Merge branch 'VitalElement-fix_carousel_presenter'

appveyor.yml

@@ -20,6 +20,7 @@ configuration:
   - Release
 
 after_test:
+- .\packages\JetBrains.dotMemoryUnit.2.1.20150828.125449\tools\dotMemoryUnit.exe -targetExecutable="%xunit20%\xunit.console.x86.exe" -returnTargetExitCode  --"tests\Perspex.LeakTests\bin\Release\Perspex.LeakTests.dll"
 - ps: nuget\build-appveyor.ps1
 
 artifacts:

samples/XamlTestApplicationPcl/ViewModels/EditorViewModel.cs

@@ -0,0 +1,103 @@
+using Perspex.Threading;
+
+namespace XamlTestApplication.ViewModels
+{
+    using ReactiveUI;
+    using System;
+    using System.Collections.Generic;
+    using System.Collections.ObjectModel;
+    using System.Linq;
+    using System.Text;
+    using System.Threading.Tasks;
+
+    public class ShellViewModel : ReactiveObject
+    {
+        private ShellViewModel()
+        {
+            documents = new ObservableCollection<EditorViewModel>();
+
+            AddDocumentCommand = ReactiveCommand.Create();
+            AddDocumentCommand.Subscribe(_ =>
+            {
+                Documents.Add(new EditorViewModel());
+            });
+
+            GCCommand = ReactiveCommand.Create();
+            GCCommand.Subscribe(_ =>
+            {
+                GC.Collect();
+            });
+        }
+
+        public static ShellViewModel Instance = new ShellViewModel();
+
+        private ObservableCollection<EditorViewModel> documents;
+        public ObservableCollection<EditorViewModel> Documents
+        {
+            get { return documents; }
+            set { this.RaiseAndSetIfChanged(ref documents, value); }
+        }
+
+        private EditorViewModel selectedDocument;
+
+        public EditorViewModel SelectedDocument
+        {
+            get { return selectedDocument; }
+            set { this.RaiseAndSetIfChanged(ref selectedDocument, value); }
+        }
+
+        private int instanceCount;
+
+        public int InstanceCount
+        {
+            get { return instanceCount; }
+            set { this.RaiseAndSetIfChanged(ref instanceCount, value); }
+        }
+
+
+
+        public ReactiveCommand<object> AddDocumentCommand { get; }
+        public ReactiveCommand<object> GCCommand { get; }
+    }
+
+    public class EditorViewModel : ReactiveObject
+    {
+        private static int InstanceCount = 0;
+
+        public EditorViewModel()
+        {
+            InstanceCount++;
+            ShellViewModel.Instance.InstanceCount = InstanceCount;
+            text = "This is some text.";
+
+            CloseCommand = ReactiveCommand.Create();
+
+            CloseCommand.Subscribe(_ =>
+            {
+                ShellViewModel.Instance.Documents.Remove(this);
+            });
+        }
+
+        ~EditorViewModel()
+        {
+            
+            
+            //System.Console.WriteLine("EVM Destructed");
+            InstanceCount--;
+            Dispatcher.UIThread.InvokeAsync(() =>
+            {
+                ShellViewModel.Instance.InstanceCount = InstanceCount;
+            });
+
+        }
+
+        private string text;
+        public string Text
+        {
+            get { return text; }
+            set { this.RaiseAndSetIfChanged(ref text, value); }
+        }
+
+        public ReactiveCommand<object> CloseCommand { get; }
+    }
+}

samples/XamlTestApplicationPcl/ViewModels/MainWindowViewModel.cs

@@ -56,7 +56,11 @@ namespace XamlTestApplication.ViewModels
                 }
             };
 
-            CollapseNodesCommand = ReactiveCommand.Create();
+            
+        
+
+
+        CollapseNodesCommand = ReactiveCommand.Create();
             CollapseNodesCommand.Subscribe(_ => ExpandNodes(false));
             ExpandNodesCommand = ReactiveCommand.Create();
             ExpandNodesCommand.Subscribe(_ => ExpandNodes(true));
@@ -77,6 +81,15 @@ namespace XamlTestApplication.ViewModels
                 ofd.ShowAsync();
             });
 
