Re: [PR PATCH] [Updated] fontconfig: fix subpixel rendering in GTK applications

[andry-dev <andry-dev@users.noreply.github.com>]

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There is an updated pull request by andry-dev against master on the void-packages repository

https://github.com/andry-dev/void-packages fontconfig
https://github.com/void-linux/void-packages/pull/23962

fontconfig: fix subpixel rendering in GTK applications
This PR hopefully closes #21429.

The first commit converts the freetype's ClearType patch to a build option; while it is not necessary for the fix, @ericonr suggested it and it seems helpful.

The second commit provides a `fontconfig` configuration file that sets `lcdfilter` to `lcddefault`, fixing the issue.
The config file provides a system-wide default without enforcing it, so the user/desktop environment can override the option in `~/.config/fontconfig/fonts.conf`. This doesn't break existing users: if they set the option anywhere then that is respected, if they didn't then subpixel rendering will work as intended.
Setting `lcdfilter` to `lcdlight` in `fonts.conf` is equivalent to the default "Harmony" engine, so it's the same as not having the patch in the first place.

## Why is this needed anyway?

A year ago I opened #13296, which enables ClearType in `freetype`. When testing it I had `lcdfilter` already set to `lcddefault` in my own `fonts.conf` and I didn't think about setting the option by default system-wide, so I never noticed any regression. Sorry for that.

I wrote the patch because without it I couldn't read text effortlessly, the font wasn't "right" for me. Major distros (Ubuntu, Debian and Fedora from the top of my head) have it enabled by default because, _generally speaking_, font rendering feels better with it.

A patch file from https://github.com/void-linux/void-packages/pull/23962.patch is attached

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From 297a04f3dc33e655832a15dae6adf4000c64707d Mon Sep 17 00:00:00 2001
From: andry-dev <peketribal2@gmail.com>
Date: Thu, 30 Jul 2020 22:24:53 +0000
Subject: [PATCH 1/2] freetype: move ClearType patch to a build option

---
 .../freetype/patches/enable-subpixel-rendering.patch  | 11 -----------
 srcpkgs/freetype/template                             | 11 ++++++++++-
 2 files changed, 10 insertions(+), 12 deletions(-)
 delete mode 100644 srcpkgs/freetype/patches/enable-subpixel-rendering.patch

diff --git a/srcpkgs/freetype/patches/enable-subpixel-rendering.patch b/srcpkgs/freetype/patches/enable-subpixel-rendering.patch
deleted file mode 100644
index 5cba955ca2c..00000000000
--- a/srcpkgs/freetype/patches/enable-subpixel-rendering.patch
+++ /dev/null
@@ -1,11 +0,0 @@
---- include/freetype/config/ftoption.h
-+++ include/freetype/config/ftoption.h
-@@ -126,7 +126,7 @@
-    * macro is not defined, FreeType offers alternative LCD rendering
-    * technology that produces excellent output without LCD filtering.
-    */
--/* #define FT_CONFIG_OPTION_SUBPIXEL_RENDERING */
-+#define FT_CONFIG_OPTION_SUBPIXEL_RENDERING
-
-
-   /**************************************************************************
diff --git a/srcpkgs/freetype/template b/srcpkgs/freetype/template
index f279908c442..d3f072ff201 100644
--- a/srcpkgs/freetype/template
+++ b/srcpkgs/freetype/template
@@ -1,7 +1,7 @@
 # Template file for 'freetype'
 pkgname=freetype
 version=2.10.2
-revision=1
+revision=2
 build_style=gnu-configure
 configure_args="--enable-freetype-config"
 hostmakedepends="pkg-config"
@@ -12,6 +12,15 @@ license="GPL-2.0-or-later, FTL"
 homepage="https://www.freetype.org/"
 distfiles="${NONGNU_SITE}/${pkgname}/${pkgname}-${version}.tar.xz"
 checksum=1543d61025d2e6312e0a1c563652555f17378a204a61e99928c9fcef030a2d8b
+build_options="cleartype"
+desc_option_cleartype="Enable subpixel rendering similar to ClearType"
+build_options_default="cleartype"
+
+post_patch() {
+	if [ "$build_option_cleartype" ]; then
+		vsed -i include/freetype/config/ftoption.h -e 's@/\* #define FT_CONFIG_OPTION_SUBPIXEL_RENDERING \*/@#define FT_CONFIG_OPTION_SUBPIXEL_RENDERING@'
+	fi
+}
 
 post_install() {
 	vlicense docs/LICENSE.TXT docs/FTL.TXT

From 3e6a8e802de53b8bbd320ce3384dc4a88eab0e06 Mon Sep 17 00:00:00 2001
From: andry-dev <peketribal2@gmail.com>
Date: Thu, 30 Jul 2020 22:30:33 +0000
Subject: [PATCH 2/2] fontconfig: set lcdfilter by default

---
 srcpkgs/fontconfig/INSTALL  | 4 ++++
 srcpkgs/fontconfig/template | 2 +-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/srcpkgs/fontconfig/INSTALL b/srcpkgs/fontconfig/INSTALL
index 1daa9b2a8f5..bf97a39b732 100644
--- a/srcpkgs/fontconfig/INSTALL
+++ b/srcpkgs/fontconfig/INSTALL
@@ -5,6 +5,10 @@ case "${ACTION}" in
 pre)
 	;;
 post)
+	if [ "$UPDATE" = "no" ]; then
+		ln -s /usr/share/fontconfig/conf.avail/11-lcdfilter-default.conf /etc/fonts/conf.d/
+	fi
+
 	echo "Building fonts cache... "
 	fc-cache -f >/dev/null
 	echo "done."
diff --git a/srcpkgs/fontconfig/template b/srcpkgs/fontconfig/template
index 18504e4503f..fca09c2c0ba 100644
--- a/srcpkgs/fontconfig/template
+++ b/srcpkgs/fontconfig/template
@@ -1,7 +1,7 @@
 # Template file for 'fontconfig'
 pkgname=fontconfig
 version=2.13.1
-revision=2
+revision=3
 build_style=gnu-configure
 configure_args="--enable-static --enable-docs --with-cache-dir=/var/cache/${pkgname}"
 hostmakedepends="gperf pkg-config"