollToHorizontalOffset(state.HorizontalOffset);
+				}
 				foldingManager = FoldingManager.Install(textEditor.TextArea);
 				foldingManager.UpdateFoldings(textOutput.Foldings.OrderBy(f => f.StartOffset), -1);
 				Debug.WriteLine("  Updating folding: {0}", w.Elapsed); w.Restart();
@@ -349,7 +354,7 @@ namespace ICSharpCode.ILSpy.TextView
 				delegate (Task<AvalonEditTextOutput> task) { // handling the result
 					try {
 						AvalonEditTextOutput textOutput = task.Result;
-						ShowOutput(textOutput, context.Language.SyntaxHighlighting);
+						ShowOutput(textOutput, context.Language.SyntaxHighlighting, context.Options.TextViewState);
 					} catch (AggregateException aggregateException) {
 						textEditor.SyntaxHighlighting = null;
 						Debug.WriteLine("Decompiler crashed: " + aggregateException.ToString());
@@ -598,5 +603,37 @@ namespace ICSharpCode.ILSpy.TextView
 			return text;
 		}
 		#endregion
+
+		public DecompilerTextViewState GetState()
+		{
+			var state = new DecompilerTextViewState();
+			if (foldingManager != null)
+				state.SaveFoldingsState(foldingManager.AllFoldings);
+			state.VerticalOffset = textEditor.VerticalOffset;
+			state.HorizontalOffset = textEditor.HorizontalOffset;
+			return state;
+		}
+	}
+
+	public class DecompilerTextViewState
+	{
+		private List<Tuple<int, int>> ExpandedFoldings;
+		private int FoldingsChecksum;
+		public double VerticalOffset;
+		public double HorizontalOffset;
+
+		public void SaveFoldingsState(IEnumerable<FoldingSection> foldings)
+		{
+			ExpandedFoldings = foldings.Where(f => !f.IsFolded).Select(f => Tuple.Create(f.StartOffset, f.EndOffset)).ToList();
+			FoldingsChecksum = foldings.Select(f => f.StartOffset * 3 - f.EndOffset).Aggregate((a, b) => a + b);
+		}
+
+		internal void RestoreFoldings(List<NewFolding> list)
+		{
+			var checksum = list.Select(f => f.StartOffset * 3 - f.EndOffset).Aggregate((a, b) => a + b);
+			if (FoldingsChecksum == checksum)
+				foreach (var folding in list)
+					folding.DefaultClosed = !ExpandedFoldings.Any(f => f.Item1 == folding.StartOffset && f.Item2 == folding.EndOffset);
+		}
 	}
 }