Merge branch 'master' into fixes/2821-remove-contentcontrolmixin

build/SharedVersion.props

@@ -4,11 +4,16 @@
     <Product>Avalonia</Product>
     <Version>0.8.999</Version>
     <Copyright>Copyright 2019 &#169; The AvaloniaUI Project</Copyright>
-    <PackageLicenseUrl>https://github.com/AvaloniaUI/Avalonia/blob/master/licence.md</PackageLicenseUrl>
+    <PackageProjectUrl>https://avaloniaui.net</PackageProjectUrl>
-    <PackageProjectUrl>https://github.com/AvaloniaUI/Avalonia/</PackageProjectUrl>
     <RepositoryUrl>https://github.com/AvaloniaUI/Avalonia/</RepositoryUrl>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <NoWarn>CS1591</NoWarn>
     <LangVersion>latest</LangVersion>
+    <PackageLicenseExpression>MIT</PackageLicenseExpression>
+    <PackageIconUrl>https://avatars2.githubusercontent.com/u/14075148?s=200</PackageIconUrl>
+    <PackageDescription>Avalonia is a WPF/UWP-inspired cross-platform XAML-based UI framework providing a flexible styling system and supporting a wide range of Operating Systems such as Windows (.NET Framework, .NET Core), Linux (via Xorg), MacOS and with experimental support for Android and iOS.</PackageDescription>
+    <PackageTags>avalonia;avaloniaui;mvvm;rx;reactive extensions;android;ios;mac;forms;wpf;net;netstandard;net461;uwp;xamarin</PackageTags>
+    <PackageReleaseNotes>https://github.com/AvaloniaUI/Avalonia/releases</PackageReleaseNotes>
+    <RepositoryType>git</RepositoryType>
   </PropertyGroup>
 </Project>

scripts/ReplaceNugetCache.sh

@@ -2,7 +2,6 @@
  
  cp ../samples/ControlCatalog.NetCore/bin/Debug/netcoreapp2.0/Avalonia**.dll ~/.nuget/packages/avalonia/$1/lib/netcoreapp2.0/
  cp ../samples/ControlCatalog.NetCore/bin/Debug/netcoreapp2.0/Avalonia**.dll ~/.nuget/packages/avalonia/$1/lib/netstandard2.0/
- cp ../samples/ControlCatalog.NetCore/bin/Debug/netcoreapp2.0/Avalonia**.dll ~/.nuget/packages/avalonia.gtk3/$1/lib/netstandard2.0/
  cp ../samples/ControlCatalog.NetCore/bin/Debug/netcoreapp2.0/Avalonia**.dll ~/.nuget/packages/avalonia.skia/$1/lib/netstandard2.0/
  cp ../samples/ControlCatalog.NetCore/bin/Debug/netcoreapp2.0/Avalonia**.dll ~/.nuget/packages/avalonia.native/$1/lib/netstandard2.0/
  

src/Avalonia.Animation/Animatable.cs

@@ -45,16 +45,17 @@ namespace Avalonia.Animation
         {
             get
             {
-                if (_transitions == null)
+                if (_transitions is null)
                     _transitions = new Transitions();
 
-                if (_previousTransitions == null)
+                if (_previousTransitions is null)
                     _previousTransitions = new Dictionary<AvaloniaProperty, IDisposable>();
 
                 return _transitions;
             }
             set
             {
+
                 SetAndRaise(TransitionsProperty, ref _transitions, value);
             }
         }
@@ -66,18 +67,20 @@ namespace Avalonia.Animation
         /// <param name="e">The event args.</param>
         protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs e)
         {
-            if (e.Priority != BindingPriority.Animation && Transitions != null && _previousTransitions != null)
+            if (_transitions is null || _previousTransitions is null || e.Priority == BindingPriority.Animation) return;
-            {
-                var match = Transitions.FirstOrDefault(x => x.Property == e.Property);
 
-                if (match != null)
+            // PERF-SENSITIVE: Called on every property change. Don't use LINQ here (too many allocations).
+            foreach (var transition in Transitions)
+            {
+                if (transition.Property == e.Property)
                 {
                     if (_previousTransitions.TryGetValue(e.Property, out var dispose))
                         dispose.Dispose();
 
-                    var instance = match.Apply(this, Clock ?? Avalonia.Animation.Clock.GlobalClock, e.OldValue, e.NewValue);
+                    var instance = transition.Apply(this, Clock ?? Avalonia.Animation.Clock.GlobalClock, e.OldValue, e.NewValue);
 
                     _previousTransitions[e.Property] = instance;
+                    return;
                 }
             }
         }

src/Avalonia.Base/AvaloniaObject.cs

@@ -82,6 +82,7 @@ namespace Avalonia
 
             set
             {
+                VerifyAccess();
                 if (_inheritanceParent != value)
                 {
                     if (_inheritanceParent != null)
@@ -89,25 +90,33 @@ namespace Avalonia
                         _inheritanceParent.InheritablePropertyChanged -= ParentPropertyChanged;
                     }
 
-                    var properties = AvaloniaPropertyRegistry.Instance.GetRegistered(this)
+                    var oldInheritanceParent = _inheritanceParent;
-                        .Concat(AvaloniaPropertyRegistry.Instance.GetRegisteredAttached(this.GetType()));
-                    var inherited = (from property in properties
-                                     where property.Inherits
-                                     select new
-                                     {
-                                         Property = property,
-                                         Value = GetValue(property),
-                                     }).ToList();
-
                     _inheritanceParent = value;
+                    var valuestore = _values;
 
-                    foreach (var i in inherited)
+                    foreach (var property in AvaloniaPropertyRegistry.Instance.GetRegisteredInherited(GetType()))
                     {
-                        object newValue = GetValue(i.Property);
+                        if (valuestore != null && valuestore.GetValue(property) != AvaloniaProperty.UnsetValue)
+                        {
+                            // if local value set there can be no change
+                            continue;
+                        }
+                        // get the value as it would have been with the previous InheritanceParent
+                        object oldValue;
+                        if (oldInheritanceParent is AvaloniaObject aobj)
+                        {
+                            oldValue = aobj.GetValueOrDefaultUnchecked(property);
+                        }
+                        else
+                        {
+                            oldValue = ((IStyledPropertyAccessor)property).GetDefaultValue(GetType());
+                        }
+
+                        object newValue = GetDefaultValue(property);
 
