Review DataGrid.Rows

2026-10-28 23:08:36 +08:00 · 2025-05-25 14:24:09 +08:00
parent 974b66106f
commit d769dc43ac
3 changed files with 458 additions and 448 deletions
@@ -2,6 +2,7 @@ using System.ComponentModel.DataAnnotations;
 using System.Diagnostics;
 using System.Reflection;
 using AtomUI.Controls.Collections;
+using AtomUI.Utils;
 using Avalonia.Controls;
 using Avalonia.Data;
 using Avalonia.Layout;
@@ -154,7 +155,7 @@ public partial class DataGrid
            }
            else
            {
-                return DataConnection!.GetPropertyIsReadOnly(path) || isReadOnly;
+                return DataConnection.GetPropertyIsReadOnly(path) || isReadOnly;
            }
        }

@@ -203,7 +204,7 @@ public partial class DataGrid
        RemoveDisplayedColumnHeaders();

        _horizontalOffset = _negHorizontalOffset = 0;
-        if (_hScrollBar != null && _hScrollBar.IsVisible) // 
+        if (_hScrollBar != null && _hScrollBar.IsVisible)
        {
            _hScrollBar.Value = 0;
        }
@@ -253,7 +254,7 @@ public partial class DataGrid
    internal void OnColumnDisplayIndexChanged(DataGridColumn dataGridColumn)
    {
        Debug.Assert(dataGridColumn != null);
-        DataGridColumnEventArgs e = new DataGridColumnEventArgs(dataGridColumn);
+        var e = new DataGridColumnEventArgs(dataGridColumn);

        // Call protected method to raise event
        if (dataGridColumn != ColumnsInternal.RowGroupSpacerColumn)
@@ -290,7 +291,7 @@ public partial class DataGrid
        {
            InDisplayIndexAdjustments = true;

-            bool trackChange = targetColumn != ColumnsInternal.RowGroupSpacerColumn;
+            var trackChange = targetColumn != ColumnsInternal.RowGroupSpacerColumn;

            DataGridColumn? column;
            // Move is legal - let's adjust the affected display indexes.
@@ -360,9 +361,9 @@ public partial class DataGrid
    {
        Debug.Assert(column != null);

-        if (column.IsVisible && oldValue != column.ActualMaxWidth)
+        if (column.IsVisible && !MathUtils.AreClose(oldValue, column.ActualMaxWidth))
        {
-            DataGridLength oldWitdh = new(oldValue, column.Width.UnitType, column.Width.DesiredValue,
+            DataGridLength oldWidth = new(oldValue, column.Width.UnitType, column.Width.DesiredValue,
                column.Width.DesiredValue);
            if (column.ActualMaxWidth < column.Width.DisplayValue)
            {
@@ -372,11 +373,11 @@ public partial class DataGrid
                AdjustColumnWidths(column.DisplayIndex + 1, column.Width.DisplayValue - column.ActualMaxWidth, false);
                column.SetWidthDisplayValue(column.ActualMaxWidth);
            }
-            else if (column.Width.DisplayValue == oldValue && column.Width.DesiredValue > column.Width.DisplayValue)
+            else if (MathUtils.AreClose(column.Width.DisplayValue, oldValue) && column.Width.DesiredValue > column.Width.DisplayValue)
            {
                // If the column was previously limited by its maximum value but has more room now, 
                // attempt to resize the column to its desired width.
-                column.Resize(oldWitdh,
+                column.Resize(oldWidth,
                    new(column.Width.Value, column.Width.UnitType, column.Width.DesiredValue,
                        column.Width.DesiredValue),
                    false);
@@ -395,9 +396,9 @@ public partial class DataGrid
    {
        Debug.Assert(column != null);

-        if (column.IsVisible && oldValue != column.ActualMinWidth)
+        if (column.IsVisible && !MathUtils.AreClose(oldValue, column.ActualMinWidth))
        {
-            DataGridLength oldWitdh = new(oldValue, column.Width.UnitType, column.Width.DesiredValue,
+            DataGridLength oldWidth = new(oldValue, column.Width.UnitType, column.Width.DesiredValue,
                column.Width.DesiredValue);
            if (column.ActualMinWidth > column.Width.DisplayValue)
            {
@@ -407,11 +408,11 @@ public partial class DataGrid
                AdjustColumnWidths(column.DisplayIndex + 1, column.Width.DisplayValue - column.ActualMinWidth, false);
                column.SetWidthDisplayValue(column.ActualMinWidth);
            }
-            else if (column.Width.DisplayValue == oldValue && column.Width.DesiredValue < column.Width.DisplayValue)
+            else if (MathUtils.AreClose(column.Width.DisplayValue, oldValue) && column.Width.DesiredValue < column.Width.DisplayValue)
            {
                // If the column was previously limited by its minimum value but but can be smaller now, 
                // attempt to resize the column to its desired width.
-                column.Resize(oldWitdh,
+                column.Resize(oldWidth,
                    new(column.Width.Value, column.Width.UnitType, column.Width.DesiredValue,
                        column.Width.DesiredValue),
                    false);
@@ -506,8 +507,8 @@ public partial class DataGrid