+            shell = ShellViewModel.Instance;
+        }
+
+        private ShellViewModel shell;
+
+        public ShellViewModel Shell
+        {
+            get { return shell; }
+            set { shell = value; }
         }
 
         public List<TestItem> Items { get; }

samples/XamlTestApplicationPcl/Views/MainWindow.xaml

@@ -316,6 +316,84 @@
           <local:TestScrollable/>
         </ScrollViewer>
       </TabItem>
+      <TabItem Header="Mem Leak Repro">
+        <Grid DataContext="{Binding Shell}">
+            <StackPanel>
+              
+            <TabStrip Name="strip"  Items="{Binding Documents}" SelectedItem="{Binding SelectedDocument, Mode=TwoWay}" Focusable="false">
+              <TabStrip.Styles>                
+
+                <Style Selector="TabStripItem">
+                  <Setter Property="Height" Value="20" />
+                  <Setter Property="Background" Value="#2D2D30" />
+                  <Setter Property="BorderBrush" Value="#3E3E42" />
+                  <Setter Property="BorderThickness" Value="0" />
+                  <Setter Property="Margin" Value="0 0 0 -1" />
+                  <Setter Property="Padding" Value="4 0 4 0" />
+                  <Setter Property="FontSize" Value="12"/>
+                </Style>
+                <Style Selector="TabStripItem:pointerover">
+                  <Setter Property="Background" Value="#1c97ea" />
+                </Style>
+                <Style Selector="TabStripItem:selected">
+                  <Setter Property="Background" Value="#007ACC" />
+                </Style>
+              </TabStrip.Styles>
+
+              <TabStrip.DataTemplates>
+                <DataTemplate>
+                  <StackPanel Orientation="Horizontal" Gap="2">                    
+                    <TextBlock Text="{Binding Title}" Foreground="WhiteSmoke" Margin="2"/>                    
+                    <Button Height="14" Width="14">
+                      <Button.Styles>
+                        <Style Selector="Button">
+                          <Setter Property="BorderThickness" Value="0"/>
+                          <Setter Property="Padding" Value="0"/>
+                          <Setter Property="Margin" Value="0"/>
+                          <Setter Property="Background" Value="Transparent" />
+                        </Style>
+
+                        <Style Selector="Button:pointerover">
+                          <Setter Property="Background" Value="#1c97ea" />
+                        </Style>
+                      </Button.Styles>
+                      <Path Margin="2" Stretch="Uniform" UseLayoutRounding="False" Data="M16,12V4H17V2H7V4H8V12L6,14V16H11.2V22H12.8V16H18V14L16,12Z" Fill="WhiteSmoke" />
+
+                    </Button>
+
+                    <Button Height="14" Width="14" Command="{Binding CloseCommand}">
+                      <Button.Styles>
+                        <Style Selector="Button">
+                          <Setter Property="BorderThickness" Value="0"/>
+                          <Setter Property="Padding" Value="0"/>
+                          <Setter Property="Margin" Value="0"/>
+                          <Setter Property="Background" Value="Transparent" />
+                        </Style>
+                        <Style Selector="Button:pointerover">
+                          <Setter Property="Background" Value="#1c97ea" />
+                        </Style>
+                      </Button.Styles>
+                      <Path Margin="2" Stretch="Uniform" UseLayoutRounding="False" Data="M19,6.41L17.59,5L12,10.59L6.41,5L5,6.41L10.59,12L5,17.59L6.41,19L12,13.41L17.59,19L19,17.59L13.41,12L19,6.41Z" Fill="WhiteSmoke" />
+                    </Button>
+                  </StackPanel>                  
+                </DataTemplate>
+              </TabStrip.DataTemplates>
+            </TabStrip>
+            <Grid Background="#007ACC" Height="2" />
+              <Button Content="AddTab" Command="{Binding AddDocumentCommand}" Width="50" Height="30" />
+              <Button Content="GC.Collecy" Command="{Binding GCCommand}" Width="50" Height="30" />
+              <TextBox Text="{Binding InstanceCount}"           />
+
+          <Carousel Items="{Binding Documents}" SelectedIndex="{Binding #strip.SelectedIndex}" IsVirtualized="false">
+            <Carousel.DataTemplates>
+              <DataTemplate>
+                <TextBox Text="{Binding Text}" />
+              </DataTemplate>
+            </Carousel.DataTemplates>
+          </Carousel>
+            </StackPanel>
+        </Grid>
+      </TabItem>
     </TabControl>
   </Grid>
 </Window>