-                        if (!Equals(i.Value, newValue))
+                        if (!Equals(oldValue, newValue))
                         {
-                            RaisePropertyChanged(i.Property, i.Value, newValue, BindingPriority.LocalValue);
+                            RaisePropertyChanged(property, oldValue, newValue, BindingPriority.LocalValue);
                         }
                     }
 

src/Avalonia.Base/AvaloniaPropertyRegistry.cs

@@ -26,6 +26,8 @@ namespace Avalonia
             new Dictionary<Type, List<AvaloniaProperty>>();
         private readonly Dictionary<Type, List<PropertyInitializationData>> _initializedCache =
             new Dictionary<Type, List<PropertyInitializationData>>();
+        private readonly Dictionary<Type, List<AvaloniaProperty>> _inheritedCache =
+            new Dictionary<Type, List<AvaloniaProperty>>();
 
         /// <summary>
         /// Gets the <see cref="AvaloniaPropertyRegistry"/> instance
@@ -103,6 +105,46 @@ namespace Avalonia
             return result;
         }
 
+        /// <summary>
+        /// Gets all inherited <see cref="AvaloniaProperty"/>s registered on a type.
+        /// </summary>
+        /// <param name="type">The type.</param>
+        /// <returns>A collection of <see cref="AvaloniaProperty"/> definitions.</returns>
+        public IEnumerable<AvaloniaProperty> GetRegisteredInherited(Type type)
+        {
+            Contract.Requires<ArgumentNullException>(type != null);
+
+            if (_inheritedCache.TryGetValue(type, out var result))
+            {
+                return result;
+            }
+
+            result = new List<AvaloniaProperty>();
+            var visited = new HashSet<AvaloniaProperty>();
+
+            foreach (var property in GetRegistered(type))
+            {
+                if (property.Inherits)
+                {
+                    result.Add(property);
+                    visited.Add(property);
+                }
+            }
+            foreach (var property in GetRegisteredAttached(type))
+            {
+                if (property.Inherits)
+                {
+                    if (!visited.Contains(property))
+                    {
+                        result.Add(property);
+                    }
+                }
+            }
+
+            _inheritedCache.Add(type, result);
+            return result;
+        }
+
         /// <summary>
         /// Gets all <see cref="AvaloniaProperty"/>s registered on a object.
         /// </summary>
@@ -230,6 +272,7 @@ namespace Avalonia
             
             _registeredCache.Clear();
             _initializedCache.Clear();
+            _inheritedCache.Clear();
         }
 
         /// <summary>
@@ -266,6 +309,7 @@ namespace Avalonia
             
             _attachedCache.Clear();
             _initializedCache.Clear();
+            _inheritedCache.Clear();
         }
 
         internal void NotifyInitialized(AvaloniaObject o)

src/Avalonia.Base/BoxedValue.cs

@@ -0,0 +1,28 @@
+// Copyright (c) The Avalonia Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
+namespace Avalonia
+{
+    /// <summary>
+    /// Represents boxed value of type <typeparamref name="T"/>.
+    /// </summary>
+    /// <typeparam name="T">Type of stored value.</typeparam>
+    internal readonly struct BoxedValue<T>
+    {
+        public BoxedValue(T value)
+        {
+            Boxed = value;
+            Typed = value;
+        }
+
+        /// <summary>
+        /// Boxed value.
+        /// </summary>
+        public object Boxed { get; }
+
+        /// <summary>
+        /// Typed value.
+        /// </summary>
+        public T Typed { get; }
+    }
+}

src/Avalonia.Base/PriorityBindingEntry.cs

@@ -2,6 +2,7 @@
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
 using System;
+using System.Runtime.ExceptionServices;
 using Avalonia.Data;
 using Avalonia.Threading;
 
@@ -10,9 +11,9 @@ namespace Avalonia
     /// <summary>
     /// A registered binding in a <see cref="PriorityValue"/>.
     /// </summary>
-    internal class PriorityBindingEntry : IDisposable
+    internal class PriorityBindingEntry : IDisposable, IObserver<object>
     {
-        private PriorityLevel _owner;
+        private readonly PriorityLevel _owner;
         private IDisposable _subscription;
 
         /// <summary>
@@ -85,7 +86,7 @@ namespace Avalonia
                 Description = ((IDescription)binding).Description;
             }
 
-            _subscription = binding.Subscribe(ValueChanged, Completed);
+            _subscription = binding.Subscribe(this);
         }
 
         /// <summary>
@@ -96,7 +97,7 @@ namespace Avalonia
             _subscription?.Dispose();
         }
 
-        private void ValueChanged(object value)
+        void IObserver<object>.OnNext(object value)
         {
             void Signal()
             {
@@ -132,7 +133,7 @@ namespace Avalonia
             }
         }
 
-        private void Completed()
+        void IObserver<object>.OnCompleted()
         {
             HasCompleted = true;
 
@@ -145,5 +146,10 @@ namespace Avalonia
                 Dispatcher.UIThread.Post(() => _owner.Completed(this));
             }
         }
+
+        void IObserver<object>.OnError(Exception error)
+        {
+            ExceptionDispatchInfo.Capture(error).Throw();
+        }
     }
 }

src/Avalonia.Base/PriorityValue.cs

@@ -24,13 +24,11 @@ namespace Avalonia
     /// <see cref="IPriorityValueOwner.Changed"/> method on the 
     /// owner object is fired with the old and new values.
     /// </remarks>
-    internal class PriorityValue
+    internal sealed class PriorityValue : ISetAndNotifyHandler<(object,int)>
     {
         private readonly Type _valueType;
         private readonly SingleOrDictionary<int, PriorityLevel> _levels = new SingleOrDictionary<int, PriorityLevel>();
-
         private readonly Func<object, object> _validate;
-        private readonly SetAndNotifyCallback<(object, int)> _setAndNotifyCallback;
         private (object value, int priority) _value;
         private DeferredSetter<object> _setter;
 
@@ -52,7 +50,6 @@ namespace Avalonia
             _valueType = valueType;
             _value = (AvaloniaProperty.UnsetValue, int.MaxValue);
             _validate = validate;
-            _setAndNotifyCallback = SetAndNotify;
         }
 
