Fix remaining TextView issues

Terminal.Gui/Views/TextInput/TextModel.cs

@@ -16,6 +16,7 @@ internal class TextModel
     // Cached max visible line width to avoid O(N×L) rescans on every layout/scroll.
     private int _cachedMaxWidth = -1;
     private int _cachedMaxWidthTabWidth = -1;
+    private Dictionary<int, int> _cachedMaxWidthPerLine = [];
 
     /// <summary>
     ///     Gets the number of times <see cref="GetMaxVisibleLine"/> performed a full line scan.
@@ -34,6 +35,38 @@ internal class TextModel
     /// <summary>Invalidates the cached max line width so the next call to <see cref="GetMaxVisibleLine"/> will rescan.</summary>
     internal void InvalidateMaxWidthCache () => _cachedMaxWidth = -1;
 
+    /// <summary>
+    ///   Determines whether the max width cache should be invalidated based on the line being modified, the column width of the modification, and whether it's an insert or delete operation.
+    /// </summary>
+    /// <param name="line">The line number being modified.</param>
+    /// <param name="isInsert">Indicates whether the operation is an insert. Defaults to true.</param>
+    /// <param name="columnWidth">The width of the column being modified. Defaults to -1 on delete.</param>
+    /// <returns><see langword="true"/> if the cache should be invalidated; otherwise, <see langword="false"/>.</returns>
+    internal bool ShouldInvalidateMaxWidthCache (int line, bool isInsert = true, int columnWidth = -1)
+    {
+        if (_cachedMaxWidth < 0)
+        {
+            return true;
+        }
+
+        if (isInsert)
+        {
+            if (_cachedMaxWidthPerLine.TryGetValue (line, out int cachedLineWidth) && columnWidth > cachedLineWidth)
+            {
+                return true;
+            }
+        }
+        else
+        {
+            if (_cachedMaxWidthPerLine.Count == 1 && _cachedMaxWidthPerLine.ContainsKey (line))
+            {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
     /// <summary>Adds a line to the model at the specified position.</summary>
     /// <param name="pos">Line number where the line will be inserted.</param>
     /// <param name="cells">The line of text and color, as a List of Cell.</param>
@@ -96,6 +129,12 @@ public int GetMaxVisibleLine (int first, int last, int tabWidth)
         var maxLength = 0;
         last = last < _lines.Count ? last : _lines.Count;
 
+        // When scanning the full range, reset cached max width per line
+        if (first == 0 && last >= _lines.Count)
+        {
+            _cachedMaxWidthPerLine = [];
+        }
+
         for (int i = first; i < last; i++)
         {
             List<Cell> line = GetLine (i);
@@ -104,6 +143,19 @@ public int GetMaxVisibleLine (int first, int last, int tabWidth)
             if (colsWidth > maxLength)
             {
                 maxLength = colsWidth;
+
+                // Cache max width per line when scanning the full range, and remove cached widths for lines that are no longer the max
+                if (first != 0 || last < _lines.Count)
+                {
+                    continue;
+                }
+                int length = maxLength;
+                _cachedMaxWidthPerLine = _cachedMaxWidthPerLine.Where (kvp => kvp.Value > length).ToDictionary (kvp => kvp.Key, kvp => kvp.Value);
+                _cachedMaxWidthPerLine.Add (i, maxLength);
+            }
+            else if (maxLength == colsWidth)
+            {
+                _cachedMaxWidthPerLine [i] = colsWidth;
             }
         }
 

Terminal.Gui/Views/TextInput/TextView/TextView.Commands.cs

@@ -480,7 +480,12 @@ private bool DeleteTextLeft ()
 
         // Always redraw and update content size because a glyph was deleted
         SetNeedsDraw ();
-        UpdateContentSize ();
+
+        if (_model.ShouldInvalidateMaxWidthCache (CurrentRow, false))
+        {
+            _model.InvalidateMaxWidthCache ();
+            UpdateContentSize ();
+        }
 
         UpdateWrapModel ();
         OnContentsChanged ();
@@ -513,8 +518,13 @@ private bool DeleteTextRight ()
             _historyText.Add (removedLines, InsertionPoint, TextEditingLineStatus.Removed);
             currentLine.AddRange (nextLine);
             _model.RemoveLine (CurrentRow + 1);
+
+            // Text was deleted, so it's always needed to redraw and update content size if needed
             SetNeedsDraw ();
 
