Add DataGrid Column reorder

src/AtomUI.Controls.DataGrid/Column/DataGridColumnHeader.cs

@@ -613,15 +613,10 @@ internal partial class DataGridColumnHeader : ContentControl
         foreach (DataGridColumn column in OwningGrid.ColumnsInternal.GetVisibleColumns())
         {
             Point  mousePosition = OwningGrid.ColumnHeaders.Translate(column.HeaderCell, mousePositionHeaders);
-            double columnMiddle  = column.HeaderCell.Bounds.Width / 2;
-            if (mousePosition.X >= 0 && mousePosition.X <= columnMiddle)
+            if (mousePosition.X >= 0 && mousePosition.X <= column.HeaderCell.Bounds.Width)
             {
                 return column;
             }
-            if (mousePosition.X > columnMiddle && mousePosition.X < column.HeaderCell.Bounds.Width)
-            {
-                return OwningGrid.ColumnsInternal.GetNextVisibleColumn(column);
-            }
         }
 
         return null;
@@ -639,7 +634,7 @@ internal partial class DataGridColumnHeader : ContentControl
         DataGridColumn? targetColumn = GetReorderingTargetColumn(mousePositionHeaders, false /*scroll*/, out double scrollAmount);
         if (targetColumn != null)
         {
-            return targetColumn.DisplayIndex > OwningColumn.DisplayIndex ? targetColumn.DisplayIndex - 1 : targetColumn.DisplayIndex;
+            return targetColumn.DisplayIndex;
         }
         return OwningGrid.Columns.Count - 1;
     }

src/AtomUI.Controls.DataGrid/Column/DataGridDraggingOverIndicator.cs

@@ -0,0 +1,87 @@
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Controls.Documents;
+using Avalonia.Media;
+
+namespace AtomUI.Controls;
+
+internal class DataGridDraggingOverIndicator : Control
+{
+    internal static readonly DirectProperty<DataGridDraggingOverIndicator, DataGridColumn?> DraggingOverColumnProperty =
+        AvaloniaProperty.RegisterDirect<DataGridDraggingOverIndicator, DataGridColumn?>(
+            nameof(DraggingOverColumn),
+            o => o.DraggingOverColumn,
+            (o, v) => o.DraggingOverColumn = v);
+    
+    internal static readonly DirectProperty<DataGridDraggingOverIndicator, DataGridColumn?> DraggedColumnProperty =
+        AvaloniaProperty.RegisterDirect<DataGridDraggingOverIndicator, DataGridColumn?>(
+            nameof(DraggedColumn),
+            o => o.DraggedColumn,
+            (o, v) => o.DraggedColumn = v);
+    
+    internal DataGridColumn? DraggingOverColumn
+    {
+        get => _draggingOverColumn;
+        set => SetAndRaise(DraggingOverColumnProperty, ref _draggingOverColumn, value);
+    }
+    private DataGridColumn? _draggingOverColumn;
+    
+    internal DataGridColumn? DraggedColumn
+    {
+        get => _draggedColumn;
+        set => SetAndRaise(DraggedColumnProperty, ref _draggedColumn, value);
+    }
+    private DataGridColumn? _draggedColumn;
+
+    static DataGridDraggingOverIndicator()
+    {
+        AffectsRender<DataGridDraggingOverIndicator>(DraggingOverColumnProperty, DraggedColumnProperty);
+    }
+
+    private double _indicatorOffsetX;
+    private double _indicatorLineWidth = 1.0;
+
+    protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs change)
+    {
+        base.OnPropertyChanged(change);
+        if (change.Property == DraggingOverColumnProperty ||
+            change.Property == DraggedColumnProperty)
+        {
+            CalculateIndicatorOffset();
+        }
+    }
+
+    private void CalculateIndicatorOffset()
+    {
+        if (DraggingOverColumn != null && DraggedColumn != null)
+        {
+            var offset = DraggingOverColumn.HeaderCell.TranslatePoint(new Point(0, 0), this);
+            if (offset.HasValue)
+            {
+                var headerSize = DraggingOverColumn.HeaderCell.Bounds.Size;
+                if (DraggedColumn.DisplayIndex < DraggingOverColumn.DisplayIndex)
+                {
+                    _indicatorOffsetX = offset.Value.X + headerSize.Width;
+                }
+                else
+                {
+                    _indicatorOffsetX = offset.Value.X;
+                }
+            }
+        }
+    }
+
+    public override void Render(DrawingContext context)
+    {
+        if (DraggingOverColumn != null)
+        {
+            using var state = context.PushRenderOptions(new RenderOptions
+            {
+                EdgeMode = EdgeMode.Aliased
+            });
+            var startPoint = new Point(_indicatorOffsetX, 0);
+            var endPoint   = new Point(_indicatorOffsetX, Bounds.Height);
+            context.DrawLine(new Pen(TextElement.GetForeground(this), _indicatorLineWidth, DashStyle.Dash), startPoint, endPoint);
+        }
+    }
+}