         /// <summary>
@@ -257,10 +254,15 @@ namespace Avalonia
                 _setter = Owner.GetNonDirectDeferredSetter(Property);
             }
 
-            _setter.SetAndNotifyCallback(Property, _setAndNotifyCallback, ref _value, newValue);
+            _setter.SetAndNotifyCallback(Property, this, ref _value, newValue);
+        }
+
+        void ISetAndNotifyHandler<(object, int)>.HandleSetAndNotify(AvaloniaProperty property, ref (object, int) backing, (object, int) value)
+        {
+            SetAndNotify(ref backing, value);
         }
 
-        private void SetAndNotify(AvaloniaProperty property, ref (object value, int priority) backing, (object value, int priority) update)
+        private void SetAndNotify(ref (object value, int priority) backing, (object value, int priority) update)
         {
             var val = update.value;
             var notification = val as BindingNotification;

src/Avalonia.Base/StyledPropertyBase.cs

@@ -68,7 +68,7 @@ namespace Avalonia
         {
             Contract.Requires<ArgumentNullException>(type != null);
 
-            return GetMetadata(type).DefaultValue;
+            return GetMetadata(type).DefaultValue.Typed;
         }
 
         /// <summary>
@@ -164,7 +164,14 @@ namespace Avalonia
         }
 
         /// <inheritdoc/>
-        object IStyledPropertyAccessor.GetDefaultValue(Type type) => GetDefaultValue(type);
+        object IStyledPropertyAccessor.GetDefaultValue(Type type) => GetDefaultBoxedValue(type);
+
+        private object GetDefaultBoxedValue(Type type)
+        {
+            Contract.Requires<ArgumentNullException>(type != null);
+
+            return GetMetadata(type).DefaultValue.Boxed;
+        }
 
         [DebuggerHidden]
         private Func<IAvaloniaObject, TValue, TValue> Cast<THost>(Func<THost, TValue, TValue> validate)

src/Avalonia.Base/StyledPropertyMetadata`1.cs

@@ -19,26 +19,26 @@ namespace Avalonia
         /// <param name="validate">A validation function.</param>
         /// <param name="defaultBindingMode">The default binding mode.</param>
         public StyledPropertyMetadata(
-            TValue defaultValue = default(TValue),
+            TValue defaultValue = default,
             Func<IAvaloniaObject, TValue, TValue> validate = null,
             BindingMode defaultBindingMode = BindingMode.Default)
                 : base(defaultBindingMode)
         {
-            DefaultValue = defaultValue;
+            DefaultValue = new BoxedValue<TValue>(defaultValue);
             Validate = validate;
         }
 
         /// <summary>
         /// Gets the default value for the property.
         /// </summary>
-        public TValue DefaultValue { get; private set; }
+        internal BoxedValue<TValue> DefaultValue { get; private set; }
 
         /// <summary>
         /// Gets the validation callback.
         /// </summary>
         public Func<IAvaloniaObject, TValue, TValue> Validate { get; private set; }
 
-        object IStyledPropertyMetadata.DefaultValue => DefaultValue;
+        object IStyledPropertyMetadata.DefaultValue => DefaultValue.Boxed;
 
         Func<IAvaloniaObject, object, object> IStyledPropertyMetadata.Validate => Cast(Validate);
 
@@ -47,11 +47,9 @@ namespace Avalonia
         {
             base.Merge(baseMetadata, property);
 
-            var src = baseMetadata as StyledPropertyMetadata<TValue>;
+            if (baseMetadata is StyledPropertyMetadata<TValue> src)
-
-            if (src != null)
             {
-                if (DefaultValue == null)
+                if (DefaultValue.Boxed == null)
                 {
                     DefaultValue = src.DefaultValue;
                 }

src/Avalonia.Base/Utilities/DeferredSetter.cs

@@ -5,15 +5,6 @@ using System;
 
 namespace Avalonia.Utilities
 {
-    /// <summary>
-    /// Callback invoked when deferred setter wants to set a value.
-    /// </summary>
-    /// <typeparam name="TValue">Value type.</typeparam>
-    /// <param name="property">Property being set.</param>
-    /// <param name="backing">Backing field reference.</param>
-    /// <param name="value">New value.</param>
-    internal delegate void SetAndNotifyCallback<TValue>(AvaloniaProperty property, ref TValue backing, TValue value);
-
     /// <summary>
     /// A utility class to enable deferring assignment until after property-changed notifications are sent.
     /// Used to fix #855.
@@ -70,14 +61,14 @@ namespace Avalonia.Utilities
             return false;
         }
 
-        public bool SetAndNotifyCallback<TValue>(AvaloniaProperty property, SetAndNotifyCallback<TValue> setAndNotifyCallback, ref TValue backing, TValue value)
+        public bool SetAndNotifyCallback<TValue>(AvaloniaProperty property, ISetAndNotifyHandler<TValue> setAndNotifyHandler, ref TValue backing, TValue value)
             where TValue : TSetRecord
         {
             if (!_isNotifying)
             {
                 using (new NotifyDisposable(this))
                 {
-                    setAndNotifyCallback(property, ref backing, value);
+                    setAndNotifyHandler.HandleSetAndNotify(property, ref backing, value);
                 }
 
                 if (!_pendingValues.Empty)
@@ -86,7 +77,7 @@ namespace Avalonia.Utilities
                     {
                         while (!_pendingValues.Empty)
                         {
-                            setAndNotifyCallback(property, ref backing, (TValue) _pendingValues.Dequeue());
+                            setAndNotifyHandler.HandleSetAndNotify(property, ref backing, (TValue)_pendingValues.Dequeue());
                         }
                     }
                 }
@@ -119,4 +110,19 @@ namespace Avalonia.Utilities
             }
         }
     }
+
+    /// <summary>
+    /// Handler for set and notify requests.
+    /// </summary>
+    /// <typeparam name="TValue">Value type.</typeparam>
+    internal interface ISetAndNotifyHandler<TValue>
+    {
+        /// <summary>
+        /// Handles deferred setter requests to set a value.
+        /// </summary>
+        /// <param name="property">Property being set.</param>
+        /// <param name="backing">Backing field reference.</param>
+        /// <param name="value">New value.</param>
+        void HandleSetAndNotify(AvaloniaProperty property, ref TValue backing, TValue value);
+    }
 }

src/Avalonia.Diagnostics/DevTools.xaml.cs

@@ -28,6 +28,11 @@ namespace Avalonia
         {
             Diagnostics.DevTools.Attach(control, gesture);
         }
+
+        public static void OpenDevTools(this TopLevel control)
+        {
+            Diagnostics.DevTools.OpenDevTools(control);
+        }
     }
 }
 
