Added scrolling support to thumbnails list

Directory.Build.props

@@ -5,7 +5,7 @@
 		<ImplicitUsings>disable</ImplicitUsings>
 		<Nullable>enable</Nullable>
 		<Copyright>Copyright © Mihnea Rădulescu 2017 - 2024</Copyright>
-		<AssemblyVersion>1.2024.07.16</AssemblyVersion>
+		<AssemblyVersion>1.2024.07.17</AssemblyVersion>
 		<Version>$(AssemblyVersion)</Version>
 		<DebugType>embedded</DebugType>
 	</PropertyGroup>

ImageFanReloaded.Core/Collections/Implementation/CollectionExtensions.cs

@@ -4,9 +4,6 @@ namespace ImageFanReloaded.Core.Collections.Implementation;
 
 public static class CollectionExtensions
 {
-	public static bool IsIndexWithinBounds<T>(this ICollection<T> collection, int index)
-		=> 0 <= index && index < collection.Count;
-
 	public static bool IsIndexWithinBounds<T>(this IReadOnlyCollection<T> collection, int index)
-		=> 0 <= index && index < collection.Count;
+		=> index >= 0 && index < collection.Count;
 }

ImageFanReloaded.Core/Controls/IContentTabItem.cs

@@ -48,6 +48,4 @@ public interface IContentTabItem
 	void SetImageStatusBarText(string imageStatusBarText);
 
 	void SaveMatchingTreeViewItem(FileSystemEntryInfo selectedFileSystemEntryInfo);
-
-	bool IsThumbnailScrollViewerFocused { get; }
 }

ImageFanReloaded.Core/Keyboard/Key.cs

@@ -27,5 +27,8 @@ public enum Key
 	I,
 
 	Plus,
-	Minus
+	Minus,
+
+	PageUp,
+	PageDown
 }

ImageFanReloaded.Core/Settings/IGlobalParameters.cs

@@ -37,6 +37,9 @@ public interface IGlobalParameters
 
 	Key PlusKey { get; }
 	Key MinusKey { get; }
+
+	Key PageUpKey { get; }
+	Key PageDownKey { get; }
 
 	bool IsBackwardNavigationKey(Key aKey);
 	bool IsForwardNavigationKey(Key aKey);

ImageFanReloaded.Core/Settings/Implementation/GlobalParametersBase.cs

@@ -40,6 +40,9 @@ public abstract class GlobalParametersBase : IGlobalParameters
 
 	public Key PlusKey { get; }
 	public Key MinusKey { get; }
+
+	public Key PageUpKey { get; }
+	public Key PageDownKey { get; }
 
 	public bool IsBackwardNavigationKey(Key aKey) => _backwardNavigationKeys.Contains(aKey);
 	public bool IsForwardNavigationKey(Key aKey) => _forwardNavigationKeys.Contains(aKey);
@@ -109,6 +112,9 @@ protected GlobalParametersBase(
 
 		PlusKey = Key.Plus;
 		MinusKey = Key.Minus;
+
+		PageUpKey = Key.PageUp;
+		PageDownKey = Key.PageDown;
 
 		NameComparer = operatingSystemSettings.IsWindows
 			? new NaturalSortingComparer(StringComparer.InvariantCultureIgnoreCase)

ImageFanReloaded.Test/GlobalParametersTest.cs

@@ -76,6 +76,9 @@ public void GlobalParameters_IsCorrectlyInitialized()
 		_globalParameters.PlusKey.Should().NotBe(Key.None);
 		_globalParameters.MinusKey.Should().NotBe(Key.None);
 
+		_globalParameters.PageUpKey.Should().NotBe(Key.None);
+		_globalParameters.PageDownKey.Should().NotBe(Key.None);
+
 		_globalParameters.NameComparer.Should().NotBeNull();
 
 		_globalParameters.ImageFileExtensions.Should().NotBeEmpty();

ImageFanReloaded/Controls/ContentTabItem.axaml.cs

@@ -3,7 +3,6 @@
 using System.Linq;
 using Avalonia;
 using Avalonia.Controls;
-using ImageFanReloaded.Core.Collections.Implementation;
 using ImageFanReloaded.Core.Controls;
 using ImageFanReloaded.Core.CustomEventArgs;
 using ImageFanReloaded.Core.DiscAccess;
@@ -45,8 +44,9 @@ public void EnableFolderTreeViewSelectedItemChanged()
 	public bool ShouldHandleControlKeyFunctions(KeyModifiers keyModifiers, Key keyPressing)
 	{
 		var shouldHandleKeyPressing = ShouldSwitchControlFocus(keyModifiers, keyPressing)
-			|| ShouldToggleRecursiveFolderAccess(keyModifiers, keyPressing)
-			|| ShouldHandleThumbnailSelection(keyPressing);
+		                              || ShouldToggleRecursiveFolderAccess(keyModifiers, keyPressing)
+		                              || ShouldHandleThumbnailSelection(keyPressing)
+		                              || ShouldHandleThumbnailScrolling(keyPressing);
 
 		return shouldHandleKeyPressing;
 	}
@@ -66,6 +66,10 @@ public void HandleControlKeyFunctions(KeyModifiers keyModifiers, Key keyPressing
 			BringThumbnailIntoView();
 			DisplayImage();
 		}
+		else if (ShouldHandleThumbnailScrolling(keyPressing))
+		{
+			HandleThumbnailScrolling(keyPressing);
+		}
 	}
 
 	public void SetFolderTreeViewSelectedItem()
@@ -214,13 +218,13 @@ public void SaveMatchingTreeViewItem(FileSystemEntryInfo selectedFileSystemEntry
 			}
 		}
 	}
-
-	public bool IsThumbnailScrollViewerFocused => _thumbnailScrollViewer.IsFocused;
 
