Make FrameSize nullable

src/Android/Avalonia.Android/Platform/SkiaPlatform/TopLevelImpl.cs

@@ -55,7 +55,7 @@ namespace Avalonia.Android.Platform.SkiaPlatform
 
         public virtual Size ClientSize => Size.ToSize(RenderScaling);
 
-        public Size FrameSize => ClientSize;
+        public Size? FrameSize => null;
 
         public IMouseDevice MouseDevice { get; } = new MouseDevice();
 

src/Avalonia.Controls/ApiCompatBaseline.txt

@@ -11,6 +11,6 @@ EnumValuesMustMatch : Enum value 'Avalonia.Platform.ExtendClientAreaChromeHints
 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.
-InterfacesShouldHaveSameMembers : Interface member 'public Avalonia.Size Avalonia.Platform.ITopLevelImpl.FrameSize' is present in the implementation but not in the contract.
-InterfacesShouldHaveSameMembers : Interface member 'public Avalonia.Size Avalonia.Platform.ITopLevelImpl.FrameSize.get()' is present in the implementation but not in the contract.
+InterfacesShouldHaveSameMembers : Interface member 'public System.Nullable<Avalonia.Size> Avalonia.Platform.ITopLevelImpl.FrameSize' is present in the implementation but not in the contract.
+InterfacesShouldHaveSameMembers : Interface member 'public System.Nullable<Avalonia.Size> Avalonia.Platform.ITopLevelImpl.FrameSize.get()' is present in the implementation but not in the contract.
 Total Issues: 14

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

@@ -35,7 +35,7 @@ namespace Avalonia.Controls.Embedding.Offscreen
             }
         }
 
-        public Size FrameSize => _clientSize;
+        public Size? FrameSize => null;
 
         public double RenderScaling
         {

src/Avalonia.Controls/Platform/ITopLevelImpl.cs

@@ -25,7 +25,7 @@ namespace Avalonia.Platform
         /// <summary>
         /// Gets the total size of the toplevel, excluding shadows.
         /// </summary>
-        Size FrameSize { get; }
+        Size? FrameSize { get; }
 
         /// <summary>
         /// Gets the scaling factor for the toplevel. This is used for rendering.

src/Avalonia.Controls/TopLevel.cs

@@ -45,8 +45,8 @@ namespace Avalonia.Controls
         /// <summary>
         /// Defines the <see cref="FrameSize"/> property.
         /// </summary>
-        public static readonly DirectProperty<TopLevel, Size> FrameSizeProperty =
-            AvaloniaProperty.RegisterDirect<TopLevel, Size>(nameof(FrameSize), o => o.FrameSize);
+        public static readonly DirectProperty<TopLevel, Size?> FrameSizeProperty =
+            AvaloniaProperty.RegisterDirect<TopLevel, Size?>(nameof(FrameSize), o => o.FrameSize);
 
         /// <summary>
         /// Defines the <see cref="IInputRoot.PointerOverElement"/> property.
@@ -80,7 +80,7 @@ namespace Avalonia.Controls
         private readonly IPlatformRenderInterface _renderInterface;
         private readonly IGlobalStyles _globalStyles;
         private Size _clientSize;
-        private Size _frameSize;
+        private Size? _frameSize;
         private WindowTransparencyLevel _actualTransparencyLevel;
         private ILayoutManager _layoutManager;
         private Border _transparencyFallbackBorder;
@@ -208,7 +208,7 @@ namespace Avalonia.Controls
         /// <summary>
         /// Gets or sets the total size of the window.
         /// </summary>
-        public Size FrameSize
+        public Size? FrameSize
         {
             get { return _frameSize; }
             protected set { SetAndRaise(FrameSizeProperty, ref _frameSize, value); }

