Changed behavior to accept keyboard overrides, added keyboard mouse state validator and indirect rules to allow keyboard and mouse navigation

Photos/Views/MainWindow.axaml

@@ -64,6 +64,8 @@
                           Background="Transparent"
                           Foreground="#EDEDED"
                           Margin="5,0,0,0"
+                          IsTabStop="False"
+                          Focusable="False"
                           >
                         <!--
                         <MenuItem Header="_File">
@@ -71,8 +73,8 @@
                             <MenuItem Header="_Close" Command="{Binding CloseDirectory}"/>
                         </MenuItem>
                         -->
-                        <MenuItem Header="_Open Library" IsVisible="{Binding !PhotosLoaded}" Command="{Binding OpenDirectory}"/>
-                        <MenuItem Header="_Close Library" IsVisible="{Binding PhotosLoaded}" Command="{Binding CloseDirectory}"/>
+                        <MenuItem Header="_Open Library" Focusable="False" IsVisible="{Binding !PhotosLoaded}" Command="{Binding OpenDirectory}"/>
+                        <MenuItem Header="_Close Library" Focusable="False" IsVisible="{Binding PhotosLoaded}" Command="{Binding CloseDirectory}"/>
                     </Menu>
                 </DockPanel>
             </Border>
@@ -114,11 +116,13 @@
                           Grid.RowSpan="2"
                           IsVisible="{Binding PhotosLoaded}">
                 <Border Padding="72,88,72,48">
-                    <ItemsRepeater ItemsSource="{Binding Photos}"
+                    <ItemsRepeater x:Name="Repeater"
+                                   ItemsSource="{Binding Photos}"
                                    HorizontalAlignment="Stretch"
                                    VerticalAlignment="Stretch"
                                    ClipToBounds="False"
-                                   IsTabStop="True">
+                                   IsTabStop="True"
+                                   >
                         <ItemsRepeater.Layout>
                             <UniformGridLayout MinItemWidth="220"
                                                MinItemHeight="290"
@@ -136,7 +140,8 @@
                                         BoxShadow="0 10 24 0 #30000000"
                                         anim:CardHoverEffectBehavior.IsEnabled="True"
                                         anim:CardHoverEffectBehavior.MaxRotationAngle="2.5"
-                                        anim:CardHoverEffectBehavior.ScaleFactor="1.08">
+                                        anim:CardHoverEffectBehavior.ScaleFactor="1.08"
+                                        >
                                     <StackPanel Orientation="Vertical"
                                                 Spacing="10">
                                         <i:Interaction.Behaviors>

Photos/Views/MainWindow.axaml.cs

@@ -1,7 +1,11 @@
+using System;
+using System.Linq;
 using System.Threading.Tasks;
 using Avalonia.Controls;
 using Avalonia.Input;
+using Avalonia.VisualTree;
 using Avalonia.Xaml.Interactions.DragAndDrop;
+using Photos.Animations;
 using Photos.Models;
 using Photos.ViewModels;
 
@@ -9,8 +13,17 @@ namespace Photos.Views;
 
 public partial class MainWindow : Window
 {
+    private enum NavigationInputMode
+    {
+        Mouse,
+        Keyboard
+    }
+
+    private NavigationInputMode _navigationInputMode = NavigationInputMode.Mouse;
+
     private IFolderPickerService _folderPickerService;
     private int _currentImageIndex = 0;
+    private Control? _currentHoveredCard;
 
     public MainWindow()
     {
@@ -24,10 +37,25 @@ public partial class MainWindow : Window
         (DataContext as MainWindowViewModel)?.WindowDropHandler(e);
     }
 
-    private void OnKeyDownHandler(object sender, KeyEventArgs e)
+    private async void OnKeyDownHandler(object sender, KeyEventArgs e)
     {
         if (DataContext is not MainWindowViewModel vm) return;
 
+        // input state changer
+        switch (e.Key)
+        {
+            case Key.Enter:
+            case Key.Escape:
+            case Key.Left:
+            case Key.Right:
+            case Key.Up:
+            case Key.Down:
+                _navigationInputMode = NavigationInputMode.Keyboard;
+                UpdatePointerHoverSuppression();
+                UpdateKeyboardHover();
+                break;
+        }
+
         async Task HandleEnter()
         {
             if (vm.IsPhotoFocused()) vm.UnfocusPhoto();
@@ -45,28 +73,98 @@ public partial class MainWindow : Window
             // TODO: move basic selection
         }
 