    internal void OnFillerColumnWidthNeeded(double finalWidth)
    {
-        DataGridFillerColumn fillerColumn      = ColumnsInternal.FillerColumn;
-        double               totalColumnsWidth = ColumnsInternal.VisibleEdgedColumnsWidth;
+        var fillerColumn      = ColumnsInternal.FillerColumn;
+        var totalColumnsWidth = ColumnsInternal.VisibleEdgedColumnsWidth;
        if (finalWidth - totalColumnsWidth > LayoutHelper.LayoutEpsilon)
        {
            fillerColumn.FillerWidth = finalWidth - totalColumnsWidth;
@@ -552,7 +553,7 @@ public partial class DataGrid
        // Insert the missing data cells
        if (SlotCount > 0)
        {
-            int newColumnCount = ColumnsItemsInternal.Count;
+            var newColumnCount = ColumnsItemsInternal.Count;

            foreach (DataGridRow row in GetAllRows())
            {
@@ -658,16 +659,15 @@ public partial class DataGrid
        DataGridCellCoordinates newCurrentCellCoordinates;

        _temporarilyResetCurrentCell = false;
-        int columnIndex = dataGridColumn.Index;
+        var columnIndex = dataGridColumn.Index;

        // Reset the current cell's address if there is one.
        if (CurrentColumnIndex != -1)
        {
-            int newCurrentColumnIndex = CurrentColumnIndex;
+            var newCurrentColumnIndex = CurrentColumnIndex;
            if (columnIndex == newCurrentColumnIndex)
            {
-                DataGridColumn? dataGridColumnNext =
-                    ColumnsInternal.GetNextVisibleColumn(ColumnsItemsInternal[columnIndex]);
+                var dataGridColumnNext = ColumnsInternal.GetNextVisibleColumn(ColumnsItemsInternal[columnIndex]);
                if (dataGridColumnNext != null)
                {
                    if (dataGridColumnNext.Index > columnIndex)
@@ -681,8 +681,7 @@ public partial class DataGrid
                }
                else
                {
-                    DataGridColumn? dataGridColumnPrevious =
-                        ColumnsInternal.GetPreviousVisibleNonFillerColumn(ColumnsItemsInternal[columnIndex]);
+                    var dataGridColumnPrevious = ColumnsInternal.GetPreviousVisibleNonFillerColumn(ColumnsItemsInternal[columnIndex]);
                    if (dataGridColumnPrevious != null)
                    {
                        if (dataGridColumnPrevious.Index > columnIndex)
@@ -715,7 +714,7 @@ public partial class DataGrid
                    CancelEdit(DataGridEditingUnit.Row, false /*raiseEvents*/);
                }

-                bool success = SetCurrentCellCore(-1, -1);
+                var success = SetCurrentCellCore(-1, -1);
                Debug.Assert(success);
            }
            else
@@ -775,7 +774,7 @@ public partial class DataGrid
        Debug.Assert(dataGridColumn != null);

        // Take care of the non-displayed loaded rows
-        for (int index = 0; index < _loadedRows.Count;)
+        for (var index = 0; index < _loadedRows.Count;)
        {
            DataGridRow dataGridRow = _loadedRows[index];
            Debug.Assert(dataGridRow != null);
@@ -812,20 +811,20 @@ public partial class DataGrid
    /// <returns>The remaining amount of adjustment.</returns>
    private double AdjustStarColumnWidths(int displayIndex, double adjustment, bool userInitiated)
    {
-        double remainingAdjustment = adjustment;
+        var remainingAdjustment = adjustment;
        if (MathUtilities.IsZero(remainingAdjustment))
        {
            return remainingAdjustment;
        }

-        bool increase = remainingAdjustment > 0;
+        var increase = remainingAdjustment > 0;

        // Make an initial pass through the star columns to total up some values.
-        bool                 scaleStarWeights           = false;
-        double               totalStarColumnsWidth      = 0;
-        double               totalStarColumnsWidthLimit = 0;
-        double               totalStarWeights           = 0;
-        List<DataGridColumn> starColumns                = new List<DataGridColumn>();
+        var scaleStarWeights           = false;
+        var totalStarColumnsWidth      = 0d;
+        var totalStarColumnsWidthLimit = 0d;
+        var totalStarWeights           = 0d;
+        var starColumns                = new List<DataGridColumn>();
        foreach (DataGridColumn column in ColumnsInternal.GetDisplayedColumns(c =>
                     c.Width.IsStar && c.IsVisible && (c.ActualCanUserResize || !userInitiated)))
        {
@@ -843,7 +842,7 @@ public partial class DataGrid

        // Set the new desired widths according to how much all the star columns can be adjusted without any
        // of them being limited by their minimum or maximum widths (as that would distort their ratios).
-        double adjustmentLimit = totalStarColumnsWidthLimit - totalStarColumnsWidth;
+        var adjustmentLimit = totalStarColumnsWidthLimit - totalStarColumnsWidth;
        adjustmentLimit = increase ? Math.Min(adjustmentLimit, adjustment) : Math.Max(adjustmentLimit, adjustment);
        foreach (DataGridColumn starColumn in starColumns)
        {
@@ -891,10 +890,10 @@ public partial class DataGrid
            return remainingAdjustment;
        }

-        bool increase = remainingAdjustment > 0;
+        var increase = remainingAdjustment > 0;

