Allow custom PageSizeList and always show PageSize

Maui.DataGrid.Sample/MainPage.xaml

@@ -34,7 +34,7 @@
         <dg:DataGrid Grid.Row="1" ItemsSource="{Binding Teams}" SelectionEnabled="True" SelectedItem="{Binding SelectedTeam}"
                      RowHeight="70" HeaderHeight="50" BorderColor="{StaticResource GridBorderColor}" RowToEdit="{Binding TeamToEdit}"
                      HeaderBackground="{StaticResource GridHeaderBgColor}" HeaderBordersVisible="{Binding HeaderBordersVisible}"
-                     PullToRefreshCommand="{Binding RefreshCommand}" IsRefreshing="{Binding IsRefreshing}" PaginationEnabled="{Binding PaginationEnabled}" PageSize="5"
+                     PullToRefreshCommand="{Binding RefreshCommand}" IsRefreshing="{Binding IsRefreshing}" PaginationEnabled="{Binding PaginationEnabled}" PageSize="6"
                      ActiveRowColor="{StaticResource ActiveRowColor}" FooterBackground="{StaticResource GridFooterBgColor}" x:Name="_dataGrid1">
             <dg:DataGrid.Columns>
                 <dg:DataGridColumn Title="Logo" PropertyName="Logo" SortingEnabled="False">

Maui.DataGrid/CompatibilitySuppressions.xml

@@ -1,6 +1,13 @@
 <?xml version="1.0" encoding="utf-8"?>
 <!-- https://learn.microsoft.com/en-us/dotnet/fundamentals/package-validation/diagnostic-ids -->
 <Suppressions xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>F:Maui.DataGrid.DataGrid.PageSizeListProperty</Target>
+    <Left>lib/net7.0/Maui.DataGrid.dll</Left>
+    <Right>lib/net7.0/Maui.DataGrid.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
   <Suppression>
     <DiagnosticId>CP0002</DiagnosticId>
     <Target>F:Maui.DataGrid.DataGrid.RowToEditProperty</Target>
@@ -29,6 +36,13 @@
     <Right>lib/net7.0/Maui.DataGrid.dll</Right>
     <IsBaselineSuppression>true</IsBaselineSuppression>
   </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Maui.DataGrid.DataGrid.set_PageSizeList(System.Collections.ObjectModel.ObservableCollection{System.Int32})</Target>
+    <Left>lib/net7.0/Maui.DataGrid.dll</Left>
+    <Right>lib/net7.0/Maui.DataGrid.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
   <Suppression>
     <DiagnosticId>CP0002</DiagnosticId>
     <Target>M:Maui.DataGrid.DataGrid.set_RowToEdit(System.Object)</Target>

Maui.DataGrid/DataGrid.xaml

@@ -65,7 +65,7 @@
             </Grid.ColumnDefinitions>
             <HorizontalStackLayout VerticalOptions="Center" IsVisible="{Binding PageSizeVisible, Source={Reference self}}">
                 <Label Text="# per page:" Margin="5,0,0,0" VerticalTextAlignment="Center" TextColor="Black" />
-                <Picker ItemsSource="{Binding PageSizeList, Source={Reference self}, Mode=OneTime}" SelectedItem="{Binding PageSize, Source={Reference self}}" TextColor="Black" />
+                <Picker ItemsSource="{Binding PageSizeList, Source={Reference self}, Mode=TwoWay}" SelectedItem="{Binding PageSize, Source={Reference self}}" TextColor="Black" />
             </HorizontalStackLayout>
             <HorizontalStackLayout Grid.Column="2" VerticalOptions="Center">
                 <Label Text="Page:" Margin="0,0,5,0" VerticalTextAlignment="Center" TextColor="Black" />

Maui.DataGrid/DataGrid.xaml.cs

@@ -2,7 +2,6 @@ namespace Maui.DataGrid;
 
 using System.Collections;
 using System.Collections.Generic;
-using System.Collections.Immutable;
 using System.Collections.ObjectModel;
 using System.Collections.Specialized;
 using System.ComponentModel;
@@ -19,6 +18,7 @@ namespace Maui.DataGrid;
 public partial class DataGrid
 {
     #region Fields
+    private static readonly SortedSet<int> DefaultPageSizeList = [5, 10, 50, 100, 200, 1000];
 
     private static readonly ColumnDefinitionCollection HeaderColumnDefinitions =
                 [
@@ -29,6 +29,7 @@ public partial class DataGrid
     private readonly WeakEventManager _itemSelectedEventManager = new();
     private readonly WeakEventManager _refreshingEventManager = new();
 
+    private readonly SortedSet<int> _pageSizeList = DefaultPageSizeList;
     private readonly Style _defaultHeaderStyle;
     private readonly Style _defaultSortIconStyle;
 
@@ -184,6 +185,24 @@ private IEnumerable<object> GetPaginatedItems(IEnumerable<object> unpaginatedIte
         return unpaginatedItems.Skip(skip).Take(PageSize);
     }
 
+    /// <summary>
+    /// Checks if PageSizeList contains the new PageSize value, so that it shows in the dropdown
+    /// </summary>
+    private void UpdatePageSizeList()
+    {
+        if (PageSizeList.Contains(PageSize))
+        {
+            return;
+        }
+
+        if (_pageSizeList.Add(PageSize))
+        {
+            PageSizeList = new(_pageSizeList);
+            OnPropertyChanged(nameof(PageSizeList));
+            OnPropertyChanged(nameof(PageSize));
+        }
+    }
+
     private void SortAndPaginate(SortData? sortData = null)
     {
         lock (_sortAndPaginateLock)
@@ -457,9 +476,23 @@ private void SortAndPaginate(SortData? sortData = null)
                         self.PageCount = (int)Math.Ceiling(self.ItemsSource.Cast<object>().Count() / (double)self.PageSize);
                     }
                     self.SortAndPaginate();
+                    self.UpdatePageSizeList();
                 }
             });
 
+    /// <summary>
+    /// Gets or sets the list of available page sizes for the DataGrid.
+    /// </summary>
+    public static readonly BindableProperty PageSizeListProperty =
+        BindablePropertyExtensions.Create<DataGrid, ObservableCollection<int>>(new(DefaultPageSizeList),
+                        propertyChanged: (b, o, n) =>
+                        {
+                            if (o != n && b is DataGrid self)
+                            {
+                                self.UpdatePageSizeList();
+                            }
+                        });
+
     /// <summary>
     /// Gets or sets a value indicating whether the page size is visible in the DataGrid.
     /// </summary>
@@ -862,9 +895,13 @@ public int PageSize
     }
 
     /// <summary>
-    /// List of page sizes
+    /// Gets or sets the list of available page sizes
     /// </summary>
-    public IReadOnlyCollection<int> PageSizeList { get; } = ImmutableArray.Create(5, 10, 50, 100, 200, 1000);
+    public ObservableCollection<int> PageSizeList
+    {
+        get => (ObservableCollection<int>)GetValue(PageSizeListProperty);
+        set => SetValue(PageSizeListProperty, value);
+    }
 
     /// <summary>
     /// Gets or sets whether the page size picker is visible
@@ -1173,6 +1210,14 @@ internal void Reload()
 
             try
             {
+                // Check if PageSizeList contains the new PageSize value, so that it shows in the dropdown
+                if (!PageSizeList.Contains(PageSize))
+                {
+                    PageSizeList.Add(PageSize);
+                    OnPropertyChanged(nameof(PageSizeList));
+                    OnPropertyChanged(nameof(PageSize));
+                }
+
                 InitHeaderView();
 
                 if (_internalItems is not null)