Merge branch 'master' into patch-1

.github/ISSUE_TEMPLATE/bug_report.md

@@ -4,7 +4,6 @@ about: Create a report to help us improve Avalonia
 title: ''
 labels: bug
 assignees: ''
-
 ---
 
 **Describe the bug**
@@ -12,6 +11,7 @@ A clear and concise description of what the bug is.
 
 **To Reproduce**
 Steps to reproduce the behavior:
+
 1. Go to '...'
 2. Click on '....'
 3. Scroll down to '....'
@@ -24,8 +24,9 @@ A clear and concise description of what you expected to happen.
 If applicable, add screenshots to help explain your problem.
 
 **Desktop (please complete the following information):**
- - OS: [e.g. Windows, Mac, Linux (State distribution)]
- - Version [e.g. 0.10.0-rc1 or 0.9.12]
+
+- OS: [e.g. Windows, Mac, Linux (State distribution)]
+- Version [e.g. 0.10.0-rc1 or 0.9.12]
 
 **Additional context**
 Add any other context about the problem here.

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,8 @@
+blank_issues_enabled: false
+contact_links:
+  - name: Questions, Discussions, Ideas
+    url: https://github.com/AvaloniaUI/Avalonia/discussions/new
+    about: Please ask and answer questions here.
+  - name: Avalonia Community Support on Gitter
+    url: https://gitter.im/AvaloniaUI/Avalonia
+    about: Please ask and answer questions here.

.github/ISSUE_TEMPLATE/feature_request.md

@@ -4,7 +4,6 @@ about: Suggest an idea for this project
 title: ''
 labels: enhancement
 assignees: ''
-
 ---
 
 **Is your feature request related to a problem? Please describe.**

native/Avalonia.Native/src/OSX/cursor.mm

@@ -62,6 +62,28 @@ public:
             
         return S_OK;
     }
+    
+    virtual HRESULT CreateCustomCursor (void* bitmapData, size_t length, AvnPixelSize hotPixel, IAvnCursor** retOut) override
+    {
+        if(bitmapData == nullptr || retOut == nullptr)
+        {
+            return E_POINTER;
+        }
+        
+        NSData *imageData = [NSData dataWithBytes:bitmapData length:length];
+        NSImage *image = [[NSImage alloc] initWithData:imageData];
+        
+        
+        NSPoint hotSpot;
+        hotSpot.x = hotPixel.Width;
+        hotSpot.y = hotPixel.Height;
+        
+        *retOut = new Cursor([[NSCursor new] initWithImage: image hotSpot: hotSpot]);
+        
+        (*retOut)->AddRef();
+        
+        return S_OK;
+    }
 };
 
 extern IAvnCursorFactory* CreateCursorFactory()

samples/ControlCatalog/MainView.xaml

@@ -22,6 +22,10 @@
       <TabItem Header="CheckBox"><pages:CheckBoxPage/></TabItem>
       <TabItem Header="ComboBox"><pages:ComboBoxPage/></TabItem>
       <TabItem Header="ContextMenu"><pages:ContextMenuPage/></TabItem>
+      <TabItem Header="Cursor"
+               ScrollViewer.VerticalScrollBarVisibility="Disabled">
+        <pages:CursorPage/>
+      </TabItem>
       <TabItem Header="DataGrid" 
                ScrollViewer.VerticalScrollBarVisibility="Disabled"
                ScrollViewer.HorizontalScrollBarVisibility="Disabled">

samples/ControlCatalog/Pages/CursorPage.xaml

@@ -0,0 +1,29 @@
+<UserControl xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             x:Class="ControlCatalog.Pages.CursorPage">
+  <Grid ColumnDefinitions="*,*" RowDefinitions="Auto,*">
+    <StackPanel Grid.ColumnSpan="2" Orientation="Vertical" Spacing="4">
+      <TextBlock Classes="h1">Cursor</TextBlock>
+      <TextBlock Classes="h2">Defines a cursor (mouse pointer)</TextBlock>
+    </StackPanel>
+
+    <ListBox Grid.Row="1" Items="{Binding StandardCursors}" Margin="0 8 8 8">
+      <ListBox.Styles>
+        <Style Selector="ListBoxItem">
+          <Setter Property="Cursor" Value="{Binding Cursor}"/>
+        </Style>
+      </ListBox.Styles>
+      <ListBox.ItemTemplate>
+        <DataTemplate>
+          <TextBlock Text="{Binding Type}"/>
+        </DataTemplate>
+      </ListBox.ItemTemplate>
+    </ListBox>
+
+    <StackPanel Grid.Column="1" Grid.Row="1" Margin="8 8 0 8">
+      <Button Cursor="{Binding CustomCursor}" Margin="0 8" Padding="16">
+        <TextBlock>Custom Cursor</TextBlock>
+      </Button>
+    </StackPanel>
+ </Grid>
+</UserControl>

samples/ControlCatalog/Pages/CursorPage.xaml.cs

@@ -0,0 +1,20 @@
+using Avalonia.Controls;
+using Avalonia.Markup.Xaml;
+using ControlCatalog.ViewModels;
+
+namespace ControlCatalog.Pages
+{
+    public class CursorPage : UserControl
+    {
+        public CursorPage()
+        {
+            this.InitializeComponent();
+            DataContext = new CursorPageViewModel();
+        }
+
+        private void InitializeComponent()
+        {
+            AvaloniaXamlLoader.Load(this);
+        }
+    }
+}

samples/ControlCatalog/ViewModels/CursorPageViewModel.cs

@@ -0,0 +1,44 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using Avalonia;
+using Avalonia.Input;
+using Avalonia.Media.Imaging;
+using Avalonia.Platform;
+using MiniMvvm;
+
+namespace ControlCatalog.ViewModels
+{
+    public class CursorPageViewModel : ViewModelBase
+    {
+        public CursorPageViewModel()
+        {
+            StandardCursors = Enum.GetValues(typeof(StandardCursorType))
+                .Cast<StandardCursorType>()
+                .Select(x => new StandardCursorModel(x))
+                .ToList();
+
+            var loader = AvaloniaLocator.Current.GetService<IAssetLoader>();
+            var s = loader.Open(new Uri("avares://ControlCatalog/Assets/avalonia-32.png"));
+            var bitmap = new Bitmap(s);
+            CustomCursor = new Cursor(bitmap, new PixelPoint(16, 16));
+        }
+
+        public IEnumerable<StandardCursorModel> StandardCursors { get; }
+        
+        public Cursor CustomCursor { get; }
+
+        public class StandardCursorModel
+        {
+            public StandardCursorModel(StandardCursorType type)
+            {
+                Type = type;
+                Cursor = new Cursor(type);
+            }
+
+            public StandardCursorType Type { get; }
+            
+            public Cursor Cursor { get; }
+        }
+    }
+}

src/Avalonia.Base/EnumExtensions.cs

@@ -11,10 +11,32 @@ namespace Avalonia
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static unsafe bool HasFlagCustom<T>(this T value, T flag) where T : unmanaged, Enum
         {
-            var intValue = *(int*)&value;
-            var intFlag = *(int*)&flag;
-
-            return (intValue & intFlag) == intFlag;
+            if (sizeof(T) == 1)
+            {
+                var byteValue = Unsafe.As<T, byte>(ref value);
+                var byteFlag = Unsafe.As<T, byte>(ref flag);
+                return (byteValue & byteFlag) == byteFlag;
+            }
+            else if (sizeof(T) == 2)
+            {
+                var shortValue = Unsafe.As<T, short>(ref value);
+                var shortFlag = Unsafe.As<T, short>(ref flag);
+                return (shortValue & shortFlag) == shortFlag;
+            }
+            else if (sizeof(T) == 4)
+            {
+                var intValue = Unsafe.As<T, int>(ref value);
+                var intFlag = Unsafe.As<T, int>(ref flag);
+                return (intValue & intFlag) == intFlag;
+            }
+            else if (sizeof(T) == 8)
+            {
+                var longValue = Unsafe.As<T, long>(ref value);
+                var longFlag = Unsafe.As<T, long>(ref flag);
+                return (longValue & longFlag) == longFlag;
+            }
+            else
+                throw new NotSupportedException("Enum with size of " + Unsafe.SizeOf<T>() + " are not supported");
         }
     }
 }

src/Avalonia.Base/Utilities/TypeUtilities.cs

@@ -372,8 +372,8 @@ namespace Avalonia.Utilities
             const string implicitName = "op_Implicit";
             const string explicitName = "op_Explicit";
 
-            bool allowImplicit = (operatorType & OperatorType.Implicit) != 0;
-            bool allowExplicit = (operatorType & OperatorType.Explicit) != 0;
+            bool allowImplicit = operatorType.HasFlagCustom(OperatorType.Implicit);
+            bool allowExplicit = operatorType.HasFlagCustom(OperatorType.Explicit);
 
             foreach (MethodInfo method in fromType.GetMethods())
             {

src/Avalonia.Controls.DataGrid/Collections/DataGridCollectionView.cs

@@ -2595,7 +2595,7 @@ namespace Avalonia.Collections
         /// <returns>Whether the specified flag is set</returns>
         private bool CheckFlag(CollectionViewFlags flags)
         {
-            return (_flags & flags) != 0;
+            return _flags.HasFlagCustom(flags);
         }
 
         /// <summary>

src/Avalonia.Controls/ApiCompatBaseline.txt

@@ -0,0 +1,6 @@
+Compat issues with assembly Avalonia.Controls:
+MembersMustExist : Member 'public void Avalonia.Controls.Embedding.Offscreen.OffscreenTopLevelImplBase.SetCursor(Avalonia.Platform.IPlatformHandle)' does not exist in the implementation but it does exist in the contract.
+InterfacesShouldHaveSameMembers : Interface member 'public void Avalonia.Platform.ITopLevelImpl.SetCursor(Avalonia.Platform.ICursorImpl)' is present in the implementation but not in the contract.
+InterfacesShouldHaveSameMembers : Interface member 'public void Avalonia.Platform.ITopLevelImpl.SetCursor(Avalonia.Platform.IPlatformHandle)' is present in the contract but not in the implementation.
+MembersMustExist : Member 'public void Avalonia.Platform.ITopLevelImpl.SetCursor(Avalonia.Platform.IPlatformHandle)' does not exist in the implementation but it does exist in the contract.
+Total Issues: 4

src/Avalonia.Controls/ComboBox.cs

@@ -188,7 +188,7 @@ namespace Avalonia.Controls
                 return;
 
             if (e.Key == Key.F4 ||
-                ((e.Key == Key.Down || e.Key == Key.Up) && ((e.KeyModifiers & KeyModifiers.Alt) != 0)))
+                ((e.Key == Key.Down || e.Key == Key.Up) && e.KeyModifiers.HasFlagCustom(KeyModifiers.Alt)))
             {
                 IsDropDownOpen = !IsDropDownOpen;
                 e.Handled = true;

src/Avalonia.Controls/Embedding/Offscreen/OffscreenTopLevelImpl.cs

@@ -61,7 +61,7 @@ namespace Avalonia.Controls.Embedding.Offscreen
 
         public virtual PixelPoint PointToScreen(Point point) => PixelPoint.FromPoint(point, 1);
 
-        public virtual void SetCursor(IPlatformHandle cursor)
+        public virtual void SetCursor(ICursorImpl cursor)
         {
         }
 

src/Avalonia.Controls/Grid.cs

@@ -637,7 +637,7 @@ namespace Avalonia.Controls
         /// </summary>
         internal bool MeasureOverrideInProgress
         {
-            get { return (CheckFlagsAnd(Flags.MeasureOverrideInProgress)); }
+            get { return CheckFlags(Flags.MeasureOverrideInProgress); }
             set { SetFlags(value, Flags.MeasureOverrideInProgress); }
         }
 
@@ -646,7 +646,7 @@ namespace Avalonia.Controls
         /// </summary>
         internal bool ArrangeOverrideInProgress
         {
-            get { return (CheckFlagsAnd(Flags.ArrangeOverrideInProgress)); }
+            get { return CheckFlags(Flags.ArrangeOverrideInProgress); }
             set { SetFlags(value, Flags.ArrangeOverrideInProgress); }
         }
 
@@ -2350,25 +2350,12 @@ namespace Avalonia.Controls
         }
 
         /// <summary>
-        /// CheckFlagsAnd returns <c>true</c> if all the flags in the
+        /// CheckFlags returns <c>true</c> if all the flags in the
         /// given bitmask are set on the object.
         /// </summary>
-        private bool CheckFlagsAnd(Flags flags)
+        private bool CheckFlags(Flags flags)
         {
-            return ((_flags & flags) == flags);
-        }
-
-        /// <summary>
-        /// CheckFlagsOr returns <c>true</c> if at least one flag in the
-        /// given bitmask is set.
-        /// </summary>
-        /// <remarks>
-        /// If no bits are set in the given bitmask, the method returns
-        /// <c>true</c>.
-        /// </remarks>
-        private bool CheckFlagsOr(Flags flags)
-        {
-            return (flags == 0 || (_flags & flags) != 0);
+            return _flags.HasFlagCustom(flags);
         }
 
         private static void OnShowGridLinesPropertyChanged(AvaloniaObject d, AvaloniaPropertyChangedEventArgs e)
@@ -2535,7 +2522,7 @@ namespace Avalonia.Controls
         /// </summary>
         private bool CellsStructureDirty
         {
-            get { return (!CheckFlagsAnd(Flags.ValidCellsStructure)); }
+            get { return !CheckFlags(Flags.ValidCellsStructure); }
             set { SetFlags(!value, Flags.ValidCellsStructure); }
         }
 
@@ -2544,7 +2531,7 @@ namespace Avalonia.Controls
         /// </summary>
         private bool ListenToNotifications
         {
-            get { return (CheckFlagsAnd(Flags.ListenToNotifications)); }
+            get { return CheckFlags(Flags.ListenToNotifications); }
             set { SetFlags(value, Flags.ListenToNotifications); }
         }
 
@@ -2553,7 +2540,7 @@ namespace Avalonia.Controls
         /// </summary>
         private bool SizeToContentU
         {
-            get { return (CheckFlagsAnd(Flags.SizeToContentU)); }
+            get { return CheckFlags(Flags.SizeToContentU); }
             set { SetFlags(value, Flags.SizeToContentU); }
         }
 
@@ -2562,7 +2549,7 @@ namespace Avalonia.Controls
         /// </summary>
         private bool SizeToContentV
         {
-            get { return (CheckFlagsAnd(Flags.SizeToContentV)); }
+            get { return CheckFlags(Flags.SizeToContentV); }
             set { SetFlags(value, Flags.SizeToContentV); }
         }
 
@@ -2571,7 +2558,7 @@ namespace Avalonia.Controls
         /// </summary>
         private bool HasStarCellsU
         {
-            get { return (CheckFlagsAnd(Flags.HasStarCellsU)); }
+            get { return CheckFlags(Flags.HasStarCellsU); }
             set { SetFlags(value, Flags.HasStarCellsU); }
         }
 
@@ -2580,7 +2567,7 @@ namespace Avalonia.Controls
         /// </summary>
         private bool HasStarCellsV
         {
-            get { return (CheckFlagsAnd(Flags.HasStarCellsV)); }
+            get { return CheckFlags(Flags.HasStarCellsV); }
             set { SetFlags(value, Flags.HasStarCellsV); }
         }
 
@@ -2589,7 +2576,7 @@ namespace Avalonia.Controls
         /// </summary>
         private bool HasGroup3CellsInAutoRows
         {
-            get { return (CheckFlagsAnd(Flags.HasGroup3CellsInAutoRows)); }
+            get { return CheckFlags(Flags.HasGroup3CellsInAutoRows); }
             set { SetFlags(value, Flags.HasGroup3CellsInAutoRows); }
         }
 
@@ -2803,10 +2790,10 @@ namespace Avalonia.Controls
             internal LayoutTimeSizeType SizeTypeU;
             internal LayoutTimeSizeType SizeTypeV;
             internal int Next;
-            internal bool IsStarU { get { return ((SizeTypeU & LayoutTimeSizeType.Star) != 0); } }
-            internal bool IsAutoU { get { return ((SizeTypeU & LayoutTimeSizeType.Auto) != 0); } }
-            internal bool IsStarV { get { return ((SizeTypeV & LayoutTimeSizeType.Star) != 0); } }
-            internal bool IsAutoV { get { return ((SizeTypeV & LayoutTimeSizeType.Auto) != 0); } }
+            internal bool IsStarU => SizeTypeU.HasFlagCustom(LayoutTimeSizeType.Star);
+            internal bool IsAutoU => SizeTypeU.HasFlagCustom(LayoutTimeSizeType.Auto);
+            internal bool IsStarV => SizeTypeV.HasFlagCustom(LayoutTimeSizeType.Star);
+            internal bool IsAutoV => SizeTypeV.HasFlagCustom(LayoutTimeSizeType.Auto);
         }
 
         /// <summary>

src/Avalonia.Controls/ListBox.cs

@@ -135,8 +135,8 @@ namespace Avalonia.Controls
                 e.Handled = UpdateSelectionFromEventSource(
                     e.Source,
                     true,
-                    (e.KeyModifiers & KeyModifiers.Shift) != 0,
-                    (e.KeyModifiers & KeyModifiers.Control) != 0);
+                    e.KeyModifiers.HasFlagCustom(KeyModifiers.Shift),
+                    e.KeyModifiers.HasFlagCustom(KeyModifiers.Control));
             }
         }
 
@@ -154,8 +154,8 @@ namespace Avalonia.Controls
                     e.Handled = UpdateSelectionFromEventSource(
                         e.Source,
                         true,
-                        (e.KeyModifiers & KeyModifiers.Shift) != 0,
-                        (e.KeyModifiers & KeyModifiers.Control) != 0,
+                        e.KeyModifiers.HasFlagCustom(KeyModifiers.Shift),
+                        e.KeyModifiers.HasFlagCustom(KeyModifiers.Control),
                         point.Properties.IsRightButtonPressed);
                 }
             }

src/Avalonia.Controls/MenuItem.cs

@@ -103,6 +103,7 @@ namespace Avalonia.Controls
         private bool _commandCanExecute = true;
         private Popup? _popup;
         private KeyGesture _hotkey;
+        private bool _isEmbeddedInMenu;
 
         /// <summary>
         /// Initializes static members of the <see cref="MenuItem"/> class.
@@ -112,6 +113,7 @@ namespace Avalonia.Controls
             SelectableMixin.Attach<MenuItem>(IsSelectedProperty);
             PressedMixin.Attach<MenuItem>();
             CommandProperty.Changed.Subscribe(CommandChanged);
+            CommandParameterProperty.Changed.Subscribe(CommandParameterChanged);
             FocusableProperty.OverrideDefaultValue<MenuItem>(true);
             HeaderProperty.Changed.AddClassHandler<MenuItem>((x, e) => x.HeaderChanged(e));
             IconProperty.Changed.AddClassHandler<MenuItem>((x, e) => x.IconChanged(e));
@@ -146,7 +148,7 @@ namespace Avalonia.Controls
                 {
                     var parent = x as Control;
                     return parent?.GetObservable(DefinitionBase.PrivateSharedSizeScopeProperty) ??
-                        Observable.Return<DefinitionBase.SharedSizeScope?>(null);
+                           Observable.Return<DefinitionBase.SharedSizeScope?>(null);
                 });
 
             this.Bind(DefinitionBase.PrivateSharedSizeScopeProperty, parentSharedSizeScope);
@@ -274,7 +276,7 @@ namespace Avalonia.Controls
         public bool IsTopLevel => Parent is Menu;
 
         /// <inheritdoc/>
-        bool IMenuItem.IsPointerOverSubMenu => _popup?.IsPointerOverPopup ?? false; 
+        bool IMenuItem.IsPointerOverSubMenu => _popup?.IsPointerOverPopup ?? false;
 
         /// <inheritdoc/>
         IMenuElement? IMenuItem.Parent => Parent as IMenuElement;
@@ -309,7 +311,7 @@ namespace Avalonia.Controls
                     .Select(x => x.ContainerControl)
                     .OfType<IMenuItem>();
             }
-        }            
+        }
 
         /// <summary>
         /// Opens the submenu.
@@ -336,6 +338,18 @@ namespace Avalonia.Controls
             return new MenuItemContainerGenerator(this);
         }
 
+        protected override void OnPointerReleased(PointerReleasedEventArgs e)
+        {
+            base.OnPointerReleased(e);
+
+            if (!_isEmbeddedInMenu)
+            {
+                //Normally the Menu's IMenuInteractionHandler is sending the click events for us
+                //However when the item is not embedded into a menu we need to send them ourselves.
+                RaiseEvent(new RoutedEventArgs(ClickEvent));
+            }
+        }
+
         protected override void OnAttachedToLogicalTree(LogicalTreeAttachmentEventArgs e)
         {
             if (_hotkey != null) // Control attached again, set Hotkey to create a hotkey manager for this control
@@ -349,6 +363,15 @@ namespace Avalonia.Controls
             {
                 Command.CanExecuteChanged += CanExecuteChanged;
             }
+
+            var parent = Parent;
+
+            while (parent is MenuItem)
+            {
+                parent = parent.Parent;
+            }
+
+            _isEmbeddedInMenu = parent is IMenu;
         }
 
         protected override void OnDetachedFromLogicalTree(LogicalTreeAttachmentEventArgs e)
@@ -506,6 +529,18 @@ namespace Avalonia.Controls
             }
         }
 
+        /// <summary>
+        /// Called when the <see cref="CommandParameter"/> property changes.
+        /// </summary>
+        /// <param name="e">The event args.</param>
+        private static void CommandParameterChanged(AvaloniaPropertyChangedEventArgs e)
+        {
+            if (e.Sender is MenuItem menuItem)
+            {
+                menuItem.CanExecuteChanged(menuItem, EventArgs.Empty);
+            }
+        }
+
         /// <summary>
         /// Called when the <see cref="ICommand.CanExecuteChanged"/> event fires.
         /// </summary>

src/Avalonia.Controls/Platform/ITopLevelImpl.cs

@@ -98,7 +98,7 @@ namespace Avalonia.Platform
         /// Sets the cursor associated with the toplevel.
         /// </summary>
         /// <param name="cursor">The cursor. Use null for default cursor</param>
-        void SetCursor(IPlatformHandle cursor);
+        void SetCursor(ICursorImpl cursor);
 
         /// <summary>
         /// Gets or sets a method called when the underlying implementation is destroyed.

