From 67c45eab1f8464fad787a7b57bfbd60231469e37 Mon Sep 17 00:00:00 2001
From: Dan Walmsley <dan@walms.co.uk>
Date: Thu, 11 Oct 2018 21:55:29 +0100
Subject: [PATCH] auto select a suitable titlebar foreground based on
 background text.

---
 src/Avalonia.Native.OSX/window.mm | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/Avalonia.Native.OSX/window.mm b/src/Avalonia.Native.OSX/window.mm
index debc8d7e1a..f61c2b42bc 100644
--- a/src/Avalonia.Native.OSX/window.mm
+++ b/src/Avalonia.Native.OSX/window.mm
@@ -981,6 +981,17 @@ private:
             
             auto nscolor = [NSColor colorWithSRGBRed:r green:g blue:b alpha:a];
             
+            // Based on the titlebar color we have to choose either light or dark
+            // OSX doesnt let you set a foreground color for titlebar.
+            if ((r*0.299 + g*0.587 + b*0.114) > 186.0f / 255.0f)
+            {
+                [Window setAppearance:[NSAppearance appearanceNamed:NSAppearanceNameVibrantLight]];
+            }
+            else
+            {
+                [Window setAppearance:[NSAppearance appearanceNamed:NSAppearanceNameVibrantDark]];
+            }
+            
             [Window setTitlebarAppearsTransparent:true];
             [Window setBackgroundColor:nscolor];
         }