From 7d3f3022871ee1f1ffd4a01e89b2ddf58d250922 Mon Sep 17 00:00:00 2001
From: Edward Miller <symbiogenisis@outlook.com>
Date: Sat, 28 Sep 2024 10:51:20 -0500
Subject: [PATCH] per-column filtering

---
 Maui.DataGrid.Sample/MainPage.xaml            |   2 +-
 Maui.DataGrid.Sample/SettingsPopup.xaml       |   4 +
 .../ViewModels/MainViewModel.cs               |   7 +
 Maui.DataGrid/CompatibilitySuppressions.xml   | 119 +++++++++++
 Maui.DataGrid/DataGrid.xaml                   |   7 +-
 Maui.DataGrid/DataGrid.xaml.cs                | 202 ++++++++++++++----
 Maui.DataGrid/DataGridColumn.cs               |  83 ++++++-
 Maui.DataGrid/DataGridHeaderRow.cs            |  88 +++++---
 Maui.DataGrid/DataGridRow.cs                  |  25 ++-
 9 files changed, 461 insertions(+), 76 deletions(-)

diff --git a/Maui.DataGrid.Sample/MainPage.xaml b/Maui.DataGrid.Sample/MainPage.xaml
index fa17df0..fa0615d 100644
--- a/Maui.DataGrid.Sample/MainPage.xaml
+++ b/Maui.DataGrid.Sample/MainPage.xaml
@@ -16,7 +16,7 @@
             <Button Text="Remove Team" WidthRequest="140" Command="{Binding Commands[RemoveTeam]}" />
         </HorizontalStackLayout>
 
-        <dg:DataGrid Grid.Row="1" ItemsSource="{Binding Teams}" SelectionMode="{Binding SelectionMode}"
+        <dg:DataGrid Grid.Row="1" ItemsSource="{Binding Teams}" SelectionMode="{Binding SelectionMode}" FilteringEnabled="{Binding FilteringEnabled}"
                      SelectedItem="{Binding SelectedTeam}" RowToEdit="{Binding TeamToEdit}" RefreshingEnabled="{Binding RefreshingEnabled}"
                      BorderColor="{StaticResource GridBorderColor}" BorderThickness="{Binding BorderThickness}"
                      HeaderBackground="{StaticResource GridHeaderBgColor}" HeaderBordersVisible="{Binding HeaderBordersVisible}"
diff --git a/Maui.DataGrid.Sample/SettingsPopup.xaml b/Maui.DataGrid.Sample/SettingsPopup.xaml
index a3340b2..47d1406 100644
--- a/Maui.DataGrid.Sample/SettingsPopup.xaml
+++ b/Maui.DataGrid.Sample/SettingsPopup.xaml
@@ -37,6 +37,10 @@
                     <Entry Text="{Binding PageSize}" Keyboard="Numeric" TextColor="White" />
                     <Label Text="Page Size" TextColor="White" VerticalOptions="Center" />
                 </HorizontalStackLayout>
+                <HorizontalStackLayout Style="{StaticResource SampleContainerStyle}">
+                    <CheckBox IsChecked="{Binding FilteringEnabled}" />
+                    <Label Text="Filtering Enabled?" TextColor="White" VerticalOptions="Center" />
+                </HorizontalStackLayout>
                 <HorizontalStackLayout Style="{StaticResource SampleContainerStyle}">
                     <CheckBox IsChecked="{Binding RefreshingEnabled}" />
                     <Label Text="Refreshing Enabled?" TextColor="White" VerticalOptions="Center" />
diff --git a/Maui.DataGrid.Sample/ViewModels/MainViewModel.cs b/Maui.DataGrid.Sample/ViewModels/MainViewModel.cs
index 30b6191..830e702 100644
--- a/Maui.DataGrid.Sample/ViewModels/MainViewModel.cs
+++ b/Maui.DataGrid.Sample/ViewModels/MainViewModel.cs
@@ -15,6 +15,7 @@ public MainViewModel()
         TeamColumnVisible = true;
         WonColumnVisible = true;
         HeaderBordersVisible = true;
+        FilteringEnabled = true;
         PaginationEnabled = true;
         RefreshingEnabled = true;
         TeamColumnWidth = 70;
@@ -92,6 +93,12 @@ public int PageSize
         set => SetValue(value);
     }
 