+        int CalculateCurrentIndexHop()
+        {
+            // Values of UniformGridLayout
+            var minItemWidth = 220;
+            var minColumnSpacing = 18;
+
+            var repeaterWidth = Repeater.Bounds.Width;
+
+            var abstractedColumnCount = Math.Floor(repeaterWidth / (minItemWidth + minColumnSpacing));
+            return Math.Max(1, (int)abstractedColumnCount);
+        }
+
+        void HandleArrowKeyDown()
+        {
+            var nextIdx = CalculateCurrentIndexHop();
+            if (_currentImageIndex + nextIdx >= vm.Photos.Count) _currentImageIndex = vm.Photos.Count - 1;
+            else _currentImageIndex += nextIdx;
+        }
+
+        void HandleArrowKeyUp()
+        {
+            var nextIdx = CalculateCurrentIndexHop();
+            if (_currentImageIndex - nextIdx < 0) _currentImageIndex = 0;
+            else _currentImageIndex -= nextIdx;
+        }
+
+        Control? FindCardControlForCurrentIndex()
+        {
+            if (_currentImageIndex < 0 || _currentImageIndex >= vm.Photos.Count)
+                return null;
+
+            var currentPhoto = vm.Photos[_currentImageIndex];
+
+            return Repeater.GetVisualDescendants()
+                .OfType<Control>()
+                .FirstOrDefault(c =>
+                    ReferenceEquals(c.DataContext, currentPhoto) &&
+                    CardHoverEffectBehavior.GetIsEnabled(c));
+        }
+
+        void UpdateKeyboardHover()
+        {
+            if (DataContext is not MainWindowViewModel vm)
+                return;
+
+            if (_currentHoveredCard is not null)
+            {
+                CardHoverEffectBehavior.ResetHover(_currentHoveredCard);
+                _currentHoveredCard = null;
+            }
+
+            var newCard = FindCardControlForCurrentIndex();
+            if (newCard is null) return;
+
+            CardHoverEffectBehavior.ApplyHover(newCard);
+            _currentHoveredCard = newCard;
+            _currentHoveredCard.BringIntoView();
+        }
+
         switch (e.Key)
         {
-            case Key.Enter:
-                HandleEnter().GetAwaiter();
+            case Key.Enter: case Key.Space:
+                if (!vm.PhotosLoaded) await vm.OpenDirectory();
+                else await HandleEnter();
                 break;
             case Key.Escape:
                 HandleEscape();
                 break;
             case Key.Down:
+                HandleArrowKeyDown();
+                UpdateKeyboardHover();
+                await HandleArrowKey();
+                break;
+            case Key.Up:
+                HandleArrowKeyUp();
+                UpdateKeyboardHover();
+                await HandleArrowKey();
                 break;
             case Key.Left:
                 if (_currentImageIndex > 0)
                 {
                     _currentImageIndex--;
-                    HandleArrowKey().GetAwaiter();
+                    UpdateKeyboardHover();
+                    await HandleArrowKey();
                 }
                 break;
             case Key.Right:
                 if (_currentImageIndex < vm.Photos.Count - 1)
                 {
                     _currentImageIndex++;
-                    HandleArrowKey().GetAwaiter();
+                    UpdateKeyboardHover();
+                    await HandleArrowKey();
                 }
                 break;
         }
@@ -74,9 +172,34 @@ public partial class MainWindow : Window
 
     private void PointerEnteredPhotoHandler(object sender, PointerEventArgs e)
     {
-        if (sender is not Image i || DataContext is not MainWindowViewModel vm) return;
-        var idx = vm.GetImageIndex(i);
-        if (idx == -1) return;
+        if (sender is not Image image || DataContext is not MainWindowViewModel vm) return;
+
+        var photo = image.DataContext as Photo;
+        if (photo is null) return;
+
+        var idx = vm.Photos.IndexOf(photo);
+        if (idx < 0) return;
+
+        _navigationInputMode = NavigationInputMode.Mouse;
+        UpdatePointerHoverSuppression();
         _currentImageIndex = idx;
+
+        if (_currentHoveredCard is null) return;
+
+        CardHoverEffectBehavior.ResetHover(_currentHoveredCard);
+        _currentHoveredCard = null;
+    }
+
+    private void UpdatePointerHoverSuppression()
+    {
+        foreach (var control in Repeater.GetVisualDescendants().OfType<Control>())
+        {
+            if (CardHoverEffectBehavior.GetIsEnabled(control))
+            {
+                CardHoverEffectBehavior.SetSuppressPointerHover(
+                    control,
+                    _navigationInputMode == NavigationInputMode.Keyboard);
+            }
+        }
     }
 }