From 888e01c166bf595c8cbb6cfb66bedce9c0d45b04 Mon Sep 17 00:00:00 2001
From: V380-Ori <infiniteloop0finsanity@gmail.com>
Date: Sun, 9 Nov 2025 14:33:15 +0200
Subject: [PATCH] Avalonia: fix HiDPI/Retina scaling for embedded window on
 macOS.

---
 src/Ryujinx.Common/Helpers/ObjectiveC.cs  | 8 ++++++++
 src/Ryujinx/UI/Renderer/EmbeddedWindow.cs | 9 +++++++--
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/src/Ryujinx.Common/Helpers/ObjectiveC.cs b/src/Ryujinx.Common/Helpers/ObjectiveC.cs
index 4c2481f6e..b7c7ffb62 100644
--- a/src/Ryujinx.Common/Helpers/ObjectiveC.cs
+++ b/src/Ryujinx.Common/Helpers/ObjectiveC.cs
@@ -42,6 +42,9 @@ namespace Ryujinx.Common.Helper
         [return: MarshalAs(UnmanagedType.Bool)]
         private static partial bool bool_objc_msgSend(nint receiver, Selector selector, nint param);
 
+        [LibraryImport(ObjCRuntime, EntryPoint = "objc_msgSend")]
+        private static partial double double_objc_msgSend(nint receiver, Selector selector);
+
         public readonly struct Object
         {
             public readonly nint ObjPtr;
@@ -105,6 +108,11 @@ namespace Ryujinx.Common.Helper
             {
                 return bool_objc_msgSend(ObjPtr, selector, obj.ObjPtr);
             }
+
+            public double GetDoubleFromMessage(string selectorName)
+            {
+                return double_objc_msgSend(ObjPtr, selectorName);
+            }
         }
 
         public readonly struct Selector
diff --git a/src/Ryujinx/UI/Renderer/EmbeddedWindow.cs b/src/Ryujinx/UI/Renderer/EmbeddedWindow.cs
index e360d42f7..fa212046a 100644
--- a/src/Ryujinx/UI/Renderer/EmbeddedWindow.cs
+++ b/src/Ryujinx/UI/Renderer/EmbeddedWindow.cs
@@ -186,12 +186,17 @@ namespace Ryujinx.Ava.UI.Renderer
             // Make its renderer our metal layer.
             child.SendMessage("setWantsLayer:", 1);
             child.SendMessage("setLayer:", metalLayer);
-            metalLayer.SendMessage("setContentsScale:", Program.DesktopScaleFactor);
+
+            double initialScaleFactor = child.GetDoubleFromMessage("backingScaleFactor");
+
+            metalLayer.SendMessage("setContentsScale:", initialScaleFactor);
 
             // Ensure the scale factor is up to date.
             _updateBoundsCallback = rect =>
             {
-                metalLayer.SendMessage("setContentsScale:", Program.DesktopScaleFactor);
+                double currentScaleFactor = child.GetDoubleFromMessage("backingScaleFactor");
+
+                metalLayer.SendMessage("setContentsScale:", currentScaleFactor);
             };
 
             nint nsView = child.ObjPtr;