feature: remember last navigated block after toggling Show All Lines (#1952)

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

Author: love-linger

src/ViewModels/BlockNavigation.cs

@@ -1,3 +1,4 @@
+using System;
 using System.Collections.Generic;
 using CommunityToolkit.Mvvm.ComponentModel;
 
@@ -35,13 +36,15 @@ public string Indicator
             }
         }
 
-        public BlockNavigation(List<Models.TextDiffLine> lines, bool gotoFirst)
+        public BlockNavigation(List<Models.TextDiffLine> lines, int cur)
         {
             _blocks.Clear();
-            _current = -1;
 
             if (lines.Count == 0)
+            {
+                _current = -1;
                 return;
+            }
 
             var lineIdx = 0;
             var blockStartIdx = 0;
@@ -73,9 +76,12 @@ public BlockNavigation(List<Models.TextDiffLine> lines, bool gotoFirst)
                 blocks.Add(new Block(blockStartIdx, lines.Count));
 
             _blocks.AddRange(blocks);
+            _current = Math.Min(_blocks.Count - 1, cur);
+        }
 
-            if (gotoFirst)
-                Goto(BlockNavigationDirection.First);
+        public int GetCurrentBlockIndex()
+        {
+            return _current;
         }
 
         public Block GetCurrentBlock()

src/ViewModels/DiffContext.cs

@@ -150,8 +150,7 @@ private void LoadContent()
 
             Task.Run(async () =>
             {
-                var showEntireFile = Preferences.Instance.UseFullTextDiff;
-                var numLines = showEntireFile ? _entireFileLine : _unifiedLines;
+                var numLines = Preferences.Instance.UseFullTextDiff ? _entireFileLine : _unifiedLines;
                 var ignoreWhitespace = Preferences.Instance.IgnoreWhitespaceChangesInDiff;
 
                 var latest = await new Commands.Diff(_repo, _option, numLines, ignoreWhitespace)
@@ -274,9 +273,9 @@ private void LoadContent()
                         IsTextDiff = true;
 
                         if (Preferences.Instance.UseSideBySideDiff)
-                            Content = new TwoSideTextDiff(_option, showEntireFile, cur, _content as TwoSideTextDiff);
+                            Content = new TwoSideTextDiff(_option, cur, _content as TwoSideTextDiff);
                         else
-                            Content = new CombinedTextDiff(_option, showEntireFile, cur, _content as CombinedTextDiff);
+                            Content = new CombinedTextDiff(_option, cur, _content as CombinedTextDiff);
                     }
                     else
                     {

src/ViewModels/TextDiffContext.cs

@@ -130,30 +130,33 @@ public virtual TextDiffContext SwitchMode()
             return null;
         }
 
-        protected bool TryKeepPrevScrollOffset(TextDiffContext prev)
+        protected void TryKeepPrevState(TextDiffContext prev, List<Models.TextDiffLine> lines)
         {
             var fastTest = prev != null &&
-                prev._showEntireFile == _showEntireFile &&
                 prev._option.IsUnstaged == _option.IsUnstaged &&
                 prev._option.Path.Equals(_option.Path, StringComparison.Ordinal) &&
                 prev._option.OrgPath.Equals(_option.OrgPath, StringComparison.Ordinal) &&
                 prev._option.Revisions.Count == _option.Revisions.Count;
 
             if (!fastTest)
-                return false;
+            {
+                _blockNavigation = new BlockNavigation(lines, 0);
+                return;
+            }
 
             for (int i = 0; i < _option.Revisions.Count; i++)
             {
                 if (!prev._option.Revisions[i].Equals(_option.Revisions[i], StringComparison.Ordinal))
-                    return false;
+                {
+                    _blockNavigation = new BlockNavigation(lines, 0);
+                    return;
+                }
             }
 
-            _scrollOffset = prev._scrollOffset;
-            return true;
+            _blockNavigation = new BlockNavigation(lines, prev._blockNavigation.GetCurrentBlockIndex());
         }
 
         protected Models.DiffOption _option = null;
-        protected bool _showEntireFile = false;
         protected Models.TextDiff _data = null;
         protected Vector _scrollOffset = Vector.Zero;
         protected BlockNavigation _blockNavigation = null;
@@ -164,19 +167,17 @@ protected bool TryKeepPrevScrollOffset(TextDiffContext prev)
 
     public class CombinedTextDiff : TextDiffContext
     {
-        public CombinedTextDiff(Models.DiffOption option, bool showEntireFile, Models.TextDiff diff, CombinedTextDiff previous = null)
+        public CombinedTextDiff(Models.DiffOption option, Models.TextDiff diff, CombinedTextDiff previous = null)
         {
             _option = option;
-            _showEntireFile = showEntireFile;
             _data = diff;
 
-            var keep = TryKeepPrevScrollOffset(previous);
-            _blockNavigation = new BlockNavigation(_data.Lines, !keep);
+            TryKeepPrevState(previous, _data.Lines);
         }
 
         public override TextDiffContext SwitchMode()
         {
-            return new TwoSideTextDiff(_option, _showEntireFile, _data);
+            return new TwoSideTextDiff(_option, _data);
         }
     }
 
@@ -185,10 +186,9 @@ public class TwoSideTextDiff : TextDiffContext
         public List<Models.TextDiffLine> Old { get; } = [];
         public List<Models.TextDiffLine> New { get; } = [];
 
-        public TwoSideTextDiff(Models.DiffOption option, bool showEntireFile, Models.TextDiff diff, TwoSideTextDiff previous = null)
+        public TwoSideTextDiff(Models.DiffOption option, Models.TextDiff diff, TwoSideTextDiff previous = null)
         {
             _option = option;
-            _showEntireFile = showEntireFile;
             _data = diff;
 
             foreach (var line in diff.Lines)
@@ -210,9 +210,7 @@ public TwoSideTextDiff(Models.DiffOption option, bool showEntireFile, Models.Tex
             }
 
             FillEmptyLines();
-
-            var keep = TryKeepPrevScrollOffset(previous);
-            _blockNavigation = new BlockNavigation(Old, !keep);
+            TryKeepPrevState(previous, Old);
         }
 
         public override bool IsSideBySide()
@@ -222,7 +220,7 @@ public override bool IsSideBySide()
 
         public override TextDiffContext SwitchMode()
         {
-            return new CombinedTextDiff(_option, _showEntireFile, _data);
+            return new CombinedTextDiff(_option, _data);
         }
 
         public void ConvertsToCombinedRange(ref int startLine, ref int endLine, bool isOldSide)