-        double totalStarWeights      = 0;
-        double totalStarColumnsWidth = 0;
+        var totalStarWeights      = 0d;
+        var totalStarColumnsWidth = 0d;

        // Order the star columns according to which one will hit their target width (or min/max limit) first.
        // Each KeyValuePair represents a column (as the key) and an ordering factor (as the value).  The ordering factor
@@ -931,9 +930,9 @@ public partial class DataGrid
        // or the total remaining amount to adjust has been depleted.
        foreach (KeyValuePair<DataGridColumn, double> starColumnPair in starColumnPairs)
        {
-            double distanceToTarget  = starColumnPair.Value * starColumnPair.Key.Width.Value;
-            double distanceAvailable = (starColumnPair.Key.Width.Value * remainingAdjustment) / totalStarWeights;
-            double adjustment = increase
+            var distanceToTarget  = starColumnPair.Value * starColumnPair.Key.Width.Value;
+            var distanceAvailable = (starColumnPair.Key.Width.Value * remainingAdjustment) / totalStarWeights;
+            var adjustment = increase
                ? Math.Min(distanceToTarget, distanceAvailable)
                : Math.Max(distanceToTarget, distanceAvailable);

@@ -948,13 +947,13 @@ public partial class DataGrid

    private bool ComputeDisplayedColumns()
    {
-        bool   invalidate                 = false;
-        int    numVisibleScrollingCols    = 0;
-        int    visibleScrollingColumnsTmp = 0;
-        double displayWidth               = CellsWidth;
-        double cx                         = 0;
-        int    firstDisplayedFrozenCol    = -1;
-        int    firstDisplayedScrollingCol = DisplayData.FirstDisplayedScrollingCol;
+        var invalidate                 = false;
+        var numVisibleScrollingCols    = 0;
+        var visibleScrollingColumnsTmp = 0;
+        var displayWidth               = CellsWidth;
+        var cx                         = 0d;
+        var firstDisplayedFrozenCol    = -1;
+        var firstDisplayedScrollingCol = DisplayData.FirstDisplayedScrollingCol;

        // the same problem with negative numbers:
        // if the width passed in is negative, then return 0
@@ -965,7 +964,7 @@ public partial class DataGrid
            return invalidate;
        }

-        foreach (DataGridColumn dataGridColumn in ColumnsInternal.GetVisibleFrozenColumns())
+        foreach (var dataGridColumn in ColumnsInternal.GetVisibleFrozenColumns())
        {
            if (firstDisplayedFrozenCol == -1)
            {
@@ -983,7 +982,7 @@ public partial class DataGrid

        if (cx < displayWidth && firstDisplayedScrollingCol >= 0)
        {
-            DataGridColumn? dataGridColumn = ColumnsItemsInternal[firstDisplayedScrollingCol];
+            var dataGridColumn = ColumnsItemsInternal[firstDisplayedScrollingCol];
            if (dataGridColumn.IsFrozen)
            {
                dataGridColumn       = ColumnsInternal.FirstVisibleScrollingColumn;
@@ -1075,7 +1074,7 @@ public partial class DataGrid
                    visibleScrollingColumnsTmp++;
                    invalidate = true;
                    cx         = displayWidth;
-                    Debug.Assert(_negHorizontalOffset == GetNegHorizontalOffsetFromHorizontalOffset(_horizontalOffset));
+                    Debug.Assert(MathUtils.AreClose(_negHorizontalOffset, GetNegHorizontalOffsetFromHorizontalOffset(_horizontalOffset)));
                }

                // update the number of visible columns to the new reality
@@ -1159,7 +1158,7 @@ public partial class DataGrid
            }
            else
            {
-                if (_negHorizontalOffset != _horizontalOffset)
+                if (!MathUtils.AreClose(_negHorizontalOffset, _horizontalOffset))
                {
                    _negHorizontalOffset = 0;
                }
@@ -1236,7 +1235,7 @@ public partial class DataGrid
            // The DisplayIndex of columns greater than the inserted column need to be incremented,
            // as do the DisplayIndexMap values of modified column Indexes
            DataGridColumn? column;
-            for (int displayIndex = 0; displayIndex < ColumnsInternal.DisplayIndexMap.Count; displayIndex++)
+            for (var displayIndex = 0; displayIndex < ColumnsInternal.DisplayIndexMap.Count; displayIndex++)
            {
                if (ColumnsInternal.DisplayIndexMap[displayIndex] >= insertedColumn.Index)
                {
@@ -1265,10 +1264,10 @@ public partial class DataGrid

    private void CorrectColumnFrozenStates()
    {
-        int    index                = 0;
-        double frozenColumnWidth    = 0;
-        double oldFrozenColumnWidth = 0;
-        foreach (DataGridColumn column in ColumnsInternal.GetDisplayedColumns())
+        var index                = 0;
+        var frozenColumnWidth    = 0d;
+        var oldFrozenColumnWidth = 0d;
+        foreach (var column in ColumnsInternal.GetDisplayedColumns())
        {
            if (column.IsFrozen)
            {
@@ -1335,7 +1334,7 @@ public partial class DataGrid
            return amount;
        }

-        double adjustment = Math.Max(
+        var adjustment = Math.Max(
            column.ActualMinWidth - column.Width.DisplayValue,
            Math.Max(targetWidth - column.Width.DisplayValue, amount));