@@ -73,7 +78,7 @@ namespace Avalonia.Diagnostics
                 RoutingStrategies.Tunnel);
         }
 
-        private static void OpenDevTools(TopLevel control)
+        internal static void OpenDevTools(TopLevel control)
         {
             if (s_open.TryGetValue(control, out var devToolsWindow))
             {

src/Avalonia.Input/Gestures.cs

@@ -31,7 +31,7 @@ namespace Avalonia.Input
             RoutedEvent.Register<ScrollGestureEventArgs>(
                 "ScrollGestureEnded", RoutingStrategies.Bubble, typeof(Gestures));
 
-        private static WeakReference<IInteractive> s_lastPress;
+        private static WeakReference<IInteractive> s_lastPress = new WeakReference<IInteractive>(null);
 
         static Gestures()
         {
@@ -39,6 +39,36 @@ namespace Avalonia.Input
             InputElement.PointerReleasedEvent.RouteFinished.Subscribe(PointerReleased);
         }
 
+        public static void AddTappedHandler(IInteractive element, EventHandler<RoutedEventArgs> handler)
+        {
+            element.AddHandler(TappedEvent, handler);
+        }
+
+        public static void AddDoubleTappedHandler(IInteractive element, EventHandler<RoutedEventArgs> handler)
+        {
+            element.AddHandler(DoubleTappedEvent, handler);
+        }
+
+        public static void AddRightTappedHandler(IInteractive element, EventHandler<RoutedEventArgs> handler)
+        {
+            element.AddHandler(RightTappedEvent, handler);
+        }
+
+        public static void RemoveTappedHandler(IInteractive element, EventHandler<RoutedEventArgs> handler)
+        {
+            element.RemoveHandler(TappedEvent, handler);
+        }
+
+        public static void RemoveDoubleTappedHandler(IInteractive element, EventHandler<RoutedEventArgs> handler)
+        {
+            element.RemoveHandler(DoubleTappedEvent, handler);
+        }
+
+        public static void RemoveRightTappedHandler(IInteractive element, EventHandler<RoutedEventArgs> handler)
+        {
+            element.RemoveHandler(RightTappedEvent, handler);
+        }
+
         private static void PointerPressed(RoutedEventArgs ev)
         {
             if (ev.Route == RoutingStrategies.Bubble)

src/Avalonia.Interactivity/EventSubscription.cs

@@ -5,8 +5,12 @@ using System;
 
 namespace Avalonia.Interactivity
 {
+    internal delegate void HandlerInvokeSignature(Delegate baseHandler, object sender, RoutedEventArgs args);
+
     internal class EventSubscription
     {
+        public HandlerInvokeSignature InvokeAdapter { get; set; }
+
         public Delegate Handler { get; set; }
 
         public RoutingStrategies Routes { get; set; }

src/Avalonia.Interactivity/Interactive.cs

@@ -4,8 +4,6 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
-using System.Reactive.Disposables;
-using System.Reactive.Linq;
 using Avalonia.Layout;
 using Avalonia.VisualTree;
 
@@ -18,15 +16,14 @@ namespace Avalonia.Interactivity
     {
         private Dictionary<RoutedEvent, List<EventSubscription>> _eventHandlers;
 
+        private static readonly Dictionary<Type, HandlerInvokeSignature> s_invokeHandlerCache = new Dictionary<Type, HandlerInvokeSignature>();
+
         /// <summary>
         /// Gets the interactive parent of the object for bubbling and tunneling events.
         /// </summary>
         IInteractive IInteractive.InteractiveParent => ((IVisual)this).VisualParent as IInteractive;
 
-        private Dictionary<RoutedEvent, List<EventSubscription>> EventHandlers
+        private Dictionary<RoutedEvent, List<EventSubscription>> EventHandlers => _eventHandlers ?? (_eventHandlers = new Dictionary<RoutedEvent, List<EventSubscription>>());
-        {
-            get { return _eventHandlers ?? (_eventHandlers = new Dictionary<RoutedEvent, List<EventSubscription>>()); }
-        }
 
         /// <summary>
         /// Adds a handler for the specified routed event.
@@ -45,24 +42,14 @@ namespace Avalonia.Interactivity
             Contract.Requires<ArgumentNullException>(routedEvent != null);
             Contract.Requires<ArgumentNullException>(handler != null);
 
-            List<EventSubscription> subscriptions;
+            var subscription = new EventSubscription
-
-            if (!EventHandlers.TryGetValue(routedEvent, out subscriptions))
-            {
-                subscriptions = new List<EventSubscription>();
-                EventHandlers.Add(routedEvent, subscriptions);
-            }
-
-            var sub = new EventSubscription
             {
                 Handler = handler,
                 Routes = routes,
                 AlsoIfHandled = handledEventsToo,
             };
 
-            subscriptions.Add(sub);
+            return AddEventSubscription(routedEvent, subscription);
-
-            return Disposable.Create(() => subscriptions.Remove(sub));
         }
 
         /// <summary>
@@ -80,7 +67,37 @@ namespace Avalonia.Interactivity
             RoutingStrategies routes = RoutingStrategies.Direct | RoutingStrategies.Bubble,
             bool handledEventsToo = false) where TEventArgs : RoutedEventArgs
         {
-            return AddHandler(routedEvent, (Delegate)handler, routes, handledEventsToo);
+            Contract.Requires<ArgumentNullException>(routedEvent != null);
+            Contract.Requires<ArgumentNullException>(handler != null);
+
+            // EventHandler delegate is not covariant, this forces us to create small wrapper
+            // that will cast our type erased instance and invoke it.
+            Type eventArgsType = routedEvent.EventArgsType;
+
+            if (!s_invokeHandlerCache.TryGetValue(eventArgsType, out var invokeAdapter))
+            {
+                void InvokeAdapter(Delegate baseHandler, object sender, RoutedEventArgs args)
+                {
+                    var typedHandler = (EventHandler<TEventArgs>)baseHandler;
+                    var typedArgs = (TEventArgs)args;
+
+                    typedHandler(sender, typedArgs);
+                }
+
+                invokeAdapter = InvokeAdapter;
+
+                s_invokeHandlerCache.Add(eventArgsType, invokeAdapter);
+            }
+
+            var subscription = new EventSubscription
+            {
+                InvokeAdapter = invokeAdapter,
+                Handler = handler,
+                Routes = routes,
+                AlsoIfHandled = handledEventsToo,
+            };
+
+            return AddEventSubscription(routedEvent, subscription);
         }
 