samples/XamlTestApplicationPcl/XamlTestApplicationPcl.csproj

@@ -42,6 +42,7 @@
   <ItemGroup>
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="TestScrollable.cs" />
+    <Compile Include="ViewModels\EditorViewModel.cs" />
     <Compile Include="ViewModels\MainWindowViewModel.cs" />
     <Compile Include="ViewModels\TestItem.cs" />
     <Compile Include="ViewModels\TestNode.cs" />

src/Perspex.Base/PerspexObject.cs

@@ -23,17 +23,6 @@ namespace Perspex
     /// </remarks>
     public class PerspexObject : IPerspexObject, IPerspexObjectDebug, INotifyPropertyChanged, IPriorityValueOwner
     {
-        /// <summary>
-        /// Maintains a list of direct property binding subscriptions so that the binding source
-        /// doesn't get collected.
-        /// </summary>
-        /// <remarks>
-        /// If/when we provide a ClearBindings() method, then this collection will be need to be
-        /// moved to an instance field and indexed by property, but until that point a static
-        /// collection will suffice.
-        /// </remarks>
-        private static List<IDisposable> s_directBindings = new List<IDisposable>();
-
         /// <summary>
         /// The parent object that inherited values are inherited from.
         /// </summary>
@@ -45,6 +34,12 @@ namespace Perspex
         private readonly Dictionary<PerspexProperty, PriorityValue> _values =
             new Dictionary<PerspexProperty, PriorityValue>();
 
+        /// <summary>
+        /// Maintains a list of direct property binding subscriptions so that the binding source
+        /// doesn't get collected.
+        /// </summary>
+        private List<IDisposable> _directBindings;
+
         /// <summary>
         /// Event handler for <see cref="INotifyPropertyChanged"/> implementation.
         /// </summary>
@@ -402,17 +397,22 @@ namespace Perspex
 
                 IDisposable subscription = null;
 
+                if (_directBindings == null)
+                {
+                    _directBindings = new List<IDisposable>();
+                }
+
                 subscription = source
                     .Select(x => CastOrDefault(x, property.PropertyType))
-                    .Do(_ => { }, () => s_directBindings.Remove(subscription))
+                    .Do(_ => { }, () => _directBindings.Remove(subscription))
                     .Subscribe(x => DirectBindingSet(property, x));
 
-                s_directBindings.Add(subscription);
+                _directBindings.Add(subscription);
 
                 return Disposable.Create(() =>
                 {
                     subscription.Dispose();
-                    s_directBindings.Remove(subscription);
+                    _directBindings.Remove(subscription);
                 });
             }
             else

src/Perspex.Controls/Generators/ItemContainerGenerator.cs

@@ -94,9 +94,15 @@ namespace Perspex.Controls.Generators
         /// <inheritdoc/>
         public virtual IEnumerable<ItemContainer> RemoveRange(int startingIndex, int count)
         {
-            var result = _containers.GetRange(startingIndex, count);
+            List<ItemContainer> result = new List<ItemContainer>();
-            _containers.RemoveRange(startingIndex, count);
+
-            Dematerialized?.Invoke(this, new ItemContainerEventArgs(startingIndex, result));
+            if (startingIndex < _containers.Count)
+            {
+                result.AddRange(_containers.GetRange(startingIndex, count));
+                _containers.RemoveRange(startingIndex, count);
+                Dematerialized?.Invoke(this, new ItemContainerEventArgs(startingIndex, result));
+            }
+
             return result;
         }
 