src/AtomUI.Controls.DataGrid/DataGrid.Columns.cs

@@ -105,6 +105,7 @@ public partial class DataGrid
 
     private DataGridColumnHeadersPresenter? _columnHeadersPresenter;
     private DataGridGroupColumnHeadersPresenter? _groupColumnHeadersPresenter;
+    private DataGridDraggingOverIndicator? _dataGridDraggingOverIndicator;
 
     protected virtual void NotifyColumnDisplayIndexChanged(DataGridColumnEventArgs e)
     {
@@ -124,6 +125,22 @@ public partial class DataGrid
     
     protected internal virtual void NotifyColumnDraggingOver(DataGridColumnDraggingOverEventArgs e)
     {
+        if (_dataGridDraggingOverIndicator != null)
+        {
+            if (e.DraggedColumn != null && e.DraggingOverColumn != null && e.DraggedColumn != e.DraggingOverColumn)
+            {
+                _dataGridDraggingOverIndicator.IsVisible          = true;
+                _dataGridDraggingOverIndicator.DraggingOverColumn = e.DraggingOverColumn;
+                _dataGridDraggingOverIndicator.DraggedColumn = e.DraggedColumn;
+            }
+            else
+            {
+                _dataGridDraggingOverIndicator.IsVisible          = false;
+                _dataGridDraggingOverIndicator.DraggingOverColumn = null;
+                _dataGridDraggingOverIndicator.DraggedColumn      = null;
+            }
+        }
+   
         ColumnDraggingOver?.Invoke(this, e);
     }
 

src/AtomUI.Controls.DataGrid/DataGrid.Privates.cs

@@ -11,7 +11,6 @@ using System.Diagnostics;
 using System.Reactive.Disposables;
 using AtomUI.Controls.Data;
 using AtomUI.Controls.Utils;
-using AtomUI.Data;
 using AtomUI.Theme;
 using AtomUI.Utils;
 using Avalonia;
@@ -32,6 +31,7 @@ public partial class DataGrid
     internal const bool DefaultCanUserSortColumns = false;
     internal const bool DefaultCanUserFilterColumns = false;
     internal const bool DefaultShowSorterTooltip = false;
+    internal const int DraggingOverIndicatorZIndex = 1000;
 
     #region 内部属性定义
     

src/AtomUI.Controls.DataGrid/DataGrid.cs

@@ -1404,7 +1404,7 @@ public partial class DataGrid : TemplatedControl,
         _columnHeadersPresenter =
             e.NameScope.Find<DataGridColumnHeadersPresenter>(DataGridThemeConstants.ColumnHeadersPresenterPart);
         _groupColumnHeadersPresenter = e.NameScope.Find<DataGridGroupColumnHeadersPresenter>(DataGridThemeConstants.GroupColumnHeadersPresenterPart);
-
+        _dataGridDraggingOverIndicator = e.NameScope.Find<DataGridDraggingOverIndicator>(DataGridThemeConstants.DraggingOverIndicatorPart);
         if (_groupColumnHeadersPresenter != null)
         {
             _groupColumnHeadersPresenter.OwningGrid = this;

src/AtomUI.Controls.DataGrid/Themes/DataGridTheme.axaml

@@ -103,6 +103,14 @@
                                 VerticalAlignment="Stretch"
                                 CornerRadius="{TemplateBinding HeaderCornerRadius}"
                                 IsEnabled="{TemplateBinding IsEnabled}" />
+                            
+                            <atom:DataGridDraggingOverIndicator
+                                Name="{x:Static atom:DataGridThemeConstants.DraggingOverIndicatorPart}"
+                                Grid.Row="1"
+                                Grid.Column="0"
+                                Grid.RowSpan="2"
+                                Grid.ColumnSpan="3"
+                                IsVisible="False"/>
                         </Grid>
                     </DockPanel>
 

src/AtomUI.Controls.DataGrid/Themes/DataGridThemeConstants.cs

@@ -102,6 +102,7 @@ internal static class DataGridThemeConstants
     public const string DisabledVisualElementPart = "PART_DisabledVisualElement";
     public const string TitlePart = "PART_Title";
     public const string FooterPart = "PART_Footer";
+    public const string DraggingOverIndicatorPart = "PART_DraggingOverIndicator";
 }
 
 internal static class DataGridTopLeftColumnHeaderThemeConstants