src/Avalonia.Controls/Platform/InProcessDragSource.cs

@@ -73,20 +73,20 @@ namespace Avalonia.Platform
         {
             if (effect == DragDropEffects.Copy || effect == DragDropEffects.Move || effect == DragDropEffects.Link || effect == DragDropEffects.None)
                 return effect; // No need to check for the modifiers.
-            if (effect.HasFlag(DragDropEffects.Link) && modifiers.HasFlag(RawInputModifiers.Alt))
+            if (effect.HasFlagCustom(DragDropEffects.Link) && modifiers.HasFlagCustom(RawInputModifiers.Alt))
                 return DragDropEffects.Link;
-            if (effect.HasFlag(DragDropEffects.Copy) && modifiers.HasFlag(RawInputModifiers.Control))
+            if (effect.HasFlagCustom(DragDropEffects.Copy) && modifiers.HasFlagCustom(RawInputModifiers.Control))
                 return DragDropEffects.Copy;
             return DragDropEffects.Move;
         }
 
         private StandardCursorType GetCursorForDropEffect(DragDropEffects effects)
         {
-            if (effects.HasFlag(DragDropEffects.Copy))
+            if (effects.HasFlagCustom(DragDropEffects.Copy))
                 return StandardCursorType.DragCopy;
-            if (effects.HasFlag(DragDropEffects.Move))
+            if (effects.HasFlagCustom(DragDropEffects.Move))
                 return StandardCursorType.DragMove;
-            if (effects.HasFlag(DragDropEffects.Link))
+            if (effects.HasFlagCustom(DragDropEffects.Link))
                 return StandardCursorType.DragLink;
             return StandardCursorType.No;
         }
@@ -161,7 +161,7 @@ namespace Avalonia.Platform
             
             void CheckDraggingAccepted(RawInputModifiers changedMouseButton)
             {
-                if (_initialInputModifiers.Value.HasFlag(changedMouseButton))
+                if (_initialInputModifiers.Value.HasFlagCustom(changedMouseButton))
                 {
                     var result = RaiseEventAndUpdateCursor(RawDragEventType.Drop, e.Root, e.Position, e.InputModifiers);
                     UpdateCursor(null, DragDropEffects.None);

src/Avalonia.Controls/Primitives/PopupPositioning/IPopupPositioner.cs

@@ -253,9 +253,8 @@ namespace Avalonia.Controls.Primitives.PopupPositioning
     {
         public static void ValidateEdge(this PopupAnchor edge)
         {
-            if (((edge & PopupAnchor.Left) != 0 && (edge & PopupAnchor.Right) != 0)
-                ||
-                ((edge & PopupAnchor.Top) != 0 && (edge & PopupAnchor.Bottom) != 0))
+            if (edge.HasFlagCustom(PopupAnchor.Left) && edge.HasFlagCustom(PopupAnchor.Right) ||
+                edge.HasFlagCustom(PopupAnchor.Top) && edge.HasFlagCustom(PopupAnchor.Bottom))
                 throw new ArgumentException("Opposite edges specified");
         }
 
@@ -266,25 +265,25 @@ namespace Avalonia.Controls.Primitives.PopupPositioning
 
         public static PopupAnchor Flip(this PopupAnchor edge)
         {
-            var hmask = PopupAnchor.Left | PopupAnchor.Right;
-            var vmask = PopupAnchor.Top | PopupAnchor.Bottom;
-            if ((edge & hmask) != 0)
-                edge ^= hmask;
-            if ((edge & vmask) != 0)
-                edge ^= vmask;
+            if (edge.HasFlagCustom(PopupAnchor.HorizontalMask))
+                edge ^= PopupAnchor.HorizontalMask;
+
+            if (edge.HasFlagCustom(PopupAnchor.VerticalMask))
+                edge ^= PopupAnchor.VerticalMask;
+
             return edge;
         }
 
         public static PopupAnchor FlipX(this PopupAnchor edge)
         {
-            if ((edge & PopupAnchor.HorizontalMask) != 0)
+            if (edge.HasFlagCustom(PopupAnchor.HorizontalMask))
                 edge ^= PopupAnchor.HorizontalMask;
             return edge;
         }
         
         public static PopupAnchor FlipY(this PopupAnchor edge)
         {
-            if ((edge & PopupAnchor.VerticalMask) != 0)
+            if (edge.HasFlagCustom(PopupAnchor.VerticalMask))
                 edge ^= PopupAnchor.VerticalMask;
             return edge;
         }

src/Avalonia.Controls/Primitives/PopupPositioning/ManagedPopupPositioner.cs

@@ -42,16 +42,16 @@ namespace Avalonia.Controls.Primitives.PopupPositioning
         private static Point GetAnchorPoint(Rect anchorRect, PopupAnchor edge)
         {
             double x, y;
-            if ((edge & PopupAnchor.Left) != 0)
+            if (edge.HasFlagCustom(PopupAnchor.Left))
                 x = anchorRect.X;
-            else if ((edge & PopupAnchor.Right) != 0)
+            else if (edge.HasFlagCustom(PopupAnchor.Right))
                 x = anchorRect.Right;
             else
                 x = anchorRect.X + anchorRect.Width / 2;
             
-            if ((edge & PopupAnchor.Top) != 0)
+            if (edge.HasFlagCustom(PopupAnchor.Top))
                 y = anchorRect.Y;
-            else if ((edge & PopupAnchor.Bottom) != 0)
+            else if (edge.HasFlagCustom(PopupAnchor.Bottom))
                 y = anchorRect.Bottom;
             else
                 y = anchorRect.Y + anchorRect.Height / 2;
@@ -61,16 +61,16 @@ namespace Avalonia.Controls.Primitives.PopupPositioning
         private static Point Gravitate(Point anchorPoint, Size size, PopupGravity gravity)
         {
             double x, y;
-            if ((gravity & PopupGravity.Left) != 0)
+            if (gravity.HasFlagCustom(PopupGravity.Left))
                 x = -size.Width;
-            else if ((gravity & PopupGravity.Right) != 0)
+            else if (gravity.HasFlagCustom(PopupGravity.Right))
                 x = 0;
             else
                 x = -size.Width / 2;
             
-            if ((gravity & PopupGravity.Top) != 0)
+            if (gravity.HasFlagCustom(PopupGravity.Top))
                 y = -size.Height;
-            else if ((gravity & PopupGravity.Bottom) != 0)
+            else if (gravity.HasFlagCustom(PopupGravity.Bottom))
                 y = 0;
             else
                 y = -size.Height / 2;
@@ -125,21 +125,13 @@ namespace Avalonia.Controls.Primitives.PopupPositioning
 
             bool FitsInBounds(Rect rc, PopupAnchor edge = PopupAnchor.AllMask)
             {
-                if ((edge & PopupAnchor.Left) != 0
-                    && rc.X < bounds.X)
-                    return false;
-
-                if ((edge & PopupAnchor.Top) != 0
-                    && rc.Y < bounds.Y)
-                    return false;
-
-                if ((edge & PopupAnchor.Right) != 0
-                    && rc.Right > bounds.Right)
-                    return false;
-
-                if ((edge & PopupAnchor.Bottom) != 0
-                    && rc.Bottom > bounds.Bottom)
+                if (edge.HasFlagCustom(PopupAnchor.Left) && rc.X < bounds.X ||
+                    edge.HasFlagCustom(PopupAnchor.Top) && rc.Y < bounds.Y ||
+                    edge.HasFlagCustom(PopupAnchor.Right) && rc.Right > bounds.Right ||
+                    edge.HasFlagCustom(PopupAnchor.Bottom) && rc.Bottom > bounds.Bottom)
+                {
                     return false;
+                }
 
                 return true;
             }
@@ -155,7 +147,7 @@ namespace Avalonia.Controls.Primitives.PopupPositioning
             // If flipping geometry and anchor is allowed and helps, use the flipped one,
             // otherwise leave it as is
             if (!FitsInBounds(geo, PopupAnchor.HorizontalMask)
-                && (constraintAdjustment & PopupPositionerConstraintAdjustment.FlipX) != 0)
+                && constraintAdjustment.HasFlagCustom(PopupPositionerConstraintAdjustment.FlipX))
             {
                 var flipped = GetUnconstrained(anchor.FlipX(), gravity.FlipX());
                 if (FitsInBounds(flipped, PopupAnchor.HorizontalMask))
@@ -163,7 +155,7 @@ namespace Avalonia.Controls.Primitives.PopupPositioning
             }
 
             // If sliding is allowed, try moving the rect into the bounds
-            if ((constraintAdjustment & PopupPositionerConstraintAdjustment.SlideX) != 0)
+            if (constraintAdjustment.HasFlagCustom(PopupPositionerConstraintAdjustment.SlideX))
             {
                 geo = geo.WithX(Math.Max(geo.X, bounds.X));
                 if (geo.Right > bounds.Right)
@@ -171,7 +163,7 @@ namespace Avalonia.Controls.Primitives.PopupPositioning
             }
             
             // Resize the rect horizontally if allowed.
-            if ((constraintAdjustment & PopupPositionerConstraintAdjustment.ResizeX) != 0)
+            if (constraintAdjustment.HasFlagCustom(PopupPositionerConstraintAdjustment.ResizeX))
             {
                 var unconstrainedRect = geo;
 
@@ -194,7 +186,7 @@ namespace Avalonia.Controls.Primitives.PopupPositioning
             // If flipping geometry and anchor is allowed and helps, use the flipped one,
             // otherwise leave it as is
             if (!FitsInBounds(geo, PopupAnchor.VerticalMask)
-                && (constraintAdjustment & PopupPositionerConstraintAdjustment.FlipY) != 0)
+                && constraintAdjustment.HasFlagCustom(PopupPositionerConstraintAdjustment.FlipY))
             {
                 var flipped = GetUnconstrained(anchor.FlipY(), gravity.FlipY());
                 if (FitsInBounds(flipped, PopupAnchor.VerticalMask))
@@ -202,7 +194,7 @@ namespace Avalonia.Controls.Primitives.PopupPositioning
             }
 
             // If sliding is allowed, try moving the rect into the bounds
-            if ((constraintAdjustment & PopupPositionerConstraintAdjustment.SlideY) != 0)
+            if (constraintAdjustment.HasFlagCustom(PopupPositionerConstraintAdjustment.SlideY))
             {
                 geo = geo.WithY(Math.Max(geo.Y, bounds.Y));
                 if (geo.Bottom > bounds.Bottom)
@@ -210,7 +202,7 @@ namespace Avalonia.Controls.Primitives.PopupPositioning
             }
 
             // Resize the rect vertically if allowed.
-            if ((constraintAdjustment & PopupPositionerConstraintAdjustment.ResizeY) != 0)
+            if (constraintAdjustment.HasFlagCustom(PopupPositionerConstraintAdjustment.ResizeY))
             {
                 var unconstrainedRect = geo;
 

src/Avalonia.Controls/Primitives/SelectingItemsControl.cs

@@ -321,7 +321,7 @@ namespace Avalonia.Controls.Primitives
         /// <summary>
         /// Gets a value indicating whether <see cref="SelectionMode.AlwaysSelected"/> is set.
         /// </summary>
-        protected bool AlwaysSelected => (SelectionMode & SelectionMode.AlwaysSelected) != 0;
+        protected bool AlwaysSelected => SelectionMode.HasFlagCustom(SelectionMode.AlwaysSelected);
 
         /// <inheritdoc/>
         public override void BeginInit()
@@ -487,7 +487,7 @@ namespace Avalonia.Controls.Primitives
 
                 if (ItemCount > 0 &&
                     Match(keymap.SelectAll) &&
-                    SelectionMode.HasFlag(SelectionMode.Multiple))
+                    SelectionMode.HasFlagCustom(SelectionMode.Multiple))
                 {
                     Selection.SelectAll();
                     e.Handled = true;
@@ -577,8 +577,8 @@ namespace Avalonia.Controls.Primitives
             }
 
             var mode = SelectionMode;
-            var multi = (mode & SelectionMode.Multiple) != 0;
-            var toggle = (toggleModifier || (mode & SelectionMode.Toggle) != 0);
+            var multi = mode.HasFlagCustom(SelectionMode.Multiple);
+            var toggle = toggleModifier || mode.HasFlagCustom(SelectionMode.Toggle);
             var range = multi && rangeModifier;
 
             if (!select)

src/Avalonia.Controls/Repeater/RepeaterLayoutContext.cs

@@ -53,8 +53,8 @@ namespace Avalonia.Controls
         {
             return _owner.GetElementImpl(
                 index,
-                (options & ElementRealizationOptions.ForceCreate) != 0,
-                (options & ElementRealizationOptions.SuppressAutoRecycle) != 0);
+                options.HasFlagCustom(ElementRealizationOptions.ForceCreate),
+                options.HasFlagCustom(ElementRealizationOptions.SuppressAutoRecycle));
         }
 
         protected override object GetItemAtCore(int index) => _owner.ItemsSourceView.GetAt(index);

src/Avalonia.Controls/TextBox.cs

@@ -585,7 +585,7 @@ namespace Avalonia.Controls
             var keymap = AvaloniaLocator.Current.GetService<PlatformHotkeyConfiguration>();
 
             bool Match(List<KeyGesture> gestures) => gestures.Any(g => g.Matches(e));
-            bool DetectSelection() => e.KeyModifiers.HasFlag(keymap.SelectionModifiers);
+            bool DetectSelection() => e.KeyModifiers.HasFlagCustom(keymap.SelectionModifiers);
 
             if (Match(keymap.SelectAll))
             {
@@ -703,7 +703,7 @@ namespace Avalonia.Controls
             }
             else
             {
-                bool hasWholeWordModifiers = modifiers.HasFlag(keymap.WholeWordTextActionModifiers);
+                bool hasWholeWordModifiers = modifiers.HasFlagCustom(keymap.WholeWordTextActionModifiers);
                 switch (e.Key)
                 {
                     case Key.Left:

src/Avalonia.Controls/TopLevel.cs

@@ -165,7 +165,7 @@ namespace Avalonia.Controls
             this.GetObservable(PointerOverElementProperty)
                 .Select(
                     x => (x as InputElement)?.GetObservable(CursorProperty) ?? Observable.Empty<Cursor>())
-                .Switch().Subscribe(cursor => PlatformImpl?.SetCursor(cursor?.PlatformCursor));
+                .Switch().Subscribe(cursor => PlatformImpl?.SetCursor(cursor?.PlatformImpl));
 
             if (((IStyleHost)this).StylingParent is IResourceHost applicationResources)
             {

src/Avalonia.Controls/TreeView.cs

@@ -412,7 +412,7 @@ namespace Avalonia.Controls
                 e.Handled = UpdateSelectionFromEventSource(
                     e.Source,
                     true,
-                    (e.KeyModifiers & KeyModifiers.Shift) != 0);
+                    e.KeyModifiers.HasFlagCustom(KeyModifiers.Shift));
             }
         }
 
@@ -521,8 +521,8 @@ namespace Avalonia.Controls
                     e.Handled = UpdateSelectionFromEventSource(
                         e.Source,
                         true,
-                        (e.KeyModifiers & KeyModifiers.Shift) != 0,
-                        (e.KeyModifiers & KeyModifiers.Control) != 0,
+                        e.KeyModifiers.HasFlagCustom(KeyModifiers.Shift),
+                        e.KeyModifiers.HasFlagCustom(KeyModifiers.Control),
                         point.Properties.IsRightButtonPressed);
                 }
             }
@@ -558,9 +558,9 @@ namespace Avalonia.Controls
             }
 
             var mode = SelectionMode;
-            var toggle = toggleModifier || (mode & SelectionMode.Toggle) != 0;
-            var multi = (mode & SelectionMode.Multiple) != 0;
-            var range = multi && selectedContainer != null && rangeModifier;
+            var toggle = toggleModifier || mode.HasFlagCustom(SelectionMode.Toggle);
+            var multi = mode.HasFlagCustom(SelectionMode.Multiple);
+            var range = multi && rangeModifier && selectedContainer != null;
 
             if (rightButton)
             {

src/Avalonia.DesignerSupport/Remote/PreviewerWindowingPlatform.cs

@@ -47,7 +47,7 @@ namespace Avalonia.DesignerSupport.Remote
             var threading = new InternalPlatformThreadingInterface();
             AvaloniaLocator.CurrentMutable
                 .Bind<IClipboard>().ToSingleton<ClipboardStub>()
-                .Bind<IStandardCursorFactory>().ToSingleton<CursorFactoryStub>()
+                .Bind<ICursorFactory>().ToSingleton<CursorFactoryStub>()
                 .Bind<IKeyboardDevice>().ToConstant(Keyboard)
                 .Bind<IPlatformSettings>().ToConstant(instance)
                 .Bind<IPlatformThreadingInterface>().ToConstant(threading)

src/Avalonia.DesignerSupport/Remote/Stubs.cs

@@ -73,7 +73,7 @@ namespace Avalonia.DesignerSupport.Remote
 
         public PixelPoint PointToScreen(Point p) => PixelPoint.FromPoint(p, 1);
 
-        public void SetCursor(IPlatformHandle cursor)
+        public void SetCursor(ICursorImpl cursor)
         {
         }
 
@@ -192,9 +192,15 @@ namespace Avalonia.DesignerSupport.Remote
         public Task<object> GetDataAsync(string format) => Task.FromResult((object)null);
     }
 
-    class CursorFactoryStub : IStandardCursorFactory
+    class CursorFactoryStub : ICursorFactory
     {
-        public IPlatformHandle GetCursor(StandardCursorType cursorType) => new PlatformHandle(IntPtr.Zero, "STUB");
+        public ICursorImpl GetCursor(StandardCursorType cursorType) => new CursorStub();
+        public ICursorImpl CreateCursor(IBitmapImpl cursor, PixelPoint hotSpot) => new CursorStub();
+
+        private class CursorStub : ICursorImpl
+        {
+            public void Dispose() { }
+        }
     }
 
     class IconLoaderStub : IPlatformIconLoader

src/Avalonia.FreeDesktop/DBusMenuExporter.cs

@@ -223,13 +223,13 @@ namespace Avalonia.FreeDesktop
                             return null;
                         var lst = new List<string>();
                         var mod = item.Gesture;
-                        if ((mod.KeyModifiers & KeyModifiers.Control) != 0)
+                        if (mod.KeyModifiers.HasFlagCustom(KeyModifiers.Control))
                             lst.Add("Control");
-                        if ((mod.KeyModifiers & KeyModifiers.Alt) != 0)
+                        if (mod.KeyModifiers.HasFlagCustom(KeyModifiers.Alt))
                             lst.Add("Alt");
-                        if ((mod.KeyModifiers & KeyModifiers.Shift) != 0)
+                        if (mod.KeyModifiers.HasFlagCustom(KeyModifiers.Shift))
                             lst.Add("Shift");
-                        if ((mod.KeyModifiers & KeyModifiers.Meta) != 0)
+                        if (mod.KeyModifiers.HasFlagCustom(KeyModifiers.Meta))
                             lst.Add("Super");
                         lst.Add(item.Gesture.Key.ToString());
                         return new[] { lst.ToArray() };

src/Avalonia.Headless.Vnc/HeadlessVncFramebufferSource.cs

@@ -33,11 +33,11 @@ namespace Avalonia.Headless.Vnc
                 {
                     Window?.MouseMove(pt);
                     foreach (var btn in CheckedButtons)
-                        if (_previousButtons.HasFlag(btn) && !buttons.HasFlag(btn))
+                        if (_previousButtons.HasFlagCustom(btn) && !buttons.HasFlagCustom(btn))
                             Window?.MouseUp(pt, TranslateButton(btn), modifiers);
                     
                     foreach (var btn in CheckedButtons)
-                        if (!_previousButtons.HasFlag(btn) && buttons.HasFlag(btn))
+                        if (!_previousButtons.HasFlagCustom(btn) && buttons.HasFlagCustom(btn))
                             Window?.MouseDown(pt, TranslateButton(btn), modifiers);
                     _previousButtons = buttons;
                 }, DispatcherPriority.Input);

src/Avalonia.Headless/AvaloniaHeadlessPlatform.cs

@@ -58,7 +58,7 @@ namespace Avalonia.Headless
             AvaloniaLocator.CurrentMutable
                 .Bind<IPlatformThreadingInterface>().ToConstant(new HeadlessPlatformThreadingInterface())
                 .Bind<IClipboard>().ToSingleton<HeadlessClipboardStub>()
-                .Bind<IStandardCursorFactory>().ToSingleton<HeadlessCursorFactoryStub>()
+                .Bind<ICursorFactory>().ToSingleton<HeadlessCursorFactoryStub>()
                 .Bind<IPlatformSettings>().ToConstant(new HeadlessPlatformSettingsStub())
                 .Bind<ISystemDialogImpl>().ToSingleton<HeadlessSystemDialogsStub>()
                 .Bind<IPlatformIconLoader>().ToSingleton<HeadlessIconLoaderStub>()

src/Avalonia.Headless/HeadlessPlatformStubs.cs

@@ -52,12 +52,14 @@ namespace Avalonia.Headless
         }
     }
 
-    class HeadlessCursorFactoryStub : IStandardCursorFactory
+    class HeadlessCursorFactoryStub : ICursorFactory
     {
+        public ICursorImpl GetCursor(StandardCursorType cursorType) => new CursorStub();
+        public ICursorImpl CreateCursor(IBitmapImpl cursor, PixelPoint hotSpot) => new CursorStub();
 
-        public IPlatformHandle GetCursor(StandardCursorType cursorType)
+        private class CursorStub : ICursorImpl
         {
-            return new PlatformHandle(new IntPtr((int)cursorType), "STUB");
+            public void Dispose() { }
         }
     }
 

src/Avalonia.Headless/HeadlessWindowImpl.cs

@@ -67,7 +67,7 @@ namespace Avalonia.Headless
 
         public PixelPoint PointToScreen(Point point) => PixelPoint.FromPoint(point, RenderScaling);
 
-        public void SetCursor(IPlatformHandle cursor)
+        public void SetCursor(ICursorImpl cursor)
         {
 
         }

src/Avalonia.Input/AccessKeyHandler.cs

@@ -177,7 +177,7 @@ namespace Avalonia.Input
         {
             bool menuIsOpen = MainMenu?.IsOpen == true;
 
-            if ((e.KeyModifiers & KeyModifiers.Alt) != 0 || menuIsOpen)
+            if (e.KeyModifiers.HasFlagCustom(KeyModifiers.Alt) || menuIsOpen)
             {
                 // If any other key is pressed with the Alt key held down, or the main menu is open,
                 // find all controls who have registered that access key.