         /// <summary>
@@ -196,10 +213,54 @@ namespace Avalonia.Interactivity
 
                     if (correctRoute && notFinished)
                     {
-                        sub.Handler.DynamicInvoke(this, e);
+                        if (sub.InvokeAdapter != null)
+                        {
+                            sub.InvokeAdapter(sub.Handler, this, e);
+                        }
+                        else
+                        {
+                            sub.Handler.DynamicInvoke(this, e);
+                        }
                     }
                 }
             }
         }
+
+        private List<EventSubscription> GetEventSubscriptions(RoutedEvent routedEvent)
+        {
+            if (!EventHandlers.TryGetValue(routedEvent, out var subscriptions))
+            {
+                subscriptions = new List<EventSubscription>();
+                EventHandlers.Add(routedEvent, subscriptions);
+            }
+
+            return subscriptions;
+        }
+
+        private IDisposable AddEventSubscription(RoutedEvent routedEvent, EventSubscription subscription)
+        {
+            List<EventSubscription> subscriptions = GetEventSubscriptions(routedEvent);
+
+            subscriptions.Add(subscription);
+
+            return new UnsubscribeDisposable(subscriptions, subscription);
+        }
+
+        private sealed class UnsubscribeDisposable : IDisposable
+        {
+            private readonly List<EventSubscription> _subscriptions;
+            private readonly EventSubscription _subscription;
+
+            public UnsubscribeDisposable(List<EventSubscription> subscriptions, EventSubscription subscription)
+            {
+                _subscriptions = subscriptions;
+                _subscription = subscription;
+            }
+
+            public void Dispose()
+            {
+                _subscriptions.Remove(_subscription);
+            }
+        }
     }
 }

src/Avalonia.Interactivity/RoutedEvent.cs

@@ -4,7 +4,6 @@
 using System;
 using System.Reactive.Subjects;
 using System.Reflection;
-using System.Runtime.ExceptionServices;
 
 namespace Avalonia.Interactivity
 {
@@ -18,8 +17,8 @@ namespace Avalonia.Interactivity
 
     public class RoutedEvent
     {
-        private Subject<Tuple<object, RoutedEventArgs>> _raised = new Subject<Tuple<object, RoutedEventArgs>>();
+        private readonly Subject<(object, RoutedEventArgs)> _raised = new Subject<(object, RoutedEventArgs)>();
-        private Subject<RoutedEventArgs> _routeFinished = new Subject<RoutedEventArgs>();
+        private readonly Subject<RoutedEventArgs> _routeFinished = new Subject<RoutedEventArgs>();
 
         public RoutedEvent(
             string name,
@@ -38,31 +37,15 @@ namespace Avalonia.Interactivity
             RoutingStrategies = routingStrategies;
         }
 
-        public Type EventArgsType
+        public Type EventArgsType { get; }
-        {
-            get;
-            private set;
-        }
 
-        public string Name
+        public string Name { get; }
-        {
-            get;
-            private set;
-        }
 
-        public Type OwnerType
+        public Type OwnerType { get; }
-        {
-            get;
-            private set;
-        }
 
-        public RoutingStrategies RoutingStrategies
+        public RoutingStrategies RoutingStrategies { get; }
-        {
-            get;
-            private set;
-        }
 
-        public IObservable<Tuple<object, RoutedEventArgs>> Raised => _raised;
+        public IObservable<(object, RoutedEventArgs)> Raised => _raised;
         public IObservable<RoutedEventArgs> RouteFinished => _routeFinished;
 
         public static RoutedEvent<TEventArgs> Register<TOwner, TEventArgs>(
@@ -98,29 +81,20 @@ namespace Avalonia.Interactivity
         {
             return Raised.Subscribe(args =>
             {
-                var sender = args.Item1;
+                (object sender, RoutedEventArgs e) = args;
-                var e = args.Item2;
 
-                if (targetType.GetTypeInfo().IsAssignableFrom(sender.GetType().GetTypeInfo()) &&
+                if (targetType.IsInstanceOfType(sender) &&
-                    ((e.Route == RoutingStrategies.Direct) || (e.Route & routes) != 0) &&
+                    (e.Route == RoutingStrategies.Direct || (e.Route & routes) != 0) &&
                     (!e.Handled || handledEventsToo))
                 {
-                    try
+                    handler(sender, e);
-                    {
-                        handler.DynamicInvoke(sender, e);
-                    }
-                    catch (TargetInvocationException ex)
-                    {
-                        // Unwrap the inner exception.
-                        ExceptionDispatchInfo.Capture(ex.InnerException).Throw();
-                    }
                 }
             });
         }
 
         internal void InvokeRaised(object sender, RoutedEventArgs e)
         {
-            _raised.OnNext(Tuple.Create(sender, e));
+            _raised.OnNext((sender, e));
         }
 
         internal void InvokeRouteFinished(RoutedEventArgs e)

src/Avalonia.Native/AvaloniaNativeDeferredRendererLock.cs

@@ -1,5 +1,8 @@
+// Copyright (c) The Avalonia Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
 using System;
-using System.Reactive.Disposables;
+using System.Threading;
 using Avalonia.Native.Interop;
 using Avalonia.Rendering;
 
@@ -13,11 +16,27 @@ namespace Avalonia.Native
         {
             _window = window;
         }
+
         public IDisposable TryLock()
         {
             if (_window.TryLock())
-                return Disposable.Create(() => _window.Unlock());
+                return new UnlockDisposable(_window);
             return null;
         }
+
+        private sealed class UnlockDisposable : IDisposable
+        {
+            private IAvnWindowBase _window;
+
+            public UnlockDisposable(IAvnWindowBase window)
+            {
+                _window = window;
+            }
+
+            public void Dispose()
+            {
+                Interlocked.Exchange(ref _window, null)?.Unlock();
+            }
+        }
     }
 }

src/Avalonia.Native/MacOSMountedVolumeInfoProvider.cs

@@ -8,16 +8,16 @@ using Avalonia.Controls.Platform;
 
 namespace Avalonia.Native
 {
-    internal class WindowsMountedVolumeInfoListener : IDisposable
+    internal class MacOSMountedVolumeInfoListener : IDisposable
     {
         private readonly CompositeDisposable _disposables;
-        private readonly ObservableCollection<MountedVolumeInfo> _targetObs;
         private bool _beenDisposed = false;
         private ObservableCollection<MountedVolumeInfo> mountedDrives;
 
