Added managed BeginResizeDrag implementation

samples/ControlCatalog/DecoratedWindow.xaml.cs

@@ -33,8 +33,8 @@ namespace ControlCatalog
             };
             SetupSide("Left", StandardCursorType.LeftSide, WindowEdge.West);
             SetupSide("Right", StandardCursorType.RightSide, WindowEdge.East);
-            SetupSide("Top", StandardCursorType.TopSide, WindowEdge.South);
-            SetupSide("Bottom", StandardCursorType.BottomSize, WindowEdge.North);
+            SetupSide("Top", StandardCursorType.TopSide, WindowEdge.North);
+            SetupSide("Bottom", StandardCursorType.BottomSize, WindowEdge.South);
             SetupSide("TopLeft", StandardCursorType.TopLeftCorner, WindowEdge.NorthWest);
             SetupSide("TopRight", StandardCursorType.TopRightCorner, WindowEdge.NorthEast);
             SetupSide("BottomLeft", StandardCursorType.BottomLeftCorner, WindowEdge.SouthWest);

src/OSX/Avalonia.MonoMac/Avalonia.MonoMac.csproj

@@ -3,6 +3,9 @@
     <TargetFrameworks>netstandard2.0</TargetFrameworks>
     <AllowUnsafeBlocks>True</AllowUnsafeBlocks>
   </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="..\..\Shared\WindowResizeDragHelper.cs" Link="WindowResizeDragHelper.cs" />
+  </ItemGroup>
   <ItemGroup>
     <PackageReference Include="MonoMac.NetStandard" Version="0.0.3" />
   </ItemGroup>

src/OSX/Avalonia.MonoMac/TopLevelImpl.cs

@@ -22,6 +22,11 @@ namespace Avalonia.MonoMac
             View = new TopLevelView(this);
         }
 
+        protected virtual void OnInput(RawInputEventArgs args)
+        {
+            Input?.Invoke(args);
+        }
+
         [Adopts("NSTextInputClient")]
         public class TopLevelView : NSView
         {
@@ -135,11 +140,11 @@ namespace Avalonia.MonoMac
                     if (delta.X == 0 && delta.Y == 0)
                         return;
                     // ReSharper restore CompareOfFloatsByEqualityOperator
-                    _tl.Input?.Invoke(new RawMouseWheelEventArgs(_mouse, ts, _tl.InputRoot, loc,
+                    _tl.OnInput(new RawMouseWheelEventArgs(_mouse, ts, _tl.InputRoot, loc,
                         delta, mod));
                 }
                 else
-                    _tl.Input?.Invoke(new RawMouseEventArgs(_mouse, ts, _tl.InputRoot, type, loc, mod));
+                    _tl.OnInput(new RawMouseEventArgs(_mouse, ts, _tl.InputRoot, type, loc, mod));
             }
 
             public override void MouseMoved(NSEvent theEvent)
@@ -229,7 +234,7 @@ namespace Avalonia.MonoMac
                 var code = KeyTransform.TransformKeyCode(ev.KeyCode);
                 if (!code.HasValue)
                     return;
-                _tl.Input?.Invoke(new RawKeyEventArgs(_keyboard, GetTimeStamp(ev),
+                _tl.OnInput(new RawKeyEventArgs(_keyboard, GetTimeStamp(ev),
                     type, code.Value, GetModifiers(ev.ModifierFlags)));
             }
 
@@ -294,7 +299,7 @@ namespace Avalonia.MonoMac
             public void InsertText(NSString str, NSRange range)
             {
                 //TODO: timestamp
-                _tl.Input?.Invoke(new RawTextInputEventArgs(_keyboard, 0, str.ToString()));
+                _tl.OnInput(new RawTextInputEventArgs(_keyboard, 0, str.ToString()));
             }
 
             [Export("characterIndexForPoint:")]

src/OSX/Avalonia.MonoMac/WindowBaseImpl.cs

@@ -1,5 +1,6 @@
 using System;
 using Avalonia.Controls;
+using Avalonia.Input.Raw;
 using Avalonia.Platform;
 using MonoMac.AppKit;
 using MonoMac.CoreGraphics;
@@ -9,10 +10,12 @@ namespace Avalonia.MonoMac
 {
     class WindowBaseImpl : TopLevelImpl, IWindowBaseImpl
     {
+        private readonly ManagedWindowResizeDragHelper _managedDrag;
         public CustomWindow Window { get; private set; }
 
         public WindowBaseImpl()
         {
+            _managedDrag = new ManagedWindowResizeDragHelper(this, _ => { }, ResizeForManagedDrag);
             Window = new CustomWindow(this)
             {
                 StyleMask = NSWindowStyle.Titled,
@@ -92,7 +95,7 @@ namespace Avalonia.MonoMac
         public Point Position
         {
             get => Window.Frame.ToAvaloniaRect().BottomLeft.ConvertPointY();
-            set => Window.CascadeTopLeftFromPoint(value.ToMonoMacPoint().ConvertPointY());
+            set => Window.SetFrameTopLeftPoint(value.ToMonoMacPoint().ConvertPointY());
         }
 
 
@@ -126,11 +129,25 @@ namespace Avalonia.MonoMac
 
         public void BeginResizeDrag(WindowEdge edge)
         {
-            //TODO: Intercept mouse events and implement resize drag manually
+            var screenPoint = NSEvent.CurrentMouseLocation.ConvertPointY().ToAvaloniaPoint();
+            _managedDrag.BeginResizeDrag(edge, PointToClient(screenPoint));
+        }
+
+        protected override void OnInput(RawInputEventArgs args)
+        {
+            if (_managedDrag.PreprocessInputEvent(ref args))
+                return;
+            base.OnInput(args);
         }
 
         public void Activate() => Window.MakeKeyWindow();
 