src/Avalonia.Input/ApiCompatBaseline.txt

@@ -0,0 +1,4 @@
+Compat issues with assembly Avalonia.Input:
+MembersMustExist : Member 'public Avalonia.Platform.IPlatformHandle Avalonia.Input.Cursor.PlatformCursor.get()' does not exist in the implementation but it does exist in the contract.
+TypesMustExist : Type 'Avalonia.Platform.IStandardCursorFactory' does not exist in the implementation but it does exist in the contract.
+Total Issues: 2

src/Avalonia.Input/Cursors.cs → src/Avalonia.Input/Cursor.cs

@@ -1,15 +1,11 @@
 using System;
+using Avalonia.Media.Imaging;
 using Avalonia.Platform;
 
+#nullable enable
+
 namespace Avalonia.Input
 {
-    /*
-    =========================================================================================
-        NOTE: Cursors are NOT disposable and are cached in platform implementation.
-        To support loading custom cursors some measures about that should be taken beforehand
-    =========================================================================================
-    */
-
     public enum StandardCursorType
     {
         Arrow,
@@ -46,21 +42,28 @@ namespace Avalonia.Input
         // SizeNorthEastSouthWest,
     }
 
-    public class Cursor
+    public class Cursor : IDisposable
     {
         public static readonly Cursor Default = new Cursor(StandardCursorType.Arrow);
 
-        internal Cursor(IPlatformHandle platformCursor)
+        internal Cursor(ICursorImpl platformImpl)
         {
-            PlatformCursor = platformCursor;
+            PlatformImpl = platformImpl;
         }
 
         public Cursor(StandardCursorType cursorType)
-            : this(GetCursor(cursorType))
+            : this(GetCursorFactory().GetCursor(cursorType))
+        {
+        }
+
+        public Cursor(IBitmap cursor, PixelPoint hotSpot)
+            : this(GetCursorFactory().CreateCursor(cursor.PlatformImpl.Item, hotSpot))
         {
         }
 
-        public IPlatformHandle PlatformCursor { get; }
+        public ICursorImpl PlatformImpl { get; }
+
+        public void Dispose() => PlatformImpl.Dispose();
 
         public static Cursor Parse(string s)
         {
@@ -69,16 +72,10 @@ namespace Avalonia.Input
                 throw new ArgumentException($"Unrecognized cursor type '{s}'.");
         }
 
-        private static IPlatformHandle GetCursor(StandardCursorType type)
+        private static ICursorFactory GetCursorFactory()
         {
-            var platform = AvaloniaLocator.Current.GetService<IStandardCursorFactory>();
-
-            if (platform == null)
-            {
-                throw new Exception("Could not create Cursor: IStandardCursorFactory not registered.");
-            }
-
-            return platform.GetCursor(type);
+            return AvaloniaLocator.Current.GetService<ICursorFactory>() ??
+                throw new Exception("Could not create Cursor: ICursorFactory not registered.");
         }
     }
 }

src/Avalonia.Input/Platform/ICursorFactory.cs

@@ -0,0 +1,12 @@
+using Avalonia.Input;
+
+#nullable enable
+
+namespace Avalonia.Platform
+{
+    public interface ICursorFactory
+    {
+        ICursorImpl GetCursor(StandardCursorType cursorType);
+        ICursorImpl CreateCursor(IBitmapImpl cursor, PixelPoint hotSpot);
+    }
+}

src/Avalonia.Input/Platform/ICursorImpl.cs

@@ -0,0 +1,14 @@
+using System;
+using Avalonia.Input;
+
+#nullable enable
+
+namespace Avalonia.Platform
+{
+    /// <summary>
+    /// Represents a platform implementation of a <see cref="Cursor"/>.
+    /// </summary>
+    public interface ICursorImpl : IDisposable
+    {
+    }
+}

src/Avalonia.Input/Platform/IStandardCursorFactory.cs

@@ -1,9 +0,0 @@
-using Avalonia.Input;
-
-namespace Avalonia.Platform
-{
-    public interface IStandardCursorFactory
-    {
-        IPlatformHandle GetCursor(StandardCursorType cursorType);
-    }
-}

src/Avalonia.Native/AvaloniaNativePlatform.cs

@@ -97,7 +97,7 @@ namespace Avalonia.Native
             AvaloniaLocator.CurrentMutable
                 .Bind<IPlatformThreadingInterface>()
                 .ToConstant(new PlatformThreadingInterface(_factory.CreatePlatformThreadingInterface()))
-                .Bind<IStandardCursorFactory>().ToConstant(new CursorFactory(_factory.CreateCursorFactory()))
+                .Bind<ICursorFactory>().ToConstant(new CursorFactory(_factory.CreateCursorFactory()))
                 .Bind<IPlatformIconLoader>().ToSingleton<IconLoader>()
                 .Bind<IKeyboardDevice>().ToConstant(KeyboardDevice)
                 .Bind<IPlatformSettings>().ToConstant(this)

src/Avalonia.Native/Cursor.cs

@@ -1,11 +1,12 @@
 using System;
+using System.IO;
 using Avalonia.Input;
 using Avalonia.Platform;
 using Avalonia.Native.Interop;
 
 namespace Avalonia.Native
 {
-    class AvaloniaNativeCursor : IPlatformHandle, IDisposable
+    class AvaloniaNativeCursor : ICursorImpl, IDisposable
     {
         public IAvnCursor Cursor { get; private set; }
         public IntPtr Handle => IntPtr.Zero;
@@ -24,7 +25,7 @@ namespace Avalonia.Native
         }
     }
 
-    class CursorFactory : IStandardCursorFactory
+    class CursorFactory : ICursorFactory
     {
         IAvnCursorFactory _native;
 
@@ -33,10 +34,28 @@ namespace Avalonia.Native
             _native = native;
         }
 
-        public IPlatformHandle GetCursor(StandardCursorType cursorType)
+        public ICursorImpl GetCursor(StandardCursorType cursorType)
         {
             var cursor = _native.GetCursor((AvnStandardCursorType)cursorType);
             return new AvaloniaNativeCursor( cursor );
         }
+
+        public unsafe ICursorImpl CreateCursor(IBitmapImpl cursor, PixelPoint hotSpot)
+        {
+            using(var ms = new MemoryStream())
+            {
+                cursor.Save(ms);
+
+                var imageData = ms.ToArray();
+
+                fixed(void* ptr = imageData)
+                {
+                    var avnCursor = _native.CreateCustomCursor(ptr, new IntPtr(imageData.Length),
+                        new AvnPixelSize { Width = hotSpot.X, Height = hotSpot.Y });
+
+                    return new AvaloniaNativeCursor(avnCursor);
+                }
+            }
+        }
     }
 }

src/Avalonia.Native/WindowImplBase.cs

@@ -53,7 +53,7 @@ namespace Avalonia.Native
         private bool _gpu = false;
         private readonly MouseDevice _mouse;
         private readonly IKeyboardDevice _keyboard;
-        private readonly IStandardCursorFactory _cursorFactory;
+        private readonly ICursorFactory _cursorFactory;
         private Size _savedLogicalSize;
         private Size _lastRenderedLogicalSize;
         private double _savedScaling;
@@ -68,7 +68,7 @@ namespace Avalonia.Native
 
             _keyboard = AvaloniaLocator.Current.GetService<IKeyboardDevice>();
             _mouse = new MouseDevice();
-            _cursorFactory = AvaloniaLocator.Current.GetService<IStandardCursorFactory>();
+            _cursorFactory = AvaloniaLocator.Current.GetService<ICursorFactory>();
         }
 
         protected void Init(IAvnWindowBase window, IAvnScreens screens, IGlContext glContext)
@@ -398,7 +398,7 @@ namespace Avalonia.Native
         public Action Deactivated { get; set; }
         public Action Activated { get; set; }
 
-        public void SetCursor(IPlatformHandle cursor)
+        public void SetCursor(ICursorImpl cursor)
         {
             if (_native == null)
             {

src/Avalonia.Native/avn.idl

@@ -619,6 +619,7 @@ interface IAvnCursor : IUnknown
 interface IAvnCursorFactory : IUnknown
 {
      HRESULT GetCursor(AvnStandardCursorType cursorType, IAvnCursor** retOut);
+     HRESULT CreateCustomCursor (void* bitmapData, size_t length, AvnPixelSize hotPixel, IAvnCursor** retOut);
 }
 
 [uuid(60452465-8616-40af-bc00-042e69828ce7)]

src/Avalonia.Visuals/Media/TextFormatting/Unicode/BreakPairTable.cs

@@ -1,56 +0,0 @@
-namespace Avalonia.Media.TextFormatting.Unicode
-{
-    internal static class BreakPairTable
-    {
-        private static readonly byte[][] s_breakPairTable = 
-            {
-             new byte[] {4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,3,4,4,4,4,4,4,4,4,4,4,4},
-             new byte[] {0,4,4,1,1,4,4,4,4,1,1,0,0,0,0,4,1,1,0,0,4,2,4,0,0,0,0,0,0,0,0,1,0},
-             new byte[] {0,4,4,1,1,4,4,4,4,1,1,1,1,1,0,4,1,1,0,0,4,2,4,0,0,0,0,0,0,0,0,1,0},
-             new byte[] {4,4,4,1,1,1,4,4,4,1,1,1,1,1,1,1,1,1,1,1,4,2,4,1,1,1,1,1,1,1,1,1,1},
-             new byte[] {1,4,4,1,1,1,4,4,4,1,1,1,1,1,1,1,1,1,1,1,4,2,4,1,1,1,1,1,1,1,1,1,1},
-             new byte[] {0,4,4,1,1,1,4,4,4,0,0,0,0,0,0,0,1,1,0,0,4,2,4,0,0,0,0,0,0,0,0,1,0},
-             new byte[] {0,4,4,1,1,1,4,4,4,0,0,0,0,0,0,1,1,1,0,0,4,2,4,0,0,0,0,0,0,0,0,1,0},
-             new byte[] {0,4,4,1,1,1,4,4,4,0,0,1,0,1,0,0,1,1,0,0,4,2,4,0,0,0,0,0,0,0,0,1,0},
-             new byte[] {0,4,4,1,1,1,4,4,4,0,0,1,1,1,0,0,1,1,0,0,4,2,4,0,0,0,0,0,0,0,0,1,0},
-             new byte[] {1,4,4,1,1,1,4,4,4,0,0,1,1,1,1,0,1,1,0,0,4,2,4,1,1,1,1,1,0,1,1,1,0},
-             new byte[] {1,4,4,1,1,1,4,4,4,0,0,1,1,1,0,0,1,1,0,0,4,2,4,0,0,0,0,0,0,0,0,1,0},
-             new byte[] {1,4,4,1,1,1,4,4,4,1,1,1,1,1,0,1,1,1,0,0,4,2,4,0,0,0,0,0,0,0,0,1,0},
-             new byte[] {1,4,4,1,1,1,4,4,4,1,1,1,1,1,0,1,1,1,0,0,4,2,4,0,0,0,0,0,0,0,0,1,0},
-             new byte[] {1,4,4,1,1,1,4,4,4,1,1,1,1,1,0,1,1,1,0,0,4,2,4,0,0,0,0,0,0,0,0,1,0},
-             new byte[] {0,4,4,1,1,1,4,4,4,0,1,0,0,0,0,1,1,1,0,0,4,2,4,0,0,0,0,0,0,0,0,1,0},
-             new byte[] {0,4,4,1,1,1,4,4,4,0,0,0,0,0,0,1,1,1,0,0,4,2,4,0,0,0,0,0,0,0,0,1,0},
-             new byte[] {0,4,4,1,0,1,4,4,4,0,0,1,0,0,0,0,1,1,0,0,4,2,4,0,0,0,0,0,0,0,0,1,0},
-             new byte[] {0,4,4,1,0,1,4,4,4,0,0,0,0,0,0,0,1,1,0,0,4,2,4,0,0,0,0,0,0,0,0,1,0},
-             new byte[] {1,4,4,1,1,1,4,4,4,1,1,1,1,1,1,1,1,1,1,1,4,2,4,1,1,1,1,1,1,1,1,1,0},
-             new byte[] {0,4,4,1,1,1,4,4,4,0,0,0,0,0,0,0,1,1,0,4,4,2,4,0,0,0,0,0,0,0,0,1,0},
-             new byte[] {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,4,0,0,0,0,0,0,0,0,0,0,0,0},
-             new byte[] {1,4,4,1,1,1,4,4,4,1,1,1,1,1,0,1,1,1,0,0,4,2,4,0,0,0,0,0,0,0,0,1,0},
-             new byte[] {1,4,4,1,1,1,4,4,4,1,1,1,1,1,1,1,1,1,1,1,4,2,4,1,1,1,1,1,1,1,1,1,1},
-             new byte[] {0,4,4,1,1,1,4,4,4,0,1,0,0,0,0,1,1,1,0,0,4,2,4,0,0,0,1,1,0,0,0,1,0},
-             new byte[] {0,4,4,1,1,1,4,4,4,0,1,0,0,0,0,1,1,1,0,0,4,2,4,0,0,0,0,1,0,0,0,1,0},
-             new byte[] {0,4,4,1,1,1,4,4,4,0,1,0,0,0,0,1,1,1,0,0,4,2,4,1,1,1,1,0,0,0,0,1,0},
-             new byte[] {0,4,4,1,1,1,4,4,4,0,1,0,0,0,0,1,1,1,0,0,4,2,4,0,0,0,1,1,0,0,0,1,0},
-             new byte[] {0,4,4,1,1,1,4,4,4,0,1,0,0,0,0,1,1,1,0,0,4,2,4,0,0,0,0,1,0,0,0,1,0},
-             new byte[] {0,4,4,1,1,1,4,4,4,0,0,0,0,0,0,0,1,1,0,0,4,2,4,0,0,0,0,0,1,0,0,1,0},
-             new byte[] {0,4,4,1,1,1,4,4,4,0,1,0,0,0,0,1,1,1,0,0,4,2,4,0,0,0,0,0,0,0,1,1,0},
-             new byte[] {0,4,4,1,1,1,4,4,4,0,1,0,0,0,0,1,1,1,0,0,4,2,4,0,0,0,0,0,0,0,0,1,0},
-             new byte[] {1,4,4,1,1,1,4,4,4,1,1,1,1,1,0,1,1,1,0,0,4,2,4,0,0,0,0,0,0,0,0,1,0},
-             new byte[] {0,4,4,1,1,0,4,4,4,0,0,0,0,0,0,0,0,0,0,0,4,2,4,0,0,0,0,0,0,0,0,1,0},
-        };
-
-        public static PairBreakType Map(LineBreakClass first, LineBreakClass second)
-        {
-            return (PairBreakType)s_breakPairTable[(int)first][(int)second];
-        }
-    }
-
-    internal enum PairBreakType : byte
-    {
-        DI = 0, // Direct break opportunity
-        IN = 1, // Indirect break opportunity
-        CI = 2, // Indirect break opportunity for combining marks
-        CP = 3, // Prohibited break for combining marks
-        PR = 4 // Prohibited break
-    }
-}

src/Avalonia.Visuals/Media/TextFormatting/Unicode/Codepoint.cs

@@ -9,37 +9,40 @@ namespace Avalonia.Media.TextFormatting.Unicode
         /// </summary>
         public static readonly Codepoint ReplacementCodepoint = new Codepoint('\uFFFD');
 
-        private readonly int _value;
-
         public Codepoint(int value)
         {
-            _value = value;
+            Value = value;
         }
 
+        /// <summary>
+        /// Get the codepoint's value.
+        /// </summary>
+        public int Value { get; }
+
         /// <summary>
         /// Gets the <see cref="Unicode.GeneralCategory"/>.
         /// </summary>
-        public GeneralCategory GeneralCategory => UnicodeData.GetGeneralCategory(_value);
+        public GeneralCategory GeneralCategory => UnicodeData.GetGeneralCategory(Value);
 
         /// <summary>
         /// Gets the <see cref="Unicode.Script"/>.
         /// </summary>
-        public Script Script => UnicodeData.GetScript(_value);
+        public Script Script => UnicodeData.GetScript(Value);
 
         /// <summary>
         /// Gets the <see cref="Unicode.BiDiClass"/>.
         /// </summary>
-        public BiDiClass BiDiClass => UnicodeData.GetBiDiClass(_value);
+        public BiDiClass BiDiClass => UnicodeData.GetBiDiClass(Value);
 
         /// <summary>
         /// Gets the <see cref="Unicode.LineBreakClass"/>.
         /// </summary>
-        public LineBreakClass LineBreakClass => UnicodeData.GetLineBreakClass(_value);
+        public LineBreakClass LineBreakClass => UnicodeData.GetLineBreakClass(Value);
 
         /// <summary>
         /// Gets the <see cref="GraphemeBreakClass"/>.
         /// </summary>
-        public GraphemeBreakClass GraphemeBreakClass => UnicodeData.GetGraphemeClusterBreak(_value);
+        public GraphemeBreakClass GraphemeBreakClass => UnicodeData.GetGraphemeClusterBreak(Value);
 
         /// <summary>
         /// Determines whether this <see cref="Codepoint"/> is a break char.
@@ -51,7 +54,7 @@ namespace Avalonia.Media.TextFormatting.Unicode
         {
             get
             {
-                switch (_value)
+                switch (Value)
                 {
                     case '\u000A':
                     case '\u000B':
@@ -93,12 +96,12 @@ namespace Avalonia.Media.TextFormatting.Unicode
 
         public static implicit operator int(Codepoint codepoint)
         {
-            return codepoint._value;
+            return codepoint.Value;
         }
 
         public static implicit operator uint(Codepoint codepoint)
         {
-            return (uint)codepoint._value;
+            return (uint)codepoint.Value;
         }
 
         /// <summary>
@@ -112,7 +115,7 @@ namespace Avalonia.Media.TextFormatting.Unicode
         {
             count = 1;
 
-            if (index > text.Length)
+            if (index >= text.Length)
             {
                 return ReplacementCodepoint;
             }

src/Avalonia.Visuals/Media/TextFormatting/Unicode/LineBreakEnumerator.cs

@@ -1,160 +1,460 @@
-// RichTextKit
-// Copyright © 2019 Topten Software. All Rights Reserved.
-// 
-// Licensed under the Apache License, Version 2.0 (the "License"); you may 
-// not use this product except in compliance with the License. You may obtain 
-// a copy of the License at
-// 
-// http://www.apache.org/licenses/LICENSE-2.0
-// 
-// Unless required by applicable law or agreed to in writing, software 
-// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 
-// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 
-// License for the specific language governing permissions and limitations 
-// under the License.
-//
-// Ported from: https://github.com/foliojs/linebreak
-// Copied from: https://github.com/toptensoftware/RichTextKit
+// Copyright (c) Six Labors.
+// Licensed under the Apache License, Version 2.0.
+// Ported from: https://github.com/SixLabors/Fonts/
 
 using Avalonia.Utilities;
 
 namespace Avalonia.Media.TextFormatting.Unicode
 {
     /// <summary>
-    /// Implementation of the Unicode Line Break Algorithm
+    /// Implementation of the Unicode Line Break Algorithm. UAX:14
+    /// <see href="https://www.unicode.org/reports/tr14/tr14-37.html"/>
     /// </summary>
     public ref struct LineBreakEnumerator
     {
-        // State
         private readonly ReadOnlySlice<char> _text;
-        private int _pos;
-        private int _lastPos;
-        private LineBreakClass? _curClass;
-        private LineBreakClass? _nextClass;
+        private int _position;
+        private int _lastPosition;
+        private LineBreakClass _currentClass;
+        private LineBreakClass _nextClass;
+        private bool _first;
+        private int _alphaNumericCount;
+        private bool _lb8a;
+        private bool _lb21a;
+        private bool _lb22ex;
+        private bool _lb24ex;
+        private bool _lb25ex;
+        private bool _lb30;
+        private int _lb30a;
+        private bool _lb31;
 
         public LineBreakEnumerator(ReadOnlySlice<char> text)
+            : this()
         {
             _text = text;
-            _pos = 0;
-            _lastPos = 0;
-            _curClass = null;
-            _nextClass = null;
-            Current = default;
+            _position = 0;
+            _currentClass = LineBreakClass.Unknown;
+            _nextClass = LineBreakClass.Unknown;
+            _first = true;
+            _lb8a = false;
+            _lb21a = false;
+            _lb22ex = false;
+            _lb24ex = false;
+            _lb25ex = false;
+            _alphaNumericCount = 0;
+            _lb31 = false;
+            _lb30 = false;
+            _lb30a = 0;
         }
-
+        
         public LineBreak Current { get; private set; }
-
+        
         public bool MoveNext()
         {
-            // get the first char if we're at the beginning of the string
-            if (!_curClass.HasValue)
+            // Get the first char if we're at the beginning of the string.
+            if (_first)
             {
-                _curClass = PeekCharClass() == LineBreakClass.Space ? LineBreakClass.WordJoiner : MapFirst(ReadCharClass());
+                var firstClass = NextCharClass();
+                _first = false;
+                _currentClass = MapFirst(firstClass);
+                _nextClass = firstClass;
+                _lb8a = firstClass == LineBreakClass.ZWJ;
+                _lb30a = 0;
             }
 
-            while (_pos < _text.Length)
+            while (_position < _text.Length)
             {
-                _lastPos = _pos;
+                _lastPosition = _position;
                 var lastClass = _nextClass;
-                _nextClass = ReadCharClass();
+                _nextClass = NextCharClass();
 
-                // explicit newline
-                if (_curClass.HasValue && (_curClass == LineBreakClass.MandatoryBreak || _curClass == LineBreakClass.CarriageReturn && _nextClass != LineBreakClass.LineFeed))
+                // Explicit newline
+                switch (_currentClass)
                 {
-                    _curClass = MapFirst(MapClass(_nextClass.Value));
-                    Current = new LineBreak(FindPriorNonWhitespace(_lastPos), _lastPos, true);
+                    case LineBreakClass.MandatoryBreak:
+                    case LineBreakClass.CarriageReturn when _nextClass != LineBreakClass.LineFeed:
+                    {
+                        _currentClass = MapFirst(_nextClass);
+                        Current = new LineBreak(FindPriorNonWhitespace(_lastPosition), _lastPosition, true);
+                        return true;
+                    }
+                }
+
+                var shouldBreak = GetSimpleBreak() ?? (bool?)GetPairTableBreak(lastClass);
+
+                // Rule LB8a
+                _lb8a = _nextClass == LineBreakClass.ZWJ;
+
+                if (shouldBreak.Value)
+                {
+                    Current = new LineBreak(FindPriorNonWhitespace(_lastPosition), _lastPosition);
                     return true;
                 }
+            }
 