-        public WindowsMountedVolumeInfoListener(ObservableCollection<MountedVolumeInfo> mountedDrives)
+        public MacOSMountedVolumeInfoListener(ObservableCollection<MountedVolumeInfo> mountedDrives)
         {
             this.mountedDrives = mountedDrives;
+
             _disposables = new CompositeDisposable();
 
             var pollTimer = Observable.Interval(TimeSpan.FromSeconds(1))
@@ -30,7 +30,8 @@ namespace Avalonia.Native
 
         private void Poll(long _)
         {
-            var mountVolInfos = Directory.GetDirectories("/Volumes")
+            var mountVolInfos = Directory.GetDirectories("/Volumes/")
+                                .Where(p=> p != null)
                                 .Select(p => new MountedVolumeInfo()
                                 {
                                     VolumeLabel = Path.GetFileName(p),
@@ -38,15 +39,15 @@ namespace Avalonia.Native
                                     VolumeSizeBytes = 0
                                 })
                                 .ToArray();
-
+                                
-            if (_targetObs.SequenceEqual(mountVolInfos))
+            if (mountedDrives.SequenceEqual(mountVolInfos))
                 return;
             else
             {
-                _targetObs.Clear();
+                mountedDrives.Clear();
 
                 foreach (var i in mountVolInfos)
-                    _targetObs.Add(i);
+                    mountedDrives.Add(i);
             }
         }
 
@@ -72,7 +73,7 @@ namespace Avalonia.Native
         public IDisposable Listen(ObservableCollection<MountedVolumeInfo> mountedDrives)
         {
             Contract.Requires<ArgumentNullException>(mountedDrives != null);
-            return new WindowsMountedVolumeInfoListener(mountedDrives);
+            return new MacOSMountedVolumeInfoListener(mountedDrives);
         }
     }
 }

src/Avalonia.Visuals/Rendering/ManagedDeferredRendererLock.cs

@@ -1,5 +1,7 @@
+// Copyright (c) The Avalonia Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
 using System;
-using System.Reactive.Disposables;
 using System.Threading;
 
 namespace Avalonia.Rendering
@@ -7,7 +9,7 @@ namespace Avalonia.Rendering
     public class ManagedDeferredRendererLock : IDeferredRendererLock
     {
         private readonly object _lock = new object();
-        
+
         /// <summary>
         /// Tries to lock the target surface or window
         /// </summary>
@@ -15,7 +17,7 @@ namespace Avalonia.Rendering
         public IDisposable TryLock()
         {
             if (Monitor.TryEnter(_lock))
-                return Disposable.Create(() => Monitor.Exit(_lock));
+                return new UnlockDisposable(_lock);
             return null;
         }
 
@@ -25,7 +27,27 @@ namespace Avalonia.Rendering
         public IDisposable Lock()
         {
             Monitor.Enter(_lock);
-            return Disposable.Create(() => Monitor.Exit(_lock));
+            return new UnlockDisposable(_lock);
+        }
+
+        private sealed class UnlockDisposable : IDisposable
+        {
+            private object _lock;
+
+            public UnlockDisposable(object @lock)
+            {
+                _lock = @lock;
+            }
+
+            public void Dispose()
+            {
+                object @lock = Interlocked.Exchange(ref _lock, null);
+
+                if (@lock != null)
+                {
+                    Monitor.Exit(@lock);
+                }
+            }
         }
     }
 }

src/Avalonia.Visuals/Vector.cs

@@ -65,9 +65,7 @@ namespace Avalonia
         /// <param name="b">Second vector</param>
         /// <returns>The dot product</returns>
         public static double operator *(Vector a, Vector b)
-        {
+            => Dot(a, b);
-            return a.X * b.X + a.Y * b.Y;
-        }
 
         /// <summary>
         /// Scales a vector.
@@ -76,9 +74,7 @@ namespace Avalonia
         /// <param name="scale">The scaling factor.</param>
         /// <returns>The scaled vector.</returns>
         public static Vector operator *(Vector vector, double scale)
-        {
+            => Multiply(vector, scale);
-            return new Vector(vector._x * scale, vector._y * scale);
-        }
 
         /// <summary>
         /// Scales a vector.
@@ -87,14 +83,17 @@ namespace Avalonia
         /// <param name="scale">The divisor.</param>
         /// <returns>The scaled vector.</returns>
         public static Vector operator /(Vector vector, double scale)
-        {
+            => Divide(vector, scale);
-            return new Vector(vector._x / scale, vector._y / scale);
-        }
 
         /// <summary>
         /// Length of the vector
         /// </summary>
-        public double Length => Math.Sqrt(X * X + Y * Y);
+        public double Length => Math.Sqrt(SquaredLength);
+
+        /// <summary>
+        /// Squared Length of the vector
+        /// </summary>
+        public double SquaredLength => _x * _x + _y * _y;
 
         /// <summary>
         /// Negates a vector.
@@ -102,9 +101,7 @@ namespace Avalonia
         /// <param name="a">The vector.</param>
         /// <returns>The negated vector.</returns>
         public static Vector operator -(Vector a)
-        {
+            => Negate(a);
-            return new Vector(-a._x, -a._y);
-        }
 
         /// <summary>
         /// Adds two vectors.
@@ -113,9 +110,7 @@ namespace Avalonia
         /// <param name="b">The second vector.</param>
         /// <returns>A vector that is the result of the addition.</returns>
         public static Vector operator +(Vector a, Vector b)
-        {
+            => Add(a, b);
-            return new Vector(a._x + b._x, a._y + b._y);
-        }
 
