Refactor to use ColumnSpacing for cell borders

Maui.DataGrid.Sample/ViewModels/MainViewModel.cs

@@ -20,7 +20,7 @@ public MainViewModel()
         TeamColumnWidth = 70;
         SelectionMode = SelectionMode.Single;
         PageSize = 6;
-        BorderThicknessNumeric = 1;
+        BorderThicknessNumeric = 2;
 
         Commands.Add("CompleteEdit", new Command(CmdCompleteEdit));
         Commands.Add("Edit", new Command<Team>(CmdEdit));

Maui.DataGrid/DataGrid.xaml.cs

@@ -617,6 +617,7 @@ public partial class DataGrid
     private readonly WeakEventManager _refreshingEventManager = new();
     private readonly WeakEventManager _rowsBackgroundColorPaletteChangedEventManager = new();
     private readonly WeakEventManager _rowsTextColorPaletteChangedEventManager = new();
+    private readonly WeakEventManager _borderThicknessChangedEventManager = new();
 
     private readonly SortedSet<int> _pageSizeList = new(DefaultPageSizeSet);
 
@@ -685,6 +686,15 @@ internal event EventHandler RowsTextColorPaletteChanged
         remove => _rowsTextColorPaletteChangedEventManager.RemoveEventHandler(value);
     }
 
+    /// <summary>
+    /// Occurs when the BorderThickness of the DataGrid is changed.
+    /// </summary>
+    internal event EventHandler BorderThicknessChanged
+    {
+        add => _borderThicknessChangedEventManager.AddEventHandler(value);
+        remove => _borderThicknessChangedEventManager.RemoveEventHandler(value);
+    }
+
     #endregion Events
 
     #region Properties
@@ -1103,11 +1113,11 @@ private set
     #region Methods
 
     /// <summary>
-    /// Scrolls to the row.
+    /// Scrolls to the row
     /// </summary>
-    /// <param name="item">Item to scroll.</param>
-    /// <param name="position">Position of the row in screen.</param>
-    /// <param name="animated">animated.</param>
+    /// <param name="item">Item to scroll</param>
+    /// <param name="position">Position of the row in screen</param>
+    /// <param name="animated">animated</param>
     public void ScrollTo(object item, ScrollToPosition position, bool animated = true) => _collectionView.ScrollTo(item, position: position, animate: animated);
 
     internal void Initialize()
@@ -1366,11 +1376,11 @@ private IEnumerable<object> GetPaginatedItems(IEnumerable<object> unpaginatedIte
     }
 
     /// <summary>
-    /// Checks if PageSizeList contains the new PageSize value, so that it shows in the dropdown.
+    /// Checks if PageSizeList contains the new PageSize value, so that it shows in the dropdown
     /// </summary>
     private void UpdatePageSizeList()
     {
-        if (_pageSizeList.Contains(PageSize))
+        if (PageSizeList.Contains(PageSize))
         {
             return;
         }

Maui.DataGrid/DataGridCell.cs

@@ -23,22 +23,6 @@ internal DataGridCell(View cellContent, Color? backgroundColor, DataGridColumn c
 
     public bool IsEditing { get; }
 
-    internal void UpdateBindings(DataGrid dataGrid, bool bordersVisible = true)
-    {
-        if (bordersVisible)
-        {
-            SetBinding(BackgroundColorProperty, new Binding(nameof(DataGrid.BorderColor), source: dataGrid));
-            SetBinding(PaddingProperty, new Binding(nameof(DataGrid.BorderThickness), source: dataGrid));
-        }
-        else
-        {
-            RemoveBinding(BackgroundColorProperty);
-            RemoveBinding(PaddingProperty);
-
-            Padding = 0;
-        }
-    }
-
     internal void UpdateCellBackgroundColor(Color? bgColor)
     {
         foreach (var child in Children)

Maui.DataGrid/DataGridHeaderRow.cs

@@ -47,6 +47,8 @@ internal void InitializeHeaderRow(bool force = false)
 
         Children.Clear();
 
+        UpdateBorders();
+
         if (DataGrid.Columns == null || DataGrid.Columns.Count == 0)
         {
             ColumnDefinitions.Clear();
@@ -77,8 +79,6 @@ internal void InitializeHeaderRow(bool force = false)
 
             col.HeaderCell ??= CreateHeaderCell(col);
 
-            col.HeaderCell.UpdateBindings(DataGrid, DataGrid.HeaderBordersVisible);
-
             if (Children.TryGetItem(i, out var existingChild))
             {
                 if (existingChild is not DataGridCell existingCell)
@@ -103,6 +103,29 @@ internal void InitializeHeaderRow(bool force = false)
         ColumnDefinitions.RemoveAfter(DataGrid.Columns.Count);
     }
 