+    public bool FilteringEnabled
+    {
+        get => GetValue<bool>();
+        set => SetValue(value);
+    }
+
     public bool PaginationEnabled
     {
         get => GetValue<bool>();
diff --git a/Maui.DataGrid/CompatibilitySuppressions.xml b/Maui.DataGrid/CompatibilitySuppressions.xml
index 4b25ebc..7179397 100644
--- a/Maui.DataGrid/CompatibilitySuppressions.xml
+++ b/Maui.DataGrid/CompatibilitySuppressions.xml
@@ -8,4 +8,123 @@
     <Right>lib/net8.0/Maui.DataGrid.dll</Right>
     <IsBaselineSuppression>true</IsBaselineSuppression>
   </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>F:Maui.DataGrid.DataGrid.FilteringEnabledProperty</Target>
+    <Left>lib/net8.0/Maui.DataGrid.dll</Left>
+    <Right>lib/net8.0/Maui.DataGrid.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>F:Maui.DataGrid.DataGrid.HeaderFilterStyleProperty</Target>
+    <Left>lib/net8.0/Maui.DataGrid.dll</Left>
+    <Right>lib/net8.0/Maui.DataGrid.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>F:Maui.DataGrid.DataGridColumn.FilteringEnabledProperty</Target>
+    <Left>lib/net8.0/Maui.DataGrid.dll</Left>
+    <Right>lib/net8.0/Maui.DataGrid.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>F:Maui.DataGrid.DataGridColumn.FilterTextProperty</Target>
+    <Left>lib/net8.0/Maui.DataGrid.dll</Left>
+    <Right>lib/net8.0/Maui.DataGrid.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>F:Maui.DataGrid.DataGridColumn.HeaderFilterStyleProperty</Target>
+    <Left>lib/net8.0/Maui.DataGrid.dll</Left>
+    <Right>lib/net8.0/Maui.DataGrid.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Maui.DataGrid.DataGrid.add_FilterChanged(System.EventHandler{Microsoft.Maui.Controls.TextChangedEventArgs})</Target>
+    <Left>lib/net8.0/Maui.DataGrid.dll</Left>
+    <Right>lib/net8.0/Maui.DataGrid.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Maui.DataGrid.DataGrid.get_FilteringEnabled</Target>
+    <Left>lib/net8.0/Maui.DataGrid.dll</Left>
+    <Right>lib/net8.0/Maui.DataGrid.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Maui.DataGrid.DataGrid.get_HeaderFilterStyle</Target>
+    <Left>lib/net8.0/Maui.DataGrid.dll</Left>
+    <Right>lib/net8.0/Maui.DataGrid.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Maui.DataGrid.DataGrid.remove_FilterChanged(System.EventHandler{Microsoft.Maui.Controls.TextChangedEventArgs})</Target>
+    <Left>lib/net8.0/Maui.DataGrid.dll</Left>
+    <Right>lib/net8.0/Maui.DataGrid.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Maui.DataGrid.DataGrid.set_FilteringEnabled(System.Boolean)</Target>
+    <Left>lib/net8.0/Maui.DataGrid.dll</Left>
+    <Right>lib/net8.0/Maui.DataGrid.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Maui.DataGrid.DataGrid.set_HeaderFilterStyle(Microsoft.Maui.Controls.Style)</Target>
+    <Left>lib/net8.0/Maui.DataGrid.dll</Left>
+    <Right>lib/net8.0/Maui.DataGrid.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Maui.DataGrid.DataGridColumn.get_FilteringEnabled</Target>
+    <Left>lib/net8.0/Maui.DataGrid.dll</Left>
+    <Right>lib/net8.0/Maui.DataGrid.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Maui.DataGrid.DataGridColumn.get_FilterText</Target>
+    <Left>lib/net8.0/Maui.DataGrid.dll</Left>
+    <Right>lib/net8.0/Maui.DataGrid.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Maui.DataGrid.DataGridColumn.get_HeaderFilterStyle</Target>
+    <Left>lib/net8.0/Maui.DataGrid.dll</Left>
+    <Right>lib/net8.0/Maui.DataGrid.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Maui.DataGrid.DataGridColumn.set_FilteringEnabled(System.Boolean)</Target>
+    <Left>lib/net8.0/Maui.DataGrid.dll</Left>
+    <Right>lib/net8.0/Maui.DataGrid.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Maui.DataGrid.DataGridColumn.set_FilterText(System.String)</Target>
+    <Left>lib/net8.0/Maui.DataGrid.dll</Left>
+    <Right>lib/net8.0/Maui.DataGrid.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Maui.DataGrid.DataGridColumn.set_HeaderFilterStyle(Microsoft.Maui.Controls.Style)</Target>
+    <Left>lib/net8.0/Maui.DataGrid.dll</Left>
+    <Right>lib/net8.0/Maui.DataGrid.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
 </Suppressions>
\ No newline at end of file
diff --git a/Maui.DataGrid/DataGrid.xaml b/Maui.DataGrid/DataGrid.xaml
index d84385d..75b7d09 100644
--- a/Maui.DataGrid/DataGrid.xaml
+++ b/Maui.DataGrid/DataGrid.xaml
@@ -10,13 +10,18 @@
     <ContentView.Resources>
         <ResourceDictionary>
             <!--Default Header Style-->
-            <Style x:Key="DefaultHeaderStyle" TargetType="Label">
+            <Style x:Key="DefaultLabelHeaderStyle" TargetType="Label">
                 <Setter Property="FontAttributes" Value="Bold" />
                 <Setter Property="HorizontalOptions" Value="Center" />
                 <Setter Property="VerticalOptions" Value="Center" />
                 <Setter Property="TextColor" Value="Black" />
                 <Setter Property="LineBreakMode" Value="TailTruncation" />
             </Style>
+
+            <Style x:Key="DefaultFilterHeaderStyle" TargetType="Entry">
+                <Setter Property="TextColor" Value="Black" />
+            </Style>
+
             <!--Default Sort Icon Style-->
             <Style x:Key="DefaultSortIconStyle" TargetType="Polygon">
                 <Setter Property="Aspect" Value="Uniform" />
diff --git a/Maui.DataGrid/DataGrid.xaml.cs b/Maui.DataGrid/DataGrid.xaml.cs
index d3854d8..657a1c6 100644
--- a/Maui.DataGrid/DataGrid.xaml.cs
+++ b/Maui.DataGrid/DataGrid.xaml.cs
@@ -6,6 +6,8 @@ namespace Maui.DataGrid;
 using System.Collections.Specialized;
 using System.ComponentModel;
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
+using System.Linq;
 using System.Windows.Input;
 using Maui.DataGrid.Collections;
 using Maui.DataGrid.Converters;
@@ -181,7 +183,7 @@ public partial class DataGrid
                 }
 