         /// <summary>
         /// Subtracts two vectors.
@@ -124,9 +119,7 @@ namespace Avalonia
         /// <param name="b">The second vector.</param>
         /// <returns>A vector that is the result of the subtraction.</returns>
         public static Vector operator -(Vector a, Vector b)
-        {
+            => Subtract(a, b);
-            return new Vector(a._x - b._x, a._y - b._y);
-        }
 
         /// <summary>
         /// Check if two vectors are equal (bitwise).
@@ -155,7 +148,8 @@ namespace Avalonia
 
         public override bool Equals(object obj)
         {
-            if (ReferenceEquals(null, obj)) return false;
+            if (ReferenceEquals(null, obj))
+                return false;
 
             return obj is Vector vector && Equals(vector);
         }
@@ -206,5 +200,131 @@ namespace Avalonia
         {
             return new Vector(_x, y);
         }
+
+        /// <summary>
+        /// Returns a normalized version of this vector.
+        /// </summary>
+        /// <returns>The normalized vector.</returns>
+        public Vector Normalize()
+            => Normalize(this);
+
+        /// <summary>
+        /// Returns a negated version of this vector.
+        /// </summary>
+        /// <returns>The negated vector.</returns>
+        public Vector Negate()
+            => Negate(this);
+
+        /// <summary>
+        /// Returns the dot product of two vectors.
+        /// </summary>
+        /// <param name="a">The first vector.</param>
+        /// <param name="b">The second vector.</param>
+        /// <returns>The dot product.</returns>
+        public static double Dot(Vector a, Vector b)
+            => a._x * b._x + a._y * b._y;
+
+        /// <summary>
+        /// Returns the cross product of two vectors.
+        /// </summary>
+        /// <param name="a">The first vector.</param>
+        /// <param name="b">The second vector.</param>
+        /// <returns>The cross product.</returns>
+        public static double Cross(Vector a, Vector b)
+            => a._x * b._y - a._y * b._x;
+
+        /// <summary>
+        /// Normalizes the given vector.
+        /// </summary>
+        /// <param name="vector">The vector</param>
+        /// <returns>The normalized vector.</returns>
+        public static Vector Normalize(Vector vector)
+            => Divide(vector, vector.Length);
+        
+        /// <summary>
+        /// Divides the first vector by the second.
+        /// </summary>
+        /// <param name="a">The first vector.</param>
+        /// <param name="b">The second vector.</param>
+        /// <returns>The scaled vector.</returns>
+        public static Vector Divide(Vector a, Vector b)
+            => new Vector(a._x / b._x, a._y / b._y);
+
+        /// <summary>
+        /// Divides the vector by the given scalar.
+        /// </summary>
+        /// <param name="vector">The vector</param>
+        /// <param name="scalar">The scalar value</param>
+        /// <returns>The scaled vector.</returns>
+        public static Vector Divide(Vector vector, double scalar)
+            => new Vector(vector._x / scalar, vector._y / scalar);
+
+        /// <summary>
+        /// Multiplies the first vector by the second.
+        /// </summary>
+        /// <param name="a">The first vector.</param>
+        /// <param name="b">The second vector.</param>
+        /// <returns>The scaled vector.</returns>
+        public static Vector Multiply(Vector a, Vector b)
+            => new Vector(a._x * b._x, a._y * b._y);
+
+        /// <summary>
+        /// Multiplies the vector by the given scalar.
+        /// </summary>
+        /// <param name="vector">The vector</param>
+        /// <param name="scalar">The scalar value</param>
+        /// <returns>The scaled vector.</returns>
+        public static Vector Multiply(Vector vector, double scalar)
+            => new Vector(vector._x * scalar, vector._y * scalar);
+
+        /// <summary>
+        /// Adds the second to the first vector
+        /// </summary>
+        /// <param name="a">The first vector.</param>
+        /// <param name="b">The second vector.</param>
+        /// <returns>The summed vector.</returns>
+        public static Vector Add(Vector a, Vector b)
+            => new Vector(a._x + b._x, a._y + b._y);
+
+        /// <summary>
+        /// Subtracts the second from the first vector
+        /// </summary>
+        /// <param name="a">The first vector.</param>
+        /// <param name="b">The second vector.</param>
+        /// <returns>The difference vector.</returns>
+        public static Vector Subtract(Vector a, Vector b)
+            => new Vector(a._x - b._x, a._y - b._y);
+
+        /// <summary>
+        /// Negates the vector
+        /// </summary>
+        /// <param name="vector">The vector to negate.</param>
+        /// <returns>The scaled vector.</returns>
+        public static Vector Negate(Vector vector)
+            => new Vector(-vector._x, -vector._y);
+
+        /// <summary>
+        /// Returnes the vector (0.0, 0.0)
+        /// </summary>
+        public static Vector Zero
+            => new Vector(0, 0);
+
+        /// <summary>
+        /// Returnes the vector (1.0, 1.0)
+        /// </summary>
+        public static Vector One
+            => new Vector(1, 1);
+
+        /// <summary>
+        /// Returnes the vector (1.0, 0.0)
+        /// </summary>
+        public static Vector UnitX
+            => new Vector(1, 0);
+
+        /// <summary>
+        /// Returnes the vector (0.0, 1.0)
+        /// </summary>
+        public static Vector UnitY
+            => new Vector(0, 1);
     }
 }

src/Windows/Avalonia.Win32/WindowsMountedVolumeInfoListener.cs

@@ -10,8 +10,7 @@ namespace Avalonia.Win32
 {
     internal class WindowsMountedVolumeInfoListener : IDisposable
     {
-        private readonly CompositeDisposable _disposables;
+        private readonly CompositeDisposable _disposables;        
-        private readonly ObservableCollection<MountedVolumeInfo> _targetObs = new ObservableCollection<MountedVolumeInfo>();
         private bool _beenDisposed = false;
         private ObservableCollection<MountedVolumeInfo> mountedDrives;
 
@@ -41,14 +40,14 @@ namespace Avalonia.Win32
                                 })
                                 .ToArray();
 