src/Avalonia.DesignerSupport/Remote/Stubs.cs

@@ -21,7 +21,7 @@ namespace Avalonia.DesignerSupport.Remote
         public IPlatformHandle Handle { get; }
         public Size MaxAutoSizeHint { get; }
         public Size ClientSize { get; }
-        public Size FrameSize => ClientSize;
+        public Size? FrameSize => null;
         public double RenderScaling { get; } = 1.0;
         public double DesktopScaling => 1.0;
         public IEnumerable<object> Surfaces { get; }

src/Avalonia.Headless/HeadlessWindowImpl.cs

@@ -41,7 +41,7 @@ namespace Avalonia.Headless
         }
 
         public Size ClientSize { get; set; }
-        public Size FrameSize => ClientSize;
+        public Size? FrameSize => null;
         public double RenderScaling { get; } = 1;
         public double DesktopScaling => RenderScaling;
         public IEnumerable<object> Surfaces { get; }

src/Avalonia.Native/WindowImplBase.cs

@@ -104,7 +104,7 @@ namespace Avalonia.Native
             }
         }
 
-        public Size FrameSize
+        public Size? FrameSize
         {
             get
             {

src/Avalonia.X11/X11Window.cs

@@ -297,7 +297,7 @@ namespace Avalonia.X11
 
         public Size ClientSize => new Size(_realSize.Width / RenderScaling, _realSize.Height / RenderScaling);
 
-        public Size FrameSize
+        public Size? FrameSize
         {
             get
             {
@@ -308,7 +308,7 @@ namespace Avalonia.X11
                 if (nitems.ToInt64() != 4)
                 {
                     // Window hasn't been mapped by the WM yet, so can't get the extents.
-                    return ClientSize;
+                    return null;
                 }
 
                 var data = (IntPtr*)prop.ToPointer();

src/Linux/Avalonia.LinuxFramebuffer/FramebufferToplevelImpl.cs

@@ -62,7 +62,7 @@ namespace Avalonia.LinuxFramebuffer
         }
 
         public Size ClientSize => ScaledSize;
-        public Size FrameSize => ClientSize;
+        public Size? FrameSize => null;
         public IMouseDevice MouseDevice => new MouseDevice();
         public IPopupImpl CreatePopup() => null;
 

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

@@ -100,7 +100,7 @@ namespace Avalonia.Win32.Interop.Wpf
         }
 
         Size ITopLevelImpl.ClientSize => _finalSize;
-        Size ITopLevelImpl.FrameSize => _finalSize;
+        Size? ITopLevelImpl.FrameSize => null;
         IMouseDevice ITopLevelImpl.MouseDevice => _mouse;
 
         double ITopLevelImpl.RenderScaling => PresentationSource.FromVisual(this)?.CompositionTarget?.TransformToDevice.M11 ?? 1;

src/Windows/Avalonia.Win32/WindowImpl.cs

@@ -213,7 +213,7 @@ namespace Avalonia.Win32
             }
         }
 
-        public Size FrameSize
+        public Size? FrameSize
         {
             get
             {

src/iOS/Avalonia.iOS/AvaloniaView.cs

@@ -91,7 +91,7 @@ namespace Avalonia.iOS
             }
 
             public Size ClientSize => new Size(_view.Bounds.Width, _view.Bounds.Height);
-            public Size FrameSize => ClientSize;
+            public Size? FrameSize => null;
             public double RenderScaling => _view.ContentScaleFactor;
             public IEnumerable<object> Surfaces { get; set; }
             public Action<RawInputEventArgs> Input { get; set; }

tests/Avalonia.UnitTests/MockWindowingPlatform.cs

@@ -29,7 +29,6 @@ namespace Avalonia.UnitTests
 
             windowImpl.SetupAllProperties();
             windowImpl.Setup(x => x.ClientSize).Returns(() => clientSize);
-            windowImpl.Setup(x => x.FrameSize).Returns(() => clientSize);
             windowImpl.Setup(x => x.MaxAutoSizeHint).Returns(s_screenSize);
             windowImpl.Setup(x => x.DesktopScaling).Returns(1);
             windowImpl.Setup(x => x.RenderScaling).Returns(1);