src/Perspex.Controls/Presenters/CarouselPresenter.cs

@@ -6,6 +6,7 @@ using System.Linq;
 using System.Reactive.Linq;
 using System.Threading.Tasks;
 using Perspex.Animation;
+using Perspex.Controls.Generators;
 using Perspex.Controls.Primitives;
 using Perspex.Controls.Utils;
 using Perspex.Data;
@@ -103,7 +104,19 @@ namespace Perspex.Controls.Presenters
         /// <inheritdoc/>
         protected override void ItemsChanged(NotifyCollectionChangedEventArgs e)
         {
-            // TODO: Handle items changing.
+            // TODO: Handle items changing.           
+            switch (e.Action)
+            {
+                case NotifyCollectionChangedAction.Remove:
+                    if (!IsVirtualized)
+                    {
+                        var generator = ItemContainerGenerator;
+                        var containers = generator.RemoveRange(e.OldStartingIndex, e.OldItems.Count);
+                        Panel.Children.RemoveAll(containers.Select(x => x.ContainerControl));
+                    }
+                    break;
+
+            }
         }
 
         /// <summary>

src/Perspex.Controls/Primitives/SelectingItemsControl.cs

@@ -377,6 +377,23 @@ namespace Perspex.Controls.Primitives
             }
         }
 
+        /// <inheritdoc/>
+        protected override void OnContainersDematerialized(ItemContainerEventArgs e)
+        {
+            base.OnContainersDematerialized(e);
+
+            var panel = (InputElement)Presenter.Panel;
+
+            foreach (var container in e.Containers)
+            {
+                if (KeyboardNavigation.GetTabOnceActiveElement(panel) == container.ContainerControl)
+                {
+                    KeyboardNavigation.SetTabOnceActiveElement(panel, null);
+                    break;
+                }
+            }
+        }
+
         /// <inheritdoc/>
         protected override void OnDataContextChanging()
         {

src/Perspex.Input/FocusManager.cs

@@ -39,7 +39,7 @@ namespace Perspex.Input
         /// <summary>
         /// Gets the currently focused <see cref="IInputElement"/>.
         /// </summary>
-        public IInputElement Current => KeyboardDevice.Instance.FocusedElement;
+        public IInputElement Current => KeyboardDevice.Instance?.FocusedElement;
 
         /// <summary>
         /// Gets the current focus scope.
@@ -82,9 +82,12 @@ namespace Perspex.Input
                     if (_focusScopes.TryGetValue(scope, out element))
                     {
                         Focus(element, method);
-                        break;
+                        return;
                     }
                 }
+
+                // Couldn't find a focus scope, clear focus.
+                SetFocusedElement(Scope, null);
             }
         }
 
@@ -111,7 +114,7 @@ namespace Perspex.Input
 
             if (Scope == scope)
             {
-                KeyboardDevice.Instance.SetFocusedElement(element, method, modifiers);
+                KeyboardDevice.Instance?.SetFocusedElement(element, method, modifiers);
             }
         }
 
@@ -176,7 +179,7 @@ namespace Perspex.Input
             if (sender == e.Source)
             {
                 var ev = (PointerPressedEventArgs)e;
-                var element = (ev.Device.Captured as IInputElement) ?? (e.Source as IInputElement);
+                var element = (ev.Device?.Captured as IInputElement) ?? (e.Source as IInputElement);
 
                 if (element == null || !CanFocus(element))
                 {

src/Perspex.Input/Gestures.cs

@@ -18,7 +18,7 @@ namespace Perspex.Input
             RoutingStrategies.Bubble,
             typeof(Gestures));
 
