fix: auto-navigating to first change sometimes does not work (#1952)

Signed-off-by: leo <longshuang@msn.cn>

Author: love-linger

src/ViewModels/BlockNavigation.cs

@@ -3,6 +3,14 @@
 
 namespace SourceGit.ViewModels
 {
+    public enum BlockNavigationDirection
+    {
+        First = 0,
+        Prev,
+        Next,
+        Last
+    }
+
     public class BlockNavigation : ObservableObject
     {
         public record Block(int Start, int End)
@@ -67,7 +75,7 @@ public BlockNavigation(List<Models.TextDiffLine> lines, bool gotoFirst)
             _blocks.AddRange(blocks);
 
             if (gotoFirst)
-                GotoFirst();
+                Goto(BlockNavigationDirection.First);
         }
 
         public Block GetCurrentBlock()
@@ -78,48 +86,20 @@ public Block GetCurrentBlock()
             return null;
         }
 
-        public Block GotoFirst()
+        public Block Goto(BlockNavigationDirection direction)
         {
             if (_blocks.Count == 0)
                 return null;
 
-            _current = 0;
-            OnPropertyChanged(nameof(Indicator));
-            return _blocks[_current];
-        }
-
-        public Block GotoPrev()
-        {
-            if (_blocks.Count == 0)
-                return null;
-
-            if (_current == -1)
-                _current = 0;
-            else if (_current > 0)
-                _current--;
-
-            OnPropertyChanged(nameof(Indicator));
-            return _blocks[_current];
-        }
-
-        public Block GotoNext()
-        {
-            if (_blocks.Count == 0)
-                return null;
-
-            if (_current < _blocks.Count - 1)
-                _current++;
-
-            OnPropertyChanged(nameof(Indicator));
-            return _blocks[_current];
-        }
-
-        public Block GotoLast()
-        {
-            if (_blocks.Count == 0)
-                return null;
+            _current = direction switch
+            {
+                BlockNavigationDirection.First => 0,
+                BlockNavigationDirection.Prev => _current <= 0 ? 0 : _current - 1,
+                BlockNavigationDirection.Next => _current >= _blocks.Count - 1 ? _blocks.Count - 1 : _current + 1,
+                BlockNavigationDirection.Last => _blocks.Count - 1,
+                _ => _current
+            };
 
-            _current = _blocks.Count - 1;
             OnPropertyChanged(nameof(Indicator));
             return _blocks[_current];
         }

src/ViewModels/DiffContext.cs

@@ -135,10 +135,7 @@ public void CheckSettings()
                 }
 
                 if (ctx.IsSideBySide() != UseSideBySide)
-                {
-                    ctx = ctx.SwitchMode();
-                    Content = ctx;
-                }
+                    Content = ctx.SwitchMode();
             }
         }
 

src/Views/DiffView.axaml.cs

@@ -21,25 +21,25 @@ protected override void OnLoaded(RoutedEventArgs e)
 
         private void OnGotoFirstChange(object _, RoutedEventArgs e)
         {
-            this.FindDescendantOfType<ThemedTextDiffPresenter>()?.GotoFirstChange();
+            this.FindDescendantOfType<ThemedTextDiffPresenter>()?.GotoChange(ViewModels.BlockNavigationDirection.First);
             e.Handled = true;
         }
 
         private void OnGotoPrevChange(object _, RoutedEventArgs e)
         {
-            this.FindDescendantOfType<ThemedTextDiffPresenter>()?.GotoPrevChange();
+            this.FindDescendantOfType<ThemedTextDiffPresenter>()?.GotoChange(ViewModels.BlockNavigationDirection.Prev);
             e.Handled = true;
         }
 
         private void OnGotoNextChange(object _, RoutedEventArgs e)
         {
-            this.FindDescendantOfType<ThemedTextDiffPresenter>()?.GotoNextChange();
+            this.FindDescendantOfType<ThemedTextDiffPresenter>()?.GotoChange(ViewModels.BlockNavigationDirection.Next);
             e.Handled = true;
         }
 
         private void OnGotoLastChange(object _, RoutedEventArgs e)
         {
-            this.FindDescendantOfType<ThemedTextDiffPresenter>()?.GotoLastChange();
+            this.FindDescendantOfType<ThemedTextDiffPresenter>()?.GotoChange(ViewModels.BlockNavigationDirection.Last);
             e.Handled = true;
         }
     }

src/Views/TextDiffView.axaml.cs

@@ -487,43 +487,21 @@ public virtual void UpdateSelectedChunk(double y)
         {
         }
 