                 self._headerRow.InitializeHeaderRow(true);
-                self.SortAndPaginate();
+                self.SortFilterAndPaginate();
 
                 // Reset SelectedItem if it's not in the new collection
                 if (self.SelectedItem != null && !self.GetInternalItems().Contains(self.SelectedItem))
@@ -200,7 +202,7 @@ public partial class DataGrid
             {
                 if (b is DataGrid self)
                 {
-                    self.SortAndPaginate();
+                    self.SortFilterAndPaginate();
                 }
             });
 
@@ -223,7 +225,7 @@ public partial class DataGrid
                 if (b is DataGrid self)
                 {
                     self.PageNumber = 1;
-                    self.SortAndPaginate();
+                    self.SortFilterAndPaginate();
                     self.UpdatePageSizeList();
                 }
             });
@@ -276,7 +278,29 @@ public partial class DataGrid
     /// Gets or sets a value indicating whether the DataGrid allows sorting.
     /// </summary>
     public static readonly BindableProperty SortingEnabledProperty =
-        BindablePropertyExtensions.Create<DataGrid, bool>(true);
+        BindablePropertyExtensions.Create<DataGrid, bool>(
+            defaultValue: true,
+            propertyChanged: (b, _, _) =>
+            {
+                if (b is DataGrid self)
+                {
+                    self._headerRow.InitializeHeaderRow(true);
+                }
+            });
+
+    /// <summary>
+    /// Gets or sets a value indicating whether the DataGrid allows filtering.
+    /// </summary>
+    public static readonly BindableProperty FilteringEnabledProperty =
+        BindablePropertyExtensions.Create<DataGrid, bool>(
+            defaultValue: false,
+            propertyChanged: (b, _, _) =>
+            {
+                if (b is DataGrid self)
+                {
+                    self._headerRow.InitializeHeaderRow(true);
+                }
+            });
 
