bug#28222: [PATCH] Use thin font smoothing in macOS

[Ben Bonfil <bonfil@gmail.com>]

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Hello,

Attached is a small patch that enables thin font smoothing on macOS, just
like in iTerm2.
It is toggled by a new variable called ns-use-thin-smoothing.

Tested only on macOS Sierra (10.12.6)

Thanks,
Ben

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From ba01cb956284193d41b9cf6b3a260385fa367039 Mon Sep 17 00:00:00 2001
From: Ben Bonfil <bonfil@gmail.com>
Date: Thu, 24 Aug 2017 12:59:50 +0200
Subject: [PATCH] Enable thin font smoothing in macOS

* src/nsterm.m (syms_of_nsterm): Define var ns-use-thin-smoothing.
* src/macfont.m (macfont_draw): Use font smoothing.
---
 src/macfont.m | 5 +++++
 src/nsterm.m  | 4 ++++
 2 files changed, 9 insertions(+)

diff --git a/src/macfont.m b/src/macfont.m
index 19145f92c0..8a4d0fa481 100644
--- a/src/macfont.m
+++ b/src/macfont.m
@@ -2888,6 +2888,11 @@ So we use CTFontDescriptorCreateMatchingFontDescriptor (no
       if (no_antialias_p)
         CGContextSetShouldAntialias (context, false);
 
+      if (!NILP (ns_use_thin_smoothing)) {
+          CGContextSetShouldSmoothFonts(context, YES);
+          CGContextSetFontSmoothingStyle(context, 16);
+      }
+
       CGContextSetTextMatrix (context, atfm);
       CGContextSetTextPosition (context, text_position.x, text_position.y);
 
diff --git a/src/nsterm.m b/src/nsterm.m
index 22f8efd6b9..ff3329d1ce 100644
--- a/src/nsterm.m
+++ b/src/nsterm.m
@@ -9133,6 +9133,10 @@ Convert an X font name (XLFD) to an NS font name.
                "Non-nil (the default) means to render text antialiased.");
   ns_antialias_text = Qt;
 
+  DEFVAR_LISP ("ns-use-thin-smoothing", ns_use_thin_smoothing,
+               "Non-nil turns on a font smoothing method that produces thinner strokes.");
+  ns_use_thin_smoothing = Qnil;
+
   DEFVAR_LISP ("ns-confirm-quit", ns_confirm_quit,
                "Whether to confirm application quit using dialog.");
   ns_confirm_quit = Qnil;
-- 
2.11.0 (Apple Git-81)