Feature: Added swipe gesture for back/forward navigation

src/Files.App/Views/ModernShellPage.xaml

@@ -5,6 +5,7 @@
 	xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
 	xmlns:local="using:Files.App.Views"
 	xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+	xmlns:wct="using:CommunityToolkit.WinUI.UI"
 	xmlns:wctconverters="using:CommunityToolkit.WinUI.UI.Converters"
 	x:Name="RootPage"
 	KeyboardAcceleratorPlacementMode="Hidden"
@@ -76,12 +77,48 @@
 			Modifiers="Menu" />
 	</local:BaseShellPage.KeyboardAccelerators>
 
-	<Frame
-		x:Name="ItemDisplayFrame"
-		HorizontalAlignment="Stretch"
-		x:FieldModifier="public"
-		BorderBrush="{x:Bind CurrentInstanceBorderBrush, Mode=OneWay}"
-		BorderThickness="{x:Bind CurrentInstanceBorderThickness, Mode=OneWay}"
-		Navigated="ItemDisplayFrame_Navigated" />
+	<Grid HorizontalAlignment="Stretch" wct:UIElementExtensions.ClipToBounds="True">
+		<Grid
+			x:Name="BackIcon"
+			Margin="-1,0,0,0"
+			HorizontalAlignment="Left"
+			VerticalAlignment="Center"
+			Canvas.ZIndex="64">
+			<Ellipse
+				Width="48"
+				Height="48"
+				Fill="White"
+				Stroke="{ThemeResource SystemAccentColor}" />
+			<SymbolIcon
+				HorizontalAlignment="Center"
+				VerticalAlignment="Center"
+				Foreground="Black"
+				Symbol="Back" />
+		</Grid>
+		<Grid
+			x:Name="ForwardIcon"
+			Margin="1,0,0,0"
+			HorizontalAlignment="Right"
+			VerticalAlignment="Center"
+			Canvas.ZIndex="64">
+			<Ellipse
+				Width="48"
+				Height="48"
+				Fill="White"
+				Stroke="{ThemeResource SystemAccentColor}" />
+			<SymbolIcon
+				HorizontalAlignment="Center"
+				VerticalAlignment="Center"
+				Foreground="Black"
+				Symbol="Forward" />
+		</Grid>
+		<Frame
+			x:Name="ItemDisplayFrame"
+			HorizontalAlignment="Stretch"
+			x:FieldModifier="public"
+			BorderBrush="{x:Bind CurrentInstanceBorderBrush, Mode=OneWay}"
+			BorderThickness="{x:Bind CurrentInstanceBorderThickness, Mode=OneWay}"
+			Navigated="ItemDisplayFrame_Navigated" />
+	</Grid>
 
 </local:BaseShellPage>

src/Files.App/Views/ModernShellPage.xaml.cs

@@ -30,6 +30,8 @@ public sealed partial class ModernShellPage : BaseShellPage
 
 		protected override Frame ItemDisplay => ItemDisplayFrame;
 
+		private NavigationInteractionTracker _navigationInteractionTracker;
+
 		public Thickness CurrentInstanceBorderThickness
 		{
 			get => (Thickness)GetValue(CurrentInstanceBorderThicknessProperty);
@@ -54,6 +56,8 @@ public ModernShellPage() : base(new CurrentInstanceViewModel())
 			ToolbarViewModel.PathControlDisplayText = "Home".GetLocalizedResource();
 
 			ToolbarViewModel.RefreshWidgetsRequested += ModernShellPage_RefreshWidgetsRequested;
+			_navigationInteractionTracker = new NavigationInteractionTracker(this, BackIcon, ForwardIcon);
+			_navigationInteractionTracker.NavigationRequested += SwipeNavigationRequested;
 		}
 
 		private void ModernShellPage_RefreshWidgetsRequested(object sender, EventArgs e)
@@ -175,6 +179,9 @@ private async void ItemDisplayFrame_Navigated(object sender, NavigationEventArgs
 
 			if (parameters.IsLayoutSwitch)
 				FilesystemViewModel_DirectoryInfoUpdated(sender, EventArgs.Empty);
+
+			_navigationInteractionTracker.CanGoBack = CanNavigateBackward;
+			_navigationInteractionTracker.CanGoForward = CanNavigateForward;
 		}
 
 		private async void KeyboardAccelerator_Invoked(KeyboardAccelerator sender, KeyboardAcceleratorInvokedEventArgs args)
@@ -253,6 +260,20 @@ private async void KeyboardAccelerator_Invoked(KeyboardAccelerator sender, Keybo
 			}
 		}
 