     /// <summary>
     /// Obsolete. Use <see cref="SortingEnabledProperty"/> instead.
@@ -535,7 +559,7 @@ public partial class DataGrid
                         self._sortedColumn = self.Columns[n.Index];
                     }
 
-                    self.SortAndPaginate(n);
+                    self.SortFilterAndPaginate(n);
                 }
             });
 
@@ -563,7 +587,7 @@ public partial class DataGrid
             {
                 if (b is DataGrid self)
                 {
-                    self.SortAndPaginate();
+                    self.SortFilterAndPaginate();
                 }
             });
 
@@ -573,6 +597,12 @@ public partial class DataGrid
     public static readonly BindableProperty HeaderLabelStyleProperty =
         BindablePropertyExtensions.Create<DataGrid, Style>();
 
+    /// <summary>
+    /// Gets or sets the style for the column filters in the DataGrid.
+    /// </summary>
+    public static readonly BindableProperty HeaderFilterStyleProperty =
+        BindablePropertyExtensions.Create<DataGrid, Style>();
+
     /// <summary>
     /// Gets or sets the sort icons for the DataGrid.
     /// </summary>
@@ -616,6 +646,7 @@ public partial class DataGrid
     private static readonly IList<int> DefaultPageSizeList = [.. DefaultPageSizeSet];
 
     private readonly WeakEventManager _itemSelectedEventManager = new();
+    private readonly WeakEventManager _filterChangedEventManager = new();
     private readonly WeakEventManager _refreshingEventManager = new();
     private readonly WeakEventManager _rowsBackgroundColorPaletteChangedEventManager = new();
     private readonly WeakEventManager _rowsTextColorPaletteChangedEventManager = new();
@@ -627,6 +658,9 @@ public partial class DataGrid
     private DataGridColumn? _sortedColumn;
     private HashSet<object>? _internalItemsHashSet;
 
+    [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicProperties)]
+    private Type? _cachedType;
+
     #endregion Fields
 
     #region ctor
@@ -638,7 +672,8 @@ public DataGrid()
     {
         InitializeComponent();
 
-        DefaultHeaderStyle = (Style)Resources["DefaultHeaderStyle"];
+        DefaultLabelHeaderStyle = (Style)Resources["DefaultLabelHeaderStyle"];
+        DefaultFilterHeaderStyle = (Style)Resources["DefaultFilterHeaderStyle"];
         DefaultSortIconStyle = (Style)Resources["DefaultSortIconStyle"];
 
         if (_collectionView != null)
@@ -660,6 +695,15 @@ public event EventHandler<SelectionChangedEventArgs> ItemSelected
         remove => _itemSelectedEventManager.RemoveEventHandler(value);
     }
 
+    /// <summary>
+    /// Occurs when an item is selected in the DataGrid.
+    /// </summary>
+    public event EventHandler<TextChangedEventArgs> FilterChanged
+    {
+        add => _filterChangedEventManager.AddEventHandler(value);
+        remove => _filterChangedEventManager.RemoveEventHandler(value);
+    }
+
     /// <summary>
     /// Occurs when the DataGrid is being refreshed.
     /// </summary>
@@ -902,6 +946,17 @@ public bool SortingEnabled
         set => SetValue(SortingEnabledProperty, value);
     }
 
+    /// <summary>
+    /// Gets or sets a value indicating whether gets or sets if the grid allows filtering. Default value is false.
+    /// If you want to enable or disable filtering for specific column please use <see cref="DataGridColumn.FilteringEnabled"/> property.
+    /// </summary>
+    public bool FilteringEnabled
+    {
+        get => (bool)GetValue(FilteringEnabledProperty);
+        set => SetValue(FilteringEnabledProperty, value);
+    }
+
+
     /// <summary>
     /// Gets or sets the page number. Default value is 1.
     /// </summary>
@@ -1043,6 +1098,16 @@ public Style HeaderLabelStyle
         set => SetValue(HeaderLabelStyleProperty, value);
     }
 
