Fix Win32 window size constraints

fixes + revert testing changes

src/Avalonia.Controls/Platform/IWindowBaseImpl.cs

@@ -55,7 +55,7 @@ namespace Avalonia.Platform
         /// Gets the platform window handle.
         /// </summary>
         IPlatformHandle Handle { get; }
-        
+       
         /// <summary>
         /// Gets the maximum size of a window on the system.
         /// </summary>
@@ -65,7 +65,27 @@ namespace Avalonia.Platform
         /// Sets the client size of the toplevel.
         /// </summary>
         void Resize(Size clientSize);
-        
+
+        /// <summary>
+        /// Minimum width of the window.
+        /// </summary>
+        double MinWidth { get; set; }
+
+        /// <summary>
+        /// Maximum width of the window.
+        /// </summary>
+        double MaxWidth { get; set; }
+
+        /// <summary>
+        /// Minimum height of the window.
+        /// </summary>
+        double MinHeight { get; set; }
+
+        /// <summary>
+        /// Maximum height of the window.
+        /// </summary>
+        double MaxHeight { get; set; }
+
         /// <summary>
         /// Gets platform specific display information
         /// </summary>

src/Avalonia.Controls/WindowBase.cs

@@ -197,7 +197,14 @@ namespace Avalonia.Controls
         {
             using (BeginAutoSizing())
             {
-                PlatformImpl?.Resize(finalSize);
+                if (PlatformImpl != null)
+                {
+                    PlatformImpl.MinHeight = MinHeight;
+                    PlatformImpl.MaxHeight = MaxHeight;
+                    PlatformImpl.MinWidth = MinWidth;
+                    PlatformImpl.MaxWidth = MaxWidth;
+                    PlatformImpl.Resize(finalSize);
+                }
             }
 
             return base.ArrangeOverride(PlatformImpl?.ClientSize ?? default(Size));

src/Avalonia.DesignerSupport/Remote/PreviewerWindowImpl.cs

@@ -67,6 +67,14 @@ namespace Avalonia.DesignerSupport.Remote
             RenderIfNeeded();
         }
 
+        public double MinWidth { get; set; }
+
+        public double MaxWidth { get; set; }
+
+        public double MinHeight { get; set; }
+
+        public double MaxHeight { get; set; }
+
         public IScreenImpl Screen { get; } = new ScreenStub();
 
         public void Activate()

src/Avalonia.DesignerSupport/Remote/Stubs.cs

@@ -78,6 +78,14 @@ namespace Avalonia.DesignerSupport.Remote
 
         public IScreenImpl Screen { get; } = new ScreenStub();
 
+        public double MinWidth { get; set; }
+
+        public double MaxWidth { get; set; }
+
+        public double MinHeight { get; set; }
+
+        public double MaxHeight { get; set; }
+
         public void SetTitle(string title)
         {
         }

src/Gtk/Avalonia.Gtk3/WindowBaseImpl.cs

@@ -341,6 +341,14 @@ namespace Avalonia.Gtk3
             }
         }
 
+        public double MinWidth { get; set; }
+
+        public double MaxWidth { get; set; }
+
+        public double MinHeight { get; set; }
+
+        public double MaxHeight { get; set; }
+
         public IMouseDevice MouseDevice => Gtk3Platform.Mouse;
 
         public double Scaling => LastKnownScaleFactor = (int) (Native.GtkWidgetGetScaleFactor?.Invoke(GtkWidget) ?? 1);

src/OSX/Avalonia.MonoMac/WindowBaseImpl.cs

@@ -161,6 +161,14 @@ namespace Avalonia.MonoMac
             Position = pos;
         }
 
+        public double MinWidth { get; set; }
+
+        public double MaxWidth { get; set; }
+
+        public double MinHeight { get; set; }
+
+        public double MaxHeight { get; set; }
+
         public IScreenImpl Screen
         {
             get;

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

@@ -615,6 +615,16 @@ namespace Avalonia.Win32.Interop
             public uint[] cols;
         }
 
+        [StructLayout(LayoutKind.Sequential)]
+        public struct MINMAXINFO
+        {
+            public POINT ptReserved;
+            public POINT ptMaxSize;
+            public POINT ptMaxPosition;
+            public POINT ptMinTrackSize;
+            public POINT ptMaxTrackSize;
+        }
+
         public const int SizeOf_BITMAPINFOHEADER = 40;
 
         [DllImport("user32.dll")]

src/Windows/Avalonia.Win32/WindowImpl.cs

@@ -102,6 +102,14 @@ namespace Avalonia.Win32
             }
         }
 
+        public double MinWidth { get; set; }
+
+        public double MaxWidth { get; set; }
+
+        public double MinHeight { get; set; }
+
+        public double MaxHeight { get; set; }
+
         public IScreenImpl Screen
         {
             get;
@@ -611,7 +619,26 @@ namespace Avalonia.Win32
                 case UnmanagedMethods.WindowsMessage.WM_MOVE:
                     PositionChanged?.Invoke(new Point((short)(ToInt32(lParam) & 0xffff), (short)(ToInt32(lParam) >> 16)));
                     return IntPtr.Zero;
-                    
+
+                case UnmanagedMethods.WindowsMessage.WM_GETMINMAXINFO:
+
+                    MINMAXINFO mmi = Marshal.PtrToStructure<UnmanagedMethods.MINMAXINFO>(lParam);
+
+                    if  (MinWidth > 0)
+                        mmi.ptMinTrackSize.X = (int)((MinWidth * Scaling) + BorderThickness.Left + BorderThickness.Right);
+
+                    if (MinHeight > 0)
+                        mmi.ptMinTrackSize.Y = (int)((MinHeight * Scaling) + BorderThickness.Top + BorderThickness.Bottom);
+
+                    if (!Double.IsInfinity(MaxWidth) && MaxWidth > 0)
+                        mmi.ptMaxTrackSize.X = (int)((MaxWidth * Scaling) + BorderThickness.Left + BorderThickness.Right);
+
+                    if (!Double.IsInfinity(MaxHeight) && MaxHeight > 0)
+                        mmi.ptMaxTrackSize.Y = (int)((MaxHeight * Scaling) + BorderThickness.Top + BorderThickness.Bottom);
+
+                    Marshal.StructureToPtr(mmi, lParam, true);
+                    return IntPtr.Zero;
+
                 case UnmanagedMethods.WindowsMessage.WM_DISPLAYCHANGE:
                     (Screen as ScreenImpl)?.InvalidateScreensCache();
                     return IntPtr.Zero;