-        private static IInteractive s_lastPress;
+        private static WeakReference s_lastPress;
 
         static Gestures()
         {
@@ -34,9 +34,9 @@ namespace Perspex.Input
 
                 if (e.ClickCount <= 1)
                 {
-                    s_lastPress = e.Source;
+                    s_lastPress = new WeakReference(e.Source);
                 }
-                else if (e.ClickCount == 2 && s_lastPress == e.Source)
+                else if (s_lastPress?.IsAlive == true && e.ClickCount == 2 && s_lastPress.Target == e.Source)
                 {
                     e.Source.RaiseEvent(new RoutedEventArgs(DoubleTappedEvent));
                 }
@@ -49,9 +49,9 @@ namespace Perspex.Input
             {
                 var e = (PointerReleasedEventArgs)ev;
 
-                if (s_lastPress == e.Source)
+                if (s_lastPress?.IsAlive == true && s_lastPress.Target == e.Source)
                 {
-                    s_lastPress.RaiseEvent(new RoutedEventArgs(TappedEvent));
+                    ((IInteractive)s_lastPress.Target).RaiseEvent(new RoutedEventArgs(TappedEvent));
                 }
             }
         }

src/Perspex.Input/InputElement.cs

@@ -376,9 +376,9 @@ namespace Perspex.Input
         }
 
         /// <inheritdoc/>
-        protected override void OnDetachedFromVisualTree(VisualTreeAttachmentEventArgs e)
+        protected override void OnDetachedFromVisualTreeCore(VisualTreeAttachmentEventArgs e)
         {
-            base.OnDetachedFromVisualTree(e);
+            base.OnDetachedFromVisualTreeCore(e);
 
             if (IsFocused)
             {
@@ -387,9 +387,9 @@ namespace Perspex.Input
         }
 
         /// <inheritdoc/>
-        protected override void OnAttachedToVisualTree(VisualTreeAttachmentEventArgs e)
+        protected override void OnAttachedToVisualTreeCore(VisualTreeAttachmentEventArgs e)
         {
-            base.OnAttachedToVisualTree(e);
+            base.OnAttachedToVisualTreeCore(e);
             UpdateIsEnabledCore();
         }
 

tests/Perspex.Base.UnitTests/PerspexObjectTests_Direct.cs

@@ -344,6 +344,7 @@ namespace Perspex.Base.UnitTests
             {
                 var source = new Subject<string>();
                 var sub = target.Bind((PerspexProperty)Class1.FooProperty, source);
+                source.OnNext("foo");
                 return new WeakReference(source);
             };
 
@@ -351,6 +352,7 @@ namespace Perspex.Base.UnitTests
 
             GC.Collect();
 
+            Assert.Equal("foo", target.Foo);
             Assert.True(weakSource.IsAlive);
         }
 

tests/Perspex.Controls.UnitTests/ListBoxTests.cs

@@ -104,30 +104,6 @@ namespace Perspex.Controls.UnitTests
                 dataContexts);
         }
 
-        [Fact]
-        public void Setting_SelectedItem_Should_Set_Panel_Keyboard_Navigation()
-        {
-            var target = new ListBox
-            {
-                Template = new FuncControlTemplate(CreateListBoxTemplate),
-                Items = new[] { "Foo", "Bar", "Baz " },
-            };
-
-            ApplyTemplate(target);
-
-            target.Presenter.Panel.Children[1].RaiseEvent(new PointerPressedEventArgs
-            {
-                RoutedEvent = InputElement.PointerPressedEvent,
-                MouseButton = MouseButton.Left,
-            });
-
-            var panel = target.Presenter.Panel;
-
-            Assert.Equal(
-                KeyboardNavigation.GetTabOnceActiveElement((InputElement)panel),
-                panel.Children[1]);
-        }
-
         private Control CreateListBoxTemplate(ITemplatedControl parent)
         {
             return new ScrollViewer

tests/Perspex.Controls.UnitTests/Presenters/CarouselPresenterTests.cs

@@ -7,6 +7,7 @@ using Perspex.Controls.Generators;
 using Perspex.Controls.Presenters;
 using Perspex.Controls.Templates;
 using Xunit;
+using System.Collections.ObjectModel;
 
 namespace Perspex.Controls.UnitTests.Presenters
 {
@@ -116,6 +117,82 @@ namespace Perspex.Controls.UnitTests.Presenters
             Assert.Equal(2, target.Panel.Children.Count);
         }
 