+    /// <summary>
+    /// Gets or sets style of the header label.
+    /// Style's <see cref="Style.TargetType"/> must be Label.
+    /// </summary>
+    public Style HeaderFilterStyle
+    {
+        get => (Style)GetValue(HeaderFilterStyleProperty);
+        set => SetValue(HeaderFilterStyleProperty, value);
+    }
+
     /// <summary>
     /// Gets or sets sort icon.
     /// </summary>
@@ -1094,7 +1159,9 @@ private set
 
 #pragma warning restore CA2227 // Collection properties should be read only
 
-    internal Style DefaultHeaderStyle { get; }
+    internal Style DefaultLabelHeaderStyle { get; }
+
+    internal Style DefaultFilterHeaderStyle { get; }
 
     internal Style DefaultSortIconStyle { get; }
 
@@ -1223,7 +1290,7 @@ private void OnSelectionChanged(object? sender, SelectionChangedEventArgs e)
     private void OnItemsSourceCollectionChanged(object? sender, NotifyCollectionChangedEventArgs e)
     {
         _internalItemsHashSet = null;
-        SortAndPaginate();
+        SortFilterAndPaginate();
     }
 
     private ICollection<object> GetInternalItems(int lookupCount = 1)
@@ -1262,6 +1329,12 @@ private ICollection<object> GetInternalItems(int lookupCount = 1)
 
     #region Sorting methods
 
+    /// <summary>
+    /// TODO: Implement this method.
+    /// </summary>
+    /// <returns>Whether the DataGrid can be filtered</returns>
+    private bool CanFilter() => true;
+
     private bool CanSort(SortData? sortData)
     {
         if (sortData is null)
@@ -1360,32 +1433,7 @@ private IEnumerable<object> GetSortedItems(IList<object> unsortedItems, SortData
 
     #region Pagination methods
 
-    private IEnumerable<object> GetPaginatedItems(IEnumerable<object> unpaginatedItems)
-    {
-        var skip = (PageNumber - 1) * PageSize;
-
-        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 List<int>(_pageSizeList);
-            OnPropertyChanged(nameof(PageSizeList));
-            OnPropertyChanged(nameof(PageSize));
-        }
-    }
-
-    private void SortAndPaginate(SortData? sortData = null)
+    internal void SortFilterAndPaginate(SortData? sortData = null)
     {
         if (ItemsSource is null)
         {
@@ -1406,7 +1454,9 @@ private void SortAndPaginate(SortData? sortData = null)
                 return;
             }
 
-            var sortedItems = CanSort(sortData) ? GetSortedItems(originalItems, sortData!) : originalItems;
+            var filteredItems = CanFilter() ? GetFilteredItems(originalItems) : originalItems;
+
+            var sortedItems = CanSort(sortData) ? GetSortedItems(filteredItems, sortData!) : filteredItems;
 
             var paginatedItems = PaginationEnabled ? GetPaginatedItems(sortedItems) : sortedItems;
 
@@ -1414,5 +1464,85 @@ private void SortAndPaginate(SortData? sortData = null)
         }
     }
 
+    private List<object> GetFilteredItems(IList<object> originalItems)
+    {
+        var filteredItems = originalItems.AsEnumerable();
+
+        foreach (var column in Columns)
+        {
+            /* if (!column.IsFilterEnabled) */
+
+            if (string.IsNullOrEmpty(column.FilterText))
+            {
+                continue;
+            }
+
+            try
+            {
+                filteredItems = filteredItems.Where(item => FilterItem(item, column));
+            }
+            catch (Exception ex)
+            {
+                Debug.WriteLine(ex);
+            }
+        }
+
+        return filteredItems.ToList();
+    }
+
+    private bool FilterItem(object item, DataGridColumn column)
+    {
+        var isItemTypeCached = _cachedType != null;
+
+        if (!isItemTypeCached)
+        {
+            _cachedType = item.GetType();
+        }
+
+        var type = _cachedType ?? item.GetType();
+        var property = type?.GetProperty(column.PropertyName);
+
+        if (property?.PropertyType == typeof(object))
+        {
+            return false;
+        }
+
+        var value = property?.GetValue(item, null)?.ToString();
+        var result = value?.Contains(column.FilterText, StringComparison.OrdinalIgnoreCase);
+
+        if (result == null && isItemTypeCached)
+        {
+            _cachedType = null;
+            result = FilterItem(item, column);
+        }
+
+        return result == true;
+    }
+
+    private IEnumerable<object> GetPaginatedItems(IEnumerable<object> unpaginatedItems)
+    {
+        var skip = (PageNumber - 1) * PageSize;
+
+        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 List<int>(_pageSizeList);
+            OnPropertyChanged(nameof(PageSizeList));
+            OnPropertyChanged(nameof(PageSize));
+        }
+    }
+
     #endregion Pagination methods
 }
diff --git a/Maui.DataGrid/DataGridColumn.cs b/Maui.DataGrid/DataGridColumn.cs
index 07dc2df..18e9c65 100644
--- a/Maui.DataGrid/DataGridColumn.cs
+++ b/Maui.DataGrid/DataGridColumn.cs
@@ -43,6 +43,19 @@ public sealed class DataGridColumn : BindableObject, IDefinition
             defaultValue: string.Empty,
             propertyChanged: (b, _, n) => ((DataGridColumn)b).HeaderLabel.Text = n);
 