+            // _model.RemoveLine already invalidates the max width cache for the removed line, but we also need to check if the merged line's width changed
+            UpdateContentSize ();
+
             _historyText.Add ([[.. currentLine]], InsertionPoint, TextEditingLineStatus.Replaced);
 
             if (_wordWrap)
@@ -531,8 +541,16 @@ private bool DeleteTextRight ()
         _historyText.Add ([[.. currentLine]], InsertionPoint);
 
         currentLine.RemoveAt (CurrentColumn);
+
+        // Text was deleted, so it's always needed to redraw and update content size if needed
         SetNeedsDraw ();
 
+        if (_model.ShouldInvalidateMaxWidthCache (CurrentRow, false))
+        {
+            _model.InvalidateMaxWidthCache ();
+            UpdateContentSize ();
+        }
+
         _historyText.Add ([[.. currentLine]], InsertionPoint, TextEditingLineStatus.Replaced);
 
         if (_wordWrap)

Terminal.Gui/Views/TextInput/TextView/TextView.Movement.cs

@@ -108,7 +108,7 @@ private bool MoveDown ()
 
             CurrentRow++;
 
-            if (CurrentRow >= Viewport.Y + Viewport.Height)
+            if (CurrentRow >= Viewport.Y + Viewport.Height || CurrentRow < Viewport.Y)
             {
                 SetNeedsDraw ();
             }
@@ -145,8 +145,9 @@ private bool MoveEndOfLine ()
         List<Cell> currentLine = GetCurrentLine ();
         CurrentColumn = currentLine.Count;
 
-        if (CurrentColumn >= Viewport.X + Viewport.Width || TextModel.CursorColumn (TextModel.CellsToStringList (currentLine), CurrentColumn, TabWidth, out _, out _) - Viewport.X >= Viewport.Width)
-{
+        if (CurrentColumn >= Viewport.X + Viewport.Width
+            || TextModel.CursorColumn (TextModel.CellsToStringList (currentLine), CurrentColumn, TabWidth, out _, out _) - Viewport.X >= Viewport.Width)
+        {
             SetNeedsDraw ();
         }
         DoNeededAction ();
@@ -160,7 +161,7 @@ private bool MoveLeft ()
         {
             CurrentColumn--;
 
-            if (Viewport.X > 0 && CurrentColumn <= Viewport.X)
+            if ((Viewport.X > 0 && CurrentColumn <= Viewport.X) || CurrentColumn >= Viewport.X + Viewport.Width)
             {
                 SetNeedsDraw ();
             }
@@ -296,7 +297,7 @@ private bool MoveRight ()
         {
             CurrentColumn++;
 
-            if (CurrentColumn >= currentLine.Count || TextModel.CursorColumn (TextModel.CellsToStringList (currentLine), CurrentColumn, TabWidth, out _, out _) >= Viewport.Width)
+            if (CurrentColumn >= currentLine.Count || (Viewport.X > 0 && CurrentColumn < Viewport.X) || TextModel.CursorColumn (TextModel.CellsToStringList (currentLine), CurrentColumn, TabWidth, out _, out _) >= Viewport.X + Viewport.Width)
             {
                 SetNeedsDraw ();
             }
@@ -355,7 +356,7 @@ private bool MoveUp ()
 
             CurrentRow--;
 
-            if (CurrentRow < Viewport.Y)
+            if (CurrentRow < Viewport.Y || CurrentRow > Viewport.Y)
             {
                 SetNeedsDraw ();
             }
@@ -393,6 +394,11 @@ private bool MoveWordLeft ()
             CurrentRow = newPos.Value.row;
         }
 
+        if (CurrentRow < Viewport.Y || CurrentColumn < Viewport.X || CurrentColumn >= Viewport.X + Viewport.Width)
+        {
+            SetNeedsDraw ();
+        }
+
         DoNeededAction ();
 
         return true;
@@ -408,6 +414,11 @@ private bool MoveWordRight ()
             CurrentRow = newPos.Value.row;
         }
 
+        if (CurrentRow >= Viewport.Y + Viewport.Height || CurrentColumn >= Viewport.X + Viewport.Width || CurrentColumn < Viewport.X)
+        {
+            SetNeedsDraw ();
+        }
+
         DoNeededAction ();
 
         return true;