+        public void ResizeForManagedDrag(Rect rc)
+        {
+            var frame = new CGRect(rc.X, rc.Position.ConvertPointY().Y - rc.Height, rc.Width, rc.Height);
+            Window.SetFrame(frame, true);
+        }
+
         public void Resize(Size clientSize)
         {
             var pos = Position;

src/Shared/WindowResizeDragHelper.cs

@@ -0,0 +1,85 @@
+using System;
+using Avalonia.Controls;
+using Avalonia.Input;
+using Avalonia.Input.Raw;
+using Avalonia.Platform;
+
+namespace Avalonia
+{
+    internal class ManagedWindowResizeDragHelper
+    {
+        private readonly IWindowBaseImpl _window;
+        private readonly Action<bool> _captureMouse;
+        private readonly Action<Rect> _resize;
+        private WindowEdge? _edge;
+        private Point _prevPoint;
+
+        public ManagedWindowResizeDragHelper(IWindowBaseImpl window, Action<bool> captureMouse, Action<Rect> resize = null)
+        {
+            _window = window;
+            _captureMouse = captureMouse;
+            _resize = resize;
+        }
+
+        public void BeginResizeDrag(WindowEdge edge, Point currentMousePosition)
+        {
+            _captureMouse(true);
+            _prevPoint = currentMousePosition;
+            _edge = edge;
+        }
+
+        public bool PreprocessInputEvent(ref RawInputEventArgs e)
+        {
+            if (_edge == null)
+                return false;
+            if (e is RawMouseEventArgs args)
+            {
+                if (args.Type == RawMouseEventType.LeftButtonUp)
+                {
+                    _edge = null;
+                    _captureMouse(false);
+                }
+                if (args.Type == RawMouseEventType.Move)
+                {
+                    MoveWindow(args.Position);
+                    return true;
+                }
+
+
+                _edge = null;
+            }
+
+            return false;
+        }
+
+        private void MoveWindow(Point position)
+        {
+            var diff = position - _prevPoint;
+            var edge = _edge.Value;
+            var rc = new Rect(_window.Position, _window.ClientSize);
+            if (edge == WindowEdge.East || edge == WindowEdge.NorthEast || edge == WindowEdge.SouthEast)
+            {
+                rc = rc.WithWidth(rc.Width + diff.X);
+                _prevPoint = _prevPoint.WithX(position.X);
+            }
+            if (edge == WindowEdge.West || edge == WindowEdge.NorthWest || edge == WindowEdge.SouthWest)
+                rc = rc.WithX(rc.X + diff.X).WithWidth(rc.Width - diff.X);
+            if (edge == WindowEdge.South || edge == WindowEdge.SouthWest || edge == WindowEdge.SouthEast)
+            {
+                rc = rc.WithHeight(rc.Height + diff.Y);
+                _prevPoint = _prevPoint.WithY(position.Y);
+            }
+            if (edge == WindowEdge.North || edge == WindowEdge.NorthWest || edge == WindowEdge.NorthEast)
+                rc = rc.WithY(rc.Y + diff.Y).WithHeight(rc.Height - diff.Y);
+            if (_resize != null)
+                _resize(rc);
+            else
+            {
+                if (_window.Position != rc.Position)
+                    _window.Position = rc.Position;
+                if (_window.ClientSize != rc.Size)
+                    _window.Resize(rc.Size);
+            }
+        }
+    }
+}

src/Windows/Avalonia.Win32/Avalonia.Win32.Shared.projitems

@@ -24,6 +24,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)Win32Platform.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)WindowFramebuffer.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)WindowImpl.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)..\..\Shared\WindowResizeDragHelper.cs" />
     <Compile Include="..\..\Shared\SharedAssemblyInfo.cs">
       <Link>Properties\SharedAssemblyInfo.cs</Link>
     </Compile>

src/Windows/Avalonia.Win32/WindowImpl.cs

@@ -38,9 +38,21 @@ namespace Avalonia.Win32
         private double _scaling = 1;
         private WindowState _showWindowState;
         private FramebufferManager _framebuffer;
+#if USE_MANAGED_DRAG
+        private readonly ManagedWindowResizeDragHelper _managedDrag;
+#endif
 
         public WindowImpl()
         {
+#if USE_MANAGED_DRAG
+            _managedDrag = new ManagedWindowResizeDragHelper(this, capture =>
+            {
+                if (capture)
+                    UnmanagedMethods.SetCapture(Handle.Handle);
+                else
+                    UnmanagedMethods.ReleaseCapture();
+            });
+#endif
             CreateWindow();
             _framebuffer = new FramebufferManager(_hwnd);
             s_instances.Add(this);
@@ -327,8 +339,12 @@ namespace Avalonia.Win32
 
         public void BeginResizeDrag(WindowEdge edge)
         {
+#if USE_MANAGED_DRAG
+            _managedDrag.BeginResizeDrag(edge, ScreenToClient(MouseDevice.Position));
+#else
             UnmanagedMethods.DefWindowProc(_hwnd, (int)UnmanagedMethods.WindowsMessage.WM_NCLBUTTONDOWN,
                 new IntPtr((int)EdgeDic[edge]), IntPtr.Zero);
+#endif
         }
 
         public Point Position
@@ -583,6 +599,11 @@ namespace Avalonia.Win32
                     PositionChanged?.Invoke(new Point((short)(ToInt32(lParam) & 0xffff), (short)(ToInt32(lParam) >> 16)));
                     return IntPtr.Zero;
             }
+#if USE_MANAGED_DRAG
+
+            if (_managedDrag.PreprocessInputEvent(ref e))
+                return UnmanagedMethods.DefWindowProc(hWnd, msg, wParam, lParam);
+#endif
 
             if (e != null && Input != null)
             {