+    /// <summary>
+    /// Gets or sets the filter text of the column.
+    /// </summary>
+    public static readonly BindableProperty FilterTextProperty =
+        BindablePropertyExtensions.Create<DataGridColumn, string>(
+            propertyChanged: (b, _, _) =>
+            {
+                if (b is DataGridColumn self)
+                {
+                    self.DataGrid?.SortFilterAndPaginate();
+                }
+            });
+
     /// <summary>
     /// Gets or sets the formatted title of the column.
     /// </summary>
@@ -117,7 +130,31 @@ public sealed class DataGridColumn : BindableObject, IDefinition
     /// Gets or sets a value indicating whether sorting is enabled for the column.
     /// </summary>
     public static readonly BindableProperty SortingEnabledProperty =
-        BindablePropertyExtensions.Create<DataGridColumn, bool>(true);
+        BindablePropertyExtensions.Create<DataGridColumn, bool>(
+            defaultValue: true,
+            propertyChanged: (b, _, _) =>
+            {
+                if (b is DataGridColumn self)
+                {
+                    self.HeaderCell = null;
+                    self.DataGrid?.Initialize();
+                }
+            });
+
+    /// <summary>
+    /// Gets or sets a value indicating whether filtering is enabled for the column.
+    /// </summary>
+    public static readonly BindableProperty FilteringEnabledProperty =
+        BindablePropertyExtensions.Create<DataGridColumn, bool>(
+            defaultValue: true,
+            propertyChanged: (b, _, _) =>
+            {
+                if (b is DataGridColumn self)
+                {
+                    self.HeaderCell = null;
+                    self.DataGrid?.Initialize();
+                }
+            });
 
     /// <summary>
     /// Gets or sets the style for the header label of the column.
@@ -132,6 +169,19 @@ public sealed class DataGridColumn : BindableObject, IDefinition
                 }
             });
 
+    /// <summary>
+    /// Gets or sets the style for the header filter of the column.
+    /// </summary>
+    public static readonly BindableProperty HeaderFilterStyleProperty =
+        BindablePropertyExtensions.Create<DataGridColumn, Style>(
+            propertyChanged: (b, _, n) =>
+            {
+                if (b is DataGridColumn self && self.HeaderLabel != null)
+                {
+                    self.FilterTextbox.Style = n;
+                }
+            });
+
     #endregion Bindable Properties
 
     #region Fields
@@ -159,6 +209,8 @@ public DataGridColumn()
             HorizontalOptions = LayoutOptions.Center,
             VerticalOptions = LayoutOptions.Center,
         };
+
+        FilterTextbox.SetBinding(Entry.TextProperty, new Binding(nameof(FilterText), BindingMode.TwoWay, source: this));
     }
 
     #region Events
@@ -227,6 +279,12 @@ public FormattedString FormattedTitle
         set => SetValue(FormattedTitleProperty, value);
     }
 
+    public string FilterText
+    {
+        get => (string)GetValue(FilterTextProperty);
+        set => SetValue(FilterTextProperty, value);
+    }
+
     /// <summary>
     /// Gets or sets property name to bind in the object.
     /// </summary>
@@ -304,7 +362,7 @@ public LayoutOptions VerticalContentAlignment
 