-                // handle classes not handled by the pair table
-                LineBreakClass? cur = null;
-                switch (_nextClass.Value)
+            if (_position >= _text.Length)
+            {
+                if (_lastPosition < _text.Length)
                 {
-                    case LineBreakClass.Space:
-                        cur = _curClass;
-                        break;
+                    _lastPosition = _text.Length;
+
+                    var required = false;
+
+                    switch (_currentClass)
+                    {
+                        case LineBreakClass.MandatoryBreak:
+                        case LineBreakClass.CarriageReturn when _nextClass != LineBreakClass.LineFeed:
+                            required = true;
+                            break;
+                    }
+
+                    Current = new LineBreak(FindPriorNonWhitespace(_lastPosition), _lastPosition, required);
+                    return true;
+                }
+            }
+
+            Current = default;
+            
+            return false;
+        }
+
+        private static LineBreakClass MapClass(Codepoint cp)
+        {
+            if (cp.Value == 327685)
+            {
+                return LineBreakClass.Alphabetic;
+            }
+            
+            // LB 1
+            // ==========================================
+            // Resolved Original    General_Category
+            // ==========================================
+            // AL       AI, SG, XX  Any
+            // CM       SA          Only Mn or Mc
+            // AL       SA          Any except Mn and Mc
+            // NS       CJ          Any
+            switch (cp.LineBreakClass)
+            {
+                case LineBreakClass.Ambiguous:
+                case LineBreakClass.Surrogate:
+                case LineBreakClass.Unknown:
+                    return LineBreakClass.Alphabetic;
 
+                case LineBreakClass.ComplexContext:
+                    return cp.GeneralCategory == GeneralCategory.NonspacingMark || cp.GeneralCategory == GeneralCategory.SpacingMark
+                        ? LineBreakClass.CombiningMark
+                        : LineBreakClass.Alphabetic;
+
+                case LineBreakClass.ConditionalJapaneseStarter:
+                    return LineBreakClass.Nonstarter;
+
+                default:
+                    return cp.LineBreakClass;
+            }
+        }
+
+        private static LineBreakClass MapFirst(LineBreakClass c)
+        {
+            switch (c)
+            {
+                case LineBreakClass.LineFeed:
+                case LineBreakClass.NextLine:
+                    return LineBreakClass.MandatoryBreak;
+
+                case LineBreakClass.Space:
+                    return LineBreakClass.WordJoiner;
+
+                default:
+                    return c;
+            }
+        }
+
+        private static bool IsAlphaNumeric(LineBreakClass cls)
+            => cls == LineBreakClass.Alphabetic
+            || cls == LineBreakClass.HebrewLetter
+            || cls == LineBreakClass.Numeric;
+
+        private LineBreakClass PeekNextCharClass()
+        {
+            var cp = Codepoint.ReadAt(_text, _position, out _);
+            
+            return MapClass(cp);
+        }
+
+        // Get the next character class
+        private LineBreakClass NextCharClass()
+        {
+            var cp = Codepoint.ReadAt(_text, _position, out var count);
+            var cls = MapClass(cp);
+            _position += count;
+
+            // Keep track of alphanumeric + any combining marks.
+            // This is used for LB22 and LB30.
+            if (IsAlphaNumeric(_currentClass) || _alphaNumericCount > 0 && cls == LineBreakClass.CombiningMark)
+            {
+                _alphaNumericCount++;
+            }
+
+            // Track combining mark exceptions. LB22
+            if (cls == LineBreakClass.CombiningMark)
+            {
+                switch (_currentClass)
+                {
                     case LineBreakClass.MandatoryBreak:
+                    case LineBreakClass.ContingentBreak:
+                    case LineBreakClass.Exclamation:
                     case LineBreakClass.LineFeed:
                     case LineBreakClass.NextLine:
-                        cur = LineBreakClass.MandatoryBreak;
-                        break;
-
+                    case LineBreakClass.Space:
+                    case LineBreakClass.ZWSpace:
                     case LineBreakClass.CarriageReturn:
-                        cur = LineBreakClass.CarriageReturn;
+                        _lb22ex = true;
                         break;
+                }
+            }
 
+            // Track combining mark exceptions. LB31
+            if (_first && cls == LineBreakClass.CombiningMark)
+            {
+                _lb31 = true;
+            }
+
+            if (cls == LineBreakClass.CombiningMark)
+            {
+                switch (_currentClass)
+                {
+                    case LineBreakClass.MandatoryBreak:
                     case LineBreakClass.ContingentBreak:
-                        cur = LineBreakClass.BreakAfter;
+                    case LineBreakClass.Exclamation:
+                    case LineBreakClass.LineFeed:
+                    case LineBreakClass.NextLine:
+                    case LineBreakClass.Space:
+                    case LineBreakClass.ZWSpace:
+                    case LineBreakClass.CarriageReturn:
+                    case LineBreakClass.ZWJ:
+                        _lb31 = true;
                         break;
                 }
+            }
+
+            if (_first
+                && (cls == LineBreakClass.PostfixNumeric || cls == LineBreakClass.PrefixNumeric || cls == LineBreakClass.Space))
+            {
+                _lb31 = true;
+            }
+
+            if (_currentClass == LineBreakClass.Alphabetic && 
+                (cls == LineBreakClass.PostfixNumeric || cls == LineBreakClass.PrefixNumeric || cls == LineBreakClass.Space))
+            {
+                _lb31 = true;
+            }
+
+            // Reset LB31 if next is U+0028 (Left Opening Parenthesis)
+            if (_lb31
+                && _currentClass != LineBreakClass.PostfixNumeric
+                && _currentClass != LineBreakClass.PrefixNumeric
+                && cls == LineBreakClass.OpenPunctuation && cp.Value == 0x0028)
+            {
+                _lb31 = false;
+            }
+
+            // Rule LB24
+            if (_first && (cls == LineBreakClass.ClosePunctuation || cls == LineBreakClass.CloseParenthesis))
+            {
+                _lb24ex = true;
+            }
 
-                if (cur != null)
+            // Rule LB25
+            if (_first
+                && (cls == LineBreakClass.ClosePunctuation || cls == LineBreakClass.InfixNumeric || cls == LineBreakClass.BreakSymbols))
+            {
+                _lb25ex = true;
+            }
+
+            if (cls == LineBreakClass.Space || cls == LineBreakClass.WordJoiner || cls == LineBreakClass.Alphabetic)
+            {
+                var next = PeekNextCharClass();
+                if (next == LineBreakClass.ClosePunctuation || next == LineBreakClass.InfixNumeric || next == LineBreakClass.BreakSymbols)
                 {
-                    _curClass = cur;
+                    _lb25ex = true;
+                }
+            }
+
+            // AlphaNumeric + and combining marks can break for OP except.
+            // - U+0028 (Left Opening Parenthesis)
+            // - U+005B (Opening Square Bracket)
+            // - U+007B (Left Curly Bracket)
+            // See custom colums|rules in the text pair table.
+            // https://www.unicode.org/Public/13.0.0/ucd/auxiliary/LineBreakTest.html
+            _lb30 = _alphaNumericCount > 0
+                && cls == LineBreakClass.OpenPunctuation
+                && cp.Value != 0x0028
+                && cp.Value != 0x005B
+                && cp.Value != 0x007B;
+
+            return cls;
+        }
+
+        private bool? GetSimpleBreak()
+        {
+            // handle classes not handled by the pair table
+            switch (_nextClass)
+            {
+                case LineBreakClass.Space:
+                    return false;
 
-                    if (_nextClass.Value == LineBreakClass.MandatoryBreak)
+                case LineBreakClass.MandatoryBreak:
+                case LineBreakClass.LineFeed:
+                case LineBreakClass.NextLine:
+                    _currentClass = LineBreakClass.MandatoryBreak;
+                    return false;
+
+                case LineBreakClass.CarriageReturn:
+                    _currentClass = LineBreakClass.CarriageReturn;
+                    return false;
+            }
+
+            return null;
+        }
+
+        private bool GetPairTableBreak(LineBreakClass lastClass)
+        {
+            // If not handled already, use the pair table
+            bool shouldBreak = false;
+            switch (LineBreakPairTable.Table[(int)_currentClass][(int)_nextClass])
+            {
+                case LineBreakPairTable.DIBRK: // Direct break
+                    shouldBreak = true;
+                    break;
+
+                // TODO: Rewrite this so that it defaults to true and rules are set as exceptions.
+                case LineBreakPairTable.INBRK: // Possible indirect break
+
+                    // LB31
+                    if (_lb31 && _nextClass == LineBreakClass.OpenPunctuation)
                     {
-                        _lastPos = _pos;
-                        Current = new LineBreak(FindPriorNonWhitespace(_lastPos), _lastPos, true);
-                        return true;
+                        shouldBreak = true;
+                        _lb31 = false;
+                        break;
                     }
 
-                    continue;
-                }
-
-                // if not handled already, use the pair table
-                var shouldBreak = false;
-                switch (BreakPairTable.Map(_curClass.Value,_nextClass.Value))
-                {
-                    case PairBreakType.DI: // Direct break
+                    // LB30
+                    if (_lb30)
+                    {
                         shouldBreak = true;
+                        _lb30 = false;
+                        _alphaNumericCount = 0;
                         break;
+                    }
 
-                    case PairBreakType.IN: // possible indirect break
-                        shouldBreak = lastClass.HasValue && lastClass.Value == LineBreakClass.Space;
+                    // LB25
+                    if (_lb25ex && (_nextClass == LineBreakClass.PrefixNumeric || _nextClass == LineBreakClass.Numeric))
+                    {
+                        shouldBreak = true;
+                        _lb25ex = false;
                         break;
+                    }
 
-                    case PairBreakType.CI:
-                        shouldBreak = lastClass.HasValue && lastClass.Value == LineBreakClass.Space;
-                        if (!shouldBreak)
-                        {
-                            continue;
-                        }
+                    // LB24
+                    if (_lb24ex && (_nextClass == LineBreakClass.PostfixNumeric || _nextClass == LineBreakClass.PrefixNumeric))
+                    {
+                        shouldBreak = true;
+                        _lb24ex = false;
                         break;
+                    }
+
+                    // LB18
+                    shouldBreak = lastClass == LineBreakClass.Space;
+                    break;
+
+                case LineBreakPairTable.CIBRK:
+                    shouldBreak = lastClass == LineBreakClass.Space;
+                    if (!shouldBreak)
+                    {
+                        return false;
+                    }
 
-                    case PairBreakType.CP: // prohibited for combining marks
-                        if (!lastClass.HasValue || lastClass.Value != LineBreakClass.Space)
+                    break;
+
+                case LineBreakPairTable.CPBRK: // prohibited for combining marks
+                    if (lastClass != LineBreakClass.Space)
+                    {
+                        return false;
+                    }
+
+                    break;
+
+                case LineBreakPairTable.PRBRK:
+                    break;
+            }
+
+            // Rule LB22
+            if (_nextClass == LineBreakClass.Inseparable)
+            {
+                switch (lastClass)
+                {
+                    case LineBreakClass.MandatoryBreak:
+                    case LineBreakClass.ContingentBreak:
+                    case LineBreakClass.Exclamation:
+                    case LineBreakClass.LineFeed:
+                    case LineBreakClass.NextLine:
+                    case LineBreakClass.Space:
+                    case LineBreakClass.ZWSpace:
+
+                        // Allow break
+                        break;
+                    case LineBreakClass.CombiningMark:
+                        if (_lb22ex)
                         {
-                            continue;
+                            // Allow break
+                            _lb22ex = false;
+                            break;
                         }
+
+                        shouldBreak = false;
+                        break;
+                    default:
+                        shouldBreak = false;
                         break;
                 }
+            }
 
-                _curClass = _nextClass;
+            if (_lb8a)
+            {
+                shouldBreak = false;
+            }
 
-                if (shouldBreak)
-                {
-                    Current = new LineBreak(FindPriorNonWhitespace(_lastPos), _lastPos);
-                    return true;
-                }
+            // Rule LB21a
+            if (_lb21a && (_currentClass == LineBreakClass.Hyphen || _currentClass == LineBreakClass.BreakAfter))
+            {
+                shouldBreak = false;
+                _lb21a = false;
+            }
+            else
+            {
+                _lb21a = _currentClass == LineBreakClass.HebrewLetter;
             }
 
-            if (_pos >= _text.Length)
+            // Rule LB30a
+            if (_currentClass == LineBreakClass.RegionalIndicator)
             {
-                if (_lastPos < _text.Length)
+                _lb30a++;
+                if (_lb30a == 2 && _nextClass == LineBreakClass.RegionalIndicator)
                 {
-                    _lastPos = _text.Length;
-                    var cls = Codepoint.ReadAt(_text, _text.Length - 1, out _).LineBreakClass;
-                    bool required = cls == LineBreakClass.MandatoryBreak || cls == LineBreakClass.LineFeed || cls == LineBreakClass.CarriageReturn;
-                    Current = new LineBreak(FindPriorNonWhitespace(_text.Length), _text.Length, required);
-                    return true;
+                    shouldBreak = true;
+                    _lb30a = 0;
                 }
             }
+            else
+            {
+                _lb30a = 0;
+            }
 
-            return false;
-        }
+            _currentClass = _nextClass;
 
+            return shouldBreak;
+        }
+        
         private int FindPriorNonWhitespace(int from)
         {
             if (from > 0)
@@ -163,7 +463,8 @@ namespace Avalonia.Media.TextFormatting.Unicode
 
                 var cls = cp.LineBreakClass;
 
-                if (cls == LineBreakClass.MandatoryBreak || cls == LineBreakClass.LineFeed || cls == LineBreakClass.CarriageReturn)
+                if (cls == LineBreakClass.MandatoryBreak || cls == LineBreakClass.LineFeed ||
+                    cls == LineBreakClass.CarriageReturn)
                 {
                     from -= count;
                 }
@@ -184,61 +485,8 @@ namespace Avalonia.Media.TextFormatting.Unicode
                     break;
                 }
             }
-            return from;
-        }
 
-        // Get the next character class
-        private LineBreakClass ReadCharClass()
-        {
-            var cp = Codepoint.ReadAt(_text, _pos, out var count);
-
-            _pos += count;
-
-            return MapClass(cp.LineBreakClass);
-        }
-
-        private LineBreakClass PeekCharClass()
-        {
-            return MapClass(Codepoint.ReadAt(_text, _pos, out _).LineBreakClass);
-        }
-
-        private static LineBreakClass MapClass(LineBreakClass c)
-        {
-            switch (c)
-            {
-                case LineBreakClass.Ambiguous:
-                    return LineBreakClass.Alphabetic;
-
-                case LineBreakClass.ComplexContext:
-                case LineBreakClass.Surrogate:
-                case LineBreakClass.Unknown:
-                    return LineBreakClass.Alphabetic;
-
-                case LineBreakClass.ConditionalJapaneseStarter:
-                    return LineBreakClass.Nonstarter;
-
-                default:
-                    return c;
-            }
-        }
-
-        private static LineBreakClass MapFirst(LineBreakClass c)
-        {
-            switch (c)
-            {
-                case LineBreakClass.LineFeed:
-                case LineBreakClass.NextLine:
-                    return LineBreakClass.MandatoryBreak;
-
-                case LineBreakClass.ContingentBreak:
-                    return LineBreakClass.BreakAfter;
-
-                case LineBreakClass.Space:
-                    return LineBreakClass.WordJoiner;
-
-                default:
-                    return c;
-            }
+            return from;
         }
     }
 }

src/Avalonia.Visuals/Media/TextFormatting/Unicode/LineBreakPairTable.cs

@@ -0,0 +1,74 @@
+// Copyright (c) Six Labors.
+// Licensed under the Apache License, Version 2.0.
+// Ported from: https://github.com/SixLabors/Fonts/
+
+namespace Avalonia.Media.TextFormatting.Unicode
+{
+    internal static class LineBreakPairTable
+    {
+        /// <summary>
+        /// Direct break opportunity
+        /// </summary>
+        public const byte DIBRK = 0;
+
+        /// <summary>
+        /// Indirect break opportunity
+        /// </summary>
+        public const byte INBRK = 1;
+
+        /// <summary>
+        /// Indirect break opportunity for combining marks
+        /// </summary>
+        public const byte CIBRK = 2;
+
+        /// <summary>
+        /// Prohibited break for combining marks
+        /// </summary>
+        public const byte CPBRK = 3;
+
+        /// <summary>
+        /// Prohibited break
+        /// </summary>
+        public const byte PRBRK = 4;
+
+        // Based on example pair table from https://www.unicode.org/reports/tr14/tr14-37.html#Table2
+        // - ZWJ special processing for LB8a
+        // - CB manually added as per Rule LB20
+        public static byte[][] Table { get; } = {
+              // .         OP     CL     CP     QU     GL     NS     EX     SY     IS     PR     PO     NU     AL     HL     ID     IN     HY     BA     BB     B2     ZW     CM     WJ     H2     H3     JL     JV     JT     RI     EB     EM     ZWJ    CB
+              new[] { PRBRK, PRBRK, PRBRK, PRBRK, PRBRK, PRBRK, PRBRK, PRBRK, PRBRK, PRBRK, PRBRK, PRBRK, PRBRK, PRBRK, PRBRK, PRBRK, PRBRK, PRBRK, PRBRK, PRBRK, PRBRK, CPBRK, PRBRK, PRBRK, PRBRK, PRBRK, PRBRK, PRBRK, PRBRK, PRBRK, PRBRK, PRBRK, PRBRK }, // OP
+              new[] { DIBRK, PRBRK, PRBRK, INBRK, INBRK, PRBRK, PRBRK, PRBRK, PRBRK, INBRK, INBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, INBRK, DIBRK, DIBRK, PRBRK, CIBRK, PRBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, DIBRK }, // CL
+              new[] { DIBRK, PRBRK, PRBRK, INBRK, INBRK, PRBRK, PRBRK, PRBRK, PRBRK, INBRK, INBRK, INBRK, INBRK, INBRK, DIBRK, DIBRK, INBRK, INBRK, DIBRK, DIBRK, PRBRK, CIBRK, PRBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, DIBRK }, // CP
+              new[] { PRBRK, PRBRK, PRBRK, INBRK, INBRK, INBRK, PRBRK, PRBRK, PRBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, PRBRK, CIBRK, PRBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK }, // QU
+              new[] { INBRK, PRBRK, PRBRK, INBRK, INBRK, INBRK, PRBRK, PRBRK, PRBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, PRBRK, CIBRK, PRBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK }, // GL
+              new[] { DIBRK, PRBRK, PRBRK, INBRK, INBRK, INBRK, PRBRK, PRBRK, PRBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, INBRK, DIBRK, DIBRK, PRBRK, CIBRK, PRBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, DIBRK }, // NS
+              new[] { DIBRK, PRBRK, PRBRK, INBRK, INBRK, INBRK, PRBRK, PRBRK, PRBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, INBRK, INBRK, DIBRK, DIBRK, PRBRK, CIBRK, PRBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, DIBRK }, // EX
+              new[] { DIBRK, PRBRK, PRBRK, INBRK, INBRK, INBRK, PRBRK, PRBRK, PRBRK, DIBRK, DIBRK, INBRK, DIBRK, INBRK, DIBRK, DIBRK, INBRK, INBRK, DIBRK, DIBRK, PRBRK, CIBRK, PRBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, DIBRK }, // SY
+              new[] { DIBRK, PRBRK, PRBRK, INBRK, INBRK, INBRK, PRBRK, PRBRK, PRBRK, DIBRK, DIBRK, INBRK, INBRK, INBRK, DIBRK, DIBRK, INBRK, INBRK, DIBRK, DIBRK, PRBRK, CIBRK, PRBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, DIBRK }, // IS
+              new[] { INBRK, PRBRK, PRBRK, INBRK, INBRK, INBRK, PRBRK, PRBRK, PRBRK, DIBRK, DIBRK, INBRK, INBRK, INBRK, INBRK, DIBRK, INBRK, INBRK, DIBRK, DIBRK, PRBRK, CIBRK, PRBRK, INBRK, INBRK, INBRK, INBRK, INBRK, DIBRK, INBRK, INBRK, INBRK, DIBRK }, // PR
+              new[] { INBRK, PRBRK, PRBRK, INBRK, INBRK, INBRK, PRBRK, PRBRK, PRBRK, DIBRK, DIBRK, INBRK, INBRK, INBRK, DIBRK, DIBRK, INBRK, INBRK, DIBRK, DIBRK, PRBRK, CIBRK, PRBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, DIBRK }, // PO
+              new[] { INBRK, PRBRK, PRBRK, INBRK, INBRK, INBRK, PRBRK, PRBRK, PRBRK, INBRK, INBRK, INBRK, INBRK, INBRK, DIBRK, INBRK, INBRK, INBRK, DIBRK, DIBRK, PRBRK, CIBRK, PRBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, DIBRK }, // NU
+              new[] { INBRK, PRBRK, PRBRK, INBRK, INBRK, INBRK, PRBRK, PRBRK, PRBRK, INBRK, INBRK, INBRK, INBRK, INBRK, DIBRK, INBRK, INBRK, INBRK, DIBRK, DIBRK, PRBRK, CIBRK, PRBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, DIBRK }, // AL
+              new[] { INBRK, PRBRK, PRBRK, INBRK, INBRK, INBRK, PRBRK, PRBRK, PRBRK, INBRK, INBRK, INBRK, INBRK, INBRK, DIBRK, INBRK, INBRK, INBRK, DIBRK, DIBRK, PRBRK, CIBRK, PRBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, DIBRK }, // HL
+              new[] { DIBRK, PRBRK, PRBRK, INBRK, INBRK, INBRK, PRBRK, PRBRK, PRBRK, DIBRK, INBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, INBRK, INBRK, DIBRK, DIBRK, PRBRK, CIBRK, PRBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, DIBRK }, // ID
+              new[] { DIBRK, PRBRK, PRBRK, INBRK, INBRK, INBRK, PRBRK, PRBRK, PRBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, INBRK, INBRK, DIBRK, DIBRK, PRBRK, CIBRK, PRBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, DIBRK }, // IN
+              new[] { DIBRK, PRBRK, PRBRK, INBRK, DIBRK, INBRK, PRBRK, PRBRK, PRBRK, DIBRK, DIBRK, INBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, INBRK, DIBRK, DIBRK, PRBRK, CIBRK, PRBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, DIBRK }, // HY
+              new[] { DIBRK, PRBRK, PRBRK, INBRK, DIBRK, INBRK, PRBRK, PRBRK, PRBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, INBRK, DIBRK, DIBRK, PRBRK, CIBRK, PRBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, DIBRK }, // BA
+              new[] { INBRK, PRBRK, PRBRK, INBRK, INBRK, INBRK, PRBRK, PRBRK, PRBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, PRBRK, CIBRK, PRBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, DIBRK }, // BB
+              new[] { DIBRK, PRBRK, PRBRK, INBRK, INBRK, INBRK, PRBRK, PRBRK, PRBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, INBRK, DIBRK, PRBRK, PRBRK, CIBRK, PRBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, DIBRK }, // B2
+              new[] { DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, PRBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK }, // ZW
+              new[] { INBRK, PRBRK, PRBRK, INBRK, INBRK, INBRK, PRBRK, PRBRK, PRBRK, INBRK, INBRK, INBRK, INBRK, INBRK, DIBRK, INBRK, INBRK, INBRK, DIBRK, DIBRK, PRBRK, CIBRK, PRBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, DIBRK }, // CM
+              new[] { INBRK, PRBRK, PRBRK, INBRK, INBRK, INBRK, PRBRK, PRBRK, PRBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, PRBRK, CIBRK, PRBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK, INBRK }, // WJ
+              new[] { DIBRK, PRBRK, PRBRK, INBRK, INBRK, INBRK, PRBRK, PRBRK, PRBRK, DIBRK, INBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, INBRK, INBRK, DIBRK, DIBRK, PRBRK, CIBRK, PRBRK, DIBRK, DIBRK, DIBRK, INBRK, INBRK, DIBRK, DIBRK, DIBRK, INBRK, DIBRK }, // H2
+              new[] { DIBRK, PRBRK, PRBRK, INBRK, INBRK, INBRK, PRBRK, PRBRK, PRBRK, DIBRK, INBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, INBRK, INBRK, DIBRK, DIBRK, PRBRK, CIBRK, PRBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, DIBRK, DIBRK, DIBRK, INBRK, DIBRK }, // H3
+              new[] { DIBRK, PRBRK, PRBRK, INBRK, INBRK, INBRK, PRBRK, PRBRK, PRBRK, DIBRK, INBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, INBRK, INBRK, DIBRK, DIBRK, PRBRK, CIBRK, PRBRK, INBRK, INBRK, INBRK, INBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, DIBRK }, // JL
+              new[] { DIBRK, PRBRK, PRBRK, INBRK, INBRK, INBRK, PRBRK, PRBRK, PRBRK, DIBRK, INBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, INBRK, INBRK, DIBRK, DIBRK, PRBRK, CIBRK, PRBRK, DIBRK, DIBRK, DIBRK, INBRK, INBRK, DIBRK, DIBRK, DIBRK, INBRK, DIBRK }, // JV
+              new[] { DIBRK, PRBRK, PRBRK, INBRK, INBRK, INBRK, PRBRK, PRBRK, PRBRK, DIBRK, INBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, INBRK, INBRK, DIBRK, DIBRK, PRBRK, CIBRK, PRBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, DIBRK, DIBRK, DIBRK, INBRK, DIBRK }, // JT
+              new[] { DIBRK, PRBRK, PRBRK, INBRK, INBRK, INBRK, PRBRK, PRBRK, PRBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, INBRK, DIBRK, DIBRK, PRBRK, CIBRK, PRBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, DIBRK, DIBRK, INBRK, DIBRK }, // RI
+              new[] { DIBRK, PRBRK, PRBRK, INBRK, INBRK, INBRK, PRBRK, PRBRK, PRBRK, DIBRK, INBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, INBRK, INBRK, DIBRK, DIBRK, PRBRK, CIBRK, PRBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, INBRK, DIBRK }, // EB
+              new[] { DIBRK, PRBRK, PRBRK, INBRK, INBRK, INBRK, PRBRK, PRBRK, PRBRK, DIBRK, INBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, INBRK, INBRK, DIBRK, DIBRK, PRBRK, CIBRK, PRBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, DIBRK }, // EM
+              new[] { INBRK, PRBRK, PRBRK, INBRK, INBRK, INBRK, PRBRK, PRBRK, PRBRK, INBRK, INBRK, INBRK, INBRK, INBRK, DIBRK, INBRK, INBRK, INBRK, DIBRK, DIBRK, PRBRK, CIBRK, PRBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, DIBRK }, // ZWJ
+              new[] { DIBRK, PRBRK, PRBRK, INBRK, INBRK, DIBRK, PRBRK, PRBRK, PRBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, PRBRK, CIBRK, PRBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, DIBRK, INBRK, DIBRK } // CB
+        };
+    }
+}