-        public virtual void GotoFirstChange()
+        public void GotoChange(ViewModels.BlockNavigationDirection direction)
         {
-            var first = BlockNavigation.GotoFirst();
-            if (first != null)
-            {
-                TextArea.Caret.Line = first.Start;
-                ScrollToLine(first.Start);
-            }
-        }
+            if (DataContext is not ViewModels.TextDiffContext ctx)
+                return;
 
-        public virtual void GotoPrevChange()
-        {
-            var prev = BlockNavigation.GotoPrev();
-            if (prev != null)
+            var block = BlockNavigation.Goto(direction);
+            if (block != null)
             {
-                TextArea.Caret.Line = prev.Start;
-                ScrollToLine(prev.Start);
-            }
-        }
+                TextArea.Caret.Line = block.Start;
+                ScrollToLine(block.Start);
 
-        public virtual void GotoNextChange()
-        {
-            var next = BlockNavigation.GotoNext();
-            if (next != null)
-            {
-                TextArea.Caret.Line = next.Start;
-                ScrollToLine(next.Start);
-            }
-        }
+                if (ctx.IsSideBySide())
+                {
 
-        public virtual void GotoLastChange()
-        {
-            var next = BlockNavigation.GotoLast();
-            if (next != null)
-            {
-                TextArea.Caret.Line = next.Start;
-                ScrollToLine(next.Start);
+                }
             }
         }
 
@@ -618,9 +596,9 @@ protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs chang
             }
         }
 
-        protected override void OnDataContextBeginUpdate()
+        protected override void OnDataContextChanged(EventArgs e)
         {
-            base.OnDataContextBeginUpdate();
+            base.OnDataContextChanged(e);
             AutoScrollToFirstChange();
         }
 
@@ -805,9 +783,6 @@ private void AutoScrollToFirstChange()
             if (DataContext is not ViewModels.TextDiffContext ctx)
                 return;
 
-            if (ctx.IsSideBySide() && !IsOld)
-                return;
-
             var curBlock = ctx.BlockNavigation.GetCurrentBlock();
             if (curBlock == null)
                 return;
@@ -819,8 +794,9 @@ private void AutoScrollToFirstChange()
                 var scroller = this.FindDescendantOfType<ScrollViewer>();
                 if (scroller != null)
                 {
-                    ctx.ScrollOffset = new Vector(0, vOffset);
-                    scroller.Offset = ctx.ScrollOffset;
+                    var scrollOffset = new Vector(0, vOffset);
+                    scroller.Offset = scrollOffset;
+                    ctx.ScrollOffset = scrollOffset;
                 }
             }
         }
@@ -1098,30 +1074,6 @@ public class SingleSideTextDiffPresenter : ThemedTextDiffPresenter
             return [];
         }
 
-        public override void GotoFirstChange()
-        {
-            base.GotoFirstChange();
-            SyncScrollOffset();
-        }
-
-        public override void GotoPrevChange()
-        {
-            base.GotoPrevChange();
-            SyncScrollOffset();
-        }
-
-        public override void GotoNextChange()
-        {
-            base.GotoNextChange();
-            SyncScrollOffset();
-        }
-
-        public override void GotoLastChange()
-        {
-            base.GotoLastChange();
-            SyncScrollOffset();
-        }
-
         public override void UpdateSelectedChunk(double y)
         {
             if (DataContext is not ViewModels.TwoSideTextDiff diff)
@@ -1318,12 +1270,6 @@ private void OnBlockNavigationPropertyChanged(object sender, PropertyChangedEven
                 TextArea?.TextView?.Redraw();
         }
 
-        private void SyncScrollOffset()
-        {
-            if (_scrollViewer is not null && DataContext is ViewModels.TwoSideTextDiff diff)
-                diff.ScrollOffset = _scrollViewer.Offset;
-        }
-
         private ScrollViewer _scrollViewer = null;
     }