     /// <summary>
     /// Gets or sets a value indicating whether the column is sortable.
-    /// Default is true.
+    /// Default is true. But the DataGrid must also have sorting enabled.
     /// Sortable columns must implement <see cref="IComparable"/>.
     /// </summary>
     public bool SortingEnabled
@@ -313,6 +371,16 @@ public bool SortingEnabled
         set => SetValue(SortingEnabledProperty, value);
     }
 
+    /// <summary>
+    /// Gets or sets a value indicating whether the column can be filtered.
+    /// Default is true. But the DataGrid must also have filtering enabled.
+    /// </summary>
+    public bool FilteringEnabled
+    {
+        get => (bool)GetValue(FilteringEnabledProperty);
+        set => SetValue(FilteringEnabledProperty, value);
+    }
+
     /// <summary>
     /// Gets or sets label style of the header. <see cref="Style.TargetType"/> must be Label.
     /// </summary>
@@ -322,8 +390,19 @@ public Style HeaderLabelStyle
         set => SetValue(HeaderLabelStyleProperty, value);
     }
 
+    /// <summary>
+    /// Gets or sets label style of the header. <see cref="Style.TargetType"/> must be Label.
+    /// </summary>
+    public Style HeaderFilterStyle
+    {
+        get => (Style)GetValue(HeaderFilterStyleProperty);
+        set => SetValue(HeaderFilterStyleProperty, value);
+    }
+
     internal Polygon SortingIcon { get; } = new();
 
+    internal Entry FilterTextbox { get; } = new() { Placeholder = "Filter" };
+
     internal Label HeaderLabel { get; } = new();
 
     internal View SortingIconContainer { get; }
diff --git a/Maui.DataGrid/DataGridHeaderRow.cs b/Maui.DataGrid/DataGridHeaderRow.cs
index 786661b..49c8c8c 100644
--- a/Maui.DataGrid/DataGridHeaderRow.cs
+++ b/Maui.DataGrid/DataGridHeaderRow.cs
@@ -14,12 +14,18 @@ internal sealed class DataGridHeaderRow : Grid
 
     #region Fields
 
-    private readonly ColumnDefinitionCollection _headerColumnDefinitions =
+    private readonly RowDefinitionCollection _headerRowDefinitions =
                 [
-                    new() { Width = new(1, GridUnitType.Star) },
-                    new() { Width = new(1, GridUnitType.Auto) }
+                    new() { Height = new(1, GridUnitType.Auto) },
+                    new() { Height = new(1, GridUnitType.Auto) },
                 ];
 
+    private readonly ColumnDefinitionCollection _headerColumnDefinitions =
+            [
+                new() { Width = new(1, GridUnitType.Star) },
+                new() { Width = new(1, GridUnitType.Auto) },
+            ];
+
     private readonly Thickness _headerCellPadding = new(0, 0, 4, 0);
 
     private readonly Command<DataGridColumn> _sortCommand = new(OnSort, CanSort);
@@ -70,15 +76,15 @@ internal void InitializeHeaderRow(bool force = false)
             // Add or update columns as needed
             ColumnDefinitions.AddOrUpdate(col.ColumnDefinition, i);
 
+            col.HeaderCell = CreateHeaderCell(col);
+
+            col.HeaderCell.UpdateBindings(DataGrid);
+
             if (!col.IsVisible)
             {
                 continue;
             }
 
-            col.HeaderCell ??= CreateHeaderCell(col);
-
-            col.HeaderCell.UpdateBindings(DataGrid);
-
             if (Children.TryGetItem(i, out var existingChild))
             {
                 if (existingChild is not DataGridCell existingCell)
@@ -173,39 +179,51 @@ private void OnVisibilityChanged(object? sender, EventArgs e)
 
     private DataGridCell CreateHeaderCell(DataGridColumn column)
     {
-        Grid cellContent;
+        var sortingEnabled = DataGrid.SortingEnabled && column.SortingEnabled && column.IsSortable();
+        var filteringEnabled = DataGrid.FilteringEnabled && column.FilteringEnabled;
 