+    private void UpdateBorders()
+    {
+        // This approach is a hack to avoid needing a slow Border control.
+        // The padding constitutes the cell's border thickness.
+        // And the BackgroundColor constitutes the border color of the cell.
+        if (DataGrid.HeaderBordersVisible)
+        {
+            var borderSize = DataGrid.BorderThickness;
+            ColumnSpacing = borderSize.Left;
+            Padding = new(0, borderSize.Top / 2, 0, borderSize.Bottom / 2);
+        }
+        else
+        {
+            ColumnSpacing = 0;
+            Padding = 0;
+        }
+    }
+
+    private void OnBorderThicknessChanged(object? sender, EventArgs e)
+    {
+        UpdateBorders();
+    }
+
     /// <inheritdoc/>
     protected override void OnBindingContextChanged()
     {
@@ -118,6 +141,7 @@ protected override void OnParentSet()
         if (Parent == null)
         {
             DataGrid.Columns.CollectionChanged -= OnColumnsChanged;
+            DataGrid.BorderThicknessChanged -= OnBorderThicknessChanged;
 
             foreach (var column in DataGrid.Columns)
             {
@@ -127,11 +151,14 @@ protected override void OnParentSet()
         else
         {
             DataGrid.Columns.CollectionChanged += OnColumnsChanged;
+            DataGrid.BorderThicknessChanged += OnBorderThicknessChanged;
 
             foreach (var column in DataGrid.Columns)
             {
                 column.VisibilityChanged += OnVisibilityChanged;
             }
+
+            SetBinding(BackgroundColorProperty, new Binding(nameof(DataGrid.BorderColor), source: DataGrid));
         }
     }
 

Maui.DataGrid/DataGridRow.cs

@@ -116,6 +116,7 @@ protected override void OnBindingContextChanged()
         InitializeRow();
     }
 
+
     /// <inheritdoc/>
     protected override void OnParentSet()
     {
@@ -127,6 +128,7 @@ protected override void OnParentSet()
             DataGrid.Columns.CollectionChanged -= OnColumnsChanged;
             DataGrid.RowsBackgroundColorPaletteChanged -= OnRowsBackgroundColorPaletteChanged;
             DataGrid.RowsTextColorPaletteChanged -= OnRowsTextColorPaletteChanged;
+            DataGrid.BorderThicknessChanged -= OnBorderThicknessChanged;
 
             foreach (var column in DataGrid.Columns)
             {
@@ -139,11 +141,14 @@ protected override void OnParentSet()
             DataGrid.Columns.CollectionChanged += OnColumnsChanged;
             DataGrid.RowsBackgroundColorPaletteChanged += OnRowsBackgroundColorPaletteChanged;
             DataGrid.RowsTextColorPaletteChanged += OnRowsTextColorPaletteChanged;
+            DataGrid.BorderThicknessChanged += OnBorderThicknessChanged;
 
             foreach (var column in DataGrid.Columns)
             {
                 column.VisibilityChanged += OnVisibilityChanged;
             }
+
+            SetBinding(BackgroundColorProperty, new Binding(nameof(DataGrid.BorderColor), source: DataGrid));
         }
     }
 
@@ -161,6 +166,8 @@ private void InitializeRow()
 
         UpdateColors();
 
+        UpdateBorders();
+
         var columns = DataGrid.Columns;
 
         if (columns == null || columns.Count == 0)
@@ -218,8 +225,6 @@ private DataGridCell GenerateCellForColumn(DataGridColumn col, int columnIndex)
     {
         var dataGridCell = CreateCell(col);
 
-        dataGridCell.UpdateBindings(DataGrid);
-
         SetColumn((BindableObject)dataGridCell, columnIndex);
 
         return dataGridCell;
@@ -409,6 +414,16 @@ private DatePicker GenerateDateTimeEditCell(DataGridColumn col)
         return datePicker;
     }
 
+    private void UpdateBorders()
+    {
+        // This approach is a hack to avoid needing a slow Border control.
+        // The padding constitutes the cell's border thickness.
+        // And the BackgroundColor constitutes the border color of the cell.
+        var borderSize = DataGrid.BorderThickness;
+        ColumnSpacing = borderSize.Left;
+        Padding = new(0, borderSize.Top / 2, 0, borderSize.Bottom / 2);
+    }
+
     private void UpdateColors()
     {
         var rowIndex = DataGrid.InternalItems.IndexOf(BindingContext);
@@ -428,6 +443,11 @@ private void UpdateColors()
                 : DataGrid.RowsTextColorPalette.GetColor(rowIndex, BindingContext);
     }
 
+    private void OnBorderThicknessChanged(object? sender, EventArgs e)
+    {
+        UpdateBorders();
+    }
+
     private void OnRowsTextColorPaletteChanged(object? sender, EventArgs e)
     {
         UpdateColors();