From 0f1f63eda8e82313aad6cb84305dcef37ccca36d Mon Sep 17 00:00:00 2001
From: Fellippe Heitor <fellippeheitor@gmail.com>
Date: Mon, 6 Jan 2020 12:09:15 -0300
Subject: [PATCH] Detects Retina displays on macOS for proper scaling.

---
 internal/c/libqb/gui.cpp | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/internal/c/libqb/gui.cpp b/internal/c/libqb/gui.cpp
index ba4905a99..2e8e5a3f5 100644
--- a/internal/c/libqb/gui.cpp
+++ b/internal/c/libqb/gui.cpp
@@ -525,7 +525,18 @@ void sub__glrender(int32 method){
             
             
             if (render_state.dest_handle==0){
-                static int32 dst_w,dst_h;
+                static int32 dst_w,dst_h;
+                static int32 scale_factor=0;
+
+                #ifdef QB64_MACOSX
+                    if (scale_factor==0) {
+                        scale_factor=1;
+                        if (system("system_profiler SPDisplaysDataType | grep Retina")==0) scale_factor=2;
+                    }
+                #else
+                    scale_factor=1;
+                #endif
+
                 dst_w=environment__window_width;
                 dst_h=environment__window_height;
                 
@@ -539,7 +550,7 @@ void sub__glrender(int32 method){
                 glLoadIdentity();
                 glScalef(1, -1, 1);//flip vertically
                 glTranslatef(0, -dst_h, 0);//move to new vertical position
-                glViewport(0,0,dst_w,dst_h);
+                glViewport(0,0,dst_w * scale_factor,dst_h * scale_factor);
                 
                 
                 }else{