+        [Fact]
+        public void Should_Remove_Controls_When_IsVirtualized_Is_False()
+        {
+            ObservableCollection<string> items = new ObservableCollection<string>();
+            
+            var target = new CarouselPresenter
+            {
+                Items = items,              
+                SelectedIndex = 0,
+                IsVirtualized = false,
+            };
+
+            target.ApplyTemplate();
+            target.SelectedIndex = 0;
+            items.Add("foo");
+            target.SelectedIndex = 0;
+
+            Assert.Equal(1, target.ItemContainerGenerator.Containers.Count());
+            Assert.Equal(1, target.Panel.Children.Count);
+
+            items.Add("bar");
+            Assert.Equal(1, target.ItemContainerGenerator.Containers.Count());
+            Assert.Equal(1, target.Panel.Children.Count);
+
+            target.SelectedIndex = 1;
+            Assert.Equal(2, target.ItemContainerGenerator.Containers.Count());
+            Assert.Equal(2, target.Panel.Children.Count);            
+
+            items.Remove(items[0]);
+            Assert.Equal(1, target.ItemContainerGenerator.Containers.Count());
+            Assert.Equal(1, target.Panel.Children.Count);            
+
+            items.Remove(items[0]);
+            Assert.Equal(0, target.ItemContainerGenerator.Containers.Count());
+            Assert.Equal(0, target.Panel.Children.Count);            
+        }
+
+        [Fact]
+        public void Should_have_correct_index_itemscontainer()
+        {
+            ObservableCollection<string> items = new ObservableCollection<string>();
+
+            var target = new CarouselPresenter
+            {
+                Items = items,
+                SelectedIndex = 0,
+                IsVirtualized = false,
+            };
+
+            target.ApplyTemplate();
+            target.SelectedIndex = 0;
+            items.Add("foo");
+            target.SelectedIndex = 0;
+
+            Assert.Equal(1, target.ItemContainerGenerator.Containers.Count());
+            Assert.Equal(1, target.Panel.Children.Count);
+
+            items.Add("bar");
+            Assert.Equal(1, target.ItemContainerGenerator.Containers.Count());
+            Assert.Equal(1, target.Panel.Children.Count);
+
+            target.SelectedIndex = 1;
+            Assert.Equal(2, target.ItemContainerGenerator.Containers.Count());
+            Assert.Equal(2, target.Panel.Children.Count);
+            Assert.Equal(0, target.ItemContainerGenerator.Containers.First().Index);
+
+            items.Remove(items[0]);
+            Assert.Equal(1, target.ItemContainerGenerator.Containers.Count());
+            Assert.Equal(1, target.Panel.Children.Count);
+            Assert.Equal(1, target.ItemContainerGenerator.Containers.First().Index);
+
+            items.Remove(items[0]);
+            Assert.Equal(0, target.ItemContainerGenerator.Containers.Count());
+            Assert.Equal(0, target.Panel.Children.Count);            
+        }
+
         private class TestItem : ContentControl
         {
         }

tests/Perspex.Controls.UnitTests/Primitives/SelectingItemsControlTests.cs

@@ -8,6 +8,7 @@ using Perspex.Collections;
 using Perspex.Controls.Presenters;
 using Perspex.Controls.Primitives;
 using Perspex.Controls.Templates;
+using Perspex.Input;
 using Perspex.Interactivity;
 using Perspex.Markup.Xaml.Data;
 using Perspex.UnitTests;
@@ -604,6 +605,57 @@ namespace Perspex.Controls.UnitTests.Primitives
             Assert.Equal(0, root.SelectedIndex);
         }
 