@@ -1363,7 +1362,7 @@ public partial class DataGrid
            return amount;
        }

-        foreach (DataGridColumn column in ColumnsInternal.GetDisplayedColumns(reverse,
+        foreach (var column in ColumnsInternal.GetDisplayedColumns(reverse,
                     column =>
                         column.IsVisible &&
                         column.Width.UnitType != DataGridLengthUnitType.Star &&
@@ -1383,7 +1382,7 @@ public partial class DataGrid

    private void FlushDisplayIndexChanged(bool raiseEvent)
    {
-        foreach (DataGridColumn column in ColumnsItemsInternal)
+        foreach (var column in ColumnsItemsInternal)
        {
            if (column.DisplayIndexHasChanged)
            {
@@ -1415,7 +1414,7 @@ public partial class DataGrid
        Debug.Assert(ColumnsItemsInternal[index].IsVisible);

        double x = 0;
-        foreach (DataGridColumn column in ColumnsInternal.GetVisibleColumns())
+        foreach (var column in ColumnsInternal.GetVisibleColumns())
        {
            if (index == column.Index)
            {
@@ -1430,7 +1429,7 @@ public partial class DataGrid

    private double GetNegHorizontalOffsetFromHorizontalOffset(double horizontalOffset)
    {
-        foreach (DataGridColumn column in ColumnsInternal.GetVisibleScrollingColumns())
+        foreach (var column in ColumnsInternal.GetVisibleScrollingColumns())
        {
            if (GetEdgedColumnWidth(column) > horizontalOffset)
            {
@@ -1462,7 +1461,7 @@ public partial class DataGrid
            return amount;
        }

-        double adjustment = Math.Min(
+        var adjustment = Math.Min(
            column.ActualMaxWidth - column.Width.DisplayValue,
            Math.Min(targetWidth - column.Width.DisplayValue, amount));

@@ -1490,7 +1489,7 @@ public partial class DataGrid
            return amount;
        }

-        foreach (DataGridColumn column in ColumnsInternal.GetDisplayedColumns(reverse,
+        foreach (var column in ColumnsInternal.GetDisplayedColumns(reverse,
                     column =>
                         column.IsVisible &&
                         column.Width.UnitType != DataGridLengthUnitType.Star &&
@@ -1534,7 +1533,7 @@ public partial class DataGrid

    private void RemoveAutoGeneratedColumns()
    {
-        int index = 0;
+        var index = 0;
        _autoGeneratingColumnOperationCount++;
        try
        {
@@ -1589,15 +1588,15 @@ public partial class DataGrid
                     (DisplayData.LastTotallyDisplayedScrollingCol != columnIndex &&
                      ColumnsInternal.DisplayInOrder(DisplayData.LastTotallyDisplayedScrollingCol, columnIndex)))
            {
-                double xColumnLeftEdge  = GetColumnXFromIndex(columnIndex);
-                double xColumnRightEdge = xColumnLeftEdge + GetEdgedColumnWidth(ColumnsItemsInternal[columnIndex]);
-                double change           = xColumnRightEdge - HorizontalOffset - CellsWidth;
-                double widthRemaining   = change;
+                var xColumnLeftEdge  = GetColumnXFromIndex(columnIndex);
+                var xColumnRightEdge = xColumnLeftEdge + GetEdgedColumnWidth(ColumnsItemsInternal[columnIndex]);
+                var change           = xColumnRightEdge - HorizontalOffset - CellsWidth;
+                var widthRemaining   = change;

-                DataGridColumn newFirstDisplayedScrollingCol =
+                var newFirstDisplayedScrollingCol =
                    ColumnsItemsInternal[DisplayData.FirstDisplayedScrollingCol];
-                DataGridColumn? nextColumn = ColumnsInternal.GetNextVisibleColumn(newFirstDisplayedScrollingCol);
-                double newColumnWidth = GetEdgedColumnWidth(newFirstDisplayedScrollingCol) - _negHorizontalOffset;
+                var nextColumn = ColumnsInternal.GetNextVisibleColumn(newFirstDisplayedScrollingCol);
+                var newColumnWidth = GetEdgedColumnWidth(newFirstDisplayedScrollingCol) - _negHorizontalOffset;
                while (nextColumn != null && widthRemaining >= newColumnWidth)
                {
                    widthRemaining                -= newColumnWidth;
@@ -1639,7 +1638,7 @@ public partial class DataGrid
    {
        DataGridColumn? newFirstVisibleScrollingCol = null;
        DataGridColumn? dataGridColumnTmp;
-        int            colCount = 0;
+        var             colCount = 0;
        if (columns > 0)
        {
            if (DisplayData.LastTotallyDisplayedScrollingCol >= 0)
@@ -1767,36 +1766,35 @@ public partial class DataGrid
        // Autogenerated Columns are added at the end so the user columns appear first
        if (DataConnection!.DataProperties != null && DataConnection.DataProperties.Length > 0)
        {
-            List<KeyValuePair<int, DataGridAutoGeneratingColumnEventArgs>> columnOrderPairs =
-                new List<KeyValuePair<int, DataGridAutoGeneratingColumnEventArgs>>();
+            var columnOrderPairs = new List<KeyValuePair<int, DataGridAutoGeneratingColumnEventArgs>>();