src/Avalonia.X11/X11CursorFactory.cs

@@ -1,12 +1,17 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Runtime.InteropServices;
+using Avalonia.Controls.Platform.Surfaces;
 using Avalonia.Input;
 using Avalonia.Platform;
+using Avalonia.Utilities;
+
+#nullable enable
 
 namespace Avalonia.X11
 {
-    class X11CursorFactory : IStandardCursorFactory
+    class X11CursorFactory : ICursorFactory
     {
         private static readonly byte[] NullCursorData = new byte[] { 0 };
 
@@ -51,7 +56,7 @@ namespace Avalonia.X11
                 .ToDictionary(id => id, id => XLib.XCreateFontCursor(_display, id));
         }
 
-        public IPlatformHandle GetCursor(StandardCursorType cursorType)
+        public ICursorImpl GetCursor(StandardCursorType cursorType)
         {
             IntPtr handle;
             if (cursorType == StandardCursorType.None)
@@ -64,7 +69,12 @@ namespace Avalonia.X11
                 ? _cursors[shape]
                 : _cursors[CursorFontShape.XC_top_left_arrow];
             }
-            return new PlatformHandle(handle, "XCURSOR");
+            return new CursorImpl(handle);
+        }
+
+        public unsafe ICursorImpl CreateCursor(IBitmapImpl cursor, PixelPoint hotSpot)
+        {
+            return new XImageCursor(_display, cursor, hotSpot);
         }
 
         private static IntPtr GetNullCursor(IntPtr display)
@@ -74,5 +84,62 @@ namespace Avalonia.X11
             IntPtr pixmap = XLib.XCreateBitmapFromData(display, window, NullCursorData, 1, 1);
             return XLib.XCreatePixmapCursor(display, pixmap, pixmap, ref color, ref color, 0, 0);
         }
+
+        private unsafe class XImageCursor : CursorImpl, IFramebufferPlatformSurface, IPlatformHandle
+        {
+            private readonly PixelSize _pixelSize;
+            private readonly IUnmanagedBlob _blob;
+
+            public XImageCursor(IntPtr display, IBitmapImpl bitmap, PixelPoint hotSpot)
+            {
+                var size = Marshal.SizeOf<XcursorImage>() +
+                    (bitmap.PixelSize.Width * bitmap.PixelSize.Height * 4);
+
+                _pixelSize = bitmap.PixelSize;
+                _blob = AvaloniaLocator.Current.GetService<IRuntimePlatform>().AllocBlob(size);
+                
+                var image = (XcursorImage*)_blob.Address;
+                image->version = 1;
+                image->size = Marshal.SizeOf<XcursorImage>();
+                image->width = bitmap.PixelSize.Width;
+                image->height = bitmap.PixelSize.Height;
+                image->xhot = hotSpot.X;
+                image->yhot = hotSpot.Y;
+                image->pixels = (IntPtr)(image + 1);
+               
+                using (var renderTarget = AvaloniaLocator.Current.GetService<IPlatformRenderInterface>().CreateRenderTarget(new[] { this }))
+                using (var ctx = renderTarget.CreateDrawingContext(null))
+                {
+                    var r = new Rect(_pixelSize.ToSize(1)); 
+                    ctx.DrawBitmap(RefCountable.CreateUnownedNotClonable(bitmap), 1, r, r);
+                }
+
+                Handle = XLib.XcursorImageLoadCursor(display, _blob.Address);
+            }
+
+            public string HandleDescriptor => "XCURSOR";
+
+            public override void Dispose()
+            {
+                XLib.XcursorImageDestroy(Handle);
+                _blob.Dispose();
+            }
+
+            public ILockedFramebuffer Lock()
+            {
+                return new LockedFramebuffer(
+                    _blob.Address + Marshal.SizeOf<XcursorImage>(),
+                    _pixelSize, _pixelSize.Width * 4,
+                    new Vector(96, 96), PixelFormat.Bgra8888, null);
+            }
+        }
+    }
+
+    class CursorImpl : ICursorImpl
+    {
+        public CursorImpl() { }
+        public CursorImpl(IntPtr handle) => Handle = handle;
+        public IntPtr Handle { get; protected set; }
+        public virtual void Dispose() { }
     }
 }

src/Avalonia.X11/X11Platform.cs

@@ -71,7 +71,7 @@ namespace Avalonia.X11
                 .Bind<IRenderLoop>().ToConstant(new RenderLoop())
                 .Bind<PlatformHotkeyConfiguration>().ToConstant(new PlatformHotkeyConfiguration(KeyModifiers.Control))
                 .Bind<IKeyboardDevice>().ToFunc(() => KeyboardDevice)
-                .Bind<IStandardCursorFactory>().ToConstant(new X11CursorFactory(Display))
+                .Bind<ICursorFactory>().ToConstant(new X11CursorFactory(Display))
                 .Bind<IClipboard>().ToConstant(new X11Clipboard(this))
                 .Bind<IPlatformSettings>().ToConstant(new PlatformSettingsStub())
                 .Bind<IPlatformIconLoader>().ToConstant(new X11IconLoader(Info))

src/Avalonia.X11/X11Structs.cs

@@ -1693,7 +1693,7 @@ namespace Avalonia.X11 {
 	[StructLayout (LayoutKind.Sequential)]
 	internal struct XcursorImage
 	{
-		private int version;
+		public int version;
 		public int size;       /* nominal size for matching */
 		public int width;      /* actual width */
 		public int height;     /* actual height */

src/Avalonia.X11/X11Window.Ime.cs

@@ -96,14 +96,14 @@ namespace Avalonia.X11
 
         void HandleKeyEvent(ref XEvent ev)
         {
-            var index = ev.KeyEvent.state.HasFlag(XModifierMask.ShiftMask);
+            var index = ev.KeyEvent.state.HasFlagCustom(XModifierMask.ShiftMask);
 
             // We need the latin key, since it's mainly used for hotkeys, we use a different API for text anyway
             var key = (X11Key)XKeycodeToKeysym(_x11.Display, ev.KeyEvent.keycode, index ? 1 : 0).ToInt32();
                 
             // Manually switch the Shift index for the keypad,
             // there should be a proper way to do this
-            if (ev.KeyEvent.state.HasFlag(XModifierMask.Mod2Mask)
+            if (ev.KeyEvent.state.HasFlagCustom(XModifierMask.Mod2Mask)
                 && key > X11Key.Num_Lock && key <= X11Key.KP_9)
                 key = (X11Key)XKeycodeToKeysym(_x11.Display, ev.KeyEvent.keycode, index ? 0 : 1).ToInt32();
             

src/Avalonia.X11/X11Window.cs

@@ -639,23 +639,23 @@ namespace Avalonia.X11
         RawInputModifiers TranslateModifiers(XModifierMask state)
         {
             var rv = default(RawInputModifiers);
-            if (state.HasFlag(XModifierMask.Button1Mask))
+            if (state.HasFlagCustom(XModifierMask.Button1Mask))
                 rv |= RawInputModifiers.LeftMouseButton;
-            if (state.HasFlag(XModifierMask.Button2Mask))
+            if (state.HasFlagCustom(XModifierMask.Button2Mask))
                 rv |= RawInputModifiers.RightMouseButton;
-            if (state.HasFlag(XModifierMask.Button3Mask))
+            if (state.HasFlagCustom(XModifierMask.Button3Mask))
                 rv |= RawInputModifiers.MiddleMouseButton;
-            if (state.HasFlag(XModifierMask.Button4Mask))
+            if (state.HasFlagCustom(XModifierMask.Button4Mask))
                 rv |= RawInputModifiers.XButton1MouseButton;
-            if (state.HasFlag(XModifierMask.Button5Mask))
+            if (state.HasFlagCustom(XModifierMask.Button5Mask))
                 rv |= RawInputModifiers.XButton2MouseButton;
-            if (state.HasFlag(XModifierMask.ShiftMask))
+            if (state.HasFlagCustom(XModifierMask.ShiftMask))
                 rv |= RawInputModifiers.Shift;
-            if (state.HasFlag(XModifierMask.ControlMask))
+            if (state.HasFlagCustom(XModifierMask.ControlMask))
                 rv |= RawInputModifiers.Control;
-            if (state.HasFlag(XModifierMask.Mod1Mask))
+            if (state.HasFlagCustom(XModifierMask.Mod1Mask))
                 rv |= RawInputModifiers.Alt;
-            if (state.HasFlag(XModifierMask.Mod4Mask))
+            if (state.HasFlagCustom(XModifierMask.Mod4Mask))
                 rv |= RawInputModifiers.Meta;
             return rv;
         }
@@ -872,15 +872,13 @@ namespace Avalonia.X11
             UpdateSizeHints(null);
         }
 
-        public void SetCursor(IPlatformHandle cursor)
+        public void SetCursor(ICursorImpl cursor)
         {
             if (cursor == null)
                 XDefineCursor(_x11.Display, _handle, _x11.DefaultCursor);
-            else
+            else if (cursor is CursorImpl impl)
             {
-                if (cursor.HandleDescriptor != "XCURSOR")
-                    throw new ArgumentException("Expected XCURSOR handle type");
-                XDefineCursor(_x11.Display, _handle, cursor.Handle);
+                XDefineCursor(_x11.Display, _handle, impl.Handle);
             }
         }
 

src/Avalonia.X11/XI2Manager.cs

@@ -342,13 +342,13 @@ namespace Avalonia.X11
             Type = ev->evtype;
             Timestamp = (ulong)ev->time.ToInt64();
             var state = (XModifierMask)ev->mods.Effective;
-            if (state.HasFlag(XModifierMask.ShiftMask))
+            if (state.HasFlagCustom(XModifierMask.ShiftMask))
                 Modifiers |= RawInputModifiers.Shift;
-            if (state.HasFlag(XModifierMask.ControlMask))
+            if (state.HasFlagCustom(XModifierMask.ControlMask))
                 Modifiers |= RawInputModifiers.Control;
-            if (state.HasFlag(XModifierMask.Mod1Mask))
+            if (state.HasFlagCustom(XModifierMask.Mod1Mask))
                 Modifiers |= RawInputModifiers.Alt;
-            if (state.HasFlag(XModifierMask.Mod4Mask))
+            if (state.HasFlagCustom(XModifierMask.Mod4Mask))
                 Modifiers |= RawInputModifiers.Meta;
 
             Modifiers |= ParseButtonState(ev->buttons.MaskLen, ev->buttons.Mask);
@@ -364,7 +364,7 @@ namespace Avalonia.X11
             if (Type == XiEventType.XI_ButtonPress || Type == XiEventType.XI_ButtonRelease)
                 Button = ev->detail;
             Detail = ev->detail;
-            Emulated = ev->flags.HasFlag(XiDeviceEventFlags.XIPointerEmulated);
+            Emulated = ev->flags.HasFlagCustom(XiDeviceEventFlags.XIPointerEmulated);
         }
     }
     

src/Avalonia.X11/XLib.cs

@@ -20,6 +20,7 @@ namespace Avalonia.X11
         const string libX11Randr = "libXrandr.so.2";
         const string libX11Ext = "libXext.so.6";
         const string libXInput = "libXi.so.6";
+        const string libXCursor = "libXcursor.so.1";
 
         [DllImport(libX11)]
         public static extern IntPtr XOpenDisplay(IntPtr display);
@@ -569,6 +570,12 @@ namespace Avalonia.X11
         [DllImport(libXInput)]
         public static extern void XIFreeDeviceInfo(XIDeviceInfo* info);
 
+        [DllImport(libXCursor)]
+        public static extern IntPtr XcursorImageLoadCursor(IntPtr display, IntPtr image);
+
+        [DllImport(libXCursor)]
+        public static extern IntPtr XcursorImageDestroy(IntPtr image);
+
         public static void XISetMask(ref int mask, XiEventType ev)
         {
             mask |= (1 << (int)ev);

src/Linux/Avalonia.LinuxFramebuffer/FramebufferToplevelImpl.cs

@@ -57,7 +57,7 @@ namespace Avalonia.LinuxFramebuffer
 
         public PixelPoint PointToScreen(Point p) => PixelPoint.FromPoint(p, 1);
 
-        public void SetCursor(IPlatformHandle cursor)
+        public void SetCursor(ICursorImpl cursor)
         {
         }
 

src/Linux/Avalonia.LinuxFramebuffer/LinuxFramebufferPlatform.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Diagnostics;
 using System.Threading;
 using Avalonia.Controls;
@@ -38,7 +38,7 @@ namespace Avalonia.LinuxFramebuffer
                 .Bind<IPlatformThreadingInterface>().ToConstant(Threading)
                 .Bind<IRenderTimer>().ToConstant(new DefaultRenderTimer(60))
                 .Bind<IRenderLoop>().ToConstant(new RenderLoop())
-                .Bind<IStandardCursorFactory>().ToTransient<CursorFactoryStub>()
+                .Bind<ICursorFactory>().ToTransient<CursorFactoryStub>()
                 .Bind<IKeyboardDevice>().ToConstant(new KeyboardDevice())
                 .Bind<IPlatformSettings>().ToSingleton<PlatformSettings>()
                 .Bind<IRenderLoop>().ToConstant(new RenderLoop())
@@ -79,6 +79,11 @@ namespace Avalonia.LinuxFramebuffer
                     tl.Prepare();
                     _topLevel = tl;
                     _topLevel.Renderer.Start();
+
+                    if (_topLevel is IFocusScope scope)
+                    {
+                        FocusManager.Instance?.SetFocusScope(scope);
+                    }
                 }
 
                 _topLevel.Content = value;

src/Linux/Avalonia.LinuxFramebuffer/Output/DrmBindings.cs

@@ -54,7 +54,7 @@ namespace Avalonia.LinuxFramebuffer.Output
         }
 
         public PixelSize Resolution => new PixelSize(Mode.hdisplay, Mode.vdisplay);
-        public bool IsPreferred => Mode.type.HasFlag(DrmModeType.DRM_MODE_TYPE_PREFERRED);
+        public bool IsPreferred => Mode.type.HasFlagCustom(DrmModeType.DRM_MODE_TYPE_PREFERRED);
 
         public string Name { get; }
     }

src/Linux/Avalonia.LinuxFramebuffer/Stubs.cs

@@ -4,11 +4,14 @@ using Avalonia.Platform;
 
 namespace Avalonia.LinuxFramebuffer
 {
-    internal class CursorFactoryStub : IStandardCursorFactory
+    internal class CursorFactoryStub : ICursorFactory
     {
-        public IPlatformHandle GetCursor(StandardCursorType cursorType)
+        public ICursorImpl GetCursor(StandardCursorType cursorType) => new CursorStub();
+        public ICursorImpl CreateCursor(IBitmapImpl cursor, PixelPoint hotSpot) => new CursorStub();
+
+        private class CursorStub : ICursorImpl
         {
-            return new PlatformHandle(IntPtr.Zero, null);
+            public void Dispose() { }
         }
     }
     internal class PlatformSettings : IPlatformSettings

src/Markup/Avalonia.Markup/Avalonia.Markup.csproj

@@ -2,6 +2,8 @@
   <PropertyGroup>
     <TargetFramework>netstandard2.0</TargetFramework>
     <RootNamespace>Avalonia</RootNamespace>
+    <Nullable>Enable</Nullable>
+    <WarningsAsErrors>CS8600;CS8602;CS8603</WarningsAsErrors>
   </PropertyGroup>
   <ItemGroup>
     <None Remove="Markup\Parsers\Nodes\ExpressionGrammer" />

src/Markup/Avalonia.Markup/Data/Binding.cs

@@ -39,17 +39,17 @@ namespace Avalonia.Data
         /// <summary>
         /// Gets or sets the name of the element to use as the binding source.
         /// </summary>
-        public string ElementName { get; set; }
+        public string? ElementName { get; set; }
 
         /// <summary>
         /// Gets or sets the relative source for the binding.
         /// </summary>
-        public RelativeSource RelativeSource { get; set; }
+        public RelativeSource? RelativeSource { get; set; }
 
         /// <summary>
         /// Gets or sets the source for the binding.
         /// </summary>
-        public object Source { get; set; }
+        public object? Source { get; set; }
 
         /// <summary>
         /// Gets or sets the binding path.
@@ -59,24 +59,36 @@ namespace Avalonia.Data
         /// <summary>
         /// Gets or sets a function used to resolve types from names in the binding path.
         /// </summary>
-        public Func<string, string, Type> TypeResolver { get; set; }
+        public Func<string, string, Type>? TypeResolver { get; set; }
 
-        protected override ExpressionObserver CreateExpressionObserver(IAvaloniaObject target, AvaloniaProperty targetProperty, object anchor, bool enableDataValidation)
+        protected override ExpressionObserver CreateExpressionObserver(IAvaloniaObject target, AvaloniaProperty targetProperty, object? anchor, bool enableDataValidation)
         {
-            Contract.Requires<ArgumentNullException>(target != null);
-            anchor = anchor ?? DefaultAnchor?.Target;
-            
+            _ = target ?? throw new ArgumentNullException(nameof(target));
+
+            anchor ??= DefaultAnchor?.Target;
             enableDataValidation = enableDataValidation && Priority == BindingPriority.LocalValue;
 
-            INameScope nameScope = null;
+            INameScope? nameScope = null;
             NameScope?.TryGetTarget(out nameScope);
 
             var (node, mode) = ExpressionObserverBuilder.Parse(Path, enableDataValidation, TypeResolver, nameScope);
 
