added keyboard navigation for selected images -> TOOD: allow visual keyboardnavigation when photo is not maximized

Photos/Views/MainWindow.axaml.cs

@@ -1,3 +1,4 @@
+using System.Threading.Tasks;
 using Avalonia.Controls;
 using Avalonia.Input;
 using Avalonia.Xaml.Interactions.DragAndDrop;
@@ -9,6 +10,7 @@ namespace Photos.Views;
 public partial class MainWindow : Window
 {
     private IFolderPickerService _folderPickerService;
+    private int _currentImageIndex = 0;
 
     public MainWindow()
     {
@@ -21,4 +23,60 @@ public partial class MainWindow : Window
     {
         (DataContext as MainWindowViewModel)?.WindowDropHandler(e);
     }
+
+    private void OnKeyDownHandler(object sender, KeyEventArgs e)
+    {
+        if (DataContext is not MainWindowViewModel vm) return;
+
+        async Task HandleEnter()
+        {
+            if (vm.IsPhotoFocused()) vm.UnfocusPhoto();
+            else await vm.TryFocusImage(_currentImageIndex);
+        }
+
+        void HandleEscape()
+        {
+            vm.UnfocusPhoto();
+        }
+
+        async Task HandleArrowKey()
+        {
+            if(vm.IsPhotoFocused()) await vm.TryFocusImage(_currentImageIndex);
+            // TODO: move basic selection
+        }
+
+        switch (e.Key)
+        {
+            case Key.Enter:
+                HandleEnter().GetAwaiter();
+                break;
+            case Key.Escape:
+                HandleEscape();
+                break;
+            case Key.Down:
+                break;
+            case Key.Left:
+                if (_currentImageIndex > 0)
+                {
+                    _currentImageIndex--;
+                    HandleArrowKey().GetAwaiter();
+                }
+                break;
+            case Key.Right:
+                if (_currentImageIndex < vm.Photos.Count - 1)
+                {
+                    _currentImageIndex++;
+                    HandleArrowKey().GetAwaiter();
+                }
+                break;
+        }
+    }
+
+    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;
+        _currentImageIndex = idx;
+    }
 }