            // Generate the columns
            foreach (PropertyInfo propertyInfo in DataConnection.DataProperties)
            {
-                string columnHeader = propertyInfo.Name;
-                int    columnOrder  = DefaultColumnDisplayOrder;
+                var columnHeader = propertyInfo.Name;
+                var columnOrder  = DefaultColumnDisplayOrder;

                // Check if DisplayAttribute is defined on the property
-                object[] attributes = propertyInfo.GetCustomAttributes(typeof(DisplayAttribute), true);
-                if (attributes != null && attributes.Length > 0)
+                var attributes = propertyInfo.GetCustomAttributes(typeof(DisplayAttribute), true);
+                if (attributes.Length > 0)
                {
-                    DisplayAttribute? displayAttribute = attributes[0] as DisplayAttribute;
+                    var displayAttribute = attributes[0] as DisplayAttribute;
                    Debug.Assert(displayAttribute != null);

-                    bool? autoGenerateField = displayAttribute.GetAutoGenerateField();
+                    var autoGenerateField = displayAttribute.GetAutoGenerateField();
                    if (autoGenerateField.HasValue && autoGenerateField.Value == false)
                    {
                        // Abort column generation because we aren't supposed to auto-generate this field
                        continue;
                    }

-                    string? header = displayAttribute.GetShortName();
+                    var header = displayAttribute.GetShortName();
                    if (header != null)
                    {
                        columnHeader = header;
                    }

-                    int? order = displayAttribute.GetOrder();
+                    var order = displayAttribute.GetOrder();
                    if (order.HasValue)
                    {
                        columnOrder = order.Value;
@@ -1804,7 +1802,7 @@ public partial class DataGrid
                }

                // Generate a single column and determine its relative order
-                int insertIndex = 0;
+                var insertIndex = 0;
                if (columnOrder == int.MaxValue)
                {
                    insertIndex = columnOrderPairs.Count;
@@ -1845,7 +1843,7 @@ public partial class DataGrid
                                                                        string header)
    {
        // Create a new DataBoundColumn for the Property
-        DataGridBoundColumn newColumn = GetDataGridColumnFromType(propertyType);
+        var newColumn = GetDataGridColumnFromType(propertyType);
        newColumn.Binding         = new Binding(propertyName);
        newColumn.Header          = header;
        newColumn.IsAutoGenerated = true;
@@ -1856,22 +1854,15 @@ public partial class DataGrid
    {
        // Raise the AutoGeneratingColumn event in case the user wants to Cancel or Replace the
        // column being generated
-        OnAutoGeneratingColumn(e);
+        HandleAutoGeneratingColumn(e);
        if (e.Cancel)
        {
            return false;
        }
-        else
-        {
-            if (e.Column != null)
-            {
-                // Set the IsAutoGenerated flag here in case the user provides a custom autogenerated column
-                e.Column.IsAutoGenerated = true;
-            }
-
-            ColumnsInternal.Add(e.Column!);
-            ColumnsInternal.AutogeneratedColumnCount++;
-            return true;
-        }
+        // Set the IsAutoGenerated flag here in case the user provides a custom autogenerated column
+        e.Column.IsAutoGenerated = true;
+        ColumnsInternal.Add(e.Column);
+        ColumnsInternal.AutogeneratedColumnCount++;
+        return true;
    }
 }
@@ -342,13 +342,13 @@ public partial class DataGrid : TemplatedControl
        set => SetValue(HeadersVisibilityProperty, value);
    }

-    public static readonly StyledProperty<IBrush> HorizontalGridLinesBrushProperty =
-        AvaloniaProperty.Register<DataGrid, IBrush>(nameof(HorizontalGridLinesBrush));
+    public static readonly StyledProperty<IBrush?> HorizontalGridLinesBrushProperty =
+        AvaloniaProperty.Register<DataGrid, IBrush?>(nameof(HorizontalGridLinesBrush));

    /// <summary>
    /// Gets or sets the <see cref="T:System.Windows.Media.Brush" /> that is used to paint grid lines separating rows.
    /// </summary>
-    public IBrush HorizontalGridLinesBrush
+    public IBrush? HorizontalGridLinesBrush
    {
        get => GetValue(HorizontalGridLinesBrushProperty);
        set => SetValue(HorizontalGridLinesBrushProperty, value);
@@ -555,13 +555,13 @@ public partial class DataGrid : TemplatedControl
        set => SetValue(SelectionModeProperty, value);
    }

-    public static readonly StyledProperty<IBrush> VerticalGridLinesBrushProperty =
-        AvaloniaProperty.Register<DataGrid, IBrush>(nameof(VerticalGridLinesBrush));
+    public static readonly StyledProperty<IBrush?> VerticalGridLinesBrushProperty =
+        AvaloniaProperty.Register<DataGrid, IBrush?>(nameof(VerticalGridLinesBrush));

    /// <summary>
    /// Gets or sets the <see cref="T:System.Windows.Media.Brush" /> that is used to paint grid lines separating columns.
    /// </summary>
-    public IBrush VerticalGridLinesBrush
+    public IBrush? VerticalGridLinesBrush
    {
        get => GetValue(VerticalGridLinesBrushProperty);
        set => SetValue(VerticalGridLinesBrushProperty, value);
@@ -697,13 +697,13 @@ public partial class DataGrid : TemplatedControl
        set => SetValue(AreRowDetailsFrozenProperty, value);
    }