-            if (_targetObs.SequenceEqual(mountVolInfos))
+            if (mountedDrives.SequenceEqual(mountVolInfos))
                 return;
             else
             {
-                _targetObs.Clear();
+                mountedDrives.Clear();
 
                 foreach (var i in mountVolInfos)
-                    _targetObs.Add(i);
+                    mountedDrives.Add(i);
             }
         }
 

tests/Avalonia.Markup.Xaml.UnitTests/Xaml/EventTests.cs

@@ -1,7 +1,6 @@
 // Copyright (c) The Avalonia Project. All rights reserved.
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
-using System;
 using Avalonia.Controls;
 using Avalonia.Input;
 using Avalonia.Interactivity;
@@ -12,45 +11,56 @@ namespace Avalonia.Markup.Xaml.UnitTests.Xaml
     public class EventTests : XamlTestBase
     {
         [Fact]
-        public void Event_Is_Attached()
+        public void Event_Is_Assigned()
         {
             var xaml = @"<Button xmlns='https://github.com/avaloniaui' Click='OnClick'/>";
             var loader = new AvaloniaXamlLoader();
             var target = new MyButton();
 
             loader.Load(xaml, rootInstance: target);
-            RaiseClick(target);
 
-            Assert.True(target.Clicked);
+            target.RaiseEvent(new RoutedEventArgs
+            {
+                RoutedEvent = Button.ClickEvent,
+            });
+
+            Assert.True(target.WasClicked);
         }
 
         [Fact]
-        public void Exception_Is_Thrown_If_Event_Not_Found()
+        public void Attached_Event_Is_Assigned()
         {
-            var xaml = @"<Button xmlns='https://github.com/avaloniaui' Click='NotFound'/>";
+            var xaml = @"<Button xmlns='https://github.com/avaloniaui' Gestures.Tapped='OnTapped'/>";
             var loader = new AvaloniaXamlLoader();
             var target = new MyButton();
 
-            XamlTestHelpers.AssertThrowsXamlException(() => loader.Load(xaml, rootInstance: target));
+            loader.Load(xaml, rootInstance: target);
-        }
 
-        private void RaiseClick(MyButton target)
+            target.RaiseEvent(new RoutedEventArgs
-        {
-            target.RaiseEvent(new KeyEventArgs
             {
-                RoutedEvent = Button.KeyDownEvent,
+                RoutedEvent = Gestures.TappedEvent,
-                Key = Key.Enter,
             });
+
+            Assert.True(target.WasTapped);
+        }
+
+        [Fact]
+        public void Exception_Is_Thrown_If_Event_Not_Found()
+        {
+            var xaml = @"<Button xmlns='https://github.com/avaloniaui' Click='NotFound'/>";
+            var loader = new AvaloniaXamlLoader();
+            var target = new MyButton();
+
+            XamlTestHelpers.AssertThrowsXamlException(() => loader.Load(xaml, rootInstance: target));
         }
 
         public class MyButton : Button
         {
-            public bool Clicked { get; private set; }
+            public bool WasClicked { get; private set; }
+            public bool WasTapped { get; private set; }
 
-            public void OnClick(object sender, RoutedEventArgs e)
+            public void OnClick(object sender, RoutedEventArgs e) => WasClicked = true;
-            {
+            public void OnTapped(object sender, RoutedEventArgs e) => WasTapped = true;
-                Clicked = true;
-            }
         }
     }
 }

tests/Avalonia.Visuals.UnitTests/VectorTests.cs

@@ -0,0 +1,112 @@
+// Copyright (c) The Avalonia Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
+using Xunit;
+using Avalonia;
+using System;
+
+namespace Avalonia.Visuals.UnitTests
+{
+    public class VectorTests
+    {
+        [Fact]
+        public void Length_Should_Return_Correct_Length_Of_Vector()
+        {
+            var vector = new Vector(2, 4);
+            var length = Math.Sqrt(2 * 2 + 4 * 4);
+
+            Assert.Equal(length, vector.Length);
+        }
+
+        [Fact]
+        public void Length_Squared_Should_Return_Correct_Length_Of_Vector()
+        {
+            var vectorA = new Vector(2, 4);
+            var squaredLengthA = 2 * 2 + 4 * 4;
+
+            Assert.Equal(squaredLengthA, vectorA.SquaredLength);
+        }
+
+        [Fact]
+        public void Normalize_Should_Return_Normalized_Vector()
+        {
+            // the length of a normalized vector must be 1
+
+            var vectorA = new Vector(13, 84);
+            var vectorB = new Vector(-34, 345);
+            var vectorC = new Vector(-34, -84);
+
+            Assert.Equal(1.0, vectorA.Normalize().Length);
+            Assert.Equal(1.0, vectorB.Normalize().Length);
+            Assert.Equal(1.0, vectorC.Normalize().Length);
+        }
+
+        [Fact]
+        public void Negate_Should_Return_Negated_Vector()
+        {
+            var vector = new Vector(2, 4);
+            var negated = new Vector(-2, -4);
+
+            Assert.Equal(negated, vector.Negate());
+        }
+
+        [Fact]
+        public void Dot_Should_Return_Correct_Value()
+        {
+            var a = new Vector(-6, 8.0);
+            var b = new Vector(5, 12.0);
+
+            Assert.Equal(66.0, Vector.Dot(a, b));
+        }
+
+        [Fact]
+        public void Cross_Should_Return_Correct_Value()
+        {
+            var a = new Vector(-6, 8.0);
+            var b = new Vector(5, 12.0);
+
+            Assert.Equal(-112.0, Vector.Cross(a, b));
+        }
+
+        [Fact]
+        public void Divied_By_Vector_Should_Return_Correct_Value()
+        {
+            var a = new Vector(10, 2);
+            var b = new Vector(5, 2);
+
+            var expected = new Vector(2, 1);
+
+            Assert.Equal(expected, Vector.Divide(a, b));
+        }
+
+        [Fact]
+        public void Divied_Should_Return_Correct_Value()
+        {
+            var vector = new Vector(10, 2);
+            var expected = new Vector(5, 1);
+
+            Assert.Equal(expected, Vector.Divide(vector, 2));
+        }
+
+        [Fact]
+        public void Multiply_By_Vector_Should_Return_Correct_Value()
+        {
+            var a = new Vector(10, 2);
+            var b = new Vector(2, 2);
+
+            var expected = new Vector(20, 4);
+
+            Assert.Equal(expected, Vector.Multiply(a, b));
+        }
+
+        [Fact]
+        public void Multiply_Should_Return_Correct_Value()
+        {
+            var vector = new Vector(10, 2);
+
+            var expected = new Vector(20, 4);
+
+            Assert.Equal(expected, Vector.Multiply(vector, 2));
+        }
+    }
+}