From 89b5d13408cca05ec939474d78a8499b6ec4fa8c Mon Sep 17 00:00:00 2001
From: Dan Walmsley <dan@walms.co.uk>
Date: Sat, 21 Nov 2020 23:01:57 +0000
Subject: [PATCH 1/2] [OSX] remove most of the stretching and flickering by
 calling updateLayer at the end of resize.

---
 native/Avalonia.Native/src/OSX/rendertarget.mm | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/native/Avalonia.Native/src/OSX/rendertarget.mm b/native/Avalonia.Native/src/OSX/rendertarget.mm
index 93a33bbbb0..6643c5c089 100644
--- a/native/Avalonia.Native/src/OSX/rendertarget.mm
+++ b/native/Avalonia.Native/src/OSX/rendertarget.mm
@@ -143,13 +143,17 @@ static IAvnGlSurfaceRenderTarget* CreateGlRenderTarget(IOSurfaceRenderTarget* ta
     return _layer;
 }
 
-- (void)resize:(AvnPixelSize)size withScale: (float) scale;{
+- (void)resize:(AvnPixelSize)size withScale: (float) scale{
     @synchronized (lock) {
         if(surface == nil
            || surface->size.Width != size.Width
            || surface->size.Height != size.Height
            || surface->scale != scale)
+        {
             surface = [[IOSurfaceHolder alloc] initWithSize:size withScale:scale withOpenGlContext:_glContext.getRaw()];
+            
+            [self updateLayer];
+        }
     }
 }
 

From d96bfe6996d7c8a3f42186f907134c4952f20466 Mon Sep 17 00:00:00 2001
From: Dan Walmsley <dan@walms.co.uk>
Date: Sat, 21 Nov 2020 23:02:32 +0000
Subject: [PATCH 2/2] Remove last bit of flickering by wrapping layer updates
 inside a CATransaction.

---
 native/Avalonia.Native/src/OSX/rendertarget.mm | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/native/Avalonia.Native/src/OSX/rendertarget.mm b/native/Avalonia.Native/src/OSX/rendertarget.mm
index 6643c5c089..00b6dab219 100644
--- a/native/Avalonia.Native/src/OSX/rendertarget.mm
+++ b/native/Avalonia.Native/src/OSX/rendertarget.mm
@@ -2,6 +2,7 @@
 #include "rendertarget.h"
 #import <IOSurface/IOSurface.h>
 #import <IOSurface/IOSurfaceObjC.h>
+#import <QuartzCore/QuartzCore.h>
 
 #include <OpenGL/CGLIOSurface.h>
 #include <OpenGL/OpenGL.h>
@@ -163,12 +164,15 @@ static IAvnGlSurfaceRenderTarget* CreateGlRenderTarget(IOSurfaceRenderTarget* ta
         @synchronized (lock) {
             if(_layer == nil)
                 return;
+            [CATransaction begin];
             [_layer setContents: nil];
             if(surface != nil)
             {
                 [_layer setContentsScale: surface->scale];
                 [_layer setContents: (__bridge IOSurface*) surface->surface];
             }
+            [CATransaction commit];
+            [CATransaction flush];
         }
     }
     else