-    public static readonly StyledProperty<IDataTemplate> RowDetailsTemplateProperty =
-        AvaloniaProperty.Register<DataGrid, IDataTemplate>(nameof(RowDetailsTemplate));
+    public static readonly StyledProperty<IDataTemplate?> RowDetailsTemplateProperty =
+        AvaloniaProperty.Register<DataGrid, IDataTemplate?>(nameof(RowDetailsTemplate));

    /// <summary>
    /// Gets or sets the template that is used to display the content of the details section of rows.
    /// </summary>
-    public IDataTemplate RowDetailsTemplate
+    public IDataTemplate? RowDetailsTemplate
    {
        get => GetValue(RowDetailsTemplateProperty);
        set => SetValue(RowDetailsTemplateProperty, value);
@@ -1835,7 +1835,7 @@ public partial class DataGrid : TemplatedControl
    /// </summary>
    /// <param name="editingEventArgs">Provides information about the user gesture that caused the call to BeginEdit. Can be null.</param>
    /// <returns>True if operation was successful. False otherwise.</returns>
-    public bool BeginEdit(RoutedEventArgs? editingEventArgs = null)
+    public bool BeginEdit(RoutedEventArgs editingEventArgs)
    {
        if (CurrentColumnIndex == -1 || !GetRowSelection(CurrentSlot))
        {
@@ -1909,11 +1909,11 @@ public partial class DataGrid : TemplatedControl
            return;
        }

-        if (item == null)
+        if (item == null && column is not null)
        {
            // scroll column into view
            ScrollSlotIntoView(
-                column!.Index,
+                column.Index,
                DisplayData.FirstScrollingSlot,
                forCurrentCellChange: false,
                forceHorizontalScroll: true);
@@ -2463,7 +2463,7 @@ public partial class DataGrid : TemplatedControl

        if (selectedItem != null)
        {
-            newIndex = DataConnection!.IndexOf(selectedItem);
+            newIndex = DataConnection.IndexOf(selectedItem);
        }

        SetValueNoCallback(SelectedIndexProperty, newIndex);
@@ -2604,13 +2604,18 @@ public partial class DataGrid : TemplatedControl
        _horizontalScrollChangesIgnored++;
        try
        {
-            if (scrollBarValueDifference != 0)
+            // TODO 这样兼容不知道是否合适
+            if (_hScrollBar is not null)
            {
-                Debug.Assert(_horizontalOffset + scrollBarValueDifference >= 0);
-                _hScrollBar!.Value = _horizontalOffset + scrollBarValueDifference;
+                if (scrollBarValueDifference != 0)
+                {
+                    Debug.Assert(_horizontalOffset + scrollBarValueDifference >= 0);
+                    _hScrollBar.Value = _horizontalOffset + scrollBarValueDifference;
+                }
+
+                UpdateHorizontalOffset(_hScrollBar.Value);
            }

-            UpdateHorizontalOffset(_hScrollBar!.Value);
        }
        finally
        {
@@ -2668,7 +2673,7 @@ public partial class DataGrid : TemplatedControl
            }
            else
            {
-                slot = SlotFromRowIndex(DataConnection!.IndexOf(item));
+                slot = SlotFromRowIndex(DataConnection.IndexOf(item));
            }

            if (slot == -1)
@@ -2768,12 +2773,12 @@ public partial class DataGrid : TemplatedControl
    //internal void ProcessVerticalScroll(double oldValue, double newValue)
    internal void ProcessVerticalScroll(ScrollEventType scrollEventType)
    {
-        if (_verticalScrollChangesIgnored > 0)
+        if (_verticalScrollChangesIgnored > 0 || _vScrollBar is null)
        {
            return;
        }
-
-        Debug.Assert(MathUtilities.LessThanOrClose(_vScrollBar!.Value, _vScrollBar.Maximum));
+        
+        Debug.Assert(MathUtilities.LessThanOrClose(_vScrollBar.Value, _vScrollBar.Maximum));

        _verticalScrollChangesIgnored++;
        try
@@ -2848,7 +2853,7 @@ public partial class DataGrid : TemplatedControl
                    //We don't need to refresh the state of AutoGenerated column headers because they're up-to-date
                    if (!column.IsAutoGenerated && column.HasHeaderCell)
                    {
-                        column.HeaderCell!.UpdatePseudoClasses();
+                        column.HeaderCell?.UpdatePseudoClasses();
                    }
                }

@@ -2961,18 +2966,19 @@ public partial class DataGrid : TemplatedControl
                return false;
            }

-            int     newCurrentPosition = -1;
-            object? item               = ItemFromSlot(slot, ref newCurrentPosition);
+            int newCurrentPosition = -1;
+            var item               = ItemFromSlot(slot, ref newCurrentPosition);

            if (EditingRow != null && slot != EditingRow.Slot && !CommitEdit(DataGridEditingUnit.Row, true))
            {
                return false;
            }

