Add KeyTrigger sample page

README.md

@@ -585,10 +585,13 @@ This section provides an overview of all available classes and their purpose in
 - **HoldingTrigger**  
   *Triggers actions when a holding gesture is detected.*
 
-- **KeyDownTrigger**  
+- **KeyDownTrigger**
   *Listens for key down events and triggers actions if the pressed key (or gesture) matches the specified criteria.*
 
-- **KeyUpTrigger**  
+- **KeyTrigger**
+  *Listens for key down or key up events and triggers actions when the configured key or gesture occurs.*
+
+- **KeyUpTrigger**
   *Listens for key up events and triggers actions when conditions are met.*
 
 - **LostFocusTrigger**  

samples/BehaviorsTestApplication/Views/MainView.axaml

@@ -121,6 +121,9 @@
     <TabItem Header="InteractionTriggerBehavior">
       <pages:InteractionTriggerBehaviorView />
     </TabItem>
+    <TabItem Header="KeyTrigger">
+      <pages:KeyTriggerView />
+    </TabItem>
     <TabItem Header="Reactive Navigation">
       <pages:ReactiveNavigationView />
     </TabItem>

samples/BehaviorsTestApplication/Views/Pages/KeyTriggerView.axaml

@@ -0,0 +1,32 @@
+<UserControl x:Class="BehaviorsTestApplication.Views.Pages.KeyTriggerView"
+             xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+             xmlns:vm="using:BehaviorsTestApplication.ViewModels"
+             x:DataType="vm:MainWindowViewModel"
+             mc:Ignorable="d" d:DesignWidth="400" d:DesignHeight="150">
+  <Design.DataContext>
+    <vm:MainWindowViewModel />
+  </Design.DataContext>
+  <StackPanel Margin="5">
+    <TextBlock Name="Message"
+               Text="Press Enter"
+               HorizontalAlignment="Center"
+               Margin="5" />
+    <TextBox Name="InputBox" Margin="5" Width="200">
+      <Interaction.Behaviors>
+        <KeyTrigger Key="Enter" Event="KeyDown">
+          <ChangePropertyAction TargetObject="Message"
+                                PropertyName="Text"
+                                Value="Enter Down" />
+        </KeyTrigger>
+        <KeyTrigger Key="Enter" Event="KeyUp">
+          <ChangePropertyAction TargetObject="Message"
+                                PropertyName="Text"
+                                Value="Enter Up" />
+        </KeyTrigger>
+      </Interaction.Behaviors>
+    </TextBox>
+  </StackPanel>
+</UserControl>

samples/BehaviorsTestApplication/Views/Pages/KeyTriggerView.axaml.cs

@@ -0,0 +1,17 @@
+using Avalonia.Controls;
+using Avalonia.Markup.Xaml;
+
+namespace BehaviorsTestApplication.Views.Pages;
+
+public partial class KeyTriggerView : UserControl
+{
+    public KeyTriggerView()
+    {
+        InitializeComponent();
+    }
+
+    private void InitializeComponent()
+    {
+        AvaloniaXamlLoader.Load(this);
+    }
+}

src/Avalonia.Xaml.Interactions.Custom/InputElement/Triggers/KeyTrigger.cs

@@ -0,0 +1,99 @@
+using Avalonia.Input;
+using Avalonia.Interactivity;
+
+namespace Avalonia.Xaml.Interactions.Custom;
+
+/// <summary>
+/// A trigger that listens for key events and executes its actions when the
+/// specified key or gesture is detected.
+/// </summary>
+public class KeyTrigger : RoutedEventTriggerBase<KeyEventArgs>
+{
+    /// <summary>
+    /// Specifies which keyboard event will fire the trigger.
+    /// </summary>
+    public enum FiredOn
+    {
+        /// <summary>
+        /// Trigger on the <see cref="InputElement.KeyDownEvent"/>.
+        /// </summary>
+        KeyDown,
+
+        /// <summary>
+        /// Trigger on the <see cref="InputElement.KeyUpEvent"/>.
+        /// </summary>
+        KeyUp
+    }
+
+    /// <inheritdoc />
+    protected override RoutedEvent<KeyEventArgs> RoutedEvent
+        => Event == FiredOn.KeyDown ? InputElement.KeyDownEvent : InputElement.KeyUpEvent;
+
+    /// <summary>
+    /// Identifies the <seealso cref="Key"/> avalonia property.
+    /// </summary>
+    public static readonly StyledProperty<Key?> KeyProperty =
+        AvaloniaProperty.Register<KeyTrigger, Key?>(nameof(Key));
+
+    /// <summary>
+    /// Identifies the <seealso cref="Gesture"/> avalonia property.
+    /// </summary>
+    public static readonly StyledProperty<KeyGesture?> GestureProperty =
+        AvaloniaProperty.Register<KeyTrigger, KeyGesture?>(nameof(Gesture));
+
+    /// <summary>
+    /// Identifies the <seealso cref="Event"/> avalonia property.
+    /// </summary>
+    public static readonly StyledProperty<FiredOn> EventProperty =
+        AvaloniaProperty.Register<KeyTrigger, FiredOn>(nameof(Event), FiredOn.KeyDown);
+
+    /// <summary>
+    /// Gets or sets the key to listen for. This is an avalonia property.
+    /// </summary>
+    public Key? Key
+    {
+        get => GetValue(KeyProperty);
+        set => SetValue(KeyProperty, value);
+    }
+
+    /// <summary>
+    /// Gets or sets the key gesture to match. This is an avalonia property.
+    /// </summary>
+    public KeyGesture? Gesture
+    {
+        get => GetValue(GestureProperty);
+        set => SetValue(GestureProperty, value);
+    }
+
+    /// <summary>
+    /// Gets or sets which key event fires the trigger. This is an avalonia property.
+    /// </summary>
+    public FiredOn Event
+    {
+        get => GetValue(EventProperty);
+        set => SetValue(EventProperty, value);
+    }
+
+    /// <inheritdoc />
+    protected override void Handler(object? sender, KeyEventArgs e)
+    {
+        if (!IsEnabled)
+        {
+            return;
+        }
+
+        var isKeySet = IsSet(KeyProperty);
+        var isGestureSet = IsSet(GestureProperty);
+        var key = Key;
+        var gesture = Gesture;
+        var haveKey = key is not null && isKeySet && e.Key == key;
+        var haveGesture = gesture is not null && isGestureSet && gesture.Matches(e);
+
+        if ((!isKeySet && !isGestureSet)
+            || haveKey
+            || haveGesture)
+        {
+            Execute(e);
+        }
+    }
+}