+		private void SwipeNavigationRequested(object? sender, SwipeNavigationEventArgs e)
+		{
+			switch (e)
+			{
+				case SwipeNavigationEventArgs.Forward:
+					Forward_Click();
+					break;
+
+				case SwipeNavigationEventArgs.Back:
+					Back_Click();
+					break;
+			}
+		}
+
 		public override void Back_Click()
 		{
 			ToolbarViewModel.CanGoBack = false;

src/Files.App/Views/NavigationInteractionTracker.cs

@@ -0,0 +1,199 @@
+using Microsoft.UI.Composition;
+using Microsoft.UI.Composition.Interactions;
+using Microsoft.UI.Input;
+using Microsoft.UI.Xaml;
+using Microsoft.UI.Xaml.Hosting;
+using Microsoft.UI.Xaml.Input;
+using System;
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using System.Linq;
+using System.Numerics;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Files.App.Views
+{
+	internal class NavigationInteractionTracker
+	{
+		public bool CanGoForward
+		{
+			get
+			{
+				_props.TryGetBoolean(nameof(CanGoForward), out bool val);
+				return val;
+			}
+			set
+			{
+				_props.InsertBoolean(nameof(CanGoForward), value);
+			}
+		}
+
+		public bool CanGoBack
+		{
+			get
+			{
+				_props.TryGetBoolean(nameof(CanGoBack), out bool val);
+				return val;
+			}
+			set
+			{
+				_props.InsertBoolean(nameof(CanGoBack), value);
+			}
+		}
+
+		private UIElement _rootElement;
+		private UIElement _backIcon;
+		private UIElement _forwardIcon;
+
+		private Visual _rootVisual;
+		private Visual _backVisual;
+		private Visual _forwardVisual;
+
+		private InteractionTracker _tracker;
+		private VisualInteractionSource _source;
+		private InteractionTrackerOwner _trackerOwner;
+		private CompositionPropertySet _props;
+
+		public event EventHandler<SwipeNavigationEventArgs>? NavigationRequested;
+
+		public NavigationInteractionTracker(UIElement rootElement, UIElement backIcon, UIElement forwardIcon)
+		{
+			_rootElement = rootElement;
+			_backIcon = backIcon;
+			_forwardIcon = forwardIcon;
+
+			ElementCompositionPreview.SetIsTranslationEnabled(_backIcon, true);
+			ElementCompositionPreview.SetIsTranslationEnabled(_forwardIcon, true);
+			_rootVisual = ElementCompositionPreview.GetElementVisual(_rootElement);
+			_backVisual = ElementCompositionPreview.GetElementVisual(_backIcon);
+			_forwardVisual = ElementCompositionPreview.GetElementVisual(_forwardIcon);
+
+			_props = _rootVisual.Compositor.CreatePropertySet();
+			CanGoBack = false;
+			CanGoForward = false;
+
+			rootElement.AddHandler(UIElement.PointerPressedEvent, new PointerEventHandler(PointerPressed), true);
+
+			SetupInteractionTracker();
+			SetupAnimations();
+		}
+
+		[MemberNotNull(nameof(_tracker), nameof(_source), nameof(_trackerOwner))]
+		private void SetupInteractionTracker()
+		{
+			var compositor = _rootVisual.Compositor;
+
+			_trackerOwner = new(this);
+			_tracker = InteractionTracker.CreateWithOwner(compositor, _trackerOwner);
+			_tracker.MinPosition = new Vector3(-96f);
+			_tracker.MaxPosition = new Vector3(96f);
+
+			_source = VisualInteractionSource.Create(_rootVisual);
+			_source.ManipulationRedirectionMode = VisualInteractionSourceRedirectionMode.CapableTouchpadOnly;
+			_source.PositionXSourceMode = InteractionSourceMode.EnabledWithoutInertia;
+			_source.PositionXChainingMode = InteractionChainingMode.Auto;
+			_source.PositionYSourceMode = InteractionSourceMode.Disabled;
+			_tracker.InteractionSources.Add(_source);
+		}
+
+		private void SetupAnimations()
+		{
+			var compositor = _rootVisual.Compositor;
+
+			var backResistance = CreateResistanceCondition(-96f, 0f);
+			var forwardResistance = CreateResistanceCondition(0f, 96f);