+            if (node is null)
+            {
+                throw new InvalidOperationException("Could not parse binding expression.");
+            }
+
+            IStyledElement GetSource()
+            {
+                return target as IStyledElement ??
+                    anchor as IStyledElement ??
+                    throw new ArgumentException("Could not find binding source: either target or anchor must be an IStyledElement.");
+            }
+
             if (ElementName != null)
             {
                 return CreateElementObserver(
-                    (target as IStyledElement) ?? (anchor as IStyledElement),
+                    GetSource(),
                     ElementName,
                     node);
             }
@@ -96,9 +108,7 @@ namespace Avalonia.Data
                 }
                 else
                 {
-                    return CreateSourceObserver(
-                        (target as IStyledElement) ?? (anchor as IStyledElement),
-                        node);
+                    return CreateSourceObserver(GetSource(), node);
                 }
             }
             else if (RelativeSource.Mode == RelativeSourceMode.DataContext)
@@ -111,15 +121,11 @@ namespace Avalonia.Data
             }
             else if (RelativeSource.Mode == RelativeSourceMode.Self)
             {
-                return CreateSourceObserver(
-                    (target as IStyledElement) ?? (anchor as IStyledElement),
-                    node);
+                return CreateSourceObserver(GetSource(), node);
             }
             else if (RelativeSource.Mode == RelativeSourceMode.TemplatedParent)
             {
-                return CreateTemplatedParentObserver(
-                    (target as IStyledElement) ?? (anchor as IStyledElement),
-                    node);
+                return CreateTemplatedParentObserver(GetSource(), node);
             }
             else if (RelativeSource.Mode == RelativeSourceMode.FindAncestor)
             {
@@ -128,10 +134,7 @@ namespace Avalonia.Data
                     throw new InvalidOperationException("AncestorType must be set for RelativeSourceMode.FindAncestor when searching the visual tree.");
                 }
 
-                return CreateFindAncestorObserver(
-                    (target as IStyledElement) ?? (anchor as IStyledElement),
-                    RelativeSource,
-                    node);
+                return CreateFindAncestorObserver(GetSource(), RelativeSource, node);
             }
             else
             {

src/Markup/Avalonia.Markup/Data/BindingBase.cs

@@ -38,22 +38,22 @@ namespace Avalonia.Data
         /// <summary>
         /// Gets or sets the <see cref="IValueConverter"/> to use.
         /// </summary>
-        public IValueConverter Converter { get; set; }
+        public IValueConverter? Converter { get; set; }
 
         /// <summary>
         /// Gets or sets a parameter to pass to <see cref="Converter"/>.
         /// </summary>
-        public object ConverterParameter { get; set; }
+        public object? ConverterParameter { get; set; }
 
         /// <summary>
         /// Gets or sets the value to use when the binding is unable to produce a value.
         /// </summary>
-        public object FallbackValue { get; set; }
+        public object? FallbackValue { get; set; }
 
         /// <summary>
         /// Gets or sets the value to use when the binding result is null.
         /// </summary>
-        public object TargetNullValue { get; set; }
+        public object? TargetNullValue { get; set; }
 
         /// <summary>
         /// Gets or sets the binding mode.
@@ -68,26 +68,27 @@ namespace Avalonia.Data
         /// <summary>
         /// Gets or sets the string format.
         /// </summary>
-        public string StringFormat { get; set; }
+        public string? StringFormat { get; set; }
 
-        public WeakReference DefaultAnchor { get; set; }
+        public WeakReference? DefaultAnchor { get; set; }
 
-        public WeakReference<INameScope> NameScope { get; set; }
+        public WeakReference<INameScope>? NameScope { get; set; }
 
         protected abstract ExpressionObserver CreateExpressionObserver(
             IAvaloniaObject target,
             AvaloniaProperty targetProperty,
-            object anchor,
+            object? anchor,
             bool enableDataValidation);
 
         /// <inheritdoc/>
         public InstancedBinding Initiate(
             IAvaloniaObject target,
             AvaloniaProperty targetProperty,
-            object anchor = null,
+            object? anchor = null,
             bool enableDataValidation = false)
         {
-            Contract.Requires<ArgumentNullException>(target != null);
+            _ = target ?? throw new ArgumentNullException(nameof(target));
+
             anchor = anchor ?? DefaultAnchor?.Target;
 
             enableDataValidation = enableDataValidation && Priority == BindingPriority.LocalValue;
@@ -133,18 +134,13 @@ namespace Avalonia.Data
             IAvaloniaObject target,
             ExpressionNode node,
             bool targetIsDataContext,
-            object anchor)
+            object? anchor)
         {
-            Contract.Requires<ArgumentNullException>(target != null);
+            _ = target ?? throw new ArgumentNullException(nameof(target));
 
             if (!(target is IDataContextProvider))
             {
-                target = anchor as IDataContextProvider;
-
-                if (target == null)
-                {
-                    throw new InvalidOperationException("Cannot find a DataContext to bind to.");
-                }
+                target = anchor as IDataContextProvider ?? throw new InvalidOperationException("Cannot find a DataContext to bind to.");
             }
 
             if (!targetIsDataContext)
@@ -171,10 +167,9 @@ namespace Avalonia.Data
             string elementName,
             ExpressionNode node)
         {
-            Contract.Requires<ArgumentNullException>(target != null);
+            _ = target ?? throw new ArgumentNullException(nameof(target));
 
-            NameScope.TryGetTarget(out var scope);
-            if (scope == null)
+            if (NameScope is null || !NameScope.TryGetTarget(out var scope) || scope is null)
                 throw new InvalidOperationException("Name scope is null or was already collected");
             var result = new ExpressionObserver(
                 NameScopeLocator.Track(scope, elementName),
@@ -188,9 +183,9 @@ namespace Avalonia.Data
             RelativeSource relativeSource,
             ExpressionNode node)
         {
-            Contract.Requires<ArgumentNullException>(target != null);
+            _ = target ?? throw new ArgumentNullException(nameof(target));
 
-            IObservable<object> controlLocator;
+            IObservable<object?> controlLocator;
 
             switch (relativeSource.Tree)
             {
@@ -220,7 +215,7 @@ namespace Avalonia.Data
             object source,
             ExpressionNode node)
         {
-            Contract.Requires<ArgumentNullException>(source != null);
+            _ = source ?? throw new ArgumentNullException(nameof(source));
 
             return new ExpressionObserver(source, node);
         }
@@ -229,7 +224,7 @@ namespace Avalonia.Data
             IAvaloniaObject target,
             ExpressionNode node)
         {
-            Contract.Requires<ArgumentNullException>(target != null);
+            _ = target ?? throw new ArgumentNullException(nameof(target));
 
             var result = new ExpressionObserver(
                 () => target.GetValue(StyledElement.TemplatedParentProperty),
@@ -240,7 +235,7 @@ namespace Avalonia.Data
             return result;
         }
 
-        protected IObservable<object> GetParentDataContext(IAvaloniaObject target)
+        protected IObservable<object?> GetParentDataContext(IAvaloniaObject target)
         {
             // The DataContext is based on the visual parent and not the logical parent: this may
             // seem counter intuitive considering the fact that property inheritance works on the logical
@@ -252,7 +247,7 @@ namespace Avalonia.Data
                 .Select(x =>
                 {
                     return (x as IAvaloniaObject)?.GetObservable(StyledElement.DataContextProperty) ??
-                           Observable.Return((object)null);
+                           Observable.Return((object?)null);
                 }).Switch();
         }
 

src/Markup/Avalonia.Markup/Data/MultiBinding.cs

@@ -22,12 +22,12 @@ namespace Avalonia.Data
         /// <summary>
         /// Gets or sets the <see cref="IMultiValueConverter"/> to use.
         /// </summary>
-        public IMultiValueConverter Converter { get; set; }
+        public IMultiValueConverter? Converter { get; set; }
 
         /// <summary>
         /// Gets or sets a parameter to pass to <see cref="Converter"/>.
         /// </summary>
-        public object ConverterParameter { get; set; }
+        public object? ConverterParameter { get; set; }
 
         /// <summary>
         /// Gets or sets the value to use when the binding is unable to produce a value.
@@ -52,12 +52,12 @@ namespace Avalonia.Data
         /// <summary>
         /// Gets or sets the relative source for the binding.
         /// </summary>
-        public RelativeSource RelativeSource { get; set; }
+        public RelativeSource? RelativeSource { get; set; }
 
         /// <summary>
         /// Gets or sets the string format.
         /// </summary>
-        public string StringFormat { get; set; }
+        public string? StringFormat { get; set; }
 
         public MultiBinding()
         {
@@ -69,7 +69,7 @@ namespace Avalonia.Data
         public InstancedBinding Initiate(
             IAvaloniaObject target,
             AvaloniaProperty targetProperty,
-            object anchor = null,
+            object? anchor = null,
             bool enableDataValidation = false)
         {
             var targetType = targetProperty?.PropertyType ?? typeof(object);
@@ -105,7 +105,7 @@ namespace Avalonia.Data
             }
         }
 
-        private object ConvertValue(IList<object> values, Type targetType, IMultiValueConverter converter)
+        private object ConvertValue(IList<object?> values, Type targetType, IMultiValueConverter? converter)
         {
             for (var i = 0; i < values.Count; ++i)
             {
@@ -116,7 +116,7 @@ namespace Avalonia.Data
             }
 
             var culture = CultureInfo.CurrentCulture;
-            values = new System.Collections.ObjectModel.ReadOnlyCollection<object>(values);
+            values = new System.Collections.ObjectModel.ReadOnlyCollection<object?>(values);
             object converted;
             if (converter != null)
             {

src/Markup/Avalonia.Markup/Data/RelativeSource.cs

@@ -94,7 +94,7 @@ namespace Avalonia.Data
         /// <summary>
         /// Gets the type of ancestor to look for when in <see cref="RelativeSourceMode.FindAncestor"/>  mode.
         /// </summary>
-        public Type AncestorType { get; set; }
+        public Type? AncestorType { get; set; }
 
         /// <summary>
         /// Gets or sets a value that describes the type of relative source lookup.

src/Markup/Avalonia.Markup/Data/TemplateBinding.cs

@@ -17,8 +17,8 @@ namespace Avalonia.Data
         ISetterValue
     {
         private bool _isSetterValue;
-        private IStyledElement _target;
-        private Type _targetType;
+        private IStyledElement _target = default!;
+        private Type? _targetType;
 
         public TemplateBinding()
         {
@@ -33,7 +33,7 @@ namespace Avalonia.Data
         public InstancedBinding Initiate(
             IAvaloniaObject target,
             AvaloniaProperty targetProperty,
-            object anchor = null,
+            object? anchor = null,
             bool enableDataValidation = false)
         {
             // Usually each `TemplateBinding` will only be instantiated once; in this case we can
@@ -68,12 +68,12 @@ namespace Avalonia.Data
         /// <summary>
         /// Gets or sets the <see cref="IValueConverter"/> to use.
         /// </summary>
-        public IValueConverter Converter { get; set; }
+        public IValueConverter? Converter { get; set; }
 
         /// <summary>
         /// Gets or sets a parameter to pass to <see cref="Converter"/>.
         /// </summary>
-        public object ConverterParameter { get; set; }
+        public object? ConverterParameter { get; set; }
 
         /// <summary>
         /// Gets or sets the binding mode.
@@ -83,7 +83,7 @@ namespace Avalonia.Data
         /// <summary>
         /// Gets or sets the name of the source property on the templated parent.
         /// </summary>
-        public AvaloniaProperty Property { get; set; }
+        public AvaloniaProperty? Property { get; set; }
 
         /// <inheritdoc/>
         public string Description => "TemplateBinding: " + Property;
@@ -164,10 +164,7 @@ namespace Avalonia.Data
         {
             if (e.Property == StyledElement.TemplatedParentProperty)
             {
-                var oldValue = (IAvaloniaObject)e.OldValue;
-                var newValue = (IAvaloniaObject)e.OldValue;
-
-                if (oldValue != null)
+                if (e.OldValue is IAvaloniaObject oldValue)
                 {
                     oldValue.PropertyChanged -= TemplatedParentPropertyChanged;
                 }

src/Markup/Avalonia.Markup/Markup/Parsers/BindingExpressionGrammar.cs

@@ -6,6 +6,8 @@ using Avalonia.Utilities;
 using System;
 using System.Collections.Generic;
 
+#nullable enable
+
 namespace Avalonia.Markup.Parsers
 {
     internal enum SourceMode
@@ -271,8 +273,8 @@ namespace Avalonia.Markup.Parsers
             }
             else if (mode.SequenceEqual("parent".AsSpan()))
             {
-                string ancestorNamespace = null;
-                string ancestorType = null;
+                string? ancestorNamespace = null;
+                string? ancestorType = null;
                 var ancestorLevel = 0;
                 if (PeekOpenBracket(ref r))
                 {
@@ -424,19 +426,19 @@ namespace Avalonia.Markup.Parsers
 
         public class PropertyNameNode : INode
         {
-            public string PropertyName { get; set; }
+            public string PropertyName { get; set; } = string.Empty;
         }
 
         public class AttachedPropertyNameNode : INode
         {
-            public string Namespace { get; set; }
-            public string TypeName { get; set; }
-            public string PropertyName { get; set; }
+            public string Namespace { get; set; } = string.Empty;
+            public string TypeName { get; set; } = string.Empty;
+            public string PropertyName { get; set; } = string.Empty;
         }
 
         public class IndexerNode : INode
         {
-            public IList<string> Arguments { get; set; }
+            public IList<string> Arguments { get; set; } = Array.Empty<string>();
         }
 
         public class NotNode : INode, ITransformNode { }
@@ -447,20 +449,20 @@ namespace Avalonia.Markup.Parsers
 
         public class NameNode : INode
         {
-            public string Name { get; set; }
+            public string Name { get; set; } = string.Empty;
         }
 
         public class AncestorNode : INode
         {
-            public string Namespace { get; set; }
-            public string TypeName { get; set; }
+            public string? Namespace { get; set; }
+            public string? TypeName { get; set; }
             public int Level { get; set; }
         }
 
         public class TypeCastNode : INode
         {
-            public string Namespace { get; set; }
-            public string TypeName { get; set; }
+            public string Namespace { get; set; } = string.Empty;
+            public string TypeName { get; set; } = string.Empty;
         }
     }
 }

src/Markup/Avalonia.Markup/Markup/Parsers/ExpressionObserverBuilder.cs

@@ -8,8 +8,8 @@ namespace Avalonia.Markup.Parsers
 {
     public static class ExpressionObserverBuilder
     {
-        internal static (ExpressionNode Node, SourceMode Mode) Parse(string expression, bool enableValidation = false, Func<string, string, Type> typeResolver = null,
-            INameScope nameScope = null)
+        internal static (ExpressionNode? Node, SourceMode Mode) Parse(string expression, bool enableValidation = false, Func<string, string, Type>? typeResolver = null,
+            INameScope? nameScope = null)
         {
             if (string.IsNullOrWhiteSpace(expression))
             {
@@ -32,8 +32,8 @@ namespace Avalonia.Markup.Parsers
             object root,
             string expression,
             bool enableDataValidation = false,
-            string description = null,
-            Func<string, string, Type> typeResolver = null)
+            string? description = null,
+            Func<string, string, Type>? typeResolver = null)
         {
             return new ExpressionObserver(
                 root,
@@ -45,10 +45,11 @@ namespace Avalonia.Markup.Parsers
             IObservable<object> rootObservable,
             string expression,
             bool enableDataValidation = false,
-            string description = null,
-            Func<string, string, Type> typeResolver = null)
+            string? description = null,
+            Func<string, string, Type>? typeResolver = null)
         {
-            Contract.Requires<ArgumentNullException>(rootObservable != null);
+            _ = rootObservable ?? throw new ArgumentNullException(nameof(rootObservable));
+
             return new ExpressionObserver(
                 rootObservable,
                 Parse(expression, enableDataValidation, typeResolver).Node,
@@ -61,10 +62,10 @@ namespace Avalonia.Markup.Parsers
             string expression,
             IObservable<Unit> update,
             bool enableDataValidation = false,
-            string description = null,
-            Func<string, string, Type> typeResolver = null)
+            string? description = null,
+            Func<string, string, Type>? typeResolver = null)
         {
-            Contract.Requires<ArgumentNullException>(rootGetter != null);
+            _ = rootGetter ?? throw new ArgumentNullException(nameof(rootGetter));
 
             return new ExpressionObserver(
                 rootGetter,

src/Markup/Avalonia.Markup/Markup/Parsers/ExpressionParser.cs

@@ -11,25 +11,25 @@ namespace Avalonia.Markup.Parsers
     internal class ExpressionParser
     {
         private readonly bool _enableValidation;
-        private readonly Func<string, string, Type> _typeResolver;
-        private readonly INameScope _nameScope;
+        private readonly Func<string, string, Type>? _typeResolver;
+        private readonly INameScope? _nameScope;
 
-        public ExpressionParser(bool enableValidation, Func<string, string, Type> typeResolver, INameScope nameScope)
+        public ExpressionParser(bool enableValidation, Func<string, string, Type>? typeResolver, INameScope? nameScope)
         {
             _typeResolver = typeResolver;
             _nameScope = nameScope;
             _enableValidation = enableValidation;
         }
 
-        public (ExpressionNode Node, SourceMode Mode) Parse(ref CharacterReader r)
+        public (ExpressionNode? Node, SourceMode Mode) Parse(ref CharacterReader r)
         {
-            ExpressionNode rootNode = null;
-            ExpressionNode node = null;
+            ExpressionNode? rootNode = null;
+            ExpressionNode? node = null;
             var (astNodes, mode) = BindingExpressionGrammar.Parse(ref r);
 
             foreach (var astNode in astNodes)
             {
-                ExpressionNode nextNode = null;
+                ExpressionNode? nextNode = null;
                 switch (astNode)
                 {
                     case BindingExpressionGrammar.EmptyExpressionNode _:
@@ -57,13 +57,13 @@ namespace Avalonia.Markup.Parsers
                         nextNode = ParseFindAncestor(ancestor);
                         break;
                     case BindingExpressionGrammar.NameNode elementName:
-                        nextNode = new ElementNameNode(_nameScope, elementName.Name);
+                        nextNode = new ElementNameNode(_nameScope ?? throw new NotSupportedException("Invalid element name binding with null name scope!"), elementName.Name);
                         break;
                     case BindingExpressionGrammar.TypeCastNode typeCast:
                         nextNode = ParseTypeCastNode(typeCast);
                         break;
                 }
-                if (rootNode is null)
+                if (node is null)
                 {
                     rootNode = node = nextNode;
                 }
@@ -79,7 +79,7 @@ namespace Avalonia.Markup.Parsers
 
         private FindAncestorNode ParseFindAncestor(BindingExpressionGrammar.AncestorNode node)
         {
-            Type ancestorType = null;
+            Type? ancestorType = null;
             var ancestorLevel = node.Level;
 
             if (!(node.Namespace is null) && !(node.TypeName is null))
@@ -97,7 +97,7 @@ namespace Avalonia.Markup.Parsers
 
         private TypeCastNode ParseTypeCastNode(BindingExpressionGrammar.TypeCastNode node)
         {
-            Type castType = null;
+            Type? castType = null;
             if (!(node.Namespace is null) && !(node.TypeName is null))
             {
                 if (_typeResolver == null)

src/Markup/Avalonia.Markup/Markup/Parsers/Nodes/ElementNameNode.cs

@@ -9,7 +9,7 @@ namespace Avalonia.Markup.Parsers.Nodes
     {
         private readonly WeakReference<INameScope> _nameScope;
         private readonly string _name;
-        private IDisposable _subscription;
+        private IDisposable? _subscription;
 
         public ElementNameNode(INameScope nameScope, string name)
         {

src/Markup/Avalonia.Markup/Markup/Parsers/Nodes/FindAncestorNode.cs

@@ -7,10 +7,10 @@ namespace Avalonia.Markup.Parsers.Nodes
     public class FindAncestorNode : ExpressionNode
     {
         private readonly int _level;
-        private readonly Type _ancestorType;
-        private IDisposable _subscription;
+        private readonly Type? _ancestorType;
+        private IDisposable? _subscription;
 
-        public FindAncestorNode(Type ancestorType, int level)
+        public FindAncestorNode(Type? ancestorType, int level)
         {
             _level = level;
             _ancestorType = ancestorType;

src/Markup/Avalonia.Markup/Markup/Parsers/Nodes/StringIndexerNode.cs

@@ -29,15 +29,15 @@ namespace Avalonia.Markup.Parsers.Nodes
             var list = target as IList;
             var dictionary = target as IDictionary;
             var indexerProperty = GetIndexer(typeInfo);
-            var indexerParameters = indexerProperty?.GetIndexParameters();
+            ParameterInfo[] indexerParameters;
 
-            if (indexerProperty != null && indexerParameters.Length == Arguments.Count)
+            if (indexerProperty != null && (indexerParameters = indexerProperty.GetIndexParameters()).Length == Arguments.Count)
             {
                 var convertedObjectArray = new object[indexerParameters.Length];
 
                 for (int i = 0; i < Arguments.Count; i++)
                 {
-                    object temp = null;
+                    object? temp = null;
 
                     if (!TypeUtilities.TryConvert(indexerParameters[i].ParameterType, Arguments[i], CultureInfo.InvariantCulture, out temp))
                     {
@@ -125,7 +125,7 @@ namespace Avalonia.Markup.Parsers.Nodes
 
         public IList<string> Arguments { get; }
 
-        public override Type PropertyType
+        public override Type? PropertyType
         {
             get
             {
@@ -144,15 +144,15 @@ namespace Avalonia.Markup.Parsers.Nodes
             var list = target as IList;
             var dictionary = target as IDictionary;
             var indexerProperty = GetIndexer(typeInfo);
-            var indexerParameters = indexerProperty?.GetIndexParameters();
+            ParameterInfo[] indexerParameters;
 
-            if (indexerProperty != null && indexerParameters.Length == Arguments.Count)
+            if (indexerProperty != null && (indexerParameters = indexerProperty.GetIndexParameters()).Length == Arguments.Count)
             {
                 var convertedObjectArray = new object[indexerParameters.Length];
 
                 for (int i = 0; i < Arguments.Count; i++)
                 {
-                    object temp = null;
+                    object? temp = null;
 
                     if (!TypeUtilities.TryConvert(indexerParameters[i].ParameterType, Arguments[i], CultureInfo.InvariantCulture, out temp))
                     {
@@ -246,7 +246,7 @@ namespace Avalonia.Markup.Parsers.Nodes
             return true;
         }
 