-            if (DataConnection!.CollectionView != null &&
-                DataConnection.CollectionView.CurrentPosition != newCurrentPosition)
+            if (DataConnection.CollectionView != null &&
+                DataConnection.CollectionView.CurrentPosition != newCurrentPosition &&
+                item is not null)
            {
-                DataConnection.MoveCurrentTo(item!, slot, columnIndex, action, scrollIntoView);
+                DataConnection.MoveCurrentTo(item, slot, columnIndex, action, scrollIntoView);
            }
            else
            {
@@ -3227,7 +3233,7 @@ public partial class DataGrid : TemplatedControl
        row.Cells.Insert(column.Index, newCell);
    }

-    private bool BeginCellEdit(RoutedEventArgs? editingEventArgs)
+    private bool BeginCellEdit(RoutedEventArgs editingEventArgs)
    {
        if (CurrentColumnIndex == -1 || !GetRowSelection(CurrentSlot))
        {
@@ -3239,8 +3245,9 @@ public partial class DataGrid : TemplatedControl
        Debug.Assert(CurrentSlot >= -1);
        Debug.Assert(CurrentSlot < SlotCount);
        Debug.Assert(EditingRow == null || EditingRow.Slot == CurrentSlot);
-        Debug.Assert(!GetColumnEffectiveReadOnlyState(CurrentColumn!));
-        Debug.Assert(CurrentColumn!.IsVisible);
+        Debug.Assert(CurrentColumn is not null);
+        Debug.Assert(!GetColumnEffectiveReadOnlyState(CurrentColumn));
+        Debug.Assert(CurrentColumn.IsVisible);

        if (_editingColumnIndex != -1)
        {
@@ -3272,7 +3279,7 @@ public partial class DataGrid : TemplatedControl

        // Raise the BeginningEdit event
        var dataGridCell = dataGridRow.Cells[CurrentColumnIndex];
-        var e = new DataGridBeginningEditEventArgs(CurrentColumn, dataGridRow, editingEventArgs!);
+        var e = new DataGridBeginningEditEventArgs(CurrentColumn, dataGridRow, editingEventArgs);
        HandleBeginningEdit(e);
        if (e.Cancel
            || currentRowIndex != CurrentSlot
@@ -3331,12 +3338,12 @@ public partial class DataGrid : TemplatedControl
        Debug.Assert(CurrentColumn != null);

        var dataItem = EditingRow.DataContext;
-        if (!DataConnection.CancelEdit(dataItem!))
+        if (dataItem is null || !DataConnection.CancelEdit(dataItem))
        {
            return false;
        }

-        foreach (DataGridColumn column in Columns)
+        foreach (var column in Columns)
        {
            if (!exitEditingMode && column.Index == _editingColumnIndex && column is DataGridBoundColumn)
            {
@@ -3412,7 +3419,7 @@ public partial class DataGrid : TemplatedControl
            return false;
        }

-        DataConnection!.EndEdit(EditingRow.DataContext!);
+        DataConnection.EndEdit(EditingRow.DataContext);

        if (!exitEditingMode)
        {
@@ -4047,7 +4054,7 @@ public partial class DataGrid : TemplatedControl
        // If we're canceling, let the editing column repopulate its old value if it wants
        if (editAction == DataGridEditAction.Cancel)
        {
-            CurrentColumn!.CancelCellEditInternal(editingElement, _uneditedValue!);
+            CurrentColumn?.CancelCellEditInternal(editingElement, _uneditedValue!);

            // Ensure that the current cell wasn't changed in the user column's CancelCellEdit
            if (_editingColumnIndex == -1 ||
@@ -4109,7 +4116,7 @@ public partial class DataGrid : TemplatedControl

        if (exitEditingMode)
        {
-            CurrentColumn!.EndCellEditInternal();
+            CurrentColumn?.EndCellEditInternal();
            _editingColumnIndex = -1;
            editingCell.UpdatePseudoClasses();

@@ -4121,17 +4128,17 @@ public partial class DataGrid : TemplatedControl

            PopulateCellContent(
                isCellEdited: !exitEditingMode,
-                dataGridColumn: CurrentColumn,
+                dataGridColumn: CurrentColumn!,
                dataGridRow: editingRow,
                dataGridCell: editingCell);

            editingRow.InvalidateDesiredHeight();
-            var column = editingCell.OwningColumn;
-            if (column!.Width.IsSizeToCells || column.Width.IsAuto)
+            var column = editingCell.OwningColumn!;
+            if (column.Width.IsSizeToCells || column.Width.IsAuto)
            {
                // Invalidate desired width and force recalculation
                column.SetWidthDesiredValue(0);
-                editingRow.OwningGrid!.AutoSizeColumn(column, editingCell.DesiredSize.Width);
+                editingRow.OwningGrid?.AutoSizeColumn(column, editingCell.DesiredSize.Width);
            }
        }

@@ -4149,7 +4156,7 @@ public partial class DataGrid : TemplatedControl
    //TODO Validation
    private bool EndRowEdit(DataGridEditAction editAction, bool exitEditingMode, bool raiseEvents)
    {
-        if (EditingRow == null || DataConnection!.CommittingEdit)
+        if (EditingRow == null || DataConnection.CommittingEdit)
        {
            return true;
        }
@@ -4239,7 +4246,7 @@ public partial class DataGrid : TemplatedControl
        if (AreColumnHeadersVisible)
        {
            double totalColumnsWidth = 0;
-            foreach (DataGridColumn column in ColumnsInternal)
+            foreach (var column in ColumnsInternal)
            {
                totalColumnsWidth += column.ActualWidth;

