Add Empty DataSource indicator support

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

@@ -52,6 +52,12 @@ public partial class DataGrid
             o => o.HeaderCornerRadius,
             (o, v) => o.HeaderCornerRadius = v);
     
+    internal static readonly DirectProperty<DataGrid, bool> IsEmptyDataSourceProperty =
+        AvaloniaProperty.RegisterDirect<DataGrid, bool>(
+            nameof(IsEmptyDataSource),
+            o => o.IsEmptyDataSource,
+            (o, v) => o.IsEmptyDataSource = v);
+    
     internal bool IsGroupHeaderMode
     {
         get => _isGroupHeaderMode;
@@ -73,6 +79,13 @@ public partial class DataGrid
     }
     private CornerRadius _headerCornerRadius;
     
+    internal bool IsEmptyDataSource
+    {
+        get => _isEmptyDataSource;
+        set => SetAndRaise(IsEmptyDataSourceProperty, ref _isEmptyDataSource, value);
+    }
+    private bool _isEmptyDataSource = false;
+    
     internal IndexToValueTable<DataGridRowGroupInfo> RowGroupHeadersTable { get; private set; }
 
     internal DataGridDisplayData DisplayData { get; private set; }
@@ -1306,13 +1319,25 @@ public partial class DataGrid
                     : default;
             }
 
-            Debug.Assert(newCollectionView != null);
-            
-            if (newCollectionView.Filter == null)
+            if (oldCollectionView != null)
             {
-                // TODO 不知道这样循环会不会有内存泄露的风险
-                _defaultFilter           = new DataGridDefaultFilter(newCollectionView);
-                newCollectionView.Filter = _defaultFilter;
+                oldCollectionView.CollectionChanged -= HandleDataCollectionViewChanged;
+            }
+            
+            if (newCollectionView != null)
+            {
+                newCollectionView.CollectionChanged += HandleDataCollectionViewChanged;
+                IsEmptyDataSource                   =  newCollectionView.IsEmpty;
+                if (newCollectionView.Filter == null)
+                {
+                    // TODO 不知道这样循环会不会有内存泄露的风险
+                    _defaultFilter           = new DataGridDefaultFilter(newCollectionView);
+                    newCollectionView.Filter = _defaultFilter;
+                }
+            }
+            else
+            {
+                IsEmptyDataSource = true;
             }
 
             DataConnection.DataSource = newCollectionView;
@@ -1363,6 +1388,14 @@ public partial class DataGrid
         }
     }
 
+    private void HandleDataCollectionViewChanged(object? sender, NotifyCollectionChangedEventArgs args)
+    {
+        if (sender is DataGridCollectionView view)
+        {
+            IsEmptyDataSource = view.IsEmpty;
+        }
+    }
+
     internal void UpdatePseudoClasses()
     {
         var visibleColumns = ColumnsInternal.GetVisibleColumns().ToList();

src/AtomUI.Controls.DataGrid/DataGrid.cs

@@ -227,6 +227,12 @@ public partial class DataGrid : TemplatedControl,
 
     public static readonly StyledProperty<IDataTemplate?> FooterTemplateProperty =
         AvaloniaProperty.Register<DataGrid, IDataTemplate?>(nameof(FooterTemplate));
+    
+    public static readonly StyledProperty<object?> EmptyIndicatorProperty =
+        AvaloniaProperty.Register<DataGrid, object?>(nameof(EmptyIndicator));
+
+    public static readonly StyledProperty<IDataTemplate?> EmptyIndicatorTemplateProperty =
+        AvaloniaProperty.Register<DataGrid, IDataTemplate?>(nameof(EmptyIndicatorTemplate));
 
     public static readonly StyledProperty<bool> IsMotionEnabledProperty =
         MotionAwareControlProperty.IsMotionEnabledProperty.AddOwner<DataGrid>();
@@ -586,11 +592,24 @@ public partial class DataGrid : TemplatedControl,
         get => GetValue(FooterTemplateProperty);
         set => SetValue(FooterTemplateProperty, value);
     }
+    
+    [DependsOn(nameof(EmptyIndicatorTemplate))]
+    public object? EmptyIndicator
+    {
+        get => GetValue(EmptyIndicatorProperty);
+        set => SetValue(EmptyIndicatorProperty, value);
+    }
+
+    public IDataTemplate? EmptyIndicatorTemplate
+    {
+        get => GetValue(EmptyIndicatorTemplateProperty);
+        set => SetValue(EmptyIndicatorTemplateProperty, value);
+    }
 