Terminal.Gui/Views/TextInput/TextView/TextView.Scrolling.cs

@@ -115,11 +115,16 @@ private void AdjustViewport ()
             }
             need = true;
         }
-        else if (!_wordWrap && (CurrentColumn - Viewport.X + 1 > Viewport.Width || dSize.size + 1 >= Viewport.Width))
+        else if (!_wordWrap && (CurrentColumn - Viewport.X + 1 > Viewport.Width || dSize.size - Viewport.X + 1 >= Viewport.Width))
         {
             Viewport = Viewport with { X = TextModel.CalculateLeftColumn (line, Viewport.X, CurrentColumn, Viewport.Width, TabWidth) };
             need = true;
         }
+        else if (tSize.size - Viewport.X + 1 <= Viewport.Width)
+        {
+            Viewport = Viewport with { X = Math.Max (0, tSize.size - Viewport.Width + 1) };
+            need = true;
+        }
         else if ((_wordWrap && Viewport.X > 0) || (dSize.size < Viewport.Width && tSize.size < Viewport.Width))
         {
             if (Viewport.X > 0)
@@ -140,11 +145,6 @@ private void AdjustViewport ()
             Viewport = Viewport with { Y = Math.Min (Math.Max (CurrentRow - Viewport.Height + 1, 0), CurrentRow) };
             need = true;
         }
-        else if (!WordWrap && Viewport.Y > 0 && CurrentRow - Viewport.Height + 1 < Viewport.Y)
-        {
-            Viewport = Viewport with { Y = Math.Max (Viewport.Y - 1, 0) };
-            need = true;
-        }
 
         if (need)
         {

Terminal.Gui/Views/TextInput/TextView/TextView.Text.cs

@@ -558,23 +558,19 @@ private void InsertText (Key a, Attribute? attribute = null)
                 return;
             }
 
-            if (Used)
-            {
-                Insert (new Cell { Grapheme = grapheme, Attribute = attribute });
-                CurrentColumn++;
-            }
-            else
-            {
-                Insert (new Cell { Grapheme = grapheme, Attribute = attribute });
-                CurrentColumn++;
-            }
-            UpdateContentSize ();
+            Insert (new Cell { Grapheme = grapheme, Attribute = attribute });
+            CurrentColumn++;
+
+            // Text was inserted, so it's always needed to redraw and update content size if needed
+            SetNeedsDraw ();
+
             List<Cell> line = GetCurrentLine ();
             (int size, int length) dSize = TextModel.DisplaySize (line, 0, CurrentColumn, true, TabWidth);
 
-            if (dSize.size + 1 - Viewport.X >= Viewport.Width)
+            if (_model.ShouldInvalidateMaxWidthCache (CurrentRow, true, dSize.size))
             {
-                SetNeedsDraw ();
+                _model.InvalidateMaxWidthCache ();
+                UpdateContentSize ();
             }
         }
 

Tests/UnitTestsParallelizable/Views/TextView.InputTests.cs

@@ -467,6 +467,54 @@ public void Tab_Advances_Correctly_To_Next_Tab_Stop (string text, int tabWidth,
         Assert.Equal (expectedColumn, visualColumn);
     }
 
+    [Fact]
+    public void Typing_Tab_At_End_Of_Line_With_Wrap_Disabled_Should_Scroll_Horizontally_And_Update_Content_Size ()
+    {
+        TextView tv = new ()
+        {
+            Width = 5,
+            Height = 2,
+            Text = "Line1\nLine2\nLine3"
+        };
+        tv.BeginInit ();
+        tv.EndInit ();
+
+        tv.InsertionPoint = new Point (6, 0);
+        Assert.Equal (new Point (1, 0), tv.Viewport.Location);
+        Assert.Equal (new Point (5, 0), tv.InsertionPoint);
+        Assert.Equal (new Size (6, 3), tv.GetContentSize ());
+
+        tv.NewKeyDownEvent (Key.Tab);
+
+        Assert.Equal (new Point (4, 0), tv.Viewport.Location);
+        Assert.Equal (new Point (6, 0), tv.InsertionPoint);
+        Assert.Equal (new Size (9, 3), tv.GetContentSize ());
+    }
+
+    [Fact]
+    public void Typing_ShiftTab_At_End_Of_Line_With_Wrap_Disabled_Should_Scroll_Horizontally_And_Update_Content_Size ()
+    {
+        TextView tv = new ()
+        {
+            Width = 5,
+            Height = 2,
+            Text = "Line1\t\nLine2\nLine3"
+        };
+        tv.BeginInit ();
+        tv.EndInit ();
+
+        tv.InsertionPoint = new Point (9, 0);
+        Assert.Equal (new Point (4, 0), tv.Viewport.Location);
+        Assert.Equal (new Point (6, 0), tv.InsertionPoint);
+        Assert.Equal (new Size (9, 3), tv.GetContentSize ());
+
+        tv.NewKeyDownEvent (Key.Tab.WithShift);
+
+        Assert.Equal (new Point (1, 0), tv.Viewport.Location);
+        Assert.Equal (new Point (5, 0), tv.InsertionPoint);
+        Assert.Equal (new Size (6, 3), tv.GetContentSize ());
+    }
+
     [Fact]
     public void EnterKeyAddsLine_Setter_Should_Not_Scroll_View ()
     {