@@ -4261,7 +4268,7 @@ public partial class DataGrid : TemplatedControl
    //TODO TabStop
    private void ExitEdit(bool keepFocus)
    {
-        if (EditingRow == null || DataConnection!.CommittingEdit)
+        if (EditingRow == null || DataConnection.CommittingEdit)
        {
            Debug.Assert(_editingColumnIndex == -1);
            return;
@@ -4493,7 +4500,7 @@ public partial class DataGrid : TemplatedControl
            return;
        }

-        if (SlotCount != SlotFromRowIndex(DataConnection!.Count))
+        if (SlotCount != SlotFromRowIndex(DataConnection.Count))
        {
            _makeFirstDisplayedCellCurrentCellPending = true;
            return;
@@ -4602,8 +4609,8 @@ public partial class DataGrid : TemplatedControl

        // Prepare the cell for editing and raise the PreparingCellForEdit event for all columns
        var dataGridColumn = CurrentColumn;
-        _uneditedValue = dataGridColumn!.PrepareCellForEditInternal(editingElement!, _editingEventArgs!);
-        HandlePreparingCellForEdit(new DataGridPreparingCellForEditEventArgs(dataGridColumn, EditingRow,
+        _uneditedValue = dataGridColumn?.PrepareCellForEditInternal(editingElement!, _editingEventArgs!);
+        HandlePreparingCellForEdit(new DataGridPreparingCellForEditEventArgs(dataGridColumn!, EditingRow,
            _editingEventArgs!,
            editingElement!));
    }
@@ -4963,7 +4970,7 @@ public partial class DataGrid : TemplatedControl
        if (CurrentColumnIndex != -1)
        {
            dataGridColumn =
-                ColumnsInternal!.GetPreviousVisibleNonFillerColumn(ColumnsItemsInternal[CurrentColumnIndex]);
+                ColumnsInternal.GetPreviousVisibleNonFillerColumn(ColumnsItemsInternal[CurrentColumnIndex]);
            if (dataGridColumn != null)
            {
                previousVisibleColumnIndex = dataGridColumn.Index;
@@ -5459,9 +5466,9 @@ public partial class DataGrid : TemplatedControl

    private void RemoveDisplayedColumnHeader(DataGridColumn dataGridColumn)
    {
-        if (_columnHeadersPresenter != null)
+        if (_columnHeadersPresenter != null && dataGridColumn.HeaderCell is not null)
        {
-            _columnHeadersPresenter.Children.Remove(dataGridColumn.HeaderCell!);
+            _columnHeadersPresenter.Children.Remove(dataGridColumn.HeaderCell);
        }
    }

@@ -5551,7 +5558,7 @@ public partial class DataGrid : TemplatedControl
        if (!RowGroupHeadersTable.Contains(slot))
        {
            int rowIndex = RowIndexFromSlot(slot);
-            if (rowIndex >= 0 && rowIndex < DataConnection!.Count)
+            if (rowIndex >= 0 && rowIndex < DataConnection.Count)
            {
                newCurrentItem = DataConnection.GetDataItem(rowIndex);
            }
@@ -5601,7 +5608,7 @@ public partial class DataGrid : TemplatedControl

        if (newCurrentItem != null)
        {
-            slot = SlotFromRowIndex(DataConnection!.IndexOf(newCurrentItem));
+            slot = SlotFromRowIndex(DataConnection.IndexOf(newCurrentItem));
        }

        if (slot == -1 && columnIndex != -1)
@@ -6124,7 +6131,7 @@ public partial class DataGrid : TemplatedControl
            if (ClipboardCopyMode == DataGridClipboardCopyMode.IncludeHeader)
            {
                DataGridRowClipboardEventArgs headerArgs = new DataGridRowClipboardEventArgs(null, true);
-                foreach (DataGridColumn column in ColumnsInternal.GetVisibleColumns())
+                foreach (var column in ColumnsInternal.GetVisibleColumns())
                {
                    headerArgs.ClipboardRowContent.Add(new DataGridClipboardCellContent(null, column, column.Header!));
                }
@@ -6133,13 +6140,13 @@ public partial class DataGrid : TemplatedControl
                textBuilder.Append(FormatClipboardContent(headerArgs));
            }

-            for (int index = 0; index < SelectedItems.Count; index++)
+            for (var index = 0; index < SelectedItems.Count; index++)
            {
                object?                       item     = SelectedItems[index];
                DataGridRowClipboardEventArgs itemArgs = new DataGridRowClipboardEventArgs(item!, false);
                foreach (DataGridColumn column in ColumnsInternal.GetVisibleColumns())
                {
-                    object? content = column.GetCellValue(item!, column.ClipboardContentBinding);
+                    var content = column.GetCellValue(item!, column.ClipboardContentBinding);
                    itemArgs.ClipboardRowContent.Add(new DataGridClipboardCellContent(item!, column, content!));
                }

@@ -6147,7 +6154,7 @@ public partial class DataGrid : TemplatedControl
                textBuilder.Append(FormatClipboardContent(itemArgs));
            }

-            string text = StringBuilderCache.GetStringAndRelease(textBuilder);
+            var text = StringBuilderCache.GetStringAndRelease(textBuilder);

            if (!string.IsNullOrEmpty(text))
            {