+			List<CompositionConditionalValue> conditionalValues = new() { backResistance, forwardResistance };
+			_source.ConfigureDeltaPositionXModifiers(conditionalValues);
+
+			var backAnim = compositor.CreateExpressionAnimation("props.CanGoBack ? (-clamp(tracker.Position.X, -96, 0) * 2) - 48 : this.CurrentValue - 48");
+			backAnim.SetReferenceParameter("tracker", _tracker);
+			backAnim.SetReferenceParameter("props", _props);
+			_backVisual.StartAnimation("Translation.X", backAnim);
+
+			var forwardAnim = compositor.CreateExpressionAnimation("props.CanGoForward ? (-clamp(tracker.Position.X, 0, 96) * 2) + 48 : this.CurrentValue + 48");
+			forwardAnim.SetReferenceParameter("tracker", _tracker);
+			forwardAnim.SetReferenceParameter("props", _props);
+			_forwardVisual.StartAnimation("Translation.X", forwardAnim);
+		}
+
+		private void PointerPressed(object sender, PointerRoutedEventArgs e)
+		{
+			if (e.Pointer.PointerDeviceType == PointerDeviceType.Touch)
+			{
+				_source.TryRedirectForManipulation(e.GetCurrentPoint(_rootElement));
+			}
+		}
+
+		private CompositionConditionalValue CreateResistanceCondition(float minValue, float maxValue)
+		{
+			var compositor = _rootVisual.Compositor;
+
+			var resistance = CompositionConditionalValue.Create(compositor);
+			var resistanceCondition = compositor.CreateExpressionAnimation($"tracker.Position.X > {minValue} && tracker.Position.X < {maxValue}");
+			resistanceCondition.SetReferenceParameter("tracker", _tracker);
+			var resistanceValue = compositor.CreateExpressionAnimation($"source.DeltaPosition.X * (1 - sqrt(1 - square((tracker.Position.X / {minValue + maxValue}) - 1)))");
+			resistanceValue.SetReferenceParameter("source", _source);
+			resistanceValue.SetReferenceParameter("tracker", _tracker);
+			resistance.Condition = resistanceCondition;
+			resistance.Value = resistanceValue;
+
+			return resistance;
+		}
+
+		private class InteractionTrackerOwner : IInteractionTrackerOwner
+		{
+			private NavigationInteractionTracker _parent;
+			private bool _shouldBounceBack;
+
+			public InteractionTrackerOwner(NavigationInteractionTracker parent)
+			{
+				_parent = parent;
+			}
+
+			public void CustomAnimationStateEntered(InteractionTracker sender, InteractionTrackerCustomAnimationStateEnteredArgs args)
+			{
+
+			}
+
+			public void IdleStateEntered(InteractionTracker sender, InteractionTrackerIdleStateEnteredArgs args)
+			{
+				if (!_shouldBounceBack)
+					return;
+
+				var compositor = _parent._rootVisual.Compositor;
+				var springAnim = compositor.CreateSpringVector3Animation();
+				springAnim.FinalValue = new(0f);
+				springAnim.DampingRatio = 1f;
+				_parent._tracker.TryUpdatePositionWithAnimation(springAnim);
+				_shouldBounceBack = false;
+
+				if (Math.Abs(sender.Position.X) < 64)
+					return;
+
+				EventHandler<SwipeNavigationEventArgs>? navEvent = _parent.NavigationRequested;
+				if (navEvent is null)
+					return;
+
+				navEvent(_parent, sender.Position.X > 0 ? SwipeNavigationEventArgs.Forward : SwipeNavigationEventArgs.Back);
+			}
+
+
+			public void InteractingStateEntered(InteractionTracker sender, InteractionTrackerInteractingStateEnteredArgs args)
+			{
+				_shouldBounceBack = true;
+			}
+
+			// required to implement IInteractionTrackerOwner
+			public void InertiaStateEntered(InteractionTracker sender, InteractionTrackerInertiaStateEnteredArgs args) { }
+			public void RequestIgnored(InteractionTracker sender, InteractionTrackerRequestIgnoredArgs args) { }
+			public void ValuesChanged(InteractionTracker sender, InteractionTrackerValuesChangedArgs args) { }
+		}
+	}
+
+	public enum SwipeNavigationEventArgs
+	{
+		Back,
+		Forward
+	}
+}