-        column.HeaderLabel.Style = column.HeaderLabelStyle ?? DataGrid.HeaderLabelStyle ?? DataGrid.DefaultHeaderStyle;
-
-        if (!DataGrid.SortingEnabled || !column.SortingEnabled || !column.IsSortable())
+        if (column.HeaderCell != null)
         {
-            cellContent = [column.HeaderLabel];
-            cellContent.Padding = _headerCellPadding;
+            column.SortingIconContainer.IsVisible = sortingEnabled;
+            column.FilterTextbox.IsVisible = filteringEnabled;
+            return column.HeaderCell;
         }
-        else
+
+        var cellContent = new Grid
         {
-            var sortIconSize = DataGrid.HeaderHeight * 0.3;
-            column.SortingIconContainer.HeightRequest = sortIconSize;
-            column.SortingIconContainer.WidthRequest = sortIconSize;
-            column.SortingIcon.Style = DataGrid.SortIconStyle ?? DataGrid.DefaultSortIconStyle;
+            Padding = _headerCellPadding,
+            ColumnDefinitions = _headerColumnDefinitions,
+            RowDefinitions = _headerRowDefinitions,
+        };
 
-            cellContent = new Grid
-            {
-                Padding = _headerCellPadding,
-                ColumnDefinitions = _headerColumnDefinitions,
-                Children = { column.HeaderLabel, column.SortingIconContainer },
-                GestureRecognizers =
-                {
-                    new TapGestureRecognizer
-                    {
-                        Command = _sortCommand,
-                        CommandParameter = column,
-                    },
-                },
-            };
-
-            cellContent.SetColumn(column.SortingIconContainer, 1);
-        }
+        column.HeaderLabel.Style = column.HeaderLabelStyle ?? DataGrid.HeaderLabelStyle ?? DataGrid.DefaultLabelHeaderStyle;
+        column.FilterTextbox.Style = column.HeaderFilterStyle ?? DataGrid.HeaderFilterStyle ?? DataGrid.DefaultFilterHeaderStyle;
+
+        cellContent.Children.Add(column.HeaderLabel);
+
+        /* Configure the sorting icon */
+
+        var sortIconSize = DataGrid.HeaderHeight * 0.3;
+        column.SortingIconContainer.IsVisible = sortingEnabled;
+        column.SortingIconContainer.HeightRequest = sortIconSize;
+        column.SortingIconContainer.WidthRequest = sortIconSize;
+        column.SortingIcon.Style = DataGrid.SortIconStyle ?? DataGrid.DefaultSortIconStyle;
+
+        cellContent.Children.Add(column.SortingIconContainer);
+        cellContent.SetColumn(column.SortingIconContainer, 1);
+
+        cellContent.GestureRecognizers.Add(new TapGestureRecognizer
+        {
+            Command = _sortCommand,
+            CommandParameter = column,
+        });
+
+        /* Configure the filter textbox */
+
+        column.FilterTextbox.IsVisible = filteringEnabled;
+        cellContent.Children.Add(column.FilterTextbox);
+        cellContent.SetRow(column.FilterTextbox, 1);
+        cellContent.SetColumnSpan(column.FilterTextbox, 2);
 
         return new DataGridCell(cellContent, DataGrid.HeaderBackground, column, false);
     }
diff --git a/Maui.DataGrid/DataGridRow.cs b/Maui.DataGrid/DataGridRow.cs
index f2cdbe6..87e474c 100644
--- a/Maui.DataGrid/DataGridRow.cs
+++ b/Maui.DataGrid/DataGridRow.cs
@@ -8,7 +8,30 @@ internal sealed class DataGridRow : Grid
     #region Bindable Properties
 
     public static readonly BindableProperty DataGridProperty =
-    BindablePropertyExtensions.Create<DataGridRow, DataGrid>(null, BindingMode.OneTime);
+        BindablePropertyExtensions.Create<DataGridRow, DataGrid>(
+            null,
+            BindingMode.OneTime,
+            propertyChanged: (b, o, n) =>
+            {
+                if (b is not DataGridRow dataGridRow)
+                {
+                    return;
+                }
+
+                if (o is DataGrid oldDataGrid)
+                {
+                    foreach (var column in oldDataGrid.Columns)
+                    {
+                        column.VisibilityChanged -= dataGridRow.OnVisibilityChanged;
+                    }
+                }
+
+                foreach (var column in dataGridRow.DataGrid.Columns)
+                {
+                    column.VisibilityChanged -= dataGridRow.OnVisibilityChanged;
+                    column.VisibilityChanged += dataGridRow.OnVisibilityChanged;
+                }
+            });
 
     public static readonly BindableProperty RowToEditProperty =
         BindablePropertyExtensions.Create<DataGridRow, object>(