     #region Private
 
     private const string FakeTreeViewItemText = "Loading...";
 
+    private const int ThumbnailScrollAdvanceCount = 20;
+
     private readonly IList<IThumbnailBox> _thumbnailBoxCollection;
 
     private int _maxThumbnailIndex;
@@ -304,7 +308,7 @@ private void OnImageChanged(object? sender, ImageChangedEventArgs e)
 		var imageView = e.ImageView;
 		var increment = e.Increment;
 
-		if (AdvanceSelectedThumbnailByIncrement(increment))
+		if (AdvanceFromSelectedThumbnail(increment))
 		{
 			imageView.SetImage(_selectedThumbnailBox!.ImageFile!, _folderAccessType.IsRecursive());
 		}
@@ -323,26 +327,37 @@ private void SelectThumbnailBox(IThumbnailBox thumbnailBox)
 		}
 	}
 
-    private bool AdvanceSelectedThumbnailByIncrement(int increment)
+	private bool AdvanceFromSelectedThumbnail(int increment)
 	{
+		var canAdvanceToNewSelectedThumbnailIndex = false;
+
 		if (_selectedThumbnailBox is not null)
 		{
 			var newSelectedThumbnailIndex = _selectedThumbnailIndex + increment;
 
-			if (_thumbnailBoxCollection.IsIndexWithinBounds(newSelectedThumbnailIndex))
+			if (newSelectedThumbnailIndex < 0)
+			{
+				newSelectedThumbnailIndex = 0;
+			}
+			else if (newSelectedThumbnailIndex >= _thumbnailBoxCollection.Count)
 			{
+				newSelectedThumbnailIndex = _thumbnailBoxCollection.Count - 1;
+			}
+
+			if (_selectedThumbnailIndex != newSelectedThumbnailIndex)
+			{
+				canAdvanceToNewSelectedThumbnailIndex = true;
+
 				UnselectThumbnail();
 
 				_selectedThumbnailIndex = newSelectedThumbnailIndex;
 				_selectedThumbnailBox = _thumbnailBoxCollection[_selectedThumbnailIndex];
 
 				SelectThumbnail();
-
-				return true;
 			}
 		}
 
-		return false;
+		return canAdvanceToNewSelectedThumbnailIndex;
 	}
 
 	private void BringThumbnailIntoView() => _selectedThumbnailBox?.BringThumbnailIntoView();
@@ -443,6 +458,17 @@ private bool ShouldHandleThumbnailSelection(Key keyPressing)
 		return false;
 	}
 
+	private bool ShouldHandleThumbnailScrolling(Key keyPressing)
+	{
+		if (_selectedThumbnailBox is not null &&
+		    (keyPressing == GlobalParameters!.PageUpKey || keyPressing == GlobalParameters!.PageDownKey))
+		{
+			return true;
+		}
+
+		return false;
+	}
+
 	private void SwitchControlFocus()
 	{
 		if (_folderTreeView.SelectedItem is null)
@@ -484,17 +510,32 @@ private void ToggleRecursiveFolderAccess(KeyModifiers keyModifiers)
 		RaiseFolderChangedEvent();
 	}
 
+	private void HandleThumbnailScrolling(Key keyPressing)
+	{
+		if (_selectedThumbnailBox is not null)
+		{
+			if (keyPressing == GlobalParameters!.PageUpKey)
+			{
+				AdvanceFromSelectedThumbnail(-ThumbnailScrollAdvanceCount);
+			}
+			else if (keyPressing == GlobalParameters!.PageDownKey)
+			{
+				AdvanceFromSelectedThumbnail(ThumbnailScrollAdvanceCount);
+			}
+		}
+	}
+
 	private void ThumbnailScrollViewerOnKeyPressing(object? sender, Avalonia.Input.KeyEventArgs e)
 	{
 		var keyPressing = e.Key.ToCoreKey();
 
 		if (GlobalParameters!.IsBackwardNavigationKey(keyPressing))
 		{
-			AdvanceSelectedThumbnailByIncrement(-1);
+			AdvanceFromSelectedThumbnail(-1);
 		}
 		else if (GlobalParameters!.IsForwardNavigationKey(keyPressing))
 		{
-			AdvanceSelectedThumbnailByIncrement(1);
+			AdvanceFromSelectedThumbnail(1);
 		}
 
 		e.Handled = true;

ImageFanReloaded/Controls/MainWindow.axaml.cs

@@ -265,7 +265,7 @@ private bool ShouldNavigateToNextTab(KeyModifiers keyModifiers, Key keyPressing)
     private bool ShouldDisplayHelp(Key keyPressing) => keyPressing == GlobalParameters!.F1Key;
 
     private bool ShouldAllowKeyPressingEventPropagation(IContentTabItem contentTabItem, Key keyPressing)
-		=> contentTabItem.IsThumbnailScrollViewerFocused || GlobalParameters!.IsNavigationKey(keyPressing);
+		=> GlobalParameters!.IsNavigationKey(keyPressing);
 
     private bool HasAtLeastOneContentTabItem()
     {

ImageFanReloaded/Keyboard/KeyExtensions.cs

@@ -31,6 +31,9 @@ public static ImageFanReloaded.Core.Keyboard.Key ToCoreKey(this Avalonia.Input.K
 			Avalonia.Input.Key.Add => Core.Keyboard.Key.Plus,
 			Avalonia.Input.Key.OemMinus => Core.Keyboard.Key.Minus,
 			Avalonia.Input.Key.Subtract => Core.Keyboard.Key.Minus,
+
+			Avalonia.Input.Key.PageUp => Core.Keyboard.Key.PageUp,
+			Avalonia.Input.Key.PageDown => Core.Keyboard.Key.PageDown,
 
 			_ => Core.Keyboard.Key.None
 		};