Fixes #37

Author: dotMorten

src/Directory.Build.targets

@@ -12,7 +12,7 @@
     <Authors>Morten Nielsen - https://xaml.dev</Authors>
     <Company>Morten Nielsen - https://xaml.dev</Company>
     <PackageIcon>logo.png</PackageIcon>
-    <Version>1.4.0</Version>
+    <Version>1.4.1</Version>
     <WinAppSDKVersion>1.0.1</WinAppSDKVersion>
     <DefineConstants Condition="$([MSBuild]::VersionGreaterThanOrEquals('$(WinAppSDKVersion)','1.1-a'))">$(DefineConstants);WINAPPSDK_1_1_OR_NEWER</DefineConstants>
   </PropertyGroup>

src/WinUIEx/WinUIEx.csproj

@@ -18,7 +18,7 @@
     <PackageId>WinUIEx</PackageId>
     <Product>WinUI Extensions</Product>
     <PackageReleaseNotes>
-        - Added WebAuthenticator API to simplify OAuth workflows with your external browser
+        - Addresses an issue with window resizing when moving across monitors with different scaling (Issue #37).
     </PackageReleaseNotes>
   </PropertyGroup>
 

src/WinUIEx/WindowEx.cs

@@ -26,7 +26,6 @@ public partial class WindowEx : Window
         private readonly ContentControl windowArea;
         private readonly WindowMessageMonitor mon;
         private readonly Microsoft.UI.Windowing.OverlappedPresenter overlappedPresenter;
-        private uint currentDpi;
 
         /// <summary>
         /// Initializes a new instance of the <see cref="WindowEx"/> class.
@@ -35,8 +34,7 @@ public WindowEx()
         {
             overlappedPresenter = Microsoft.UI.Windowing.OverlappedPresenter.Create();
             AppWindow.SetPresenter(overlappedPresenter);
-            currentDpi = this.GetDpiForWindow();
-
+            
             var rootContent = new Grid();
             rootContent.RowDefinitions.Add(new RowDefinition() { Height = new GridLength(1, GridUnitType.Auto), MinHeight = 0 });
             rootContent.RowDefinitions.Add(new RowDefinition() { Height = new GridLength(1, GridUnitType.Star) });
@@ -77,32 +75,22 @@ private unsafe void OnWindowMessage(object? sender, Messaging.WindowMessageEvent
                     {
                         // Restrict min-size
                         MINMAXINFO* rect2 = (MINMAXINFO*)e.Message.LParam;
+                        var currentDpi = this.GetDpiForWindow();
                         rect2->ptMinTrackSize.x = (int)(Math.Max(MinWidth * (currentDpi / 96f), rect2->ptMinTrackSize.x));
                         rect2->ptMinTrackSize.y = (int)(Math.Max(MinHeight * (currentDpi / 96f), rect2->ptMinTrackSize.y));
                     }
                     break;
                 case WindowsMessages.WM_DPICHANGED:
                     {
-                        var newDpi = this.GetDpiForWindow();
-                        if (newDpi != currentDpi)
-                        {
-                            var oldDpi = currentDpi;
-                            currentDpi = newDpi;
-                            OnDpiChanged(oldDpi, newDpi);
-                        }
+                        // Resize to account for DPI change
+                        var suggestedRect = (Windows.Win32.Foundation.RECT*)e.Message.LParam;
+                        bool result = Windows.Win32.PInvoke.SetWindowPos(new Windows.Win32.Foundation.HWND(this.GetWindowHandle()), new Windows.Win32.Foundation.HWND(), suggestedRect->left, suggestedRect->top,
+                            suggestedRect->right - suggestedRect->left, suggestedRect->bottom - suggestedRect->top, Windows.Win32.UI.WindowsAndMessaging.SET_WINDOW_POS_FLAGS.SWP_NOZORDER | Windows.Win32.UI.WindowsAndMessaging.SET_WINDOW_POS_FLAGS.SWP_NOACTIVATE);
                         break;
                     }
             }
         }
 
-        private void OnDpiChanged(uint oldDpi, uint newDpi)
-        {
-            var oldScale = oldDpi / 96f;
-            var currentSize = AppWindow.Size;
-            this.SetWindowSize((int)(currentSize.Width / oldScale), (int)(currentSize.Height / oldScale));
-            currentDpi = newDpi;
-        }
-
         private struct MINMAXINFO
         {
 #pragma warning disable CS0649
@@ -408,7 +396,7 @@ public Microsoft.UI.Windowing.AppWindowPresenterKind PresenterKind
         /// </summary>
         public double Width
         {
-            get { return AppWindow.Size.Width / (currentDpi / 96d); }
+            get { return AppWindow.Size.Width / (this.GetDpiForWindow() / 96d); }
             set
             {
                 this.SetWindowSize(value, Height);
@@ -420,7 +408,7 @@ public double Width
         /// </summary>
         public double Height
         {
-            get { return AppWindow.Size.Height / (currentDpi / 96d); }
+            get { return AppWindow.Size.Height / (this.GetDpiForWindow() / 96d); }
             set
             {
                 this.SetWindowSize(Width, value);