Add TableView.ApplyColumnFilterImmediately

docs/docs/filtering.md

@@ -46,6 +46,14 @@ Show how many rows match each filter value:
 <tv:TableView ShowFilterItemsCount="True" />
 ```
 
+## Applying filters as they change
+
+By default the filter flyout applies a column's filter when OK is pressed. To apply it as soon as an item is checked or unchecked, or the search text changes, turn on `ApplyColumnFilterImmediately`. The flyout then drops its OK and Cancel buttons, and closing it keeps the filter:
+
+```xml
+<tv:TableView ApplyColumnFilterImmediately="True" />
+```
+
 ## Filtering programmatically
 
 Add filter descriptions to `TableView.FilterDescriptions`:

src/Controls/TableViewFilterItemsControl.xaml.cs

@@ -16,6 +16,8 @@ namespace WinUI.TableView.Controls;
 public partial class TableViewFilterItemsControl : UserControl
 {
     private bool _canSetState = true;
+    private bool _isClearingSearchBox;
+    private bool _isUpdatingSelectAllCheckBox;
 
     /// <summary>
     /// Initializes a new instance of the <see cref="TableViewFilterItemsControl"/> class.
@@ -49,12 +51,32 @@ internal async void Initialize()
     /// </summary>
     internal void ClearSearchBox()
     {
+        // The flyout clears its search when it closes; that isn't the user changing the filter, so it mustn't
+        // undo a filter that was applied from the search.
+        _isClearingSearchBox = true;
         searchBox?.Text = string.Empty;
+        _isClearingSearchBox = false;
     }
 
     private void OnSearchBoxTextChanged(object sender, TextChangedEventArgs e)
     {
         FilterItems = TableView?.FilterHandler?.GetFilterItems(ColumnHeader?.Column!, searchBox!.Text);
+
+        if (!_isClearingSearchBox)
+        {
+            ApplyFilterIfImmediate();
+        }
+    }
+
+    /// <summary>
+    /// Applies the filter as it stands, as OK would, when <see cref="TableView.ApplyColumnFilterImmediately"/> is on.
+    /// </summary>
+    private void ApplyFilterIfImmediate()
+    {
+        if (TableView?.ApplyColumnFilterImmediately is true)
+        {
+            ColumnHeader?.ApplyFilter();
+        }
     }
 
     /// <summary>
@@ -76,7 +98,14 @@ private void OnSearchBoxKeyDown(object sender, KeyRoutedEventArgs e)
     /// </summary>
     private void OnSelectAllCheckBoxCheckChanged(object sender, RoutedEventArgs e)
     {
+        // The checkbox also follows the items (SetSelectAllCheckBoxState); only a click on it changes the filter.
+        if (_isUpdatingSelectAllCheckBox)
+        {
+            return;
+        }
+
         SetFilterItemsState(selectAllCheckBox.IsChecked is true);
+        ApplyFilterIfImmediate();
     }
 
     /// <summary>
@@ -90,9 +119,11 @@ internal void SetSelectAllCheckBoxState()
         }
 
 
+        _isUpdatingSelectAllCheckBox = true;
         selectAllCheckBox.IsChecked = FilterItems?.All(x => x.IsSelected) ?? false ? true
                                       : FilterItems?.All(x => !x.IsSelected) ?? false ? false
                                       : null;
+        _isUpdatingSelectAllCheckBox = false;
     }
 
     /// <summary>
@@ -145,6 +176,12 @@ private void DetachPropertyChangedHandlers()
     private void OnFilterItemPropertyChanged(object? sender, PropertyChangedEventArgs e)
     {
         SetSelectAllCheckBoxState();
+
+        // SetFilterItemsState changes every item at once and applies once itself.
+        if (_canSetState && e.PropertyName is nameof(TableViewFilterItem.IsSelected))
+        {
+            ApplyFilterIfImmediate();
+        }
     }
 
     /// <summary>

src/TableView.Properties.cs

@@ -308,6 +308,11 @@ public partial class TableView
     /// </summary>
     public static readonly DependencyProperty ShowFilterItemsCountProperty = DependencyProperty.Register(nameof(ShowFilterItemsCount), typeof(bool), typeof(TableView), new PropertyMetadata(false));
 
+    /// <summary>
+    /// Identifies the <see cref="ApplyColumnFilterImmediately"/> dependency property.
+    /// </summary>
+    public static readonly DependencyProperty ApplyColumnFilterImmediatelyProperty = DependencyProperty.Register(nameof(ApplyColumnFilterImmediately), typeof(bool), typeof(TableView), new PropertyMetadata(false));
+
 
     /// <summary>
     /// Identifies the <see cref="ForceRowOrCellSelectionOnContextRequested"/> dependency property.
@@ -412,6 +417,17 @@ public bool ShowFilterItemsCount
         set => SetValue(ShowFilterItemsCountProperty, value);
     }
 
+    /// <summary>
+    /// Gets or sets a value that indicates whether a column's filter applies as soon as it changes in the filter
+    /// flyout (an item is checked or unchecked, or the search text changes) instead of when OK is pressed.
+    /// The flyout then has no OK and Cancel buttons; closing it keeps the filter.
+    /// </summary>
+    public bool ApplyColumnFilterImmediately
+    {
+        get => (bool)GetValue(ApplyColumnFilterImmediatelyProperty);
+        set => SetValue(ApplyColumnFilterImmediatelyProperty, value);
+    }
+
     /// <summary>
     /// Gets or sets a value indicating whether the drag selection rectangle is shown during cell drag selection.
     /// </summary>

src/TableViewFilterMenuFlyout.cs

@@ -12,6 +12,7 @@ namespace WinUI.TableView;
 public partial class TableViewFilterMenuFlyout : Flyout
 {
     private TableViewFilterItemsControl? _filterItemsControl;
+    private FrameworkElement? _buttonsPanel;
     private readonly StandardUICommand _okCommand = new() { Label = TableViewLocalizedStrings.Ok };
     private readonly StandardUICommand _cancelCommand = new() { Label = TableViewLocalizedStrings.Cancel };
 
@@ -44,6 +45,15 @@ protected override Control CreatePresenter()
     private void OnOpening(object? sender, object e)
     {
         _filterItemsControl?.Initialize();
+        UpdateButtonsVisibility();
+    }
+
+    /// <summary>
+    /// Hides OK and Cancel when the filter applies as it changes: there's nothing left for them to do.
+    /// </summary>
+    private void UpdateButtonsVisibility()
+    {
+        _buttonsPanel?.Visibility = TableView?.ApplyColumnFilterImmediately is true ? Visibility.Collapsed : Visibility.Visible;
     }
 
     /// <summary>
@@ -71,6 +81,8 @@ private void OnPresenterLoaded(object sender, RoutedEventArgs e)
 
         okButton?.Command = _okCommand;
         cancelButton?.Command = _cancelCommand;
+        _buttonsPanel = okButton?.Parent as FrameworkElement;
+        UpdateButtonsVisibility();
 
         presenter.Loaded -= OnPresenterLoaded;
         _filterItemsControl?.Initialize();