+        [Fact]
+        public void Setting_SelectedItem_With_Pointer_Should_Set_TabOnceActiveElement()
+        {
+            var target = new ListBox
+            {
+                Template = Template(),
+                Items = new[] { "Foo", "Bar", "Baz " },
+            };
+
+            target.ApplyTemplate();
+            target.Presenter.ApplyTemplate();
+
+            target.Presenter.Panel.Children[1].RaiseEvent(new PointerPressedEventArgs
+            {
+                RoutedEvent = InputElement.PointerPressedEvent,
+                MouseButton = MouseButton.Left,
+            });
+
+            var panel = target.Presenter.Panel;
+
+            Assert.Equal(
+                KeyboardNavigation.GetTabOnceActiveElement((InputElement)panel),
+                panel.Children[1]);
+        }
+
+        [Fact]
+        public void Removing_SelectedItem_Should_Clear_TabOnceActiveElement()
+        {
+            var items = new ObservableCollection<string>(new[] { "Foo", "Bar", "Baz " });
+
+            var target = new ListBox
+            {
+                Template = Template(),
+                Items = items,
+            };
+
+            target.ApplyTemplate();
+            target.Presenter.ApplyTemplate();
+
+            target.Presenter.Panel.Children[1].RaiseEvent(new PointerPressedEventArgs
+            {
+                RoutedEvent = InputElement.PointerPressedEvent,
+                MouseButton = MouseButton.Left,
+            });
+
+            items.RemoveAt(1);
+
+            var panel = target.Presenter.Panel;
+
+            Assert.Null(KeyboardNavigation.GetTabOnceActiveElement((InputElement)panel));
+        }
 
         private FuncControlTemplate Template()
         {

tests/Perspex.Input.UnitTests/InputElement_Focus.cs

@@ -0,0 +1,49 @@
+// Copyright (c) The Perspex Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
+using Perspex.Controls;
+using Perspex.UnitTests;
+using Xunit;
+
+namespace Perspex.Input.UnitTests
+{
+    public class InputElement_Focus
+    {
+        [Fact]
+        public void Focus_Should_Set_FocusManager_Current()
+        {
+            Button target;
+
+            using (UnitTestApplication.Start(TestServices.RealFocus))
+            {
+                var root = new TestRoot
+                {
+                    Child = target = new Button()
+                };
+
+                target.Focus();
+
+                Assert.Same(target, FocusManager.Instance.Current);
+            }
+        }
+
+        [Fact]
+        public void Focus_Should_Be_Cleared_When_Control_Is_Removed_From_VisualTree()
+        {
+            Button target;
+
+            using (UnitTestApplication.Start(TestServices.RealFocus))
+            {
+                var root = new TestRoot
+                {
+                    Child = target = new Button()
+                };
+
+                target.Focus();
+                root.Child = null;
+
+                Assert.Null(FocusManager.Instance.Current);
+            }
+        }
+    }
+}

tests/Perspex.Input.UnitTests/Perspex.Input.UnitTests.csproj

@@ -60,6 +60,7 @@
     </Reference>
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="InputElement_Focus.cs" />
     <Compile Include="InputElement_HitTesting.cs" />
     <Compile Include="KeyboardNavigationTests_Arrows.cs" />
     <Compile Include="KeyboardNavigationTests_Tab.cs" />
@@ -103,6 +104,10 @@
       <Project>{F1BAA01A-F176-4C6A-B39D-5B40BB1B148F}</Project>
       <Name>Perspex.Styling</Name>
     </ProjectReference>
+    <ProjectReference Include="..\Perspex.UnitTests\Perspex.UnitTests.csproj">
+      <Project>{88060192-33D5-4932-B0F9-8BD2763E857D}</Project>
+      <Name>Perspex.UnitTests</Name>
+    </ProjectReference>
   </ItemGroup>
   <ItemGroup>
     <Service Include="{82A7F48D-3B50-4B1E-B82E-3ADA8210C358}" />

tests/Perspex.UnitTests/TestRoot.cs

@@ -3,6 +3,7 @@
 
 using System;
 using Perspex.Controls;
+using Perspex.Input;
 using Perspex.Layout;
 using Perspex.Platform;
 using Perspex.Rendering;
@@ -10,7 +11,7 @@ using Perspex.Styling;
 