-        private static PropertyInfo GetIndexer(TypeInfo typeInfo)
+        private static PropertyInfo? GetIndexer(TypeInfo? typeInfo)
         {
             PropertyInfo indexer;
 

src/Markup/Avalonia.Markup/Markup/Parsers/PropertyPathGrammar.cs

@@ -3,6 +3,8 @@ using System.Collections.Generic;
 using Avalonia.Data.Core;
 using Avalonia.Utilities;
 
+#nullable enable
+
 namespace Avalonia.Markup.Parsers
 {
 #if !BUILDTASK
@@ -30,7 +32,7 @@ namespace Avalonia.Markup.Parsers
             var parsed = new List<ISyntax>();
             while (state != State.End)
             {
-                ISyntax syntax = null;
+                ISyntax? syntax = null;
                 if (state == State.Start)
                     (state, syntax) = ParseStart(ref r);
                 else if (state == State.Next)
@@ -53,7 +55,7 @@ namespace Avalonia.Markup.Parsers
             return parsed;
         }
         
-        private static (State, ISyntax) ParseNext(ref CharacterReader r)
+        private static (State, ISyntax?) ParseNext(ref CharacterReader r)
         {
             r.SkipWhitespace();
             if (r.End)
@@ -106,7 +108,7 @@ namespace Avalonia.Markup.Parsers
                 });
         }
 
-        static (string ns, string name) ParseXamlIdentifier(ref CharacterReader r)
+        static (string? ns, string name) ParseXamlIdentifier(ref CharacterReader r)
         {
             var ident = r.ParseIdentifier();
             if (ident.IsEmpty)
@@ -147,7 +149,7 @@ namespace Avalonia.Markup.Parsers
             return true;
         }
         
-        private static (State, ISyntax) ParseAfterProperty(ref CharacterReader r)
+        private static (State, ISyntax?) ParseAfterProperty(ref CharacterReader r)
         {
             if (TryParseCasts(ref r, out var rv))
                 return rv;
@@ -184,20 +186,20 @@ namespace Avalonia.Markup.Parsers
 
         public class PropertySyntax : ISyntax
         {
-            public string Name { get; set; }
+            public string Name { get; set; } = string.Empty;
 
-            public override bool Equals(object obj)
+            public override bool Equals(object? obj)
                 => obj is PropertySyntax other
                    && other.Name == Name;
         }
         
         public class TypeQualifiedPropertySyntax : ISyntax
         {
-            public string Name { get; set; }
-            public string TypeName { get; set; }
-            public string TypeNamespace { get; set; }
+            public string Name { get; set; } = string.Empty;
+            public string TypeName { get; set; } = string.Empty;
+            public string? TypeNamespace { get; set; }
 
-            public override bool Equals(object obj)
+            public override bool Equals(object? obj)
                 => obj is TypeQualifiedPropertySyntax other
                    && other.Name == Name
                    && other.TypeName == TypeName
@@ -207,14 +209,14 @@ namespace Avalonia.Markup.Parsers
         public class ChildTraversalSyntax : ISyntax
         {
             public static ChildTraversalSyntax Instance { get;  } = new ChildTraversalSyntax();
-            public override bool Equals(object obj) => obj is ChildTraversalSyntax;
+            public override bool Equals(object? obj) => obj is ChildTraversalSyntax;
         }
         
         public class EnsureTypeSyntax : ISyntax
         {
-            public string TypeName { get; set; }
-            public string TypeNamespace { get; set; }
-            public override bool Equals(object obj)
+            public string TypeName { get; set; } = string.Empty;
+            public string? TypeNamespace { get; set; }
+            public override bool Equals(object? obj)
                 => obj is EnsureTypeSyntax other
                    && other.TypeName == TypeName
                    && other.TypeNamespace == TypeNamespace;
@@ -222,9 +224,9 @@ namespace Avalonia.Markup.Parsers
         
         public class CastTypeSyntax : ISyntax
         {
-            public string TypeName { get; set; }
-            public string TypeNamespace { get; set; }
-            public override bool Equals(object obj)
+            public string TypeName { get; set; } = string.Empty;
+            public string? TypeNamespace { get; set; }
+            public override bool Equals(object? obj)
                 => obj is CastTypeSyntax other
                    && other.TypeName == TypeName
                    && other.TypeNamespace == TypeNamespace;

src/Markup/Avalonia.Markup/Markup/Parsers/SelectorGrammar.cs

@@ -4,6 +4,8 @@ using System.Linq;
 using Avalonia.Data.Core;
 using Avalonia.Utilities;
 
+#nullable enable
+
 // Don't need to override GetHashCode as the ISyntax objects will not be stored in a hash; the 
 // only reason they have overridden Equals methods is for unit testing.
 #pragma warning disable 659
@@ -39,7 +41,7 @@ namespace Avalonia.Markup.Parsers
             var selector = new List<ISyntax>();
             while (!r.End && state != State.End)
             {
-                ISyntax syntax = null;
+                ISyntax? syntax = null;
                 switch (state)
                 {
                     case State.Start:
@@ -110,7 +112,7 @@ namespace Avalonia.Markup.Parsers
             return State.TypeName;
         }
 
-        private static (State, ISyntax) ParseMiddle(ref CharacterReader r, char? end)
+        private static (State, ISyntax?) ParseMiddle(ref CharacterReader r, char? end)
         {
             if (r.TakeIf(':'))
             {
@@ -190,7 +192,7 @@ namespace Avalonia.Markup.Parsers
             }
         }
 
-        private static (State, ISyntax) ParseTraversal(ref CharacterReader r)
+        private static (State, ISyntax?) ParseTraversal(ref CharacterReader r)
         {
             r.SkipWhitespace();
             if (r.TakeIf('>'))
@@ -325,11 +327,11 @@ namespace Avalonia.Markup.Parsers
 
         public class OfTypeSyntax : ISyntax, ITypeSyntax
         {
-            public string TypeName { get; set; }
+            public string TypeName { get; set; } = string.Empty;
 
             public string Xmlns { get; set; } = string.Empty;
 
-            public override bool Equals(object obj)
+            public override bool Equals(object? obj)
             {
                 var other = obj as OfTypeSyntax;
                 return other != null && other.TypeName == TypeName && other.Xmlns == Xmlns;
@@ -338,11 +340,11 @@ namespace Avalonia.Markup.Parsers
 
         public class IsSyntax : ISyntax, ITypeSyntax
         {
-            public string TypeName { get; set; }
+            public string TypeName { get; set; } = string.Empty;
 
             public string Xmlns { get; set; } = string.Empty;
 
-            public override bool Equals(object obj)
+            public override bool Equals(object? obj)
             {
                 var other = obj as IsSyntax;
                 return other != null && other.TypeName == TypeName && other.Xmlns == Xmlns;
@@ -351,9 +353,9 @@ namespace Avalonia.Markup.Parsers
 
         public class ClassSyntax : ISyntax
         {
-            public string Class { get; set; }
+            public string Class { get; set; } = string.Empty;
 
-            public override bool Equals(object obj)
+            public override bool Equals(object? obj)
             {
                 return obj is ClassSyntax && ((ClassSyntax)obj).Class == Class;
             }
@@ -361,9 +363,9 @@ namespace Avalonia.Markup.Parsers
 
         public class NameSyntax : ISyntax
         {
-            public string Name { get; set; }
+            public string Name { get; set; } = string.Empty;
 
-            public override bool Equals(object obj)
+            public override bool Equals(object? obj)
             {
                 return obj is NameSyntax && ((NameSyntax)obj).Name == Name;
             }
@@ -371,11 +373,11 @@ namespace Avalonia.Markup.Parsers
 
         public class PropertySyntax : ISyntax
         {
-            public string Property { get; set; }
+            public string Property { get; set; } = string.Empty;
 
-            public string Value { get; set; }
+            public string Value { get; set; } = string.Empty;
 
-            public override bool Equals(object obj)
+            public override bool Equals(object? obj)
             {
                 return obj is PropertySyntax && 
                     ((PropertySyntax)obj).Property == Property && 
@@ -385,7 +387,7 @@ namespace Avalonia.Markup.Parsers
 
         public class ChildSyntax : ISyntax
         {
-            public override bool Equals(object obj)
+            public override bool Equals(object? obj)
             {
                 return obj is ChildSyntax;
             }
@@ -393,7 +395,7 @@ namespace Avalonia.Markup.Parsers
 
         public class DescendantSyntax : ISyntax
         {
-            public override bool Equals(object obj)
+            public override bool Equals(object? obj)
             {
                 return obj is DescendantSyntax;
             }
@@ -401,7 +403,7 @@ namespace Avalonia.Markup.Parsers
 
         public class TemplateSyntax : ISyntax
         {
-            public override bool Equals(object obj)
+            public override bool Equals(object? obj)
             {
                 return obj is TemplateSyntax;
             }
@@ -409,9 +411,9 @@ namespace Avalonia.Markup.Parsers
 
         public class NotSyntax : ISyntax
         {
-            public IEnumerable<ISyntax> Argument { get; set; }
+            public IEnumerable<ISyntax> Argument { get; set; } = Enumerable.Empty<ISyntax>();
 
-            public override bool Equals(object obj)
+            public override bool Equals(object? obj)
             {
                 return (obj is NotSyntax not) && Argument.SequenceEqual(not.Argument);
             }
@@ -419,7 +421,7 @@ namespace Avalonia.Markup.Parsers
 
         public class CommaSyntax : ISyntax
         {
-            public override bool Equals(object obj)
+            public override bool Equals(object? obj)
             {
                 return obj is CommaSyntax or;
             }

src/Markup/Avalonia.Markup/Markup/Parsers/SelectorParser.cs

@@ -31,13 +31,13 @@ namespace Avalonia.Markup.Parsers
         /// </summary>
         /// <param name="s">The string.</param>
         /// <returns>The parsed selector.</returns>
-        public Selector Parse(string s)
+        public Selector? Parse(string s)
         {
             var syntax = SelectorGrammar.Parse(s);
             return Create(syntax);
         }
 
-        private Selector Create(IEnumerable<SelectorGrammar.ISyntax> syntax)
+        private Selector? Create(IEnumerable<SelectorGrammar.ISyntax> syntax)
         {
             var result = default(Selector);
             var results = default(List<Selector>);
@@ -110,7 +110,7 @@ namespace Avalonia.Markup.Parsers
                             results = new List<Selector>();
                         }
 
-                        results.Add(result);
+                        results.Add(result ?? throw new NotSupportedException("Invalid selector!"));
                         result = null;
                         break;
                     default:

src/Skia/Avalonia.Skia/SKTypefaceCollection.cs

@@ -32,7 +32,7 @@ namespace Avalonia.Skia
 
             weight -= weight % 100; // make sure we start at a full weight
 
-            for (var i = (int)key.Style; i < 2; i++)
+            for (var i = 0; i < 2; i++)
             {
                 // only try 2 font weights in each direction
                 for (var j = 0; j < 200; j += 100)
@@ -57,8 +57,8 @@ namespace Avalonia.Skia
                 }
             }
 
-            //Nothing was found so we use the first typeface we can get.
-            return typefaces.Values.FirstOrDefault();
+            //Nothing was found so we try to get a regular typeface.
+            return typefaces.TryGetValue(new Typeface(key.FontFamily), out typeface) ? typeface : null;
         }
     }
 }

src/Windows/Avalonia.Direct2D1/Media/DrawingContextImpl.cs

@@ -21,6 +21,7 @@ namespace Avalonia.Direct2D1.Media
         private readonly ILayerFactory _layerFactory;
         private readonly SharpDX.Direct2D1.RenderTarget _renderTarget;
         private readonly DeviceContext _deviceContext;
+        private readonly bool _ownsDeviceContext;
         private readonly SharpDX.DXGI.SwapChain1 _swapChain;
         private readonly Action _finishedCallback;
 
@@ -51,10 +52,12 @@ namespace Avalonia.Direct2D1.Media
             if (_renderTarget is DeviceContext deviceContext)
             {
                 _deviceContext = deviceContext;
+                _ownsDeviceContext = false;
             }
             else
             {
                 _deviceContext = _renderTarget.QueryInterface<DeviceContext>();
+                _ownsDeviceContext = true;
             }
 
             _deviceContext.BeginDraw();
@@ -96,6 +99,13 @@ namespace Avalonia.Direct2D1.Media
             {
                 throw new RenderTargetCorruptedException(ex);
             }
+            finally
+            {
+                if (_ownsDeviceContext)
+                {
+                    _deviceContext.Dispose();
+                }
+            }
         }
 
         /// <summary>
@@ -151,7 +161,7 @@ namespace Avalonia.Direct2D1.Media
             using (var d2dSource = ((BitmapImpl)source.Item).GetDirect2DBitmap(_deviceContext))
             using (var sourceBrush = new BitmapBrush(_deviceContext, d2dSource.Value))
             using (var d2dOpacityMask = CreateBrush(opacityMask, opacityMaskRect.Size))
-            using (var geometry = new SharpDX.Direct2D1.RectangleGeometry(_deviceContext.Factory, destRect.ToDirect2D()))
+            using (var geometry = new SharpDX.Direct2D1.RectangleGeometry(Direct2D1Platform.Direct2D1Factory, destRect.ToDirect2D()))
             {
                 if (d2dOpacityMask.PlatformBrush != null)
                 {

src/Windows/Avalonia.Direct2D1/Media/GeometryImpl.cs

@@ -33,13 +33,13 @@ namespace Avalonia.Direct2D1.Media
         /// <inheritdoc/>
         public IGeometryImpl Intersect(IGeometryImpl geometry)
         {
-            var result = new PathGeometry(Geometry.Factory);
-
+            var result = new PathGeometry(Direct2D1Platform.Direct2D1Factory);
             using (var sink = result.Open())
             {
                 Geometry.Combine(((GeometryImpl)geometry).Geometry, CombineMode.Intersect, sink);
-                return new StreamGeometryImpl(result);
+                sink.Close();
             }
+            return new StreamGeometryImpl(result);
         }
 
         /// <inheritdoc/>

src/Windows/Avalonia.Direct2D1/Media/Imaging/WicBitmapImpl.cs

@@ -13,7 +13,7 @@ namespace Avalonia.Direct2D1.Media
     /// </summary>
     public class WicBitmapImpl : BitmapImpl
     {
-        private BitmapDecoder _decoder;
+        private readonly BitmapDecoder _decoder;
 
         private static BitmapInterpolationMode ConvertInterpolationMode(Avalonia.Visuals.Media.Imaging.BitmapInterpolationMode interpolationMode)
         {
@@ -41,7 +41,7 @@ namespace Avalonia.Direct2D1.Media
         /// <param name="fileName">The filename of the bitmap to load.</param>
         public WicBitmapImpl(string fileName)
         {
-            using (BitmapDecoder decoder = new BitmapDecoder(Direct2D1Platform.ImagingFactory, fileName, DecodeOptions.CacheOnDemand))
+            using (var decoder = new BitmapDecoder(Direct2D1Platform.ImagingFactory, fileName, DecodeOptions.CacheOnDemand))
             {
                 WicImpl = new Bitmap(Direct2D1Platform.ImagingFactory, decoder.GetFrame(0), BitmapCreateCacheOption.CacheOnDemand);
                 Dpi = new Vector(96, 96);
@@ -177,7 +177,7 @@ namespace Avalonia.Direct2D1.Media
         /// <returns>The Direct2D bitmap.</returns>
         public override OptionalDispose<D2DBitmap> GetDirect2DBitmap(SharpDX.Direct2D1.RenderTarget renderTarget)
         {
-            FormatConverter converter = new FormatConverter(Direct2D1Platform.ImagingFactory);
+            using var converter = new FormatConverter(Direct2D1Platform.ImagingFactory);
             converter.Initialize(WicImpl, SharpDX.WIC.PixelFormat.Format32bppPBGRA);
             return new OptionalDispose<D2DBitmap>(D2DBitmap.FromWicBitmap(renderTarget, converter), true);
         }

src/Windows/Avalonia.Direct2D1/Media/StreamGeometryImpl.cs

@@ -29,9 +29,12 @@ namespace Avalonia.Direct2D1.Media
         public IStreamGeometryImpl Clone()
         {
             var result = new PathGeometry(Direct2D1Platform.Direct2D1Factory);
-            var sink = result.Open();
-            ((PathGeometry)Geometry).Stream(sink);
-            sink.Close();
+            using (var sink = result.Open())
+            {
+                ((PathGeometry)Geometry).Stream(sink);
+                sink.Close();
+            }
+
             return new StreamGeometryImpl(result);
         }
 

src/Windows/Avalonia.Direct2D1/PrimitiveExtensions.cs

@@ -111,7 +111,7 @@ namespace Avalonia.Direct2D1
         /// <returns>The Direct2D brush.</returns>
         public static StrokeStyle ToDirect2DStrokeStyle(this Avalonia.Media.IPen pen, SharpDX.Direct2D1.RenderTarget renderTarget)
         {
-            return pen.ToDirect2DStrokeStyle(renderTarget.Factory);
+            return pen.ToDirect2DStrokeStyle(Direct2D1Platform.Direct2D1Factory);
         }
 
         /// <summary>

src/Windows/Avalonia.Win32.Interop/Wpf/WpfTopLevelImpl.cs

@@ -147,13 +147,13 @@ namespace Avalonia.Win32.Interop.Wpf
         {
             var state = Keyboard.Modifiers;
             var rv = default(RawInputModifiers);
-            if (state.HasFlag(ModifierKeys.Windows))
+            if (state.HasFlagCustom(ModifierKeys.Windows))
                 rv |= RawInputModifiers.Meta;
-            if (state.HasFlag(ModifierKeys.Alt))
+            if (state.HasFlagCustom(ModifierKeys.Alt))
                 rv |= RawInputModifiers.Alt;
-            if (state.HasFlag(ModifierKeys.Control))
+            if (state.HasFlagCustom(ModifierKeys.Control))
                 rv |= RawInputModifiers.Control;
-            if (state.HasFlag(ModifierKeys.Shift))
+            if (state.HasFlagCustom(ModifierKeys.Shift))
                 rv |= RawInputModifiers.Shift;
             if (e != null)
             {
@@ -225,12 +225,12 @@ namespace Avalonia.Win32.Interop.Wpf
         protected override void OnTextInput(TextCompositionEventArgs e) 
             => _ttl.Input?.Invoke(new RawTextInputEventArgs(_keyboard, (uint) e.Timestamp, _inputRoot, e.Text));
 
-        void ITopLevelImpl.SetCursor(IPlatformHandle cursor)
+        void ITopLevelImpl.SetCursor(ICursorImpl cursor)
         {
             if (cursor == null)
                 Cursor = Cursors.Arrow;
-            else if (cursor.HandleDescriptor == "HCURSOR")
-                Cursor = CursorShim.FromHCursor(cursor.Handle);
+            else if (cursor is IPlatformHandle handle)
+                Cursor = CursorShim.FromHCursor(handle.Handle);
         }
 
         Action<RawInputEventArgs> ITopLevelImpl.Input { get; set; } //TODO

src/Windows/Avalonia.Win32/CursorFactory.cs

@@ -1,12 +1,17 @@
 using System;
 using System.Collections.Generic;
+using System.Drawing;
+using System.Drawing.Imaging;
+using System.IO;
 using Avalonia.Input;
 using Avalonia.Platform;
 using Avalonia.Win32.Interop;
+using SdBitmap = System.Drawing.Bitmap;
+using SdPixelFormat = System.Drawing.Imaging.PixelFormat;
 
 namespace Avalonia.Win32
 {
-    internal class CursorFactory : IStandardCursorFactory
+    internal class CursorFactory : ICursorFactory
     {
         public static CursorFactory Instance { get; } = new CursorFactory();
 
@@ -29,8 +34,7 @@ namespace Avalonia.Win32
                 IntPtr cursor = UnmanagedMethods.LoadCursor(mh, new IntPtr(id));
                 if (cursor != IntPtr.Zero)
                 {
-                    PlatformHandle phCursor = new PlatformHandle(cursor, PlatformConstants.CursorHandleType);
-                    Cache.Add(cursorType, phCursor);
+                    Cache.Add(cursorType, new CursorImpl(cursor, false));
                 }
             }
         }
@@ -70,22 +74,119 @@ namespace Avalonia.Win32
             {StandardCursorType.DragLink, 32516},
         };
 
-        private static readonly Dictionary<StandardCursorType, IPlatformHandle> Cache =
-            new Dictionary<StandardCursorType, IPlatformHandle>();
+        private static readonly Dictionary<StandardCursorType, CursorImpl> Cache =
+            new Dictionary<StandardCursorType, CursorImpl>();
 
