Add TableView.StarColumnResizeDelay

docs/docs/column-sizing.md

@@ -109,6 +109,16 @@ Disable resizing for a specific column:
 
 Prefer `Preview` if users report a slow or stuttery resize drag on grids with many visible rows; keep the default `Live` if you need cells to reflect the in-progress width at every instant (for example, a template column that reacts to its own width while dragging).
 
+### Star columns while the window resizes
+
+Star (`*`) columns take the width the other columns leave, so every change in the TableView's width recalculates them, and every realized cell in a star column lays out again. While the user drags the window edge that happens on every frame, which can make resizing stutter on wide or text-heavy tables. [`StarColumnResizeDelay`](xref:WinUI.TableView.TableView.StarColumnResizeDelay) makes star columns wait until the width has stopped changing for that long:
+
+```xml
+<tv:TableView StarColumnResizeDelay="0:0:0.12" />
+```
+
+During the drag, star columns keep their previous width (the table may briefly show a gap or a horizontal scroll bar), then catch up. The first layout and fixed-width columns don't wait. The default, zero, recalculates on every change.
+
 ## Row and header row heights
 
 Control row heights with the following `TableView` properties:

src/TableView.Properties.cs

@@ -308,6 +308,11 @@ public partial class TableView
     /// </summary>
     public static readonly DependencyProperty ShowFilterItemsCountProperty = DependencyProperty.Register(nameof(ShowFilterItemsCount), typeof(bool), typeof(TableView), new PropertyMetadata(false));
 
+    /// <summary>
+    /// Identifies the <see cref="StarColumnResizeDelay"/> dependency property.
+    /// </summary>
+    public static readonly DependencyProperty StarColumnResizeDelayProperty = DependencyProperty.Register(nameof(StarColumnResizeDelay), typeof(TimeSpan), typeof(TableView), new PropertyMetadata(TimeSpan.Zero));
+
 
     /// <summary>
     /// Identifies the <see cref="ForceRowOrCellSelectionOnContextRequested"/> dependency property.
@@ -412,6 +417,18 @@ public bool ShowFilterItemsCount
         set => SetValue(ShowFilterItemsCountProperty, value);
     }
 
+    /// <summary>
+    /// Gets or sets how long star-sized columns wait, after the TableView's width stops changing, before they take up
+    /// the new width. While the window is being resized, recalculating them on every frame re-lays out every realized
+    /// cell in those columns, which makes resizing stutter on wide or text-heavy tables. Zero (the default) recalculates
+    /// on every change.
+    /// </summary>
+    public TimeSpan StarColumnResizeDelay
+    {
+        get => (TimeSpan)GetValue(StarColumnResizeDelayProperty);
+        set => SetValue(StarColumnResizeDelayProperty, value);
+    }
+
     /// <summary>
     /// Gets or sets a value indicating whether the drag selection rectangle is shown during cell drag selection.
     /// </summary>

src/TableViewHeaderRow.cs

@@ -43,6 +43,7 @@ public partial class TableViewHeaderRow : Control
     private TranslateTransform? _columnDropIndicatorTransform;
     private Image? _dragHeaderImage;
     private DispatcherTimer? _desiredWidthTimer;
+    private DispatcherTimer? _starResizeTimer;
     private bool _calculatingHeaderWidths;
     private int _dropColumnIndex;
     private bool _isValidDropTarget;
@@ -760,6 +761,25 @@ public void ClearHeaders()
     /// </summary>
     private void OnTableViewSizeChanged(object sender, SizeChangedEventArgs e)
     {
+        // Resizing a star column re-lays out every realized cell in it, on every frame of a window resize. With a
+        // delay set, star widths catch up once the resize pauses; the first layout and fixed-width columns don't wait.
+        if (TableView is { StarColumnResizeDelay: { } delay } && delay > TimeSpan.Zero && e.PreviousSize.Width > 0)
+        {
+            _starResizeTimer ??= new DispatcherTimer();
+            _starResizeTimer.Interval = delay;
+            _starResizeTimer.Tick -= OnStarResizeTimerTick;
+            _starResizeTimer.Tick += OnStarResizeTimerTick;
+            _starResizeTimer.Stop();
+            _starResizeTimer.Start();
+            return;
+        }
+
+        CalculateHeaderWidths();
+    }
+
+    private void OnStarResizeTimerTick(object? sender, object e)
+    {
+        _starResizeTimer?.Stop();
         CalculateHeaderWidths();
     }