 namespace Perspex.UnitTests
 {
-    public class TestRoot : Decorator, ILayoutRoot, INameScope, IRenderRoot, IStyleRoot
+    public class TestRoot : Decorator, IFocusScope, ILayoutRoot, INameScope, IRenderRoot, IStyleRoot
     {
         private readonly NameScope _nameScope = new NameScope();
 

tests/Perspex.UnitTests/TestServices.cs

@@ -36,12 +36,19 @@ namespace Perspex.UnitTests
         public static readonly TestServices MockThreadingInterface = new TestServices(
             threadingInterface: Mock.Of<IPlatformThreadingInterface>(x => x.CurrentThreadIsLoopThread == true));
 
+        public static readonly TestServices RealFocus = new TestServices(
+            focusManager: new FocusManager(),
+            keyboardDevice: () => new KeyboardDevice(),
+            inputManager: new InputManager());
+
         public static readonly TestServices RealStyler = new TestServices(
             styler: new Styler());
 
         public TestServices(
             IAssetLoader assetLoader = null,
+            IFocusManager focusManager = null,
             IInputManager inputManager = null,
+            Func<IKeyboardDevice> keyboardDevice = null,
             ILayoutManager layoutManager = null,
             IPclPlatformWrapper platformWrapper = null,
             IPlatformRenderInterface renderInterface = null,
@@ -53,7 +60,9 @@ namespace Perspex.UnitTests
             IWindowingPlatform windowingPlatform = null)
         {
             AssetLoader = assetLoader;
+            FocusManager = focusManager;
             InputManager = inputManager;
+            KeyboardDevice = keyboardDevice;
             LayoutManager = layoutManager;
             PlatformWrapper = platformWrapper;
             RenderInterface = renderInterface;
@@ -67,6 +76,8 @@ namespace Perspex.UnitTests
 
         public IAssetLoader AssetLoader { get; }
         public IInputManager InputManager { get; }
+        public IFocusManager FocusManager { get; }
+        public Func<IKeyboardDevice> KeyboardDevice { get; }
         public ILayoutManager LayoutManager { get; }
         public IPclPlatformWrapper PlatformWrapper { get; }
         public IPlatformRenderInterface RenderInterface { get; }
@@ -79,7 +90,9 @@ namespace Perspex.UnitTests
 
         public TestServices With(
             IAssetLoader assetLoader = null,
+            IFocusManager focusManager = null,
             IInputManager inputManager = null,
+            Func<IKeyboardDevice> keyboardDevice = null,
             ILayoutManager layoutManager = null,
             IPclPlatformWrapper platformWrapper = null,
             IPlatformRenderInterface renderInterface = null,
@@ -92,7 +105,9 @@ namespace Perspex.UnitTests
         {
             return new TestServices(
                 assetLoader: assetLoader ?? AssetLoader,
+                focusManager: focusManager ?? FocusManager,
                 inputManager: inputManager ?? InputManager,
+                keyboardDevice: keyboardDevice ?? KeyboardDevice,
                 layoutManager: layoutManager ?? LayoutManager,
                 platformWrapper: platformWrapper ?? PlatformWrapper,
                 renderInterface: renderInterface ?? RenderInterface,

tests/Perspex.UnitTests/UnitTestApplication.cs

@@ -40,8 +40,10 @@ namespace Perspex.UnitTests
         {
             PerspexLocator.CurrentMutable
                 .Bind<IAssetLoader>().ToConstant(Services.AssetLoader)
+                .Bind<IFocusManager>().ToConstant(Services.FocusManager)
                 .BindToSelf<IGlobalStyles>(this)
                 .Bind<IInputManager>().ToConstant(Services.InputManager)
+                .Bind<IKeyboardDevice>().ToConstant(Services.KeyboardDevice?.Invoke())
                 .Bind<ILayoutManager>().ToConstant(Services.LayoutManager)
                 .Bind<IPclPlatformWrapper>().ToConstant(Services.PlatformWrapper)
                 .Bind<IPlatformRenderInterface>().ToConstant(Services.RenderInterface)