-        public IPlatformHandle GetCursor(StandardCursorType cursorType)
+        public ICursorImpl GetCursor(StandardCursorType cursorType)
         {
-            IPlatformHandle rv;
-            if (!Cache.TryGetValue(cursorType, out rv))
+            if (!Cache.TryGetValue(cursorType, out var rv))
             {
-                Cache[cursorType] =
-                    rv =
-                        new PlatformHandle(
-                            UnmanagedMethods.LoadCursor(IntPtr.Zero, new IntPtr(CursorTypeMapping[cursorType])),
-                            PlatformConstants.CursorHandleType);
+                rv = new CursorImpl(
+                    UnmanagedMethods.LoadCursor(IntPtr.Zero, new IntPtr(CursorTypeMapping[cursorType])),
+                    false);
+                Cache.Add(cursorType, rv);
             }
 
             return rv;
         }
+
+        public ICursorImpl CreateCursor(IBitmapImpl cursor, PixelPoint hotSpot)
+        {
+            using var source = LoadSystemDrawingBitmap(cursor);
+            using var mask = AlphaToMask(source);
+
+            var info = new UnmanagedMethods.ICONINFO
+            {
+                IsIcon = false,
+                xHotspot = hotSpot.X,
+                yHotspot = hotSpot.Y,
+                MaskBitmap = mask.GetHbitmap(),
+                ColorBitmap = source.GetHbitmap(),
+            };
+
+            return new CursorImpl(UnmanagedMethods.CreateIconIndirect(ref info), true);
+        }
+
+        private SdBitmap LoadSystemDrawingBitmap(IBitmapImpl bitmap)
+        {
+            using var memoryStream = new MemoryStream();
+            bitmap.Save(memoryStream);
+            return new SdBitmap(memoryStream);
+        }
+
+        private unsafe SdBitmap AlphaToMask(SdBitmap source)
+        {
+            var dest = new SdBitmap(source.Width, source.Height, SdPixelFormat.Format1bppIndexed);
+
+            if (source.PixelFormat == SdPixelFormat.Format32bppPArgb)
+            {
+                throw new NotSupportedException(
+                    "Images with premultiplied alpha not yet supported as cursor images.");
+            }
+
+            if (source.PixelFormat != SdPixelFormat.Format32bppArgb)
+            {
+                return dest;
+            }
+
+            var sourceData = source.LockBits(
+                new Rectangle(default, source.Size),
+                ImageLockMode.ReadOnly,
+                SdPixelFormat.Format32bppArgb);
+            var destData = dest.LockBits(
+                new Rectangle(default, source.Size),
+                ImageLockMode.ReadOnly,
+                SdPixelFormat.Format1bppIndexed);
+
+            try
+            {
+                var pSource = (byte*)sourceData.Scan0.ToPointer();
+                var pDest = (byte*)destData.Scan0.ToPointer();
+
+                for (var y = 0; y < dest.Height; ++y)
+                {
+                    for (var x = 0; x < dest.Width; ++x)
+                    {
+                        if (pSource[x * 4] == 0)
+                        {
+                            pDest[x / 8] |= (byte)(1 << (x % 8));
+                        }
+                    }
+
+                    pSource += sourceData.Stride;
+                    pDest += destData.Stride;
+                }
+
+                return dest;
+            }
+            finally
+            {
+                source.UnlockBits(sourceData);
+                dest.UnlockBits(destData);
+            }
+        }
+    }
+
+    internal class CursorImpl : ICursorImpl, IPlatformHandle
+    {
+        private readonly bool _isCustom;
+
+        public CursorImpl(IntPtr handle, bool isCustom)
+        {
+            Handle = handle;
+            _isCustom = isCustom;
+        }
+
+        public IntPtr Handle { get; private set; }
+        public string HandleDescriptor => PlatformConstants.CursorHandleType;
+
+        public void Dispose()
+        {
+            if (_isCustom && Handle != IntPtr.Zero)
+            {
+                UnmanagedMethods.DestroyIcon(Handle);
+                Handle = IntPtr.Zero;
+            }
+        }
     }
 }

src/Windows/Avalonia.Win32/DataObject.cs

@@ -181,7 +181,7 @@ namespace Avalonia.Win32
                 ole.GetData(ref format, out medium);
                 return;
             }
-            if(!format.tymed.HasFlag(TYMED.TYMED_HGLOBAL))
+            if(!format.tymed.HasFlagCustom(TYMED.TYMED_HGLOBAL))
                 Marshal.ThrowExceptionForHR(DV_E_TYMED);
 
             if (format.dwAspect != DVASPECT.DVASPECT_CONTENT)
@@ -205,7 +205,7 @@ namespace Avalonia.Win32
                 return;
             }
 
-            if (medium.tymed != TYMED.TYMED_HGLOBAL || !format.tymed.HasFlag(TYMED.TYMED_HGLOBAL))
+            if (medium.tymed != TYMED.TYMED_HGLOBAL || !format.tymed.HasFlagCustom(TYMED.TYMED_HGLOBAL))
                 Marshal.ThrowExceptionForHR(DV_E_TYMED);
 
             if (format.dwAspect != DVASPECT.DVASPECT_CONTENT)
@@ -228,7 +228,7 @@ namespace Avalonia.Win32
                 return ole.QueryGetData(ref format);
             if (format.dwAspect != DVASPECT.DVASPECT_CONTENT)
                 return DV_E_DVASPECT;
-            if (!format.tymed.HasFlag(TYMED.TYMED_HGLOBAL))
+            if (!format.tymed.HasFlagCustom(TYMED.TYMED_HGLOBAL))
                 return DV_E_TYMED;
 
             string dataFormat = ClipboardFormats.GetFormat(format.cfFormat);

src/Windows/Avalonia.Win32/Interop/UnmanagedMethods.cs

@@ -1035,6 +1035,12 @@ namespace Avalonia.Win32.Interop
         [DllImport("user32.dll")]
         public static extern IntPtr LoadCursor(IntPtr hInstance, IntPtr lpCursorName);
 
+        [DllImport("user32.dll")]
+        public static extern IntPtr CreateIconIndirect([In] ref ICONINFO iconInfo);
+
+        [DllImport("user32.dll")]
+        public static extern bool DestroyIcon(IntPtr hIcon);
+
         [DllImport("user32.dll")]
         public static extern bool PeekMessage(out MSG lpMsg, IntPtr hWnd, uint wMsgFilterMin, uint wMsgFilterMax, uint wRemoveMsg);
 
@@ -1762,6 +1768,16 @@ namespace Avalonia.Win32.Interop
             public int CyContact;
         }
 
+        [StructLayout(LayoutKind.Sequential)]
+        public struct ICONINFO
+        {
+            public bool IsIcon;
+            public int xHotspot;
+            public int yHotspot;
+            public IntPtr MaskBitmap;
+            public IntPtr ColorBitmap;
+        };
+
         [Flags]
         public enum TouchInputFlags
         {

src/Windows/Avalonia.Win32/OleDropTarget.cs

@@ -24,11 +24,11 @@ namespace Avalonia.Win32
         public static DropEffect ConvertDropEffect(DragDropEffects operation)
         {
             DropEffect result = DropEffect.None;
-            if (operation.HasFlag(DragDropEffects.Copy))
+            if (operation.HasFlagCustom(DragDropEffects.Copy))
                 result |= DropEffect.Copy;
-            if (operation.HasFlag(DragDropEffects.Move))
+            if (operation.HasFlagCustom(DragDropEffects.Move))
                 result |= DropEffect.Move;
-            if (operation.HasFlag(DragDropEffects.Link))
+            if (operation.HasFlagCustom(DragDropEffects.Link))
                 result |= DropEffect.Link;
             return result;
         }
@@ -36,11 +36,11 @@ namespace Avalonia.Win32
         public static DragDropEffects ConvertDropEffect(DropEffect effect)
         {
             DragDropEffects result = DragDropEffects.None;
-            if (effect.HasFlag(DropEffect.Copy))
+            if (effect.HasFlagCustom(DropEffect.Copy))
                 result |= DragDropEffects.Copy;
-            if (effect.HasFlag(DropEffect.Move))
+            if (effect.HasFlagCustom(DropEffect.Move))
                 result |= DragDropEffects.Move;
-            if (effect.HasFlag(DropEffect.Link))
+            if (effect.HasFlagCustom(DropEffect.Link))
                 result |= DragDropEffects.Link;
             return result;
         }
@@ -50,17 +50,17 @@ namespace Avalonia.Win32
             var modifiers = RawInputModifiers.None;
             var state = (UnmanagedMethods.ModifierKeys)grfKeyState;
 
-            if (state.HasFlag(UnmanagedMethods.ModifierKeys.MK_LBUTTON))
+            if (state.HasFlagCustom(UnmanagedMethods.ModifierKeys.MK_LBUTTON))
                 modifiers |= RawInputModifiers.LeftMouseButton;
-            if (state.HasFlag(UnmanagedMethods.ModifierKeys.MK_MBUTTON))
+            if (state.HasFlagCustom(UnmanagedMethods.ModifierKeys.MK_MBUTTON))
                 modifiers |= RawInputModifiers.MiddleMouseButton;
-            if (state.HasFlag(UnmanagedMethods.ModifierKeys.MK_RBUTTON))
+            if (state.HasFlagCustom(UnmanagedMethods.ModifierKeys.MK_RBUTTON))
                 modifiers |= RawInputModifiers.RightMouseButton;
-            if (state.HasFlag(UnmanagedMethods.ModifierKeys.MK_SHIFT))
+            if (state.HasFlagCustom(UnmanagedMethods.ModifierKeys.MK_SHIFT))
                 modifiers |= RawInputModifiers.Shift;
-            if (state.HasFlag(UnmanagedMethods.ModifierKeys.MK_CONTROL))
+            if (state.HasFlagCustom(UnmanagedMethods.ModifierKeys.MK_CONTROL))
                 modifiers |= RawInputModifiers.Control;
-            if (state.HasFlag(UnmanagedMethods.ModifierKeys.MK_ALT))
+            if (state.HasFlagCustom(UnmanagedMethods.ModifierKeys.MK_ALT))
                 modifiers |= RawInputModifiers.Alt;
             return modifiers;
         }

src/Windows/Avalonia.Win32/Win32Platform.cs

@@ -104,7 +104,7 @@ namespace Avalonia.Win32
             Options = options;
             AvaloniaLocator.CurrentMutable
                 .Bind<IClipboard>().ToSingleton<ClipboardImpl>()
-                .Bind<IStandardCursorFactory>().ToConstant(CursorFactory.Instance)
+                .Bind<ICursorFactory>().ToConstant(CursorFactory.Instance)
                 .Bind<IKeyboardDevice>().ToConstant(WindowsKeyboardDevice.Instance)
                 .Bind<IPlatformSettings>().ToConstant(s_instance)
                 .Bind<IPlatformThreadingInterface>().ToConstant(s_instance)

src/Windows/Avalonia.Win32/WindowImpl.CustomCaptionProc.cs

@@ -23,13 +23,13 @@ namespace Avalonia.Win32
             AdjustWindowRectEx(ref rcFrame, (uint)(WindowStyles.WS_OVERLAPPEDWINDOW & ~WindowStyles.WS_CAPTION), false, 0);
 
             var borderThickness = new RECT();
-            if (GetStyle().HasFlag(WindowStyles.WS_THICKFRAME))
+            if (GetStyle().HasFlagCustom(WindowStyles.WS_THICKFRAME))
             {
                 AdjustWindowRectEx(ref borderThickness, (uint)(GetStyle()), false, 0);
                 borderThickness.left *= -1;
                 borderThickness.top *= -1;
             }
-            else if (GetStyle().HasFlag(WindowStyles.WS_BORDER))
+            else if (GetStyle().HasFlagCustom(WindowStyles.WS_BORDER))
             {
                 borderThickness = new RECT { bottom = 1, left = 1, right = 1, top = 1 };
             }

src/Windows/Avalonia.Win32/WindowImpl.cs

@@ -608,14 +608,19 @@ namespace Avalonia.Win32
             SetWindowText(_hwnd, title);
         }
 
-        public void SetCursor(IPlatformHandle cursor)
+        public void SetCursor(ICursorImpl cursor)
         {
-            var hCursor = cursor?.Handle ?? DefaultCursor;
-            SetClassLong(_hwnd, ClassLongIndex.GCLP_HCURSOR, hCursor);
+            var impl = cursor as CursorImpl;
 
-            if (_owner.IsPointerOver)
+            if (cursor is null || impl is object)
             {
-                UnmanagedMethods.SetCursor(hCursor);
+                var hCursor = impl?.Handle ?? DefaultCursor;
+                SetClassLong(_hwnd, ClassLongIndex.GCLP_HCURSOR, hCursor);
+
+                if (_owner.IsPointerOver)
+                {
+                    UnmanagedMethods.SetCursor(hCursor);
+                }
             }
         }
 
@@ -831,7 +836,7 @@ namespace Avalonia.Win32
             borderCaptionThickness.left *= -1;
             borderCaptionThickness.top *= -1;
 
-            bool wantsTitleBar = _extendChromeHints.HasFlag(ExtendClientAreaChromeHints.SystemChrome) || _extendTitleBarHint == -1;
+            bool wantsTitleBar = _extendChromeHints.HasFlagCustom(ExtendClientAreaChromeHints.SystemChrome) || _extendTitleBarHint == -1;
 
             if (!wantsTitleBar)
             {
@@ -848,7 +853,7 @@ namespace Avalonia.Win32
                 borderCaptionThickness.top = (int)(_extendTitleBarHint * RenderScaling);                
             }
 
-            margins.cyTopHeight = _extendChromeHints.HasFlag(ExtendClientAreaChromeHints.SystemChrome) && !_extendChromeHints.HasFlag(ExtendClientAreaChromeHints.PreferSystemChrome) ? borderCaptionThickness.top : 1;
+            margins.cyTopHeight = _extendChromeHints.HasFlagCustom(ExtendClientAreaChromeHints.SystemChrome) && !_extendChromeHints.HasFlagCustom(ExtendClientAreaChromeHints.PreferSystemChrome) ? borderCaptionThickness.top : 1;
 
             if (WindowState == WindowState.Maximized)
             {
@@ -896,8 +901,8 @@ namespace Avalonia.Win32
                 _extendedMargins = new Thickness();
             }
 
-            if(!_isClientAreaExtended || (_extendChromeHints.HasFlag(ExtendClientAreaChromeHints.SystemChrome) &&
-                !_extendChromeHints.HasFlag(ExtendClientAreaChromeHints.PreferSystemChrome)))
+            if(!_isClientAreaExtended || (_extendChromeHints.HasFlagCustom(ExtendClientAreaChromeHints.SystemChrome) &&
+                !_extendChromeHints.HasFlagCustom(ExtendClientAreaChromeHints.PreferSystemChrome)))
             {
                 EnableCloseButton(_hwnd);
             }
@@ -1234,7 +1239,7 @@ namespace Avalonia.Win32
         public Action<bool> ExtendClientAreaToDecorationsChanged { get; set; }
         
         /// <inheritdoc/>
-        public bool NeedsManagedDecorations => _isClientAreaExtended && _extendChromeHints.HasFlag(ExtendClientAreaChromeHints.PreferSystemChrome);
+        public bool NeedsManagedDecorations => _isClientAreaExtended && _extendChromeHints.HasFlagCustom(ExtendClientAreaChromeHints.PreferSystemChrome);
 
         /// <inheritdoc/>
         public Thickness ExtendedMargins => _extendedMargins;

src/iOS/Avalonia.iOS/AvaloniaView.cs

@@ -74,7 +74,7 @@ namespace Avalonia.iOS
 
             public PixelPoint PointToScreen(Point point) => new PixelPoint((int) point.X, (int) point.Y);
 
-            public void SetCursor(IPlatformHandle cursor)
+            public void SetCursor(ICursorImpl _)
             {
                 // no-op
             }
@@ -136,4 +136,4 @@ namespace Avalonia.iOS
             set => _topLevel.Content = value;
         }
     }
-}
+}

src/iOS/Avalonia.iOS/Platform.cs

@@ -27,7 +27,7 @@ namespace Avalonia.iOS
             var softKeyboard = new SoftKeyboardHelper();
             AvaloniaLocator.CurrentMutable
                 .Bind<IPlatformOpenGlInterface>().ToConstant(GlFeature)
-                .Bind<IStandardCursorFactory>().ToConstant(new CursorFactoryStub())
+                .Bind<ICursorFactory>().ToConstant(new CursorFactoryStub())
                 .Bind<IWindowingPlatform>().ToConstant(new WindowingPlatformStub())
                 .Bind<IClipboard>().ToConstant(new ClipboardImpl())
                 .Bind<IPlatformSettings>().ToConstant(new PlatformSettings())

src/iOS/Avalonia.iOS/Stubs.cs

@@ -5,9 +5,15 @@ using Avalonia.Platform;
 
 namespace Avalonia.iOS
 {
-    class CursorFactoryStub : IStandardCursorFactory
+    class CursorFactoryStub : ICursorFactory
     {
-        public IPlatformHandle GetCursor(StandardCursorType cursorType) => new PlatformHandle(IntPtr.Zero, "NULL");
+        public ICursorImpl CreateCursor(IBitmapImpl cursor, PixelPoint hotSpot) => new CursorImplStub();
+        ICursorImpl ICursorFactory.GetCursor(StandardCursorType cursorType) => new CursorImplStub();
+
+        private class CursorImplStub : ICursorImpl
+        {
+            public void Dispose() { }
+        }
     }
 
     class WindowingPlatformStub : IWindowingPlatform
@@ -57,4 +63,4 @@ namespace Avalonia.iOS
             _ms.CopyTo(outputStream);
         }
     }
-}
+}

tests/Avalonia.Benchmarks/NullCursorFactory.cs

@@ -4,11 +4,14 @@ using Avalonia.Platform;
 
 namespace Avalonia.Benchmarks
 {
-    internal class NullCursorFactory : IStandardCursorFactory
+    internal class NullCursorFactory : ICursorFactory
     {
-        public IPlatformHandle GetCursor(StandardCursorType cursorType)
+        public ICursorImpl CreateCursor(IBitmapImpl cursor, PixelPoint hotSpot) => new NullCursorImpl();
+        ICursorImpl ICursorFactory.GetCursor(StandardCursorType cursorType) => new NullCursorImpl();
+
+        private class NullCursorImpl : ICursorImpl
         {
-            return new PlatformHandle(IntPtr.Zero, "null");
+            public void Dispose() { }
         }
     }
 }

tests/Avalonia.Controls.UnitTests/CalendarDatePickerTests.cs

@@ -74,7 +74,7 @@ namespace Avalonia.Controls.UnitTests
         }
 
         private static TestServices Services => TestServices.MockThreadingInterface.With(
-            standardCursorFactory: Mock.Of<IStandardCursorFactory>());
+            standardCursorFactory: Mock.Of<ICursorFactory>());
 
         private CalendarDatePicker CreateControl()
         {

tests/Avalonia.Controls.UnitTests/CursorFactoryMock.cs

@@ -1,14 +1,25 @@
-using System;
 using Avalonia.Input;
 using Avalonia.Platform;
 
 namespace Avalonia.Controls.UnitTests
 {
-    public class CursorFactoryMock : IStandardCursorFactory
+    public class CursorFactoryMock : ICursorFactory
     {
-        public IPlatformHandle GetCursor(StandardCursorType cursorType)
+        public ICursorImpl GetCursor(StandardCursorType cursorType)
         {
-            return new PlatformHandle(IntPtr.Zero, cursorType.ToString());
+            return new MockCursorImpl();
+        }
+
+        public ICursorImpl CreateCursor(IBitmapImpl cursor, PixelPoint hotSpot)
+        {
+            return new MockCursorImpl();
+        }
+
+        private class MockCursorImpl : ICursorImpl
+        {
+            public void Dispose()
+            {
+            }
         }
     }
 }

tests/Avalonia.Controls.UnitTests/DatePickerTests.cs

@@ -204,7 +204,7 @@ namespace Avalonia.Controls.UnitTests
 
         private static TestServices Services => TestServices.MockThreadingInterface.With(
             fontManagerImpl: new MockFontManagerImpl(),
-            standardCursorFactory: Mock.Of<IStandardCursorFactory>(),
+            standardCursorFactory: Mock.Of<ICursorFactory>(),
             textShaperImpl: new MockTextShaperImpl());
 
         private IControlTemplate CreateTemplate()

tests/Avalonia.Controls.UnitTests/GridSplitterTests.cs

@@ -11,8 +11,8 @@ namespace Avalonia.Controls.UnitTests
     {
         public GridSplitterTests()
         {
-            var cursorFactoryImpl = new Mock<IStandardCursorFactory>();
-            AvaloniaLocator.CurrentMutable.Bind<IStandardCursorFactory>().ToConstant(cursorFactoryImpl.Object);
+            var cursorFactoryImpl = new Mock<ICursorFactory>();
+            AvaloniaLocator.CurrentMutable.Bind<ICursorFactory>().ToConstant(cursorFactoryImpl.Object);
         }
 
         [Fact]

tests/Avalonia.Controls.UnitTests/MenuItemTests.cs

@@ -156,15 +156,35 @@ namespace Avalonia.Controls.UnitTests
             root.Child = null;
             Assert.Equal(0, command.SubscriptionCount);
         }
+        
+        [Fact]
+        public void MenuItem_Invokes_CanExecute_When_CommandParameter_Changed()
+        {
+            var command = new TestCommand(p => p is bool value && value);
+            var target = new MenuItem { Command = command };
+
+            target.CommandParameter = true;
+            Assert.True(target.IsEffectivelyEnabled);
+
+            target.CommandParameter = false;
+            Assert.False(target.IsEffectivelyEnabled);
+        }
 
         private class TestCommand : ICommand
         {
-            private bool _enabled;
+            private readonly Func<object, bool> _canExecute;
+            private readonly Action<object> _execute;
             private EventHandler _canExecuteChanged;
 
             public TestCommand(bool enabled = true)
+                : this(_ => enabled, _ => { })
+            {
+            }
+
+            public TestCommand(Func<object, bool> canExecute, Action<object> execute = null)
             {
-                _enabled = enabled;
+                _canExecute = canExecute;
+                _execute = execute ?? (_ => { });
             }
 
             public int SubscriptionCount { get; private set; }
@@ -175,11 +195,9 @@ namespace Avalonia.Controls.UnitTests
                 remove { _canExecuteChanged -= value; --SubscriptionCount; }
             }
 
-            public bool CanExecute(object parameter) => _enabled;
+            public bool CanExecute(object parameter) => _canExecute(parameter);
 
-            public void Execute(object parameter)
-            {
-            }
+            public void Execute(object parameter) => _execute(parameter);
         }
     }
 }

tests/Avalonia.Controls.UnitTests/TextBoxTests.cs

@@ -698,10 +698,10 @@ namespace Avalonia.Controls.UnitTests
             keyboardDevice: () => new KeyboardDevice(),
             keyboardNavigation: new KeyboardNavigationHandler(),
             inputManager: new InputManager(),
-            standardCursorFactory: Mock.Of<IStandardCursorFactory>());
+            standardCursorFactory: Mock.Of<ICursorFactory>());
 
         private static TestServices Services => TestServices.MockThreadingInterface.With(
-            standardCursorFactory: Mock.Of<IStandardCursorFactory>());
+            standardCursorFactory: Mock.Of<ICursorFactory>());
 
         private IControlTemplate CreateTemplate()
         {

tests/Avalonia.Controls.UnitTests/TextBoxTests_DataValidation.cs

@@ -86,7 +86,7 @@ namespace Avalonia.Controls.UnitTests
         }
 
         private static TestServices Services => TestServices.MockThreadingInterface.With(
-            standardCursorFactory: Mock.Of<IStandardCursorFactory>());
+            standardCursorFactory: Mock.Of<ICursorFactory>());
 
         private IControlTemplate CreateTemplate()
         {

tests/Avalonia.Controls.UnitTests/TimePickerTests.cs

@@ -100,7 +100,7 @@ namespace Avalonia.Controls.UnitTests
 
         private static TestServices Services => TestServices.MockThreadingInterface.With(
             fontManagerImpl: new MockFontManagerImpl(),
-            standardCursorFactory: Mock.Of<IStandardCursorFactory>(),
+            standardCursorFactory: Mock.Of<ICursorFactory>(),
             textShaperImpl: new MockTextShaperImpl());
 
         private IControlTemplate CreateTemplate()