Fixed feature to preserve the state (expansions and selection) in the 'Files' tab when switching between commits.

Author: johanw1232

src/Views/RevisionFileTreeView.axaml

@@ -8,7 +8,7 @@
              mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
              x:Class="SourceGit.Views.RevisionFileTreeView"
              x:Name="ThisControl">
-  <v:RevisionFileRowsListBox ItemsSource="{Binding #ThisControl.Rows}"
+  <v:RevisionFileRowsListBox x:Name="RevisionFileRowsListBox" ItemsSource="{Binding #ThisControl.Rows}"
                              Background="Transparent"
                              SelectionMode="Single"
                              SelectionChanged="OnRowsSelectionChanged"

src/Views/RevisionFileTreeView.axaml.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using System.IO;
 using System.Threading.Tasks;
 using Avalonia;
@@ -11,6 +12,7 @@
 using Avalonia.Media;
 using Avalonia.Platform.Storage;
 using Avalonia.VisualTree;
+using SourceGit.ViewModels;
 
 namespace SourceGit.Views
 {
@@ -132,7 +134,7 @@ protected override async void OnKeyDown(KeyEventArgs e)
 
                         await App.CopyTextAsync(path);
                         e.Handled = true;
-                    }
+            }
                 }
                 else if (node.Backend is { Type: Models.ObjectType.Blob } file &&
                     e.Key == Key.S &&
@@ -295,6 +297,17 @@ protected override async void OnPropertyChanged(AvaloniaPropertyChangedEventArgs
 
             if (change.Property == RevisionProperty)
             {
+                var selectedNode = _revisionFileRowsListBox?.SelectedItem as RevisionFileTreeNode;
+
+                var expandedObjects = new List<Models.Object>();
+                foreach (var node in _rows)
+                {
+                    if (node.IsExpanded)
+                    {
+                        expandedObjects.Add(node.Backend);
+                    }
+                }
+
                 _tree.Clear();
                 _searchResult.Clear();
 
@@ -324,10 +337,51 @@ protected override async void OnPropertyChanged(AvaloniaPropertyChangedEventArgs
 
                 Rows.Clear();
                 Rows.AddRange(topTree);
+
+                _revisionFileRowsListBox ??= this.Find<RevisionFileRowsListBox>("RevisionFileRowsListBox");
+
+                if (_revisionFileRowsListBox is { IsArrangeValid: true })
+                {
+                    RestoreTreeState(expandedObjects, selectedNode);
+                }
+
                 GC.Collect();
             }
         }
 
+        private void RestoreTreeState(List<Models.Object> expandedObjects, RevisionFileTreeNode selectedNode)
+        {
+            for (int i = 0; i < _rows.Count; i++)
+            {
+                var revisionFileTreeNode = _rows[i];
+
+                if (!revisionFileTreeNode.IsFolder)
+                    continue;
+
+                if (expandedObjects.FirstOrDefault(o => o.SHA == revisionFileTreeNode.Backend.SHA || o.Path == revisionFileTreeNode.Backend.Path) != null)
+                {
+                    ToggleNodeIsExpanded(revisionFileTreeNode);
+                }
+            }
+
+            if (selectedNode != null)
+            {
+                foreach (var node in _rows)
+                {
+                    if (node.Backend.SHA != selectedNode.Backend.SHA && node.Backend.Path != selectedNode.Backend.Path)
+                        continue;
+
+                    selectedNode = node;
+                    break;
+                }
+            }
+
+            if (_revisionFileRowsListBox != null)
+            {
+                _revisionFileRowsListBox.SelectedItem = selectedNode;
+            }
+        }
+
         private void OnTreeNodeContextRequested(object sender, ContextRequestedEventArgs e)
         {
             if (DataContext is ViewModels.CommitDetail { Repository: ViewModels.Repository repo, Commit: Models.Commit commit } vm &&
@@ -339,7 +393,7 @@ private void OnTreeNodeContextRequested(object sender, ContextRequestedEventArgs
                     _ => CreateRevisionFileContextMenu(repo, vm, commit, obj),
                 };
                 menu.Open(grid);
-            }
+                }
 
             e.Handled = true;
         }
@@ -363,9 +417,9 @@ private async void OnRowsSelectionChanged(object sender, SelectionChangedEventAr
 
             if (sender is ListBox { SelectedItem: ViewModels.RevisionFileTreeNode { IsFolder: false } node })
                 await vm.ViewRevisionFileAsync(node.Backend);
-            else
+                else
                 await vm.ViewRevisionFileAsync(null);
-        }
+            }
 
         private async Task<List<ViewModels.RevisionFileTreeNode>> GetChildrenOfTreeNodeAsync(ViewModels.RevisionFileTreeNode node)
         {
@@ -671,5 +725,6 @@ public ContextMenu CreateRevisionFileContextMenu(ViewModels.Repository repo, Vie
         private List<ViewModels.RevisionFileTreeNode> _tree = [];
         private bool _disableSelectionChangingEvent = false;
         private List<ViewModels.RevisionFileTreeNode> _searchResult = [];
+        private RevisionFileRowsListBox _revisionFileRowsListBox;
     }
 }