     /// <summary>
-                                            /// Gets or sets the column that contains the current cell.
-                                            /// </summary>
-                                            public DataGridColumn? CurrentColumn
+    /// Gets or sets the column that contains the current cell.
+    /// </summary>
+    public DataGridColumn? CurrentColumn
     {
         get
         {
@@ -1530,6 +1549,11 @@ public partial class DataGrid : TemplatedControl,
         }
 
         ConfigureHeaderCornerRadius();
+        SetValue(EmptyIndicatorProperty, new EmptyIndicator()
+        {
+            SizeType = SizeType.Middle,
+            PresetImage = PresetEmptyImage.Simple
+        }, BindingPriority.Template);
     }
 
     /// <summary>

src/AtomUI.Controls.DataGrid/Row/DataGridEmptyDataIndicator.cs

@@ -1,8 +0,0 @@
-using Avalonia.Controls.Primitives;
-
-namespace AtomUI.Controls;
-
-internal class DataGridEmptyDataIndicator : TemplatedControl
-{
-    
-}

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

@@ -1,7 +0,0 @@
-<ResourceDictionary
-    xmlns="https://github.com/avaloniaui"
-    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-    xmlns:atom="https://atomui.net">
-    <ControlTheme x:Key="{x:Type atom:DataGridEmptyDataIndicator}" TargetType="atom:DataGridEmptyDataIndicator">
-    </ControlTheme>
-</ResourceDictionary>

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

@@ -67,7 +67,8 @@
                                 Grid.Column="0"
                                 Grid.RowSpan="2"
                                 Grid.ColumnSpan="3"
-                                ScrollViewer.IsScrollInertiaEnabled="{TemplateBinding IsScrollInertiaEnabled}">
+                                ScrollViewer.IsScrollInertiaEnabled="{TemplateBinding IsScrollInertiaEnabled}"
+                                IsVisible="{TemplateBinding IsEmptyDataSource, Converter={x:Static BoolConverters.Not}}">
                                 <atom:DataGridRowsPresenter.GestureRecognizers>
                                     <ScrollGestureRecognizer
                                         CanHorizontallyScroll="True"
@@ -75,6 +76,20 @@
                                         IsScrollInertiaEnabled="{Binding (ScrollViewer.IsScrollInertiaEnabled), ElementName=PART_RowPresenter}" />
                                 </atom:DataGridRowsPresenter.GestureRecognizers>
                             </atom:DataGridRowsPresenter>
+                            
+                            <ContentPresenter
+                                Name="{x:Static atom:DataGridThemeConstants.EmptyIndicatorPart}"
+                                Grid.Row="1"
+                                Grid.Column="0"
+                                Grid.RowSpan="2"
+                                Grid.ColumnSpan="3"
+                                HorizontalContentAlignment="Center"
+                                VerticalContentAlignment="Center"
+                                IsVisible="{TemplateBinding IsEmptyDataSource}"
+                                Content="{TemplateBinding EmptyIndicator}"
+                                ContentTemplate="{TemplateBinding EmptyIndicatorTemplate}"
+                                />
+                            
                             <Rectangle
                                 Name="{x:Static atom:DataGridThemeConstants.BottomRightCornerPart}"
                                 Grid.Row="2"
@@ -143,6 +158,11 @@
             <Setter Property="Background" Value="{DynamicResource {x:Static atom:DataGridTokenKey.TableFooterBg}}" />
         </Style>
 
+        <Style Selector="^ /template/ ContentPresenter#PART_EmptyIndicator">
+            <Setter Property="Padding"
+                    Value="{DynamicResource {x:Static atom:SharedTokenKey.PaddingXL}}" />
+        </Style>
+        
         <Style Selector="^[SizeType=Large]">
             <Style Selector="^ /template/ ContentPresenter#PART_Title">
                 <Setter Property="Padding" Value="{DynamicResource {x:Static atom:DataGridTokenKey.TablePadding}}" />

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

@@ -88,6 +88,7 @@ internal static class DataGridSortIndicatorThemeConstants
 internal static class DataGridThemeConstants
 {
     public const string RowsPresenterPart = "PART_RowPresenter";
+    public const string EmptyIndicatorPart = "PART_EmptyIndicator";
     public const string ColumnHeadersPresenterPart = "PART_ColumnHeadersPresenter";
     public const string GroupColumnHeadersPresenterPart = "PART_GroupColumnHeadersPresenter";
     public const string HorizontalScrollbarPart = "PART